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Poly-3-hydroxybutyrate (P(3HB)), a member of the polyhydroxyalkanoate (PHA) family, is a biodegradable polyester with diverse industrial applications. NADPH-dependent acetoacetyl-CoA reductase (pha B) is the enzyme which plays an essential role in P(3HB) synthesis by catalyzing the conversion of the intermediates. The expression of pha B enzyme using the recombinant Escherichia coli BL-21(DE3) and the purification of the synthesized enzyme were studied. The pET-B3 plasmid harbouring the pha B gene derived from Ralstonia eutropha H16, was driven by the lac promoter in E. coli BL-21(DE3). The enzyme was expressed with different induction time, temperatures and cell age. Results showed that the cell age of 4 h, induction time of 12 h at 37°C were identified as the optimal conditions for the enzyme reductase expression. A specific activity of 0.151 U mg−1 protein and total protein concentration of 0.518 mg mg−1 of dry cell weight (DCW) were attained. Affinity chromatography was performed to purify the His-tagged pha B enzyme, in which enhanced the specific activity (14.44 U mg−1) and purification fold (38-fold), despite relative low yield (44.6%) of the enzyme was obtained. The purified pha B showed an optimal enzyme activity at 30°C and pH 8.0. The findings provide an alternative for the synthesis of the reductase enzyme which can be used in the industrial-scale production of the biodegradable polymers. • The His-tagged pha B was successfully expressed in recombinant Escherichia coli BL-21(DE3). • Affinity chromatography was applied for the purification of His-tagged pha B enzyme. • Specific activity and purification fold of purified pha B enzyme was notably enhanced. [ABSTRACT FROM AUTHOR]

Fossil-based plastic has become a global-threat due to its high stability and transformation into more lethal forms such as micro plastics with time. An alternative should be found to combat this global enemy. Polyhydroxybutyrate or PHB can be such an alternative to plastic. Present study explores the synthesis of PHB in Neowollea manoromense , using two different cultivation-approaches: acute and chronic stress. This study has used 6 carbon sources and 3 different level of phosphate to study the accumulation of PHB along with lipid, carbohydrate, and proteins. Highest PHB in chronic-stress was achieved under glucose supplementation without phosphate at 21st day (156.5 ± 22.5 μg/mg), whereas in acute-stress, it was achieved under acetate without phosphate (91.0 ± 2.7 μg/mg). Despite higher accumulation in chronic-stress, high PHB productivity was achieved in acute-stress. Principal Component Analysis suggests that all the variables were positively correlated with each other. Here we first report PHB accumulation in Neowollea manoromense. This study highlights that acute-stress can be a powerful tool in establishment of a sustainable cyanobacteria based bio refinery for PHB production. • First report for PHB accumulation in Neowollea manoromense • Acute vs chronic stress study • Effect of mixotrophic growth coupled with phosphate supplementation • 3.7-fold increase in productivity in acute stress • Sustainable approach for cyanobacterial biorefinery [ABSTRACT FROM AUTHOR]

• Composting rates of polyesters differ strongly depending on the individual studies. • Comparison of composting results and times of polyesters is difficult as no standard conditions are used. • There is no particular standard protocol that give the best composting assessment for polyesters. • This article summarises composting data of representative polyesters using different testing protocol. The aerobic composting of biodegradable plastics can be a promising solution to the growing issue of waste accumulation. Therefore, this article offers a review of papers investigating the biodegradability of polyesters (PLA, PHB, PBS and PCL) in home- and industrial composting. Not only the thermal and biodegradation properties are discussed, but also a comparison is made between the different polyesters under the same composting conditions. From this review, it becomes clear that composting shows promise for polyester waste management. However, although several methods for assessing the composting properties of polyester have been developed, the fact that they rarely follow the same standards does not allow for a comparative analysis that would clearly define composting as the most viable solution. [ABSTRACT FROM AUTHOR]

Volatile fatty acids (VFAs) derived from biomass are considered to be economical and environmentally friendly feedstocks for microbial fermentation. Converting VFAs to polyhydroxyalkanoate (PHA) could reduce the substrate cost and provide an economically viable route for the commercialization of PHA. The halophilic bacteria Salinivibrio spp. TGB4 and TGB19, newly isolated from salt fields, were found to accumulate poly-3-hydroxybutyrate (PHB) using acetate or butyrate as the substrate. Both strains exhibited considerable cell growth (OD 600 of ~8) even at acetate concentration of 100 g/L. In shake flask cultures, TGB4 produced PHB titers of 0.90 and 1.34 g/L, while TGB19 produced PHB titers of 0.25 and 2.53 g/L with acetate and butyrate, respectively. When acetate and butyrate were both applied, PHB production was significantly increased, and the PHB titer of TGB4 and TGB19 reached 6.14 and 6.84 g/L, respectively. After optimizing the culture medium, TGB19 produced 8.42 g/L PHB, corresponding to 88.55 wt% of cell dry weight. During fed-batch cultivation, TGB19 produced a PHB titer of 53.23 g/L. This is the highest reported PHB titer using acetate and butyrate by pure microbial cultures and would provide promising hosts for the industrial production of PHA from VFAs. • Salinivibrio spp. TGB4 and TGB19 were newly isolated to produce PHB. • Both strains utilized VFAs but not carbohydrates for PHB production. • The acetate tolerance level was as high as 100 g/L. • The highest PHB titer of 53.23 g/L using VFAs was achieved. [ABSTRACT FROM AUTHOR]

Poly[(R)-3-hydroxybutyrate- co -(R)-3-hydroxyhexanoate] [P(3HB- co -3HHx)] has a high potential to serve as a commercial bioplastic due to its biodegradability, thermoplastic and mechanical properties. The properties of this copolymer are greatly affected by the composition of 3HHx monomer. One of the most efficient ways to modulate the composition of 3HHx monomer in P(3HB- co -3HHx) is by manipulating the (R)-3HHx-CoA monomer supply. In this study, a new (R)-specific enoyl-CoA hydratase originating from a non-PHA producer, Streptomyces sp. strain CFMR 7 (PhaJ S s), was characterized and found to be effective in supplying 3HHx monomer during in vivo production of P(3HB -co- 3HHx) copolymer. The P(3HB- co -3HHx) copolymer produced from the Cupriavidus necator transformant that harbors p haJ Ss , PHB−4/pBBR1- C BP-M-CPF4 J Ss , showed enhanced 3HHx incorporation of up to 11 mol% without affecting the P(3HB- co -3HHx) production when palm oil was used as the carbon source. In addition, both k cat and k cat / K m of PhaJ S s were higher toward the C6 than the shorter C4 substrates, underscoring the preference for 3-hydroxyhexanoyl-CoA. These results suggest that PhaJ S s has a significant ability to supply 3HHx monomers for PHA biosynthesis via β-oxidation and can be applied for metabolic engineering of robust PHA-producing strains. [ABSTRACT FROM AUTHOR]

The pressing problem posed by plastic pollution has led to other, environmentally friendly alternatives, such as polyhydroxyalkanoates. This work proposes an innovative process to produce poly(3-hydroxybutyrate) by replacing expensive substrates, such as sugars, with methane. A two-step process was simulated: a first fermentation is performed in a continuous mode for 20 days to grow a strain belonging to the genus Methylocystis , while a second semi-continuous and nitrogen-limited fermentation is employed to induce the poly(3-hydroxybutyrate) accumulation within 12 days. The effects of the superficial gas velocity on the mass transfer and the poly(3-hydroxybutyrate) production yields were evaluated. Several scenarios were analyzed to optimize the geometry of the reactors and the methane utilization. The working volume of the reactors, as well as the presence of gas recycling stream, were shown to affect the global yields positively, while improving the aspect ratio from 8 to 19, with equal volume, lowered the fraction of poly(3-hydroxybutyrate) into the biomass by up to 37.5%. [Display omitted] • Methane is a valuable substrate for production of PHB. • Improving superficial gas velocity enhanced PHB production yield. • Internal gas recirculation saved methane. • Reactor geometry affected PHB production yield. • To parity of aspect ratio, larger volumes increased PHB production yield. [ABSTRACT FROM AUTHOR]

Halomonas smyrnensis AAD6T is a moderately halophilic bacterium proven to be a powerful biotechnological tool with its ability to accumulate valuable biopolymers such as levan and poly(3-hydroxybutyrate) (PHB). Levan is a fructose homopolymer with β-2,6 fructofuranosidic linkages on the polymer backbone, and its distinctive applications in various industries such as food, pharmaceutical, medical, and chemical have been well-defined. On the other hand, PHB is a promising raw material to produce biodegradable plastics. Although it was shown in our previous studies that H. smyrnensis AAD6T exhibits one of the highest conversion yields of sucrose to levan reported to date, novel strategies are required to overcome high costs of levan production. In this study, we aimed at increasing levan productivity of H. smyrnensis AAD6T cultures using random mutagenesis techniques combined (i.e., ethyl methanesulfate treatment and/or ultraviolet irradiation). After several consecutive treatments, mutant strains BAE2, BAE5 and BAE6 were selected as efficient levan producers, as BAE2 standing out as the most efficient one not only in sucrose utilization and levan production rates, but also in final PHB concentrations. The mutants' whole genome sequences were analysed to determine the mutations occurred. Several mutations in genes related to central carbon metabolism and osmoregulation were found. Our results suggest that random mutagenesis can be a facile and efficient strategy to enhance the performance of extremophiles in adverse conditions. • Random mutagenesis can be a facile and efficient strategy to enhance the performance of extremophiles in adverse conditions. • An improved levan producer Halomonas strain is obtained, characterized and described. • Sucrose utilization and levan production rates, as well as final PHB yields were enhanced. [ABSTRACT FROM AUTHOR]

The intracellular nature of microbial polyhydroxyalkanoates (PHAs) requires two main steps in their production: bioconversion and extraction. The most widely used method for recovering poly(3-hydroxybutyrate) (PHB) is solvent extraction. Traditional approaches involve the use of halogenated solvents, whose environmental and health hazards are well known. New alternatives advocate the use of sustainable agents, which can be an effective and economical choice. In this work, the bioconversion process of starch-based water into PHB by Cupriavidus necator DSM 545 was first scaled-up using previously optimized conditions. A statistical model was then developed to optimize the best conditions for polymer extraction using NaOH by response surface methodology with a central composite design. The optimized and validated conditions were: 0.05 M NaOH at 29.6 °C for 1 h, resulting in 87.31 ± 0.33 % polymer yield, 104.13 ± 2.22 % polymer purity and 104.76 ± 2.41 % polymer recovery. These conditions were validated for operation at three different biomass-to-NaOH concentrations: 5.7 g/L, 20 g/L and 79.5 g/L, and scaled-up without sacrificing polymer yield, with high levels of PHB purity and recovery. In addition, this work proposed an approach for the scale-up of a halogen-free process for PHB extraction using NaOH, considering parameters that can be easily integrated into the common ranges used in the industry. [Display omitted] • PHB production by Cupriavidus necator DSM 545 using potato wastewater is scaled. • NaOH solution could be a sustainable and cost-effective method for PHA extraction. • PHB extraction is performed using the lowest concentration of the halogen-free agent. • Optimal conditions for PHB extraction are 0.05 M NaOH at 29.6 °C for 1 h. • NaOH extraction yields a polymer with a purity of over 99%. [ABSTRACT FROM AUTHOR]

Paclitaxel (PTX) is a potent anticancer drug. However, PTX exhibits extremely poor solubility in aqueous solution along with severe side effects. Therefore, in this study, an inclusion complex was prepared between PTX and hydroxypropyl-β-cyclodextrin (HPβCD) by solvent evaporation to enhance the drug's solubility. The HPβCD-PTX inclusion complex was then encapsulated in poly-3-hydroxybutyrate (PHB) to fabricate drug-loaded nanoparticles (HPβCD-PTX/PHB NPs) by nanoprecipitation. The HPβCD-PTX/PHB NPs depicted a higher release of PTX at pH 5.5 thus demonstrating a pH-dependent release profile. The cytotoxic properties of HPβCD-PTX/PHB NPs were tested against MCF-7, MDA-MB-231 and SW-620 cell lines. The cytotoxic potential of HPβCD-PTX/PHB NPs was 2.59-fold improved in MCF-7 cells in comparison to free PTX. Additionally, the HPβCD-PTX/PHB NPs improved the antimitotic (1.68-fold) and apoptotic (8.45-fold) effects of PTX in MCF-7 cells in comparison to PTX alone. In summary, these pH-responsive nanoparticles could be prospective carriers for enhancing the cytotoxic properties of PTX for the treatment of breast cancer. [ABSTRACT FROM AUTHOR]

This study ventures into the exploration of potential poly-3-hydroxybutyrate (PHB) degradation in alpine environments. PHB-degrading bacteria were identified in both campus soil, representing a residential area, and Mt. Kurodake soil, an alpine region in Hokkaido, Japan. Next-generation sequencing analysis indicated that the campus soil exhibited higher microbial diversity, while Ralstonia insidiosa C1, isolated from Mt. Kurodake soil, displayed the highest proficiency in PHB degradation. R. insidiosa C1 efficiently degraded up to 3% (w/v) of PHB and various films composed of other biopolymers at 14 °C. This bacterium synthesized homopolymers using substrates such as 3-hydroxybutyric acid, sugars, and acetic acid, while also produced copolymers using a mixture of fatty acids. The analysis results confirmed that the biopolymer synthesized by strain C1 using glucose was PHB, with physical properties comparable to commercial products. The unique capabilities of R. insidiosa C1, encompassing both the production and degradation of bioplastics, highlight its potential to establish a novel material circulation model. [Display omitted] • Soil samples from the alpine area were used for PHB degradation. • Ralstonia insidiosa from Mt. Kurodake soil had the highest PHB degradation ability. • The strain degraded PHB film and other polymer films. • The strain produced PHB and P(3HB-co-3HV) using 3-HB, sugars, and fatty acids. • Thermal and physical properties of PHB were evaluated using analytical methods. [ABSTRACT FROM AUTHOR]

Dental implant success is threatened by peri-implantitis, an inflammation leading to implant failure. Conventional treatments struggle with the intricate microbial and host factors involved. Antibacterial membranes, acting as barriers and delivering antimicrobials, may offer a promising solution. Thus, this study highlights the potential of developing antibacterial membranes of poly-3-hydroxybutyrate and silver nanoparticles (Ag Nps) to address peri-implantitis challenges, discussing design and efficacy against potential pathogens. Electrospun membranes composed of PHB microfibers and Ag Nps were synthesized in a blend of DMF/chloroform at three different concentrations. Various studies were conducted on the characterization and antimicrobial activity of the membranes. The synthesized Ag Nps ranged from 4 to 8 nm in size. Furthermore, Young's modulus decreased, reducing from 13.308 MPa in PHB membranes without Ag Nps to 0.983 MPa in PHB membranes containing higher concentrations of Ag Nps. This demonstrates that adding Ag Nps results in a less stiff membrane. An increase in elongation at break was noted with the rise in Ag Nps concentration, from 23.597 % in PHB membranes to 60.136 % in PHB membranes loaded with Ag Nps. The antibiotic and antibiofilm activity of the membranes were evaluated against Pseudomonas aeruginosa , Staphylococcus aureus , Streptococcus mutans , and Candida albicans. The results indicated that all PHB membranes containing Ag Nps exhibited potent antibacterial activity by inhibiting the growth of biofilms and planktonic bacteria. However, inhibition of C. albicans occurred only with the PHB-Ag Nps C membrane. These findings emphasize the versatility and potential of Ag Nps-incorporated membranes as a multifunctional approach for preventing and addressing microbial infections associated with peri-implantitis. The combination of antibacterial and antibiofilm properties in these membranes holds promise for improving the management and treatment of peri-implantitis-related complications. • The study involved synthesizing silver nanoparticles (Ag Nps) into the Poly-3-hydroxybutyrate (PHB) solution. • PHB solution containing silver nanoparticles was electrospun to develop scaffolds for tissue regeneration. • The antimicrobial activity of the PHB/Ag Nps scaffolds was evaluated over four different microorganisms. • The scaffolds loaded with Ag Nps showed a strong antibacterial activity over the different strains evaluated • Notably, inhibiting the growth of C. albicans required higher concentrations of Ag Nps loaded in scaffolds than the bacteria. [ABSTRACT FROM AUTHOR]

A middle ear infection occurs due to the presence of several microorganisms behind the eardrum (tympanic membrane) and is very challenging to treat due to its unique location and requires a well-designed treatment. If not treated properly, the infection can result in severe symptoms and unavoidable side effects. In this study, excellent biocompatible ethyl cellulose (EC) and biodegradable polyhydroxybutyrate (PHB) biopolymer were used to fabricate drug-loaded nanofiber scaffolds using an electrospinning technique to overcome antibiotic overdose and insufficient efficacy of drug release during treatment. PHB polymer was produced from Halomonas sp., and the purity of PHB was found to around be 90 %. Additionally, ciprofloxacin (CIP) and amoxicillin (AMX) are highly preferable since both drugs are highly effective against gram-negative and gram-positive bacteria to treat several infections. Obtained smooth nanofibers were between 116.24 and 171.82 nm in diameter and the addition of PHB polymer and antibiotics improved the morphology of the nanofiber scaffolds. Thermal properties of the nanofiber scaffolds were tested and the highest T g temperature resulted at 229 °C. The mechanical properties of the scaffolds were tested, and the highest tensile strength resulted in 4.65 ± 6.33 MPa. Also, drug-loaded scaffolds were treated against the most common microorganisms that cause the infection, such as S.aureus, E.coli, and P.aeruginosa, and resulted in inhibition zones between 10 and 21 mm. MTT assay was performed by culturing human adipose-derived mesenchymal stem cells (hAD MSCs) on the scaffolds. The morphology of the hAD MSCs' attachment was tested with SEM analysis and hAD MSCs were able to attach, spread, and live on each scaffold even on the day of 7. The cumulative drug release kinetics of CIP and AMX from drug-loaded scaffolds were analysed in phosphate-buffered saline (pH: 7.4) within different time intervals of up to 14 days using a UV spectrophotometer. Furthermore, the drug release showed that the First-Order and Korsmeyer-Peppas models were the most suitable kinetic models. Animal testing was performed on SD rats, matrix and collagen deposition occurred on days 5 and 10, which were observed using Hematoxylin-eosin and Masson's trichrome staining. At the highest drug concentration, a better repair effect was observed. Results were promising and showed potential for novel treatment. [ABSTRACT FROM AUTHOR]

In this chapter, N and S co-doped mesh porous carbon materials (NSC) were prepared using freeze-drying assisted high-temperature carbonization, where sodium polyacrylate was used as the carbon source and sodium thiosulfate (Na 2 S 2 O 3) and sodium nitrate (NaNO 3) is the sulfur and nitrogen sources, respectively. Its unique layered porosity and the ability to dope sulfur atoms up to 5.9 % allows for the introduction of more defect sites and expanded interlayer spatial interactions, achieving impressive electrochemical properties. Enlightened by the properties of N/S double doping and high pore defects, NSC anodes exhibit a high storage of K+ (441.6 mA h/g at 0.05 A/g) and superior rate performance. The density functional theory (DFT) and electrochemical experimental investigation showed the N/S dual doping can successfully modify the electronic structure and improve the capacity of adsorbing K+. Significantly, the assembled dual-carbon PIHC can deliver an impressive energy density of 141.2 Wh kg−1 at a power density of 400 W kg−1 and a satisfactory cycle life when using the NSC-700 porous carbon as the cathode, which can light the "CUMT" pattern, sheding new light on creating improved carbon materials for using in practical applications. [Display omitted] • N and S co-doped mesh carbon materials were prepared for K-ion hybrid capacitors. • High specific surface area and S-rich carbon is designed with a sulfur content of 5.9 %. • The K+ storage mechanism was deeply studied by electrochemical and DFT calculations. • The dual-doped carbon employed in PIHC exhibits an energy density of 141.2 Wh kg-1. The primary research challenge concerning K-ion batteries revolves around ensuring their optimal cycle stability and specific capacity, particularly the inherent sluggish kinetics induced by the relatively large radius of K+. In this study, we report a pore-size controllable synthetic approach employing salt-template precursors. Herein, nitrogen and sulfur co-doped porous carbon materials with rich carbon defect engineering was synthesized through the salt template method, where the doped heteroatoms can both offer a lot of carbon defect content and redox active sites that are helpful for enhancing potassium ion storage kinetics. As a result, the electrode with abundant doping atom content realizes a good capacity and long cycle lifespan (274.8 mA h g−1 after 200 cycles at 0.05 A/g). Inspiringly, PIHCs assembled by N/S co-doped carbon anode exhibit excellent cycling stability (93.4 % capacity retention for 1000 cycles) and a high energy density of 141.2 Wh kg−1 and a power density of 1.6 kW kg−1. Importantly, the density functional theory calculation combining electrochemical kinetic analysis further demonstrates that role of N and S doping plays dominant roles in total storage mechanism. This work gives a deep insight about the roles of external defects in doping carbon materials for potassium storage. [ABSTRACT FROM AUTHOR]

Polyhydroxyalkanoates (PHAs) are promising alternatives to existing petrochemical-based plastics because of their bio-degradable properties. However, the limited structural diversity of PHAs has hindered their application. In this study, high mole-fractions of Poly (39 mol% 3HB- co -17 mol% 3 HV- co -44 mol% 4 HV) and Poly (25 mol% 3HB- co -75 mol% 5 HV) were produced from 4- hydroxyvaleric acid and 5-hydroxyvaleric acid, using Cupriavidus necator PHB−4 harboring the gene phaC BP-M-CPF4 with modified sequences. In addition, the complex toxicity of precursor mixtures was tested, and it was confirmed that the engineered C. necator was capable of synthesizing Poly (32 mol% 3HB- co -11 mol% 3 HV- co -25 mol% 4 HV- co -32 mol% 5 HV) at low mixture concentrations. Correlation analyses of the precursor ratio and the monomeric mole fractions indicated that each mole fractions could be precisely controlled using the precursor proportion. Physical property analysis confirmed that Poly (3HB- co -3 HV- co -4 HV) is a rubber-like amorphous polymer and Poly (3HB- co -5 HV) has a high tensile strength and elongation at break. Poly (3HB- co -3 HV- co -4 HV- co -5 HV) had a much lower glass transition temperature than the co-, terpolymers containing 3 HV, 4 HV and 5 HV. This study expands the range of possible physical properties of PHAs and contributes to the realization of custom PHA production by suggesting a method for producing PHAs with various physical properties through mole-fraction control of 3 HV, 4 HV and 5 HV. [ABSTRACT FROM AUTHOR]

This study investigates the effects of SCG embedded into biodegradable polymer blends and aimed to formulate and characterise biomass-reinforced biocomposites using spent coffee ground (SCG) as reinforcement in PHB/PLA polymer blend. The effect of SCG filler loading and varying PHB/PLA ratios on the tensile properties and morphological characteristics of the biocomposites were examined. The results indicated that tensile properties reduction could be due to its incompatibility with the PHB/PLA matrixSCG aggregation at 40 wt% content resulted in higher void formation compared to lower content at 10 wt%. A PHB/PLA ratio of 50/50 with SCG loading 20 wt% was chosen for biocomposites with treated SCG. Biological treatment of SCG using Phanerochaete chrysosporium CK01 and Aspergillus niger DWA8 indicated P. chrysosporium CK01 necessitated a higher moisture content for optimum growth and enzyme production, whereas the optimal conditions for enzyme production (50–55 %, w /w) differed from those promoting A. niger DWA8 growth (40 %, w/w). SEM micrographs highlighted uniform distribution and effective wetting of treated SCG, resulting in improvements of tensile strength and modulus of biocomposites, respectively. The study demonstrated the effectiveness of sustainable fungal treatment in enhancing the interfacial adhesion between treated SCG and the PHB/PLA matrix. • Excessive SCG content induced agglomeration and decreased tensile properties. • High PLA content contributed to higher tensile strength and modulus in biocomposites. • Biological treatment removed non-cellulosic components and impurities from the SCG surface. [ABSTRACT FROM AUTHOR]

• FA was grafted on PHB and PHBV to fabricate FA/PHB and FA/PHBV. • EPI was encapsulated in FA/PHB and FA/PHBV to produce drug-loaded nanoparticles. • Drug-loaded nanoparticles depicted pH-responsive sustained release of EPI. • Drug-loaded nanoparticles demonstrated time- and dose-dependent toxicity in MCF-7 cells. • Drug-loaded nanoparticles displayed enhanced cellular uptake and apoptosis. Polymeric nanoparticles coated with ligand molecules demonstrated great potential in targeted delivery of drug molecules to cancer cells. In this study, poly(3-hydroxybutyrate) (PHB) and poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) were functionalized separately with folic acid (FA) to obtain FA/PHB and FA/PHBV, respectively. Subsequently, FA/PHB and FA/PHBV along with polyethylene glycol (PEG) were used for encapsulation of EPI to prepare the FA/PEG@EPI-PHB and FA/PEG@EPI-PHBV (drug-loaded) nanoparticles, respectively. Blank FA/PEG-PHB and FA/PEG-PHBV nanoparticles were also prepared. The FA/PEG@EPI-PHB nanoparticles (57±2.45 %) showed higher EPI loading as compared to FA/PEG@EPI-PHBV nanoparticles (43.16±1.35 %). A sustained release of EPI (65.70±5.10 %) was evident from FA/PEG@EPI-PHB nanoparticles at pH 5.5 for 28 h, thus following the Korsmeyer–Peppas mechanism. Enzymatic degradation of FA/PEG@EPI-PHB and FA/PEG@EPI-PHBV nanoparticles was carried out using lipases. The in-vitro cytotoxicity of FA/PEG@EPI-PHB and FA/PEG@EPI-PHBV nanoparticles was evaluated in the MCF-7 cell line. Blank nanoparticles did not inhibit the proliferation of the MCF-7 cell lines due to their non-toxicity and biocompatibility. The FA/PEG@EPI-PHB nanoparticles depicted 6.39-fold higher cytotoxicity in the MCF-7 cell line as compared to a similar quantity of free EPI. Additionally, cellular uptake and apoptotic behavior of FA/PEG@EPI-PHB nanoparticles were checked in the MCF-7 cell line. Thus, the FA/PEG-PHB targeted delivery system could be an efficient carrier for the sustained release of hydrophilic drug molecules to selectively kill a high proportion of tumor cells. [Display omitted] [ABSTRACT FROM AUTHOR]

Raman imaging in the low- and high-frequency regions accomplished visualization the intermolecular interaction and crystallization of polymer blend. [Display omitted] • Low-frequency Raman observed the intermolecular interactions during the phase separation and crystallization of PHB/PLLA. • The changes in the intermolecular interaction of PHB/PLLA were visualized by Raman imaging using the hydrogen bonding of PHB. • The low-frequency Raman spectra show high sensitivity in detection at the start of phase separation and crystallization. The visualization of the variation of the inter/intra molecular interaction (C = O⋯CH 3) between poly[(R)-3-hydroxybutyrate] (PHB) and poly-L-lactic acid (PLLA) in the PHB/PLLA miscible blend during phase separation and crystallization process was successfully investigated using Raman imaging. Images of the blend were developed using high- and low-frequency Raman spectra acquired during the isothermal crystallization of the blend, and both of them were compared. The low-frequency region allowed to observe the changes in the hydrogen bonds between the molecular chains in the blend during phase separation and crystallization via a band at 75 cm−1 derived from PHB. The imaging results obtained using the band at 75 cm−1 due to hydrogen bonding (C = O⋯CH 3) between molecular chains were in good agreement with the results obtained using the C = O stretching band at 1720 cm−1. Herein, we demonstrated that the low-frequency region of the Raman spectrum is more sensitive to detecting the start of the phase separation and crystallization of PHB than the corresponding high-frequency region. [ABSTRACT FROM AUTHOR]

• Two potential natural PHB producers were identified from 74 isolates using Sudan black B, Nile red, and Nile blue a staining methods. • The optimization of various parameters such as carbon and nitrogen sources, pH, temperature, and incubation period enhanced the PHB production. • Seaweed hydrolysate is used as a substrate for the effective production of PHB using the novel bacterial isolates. • The PHB produced by the strains NAA2 and NAA4 were characterized using FTIR and FE-SEM-EDX analysis. Poly-(3-hydroxybutyrate) (PHB), is a partially crystalline polymer naturally synthesized by microorganisms, and the production of PHB has attracted much attention recently due to its exceptional biodegradable and biocompatible nature. By serving as a copolymer and by being a block copolymer, PHB enhances the mechanical properties of the polymer materials. The materials developed using PHB as a block copolymer are used in numerous applications such as polymer aging resistance, controlled drug delivery, cardiovascular engineering, thin film formation, etc. This study focuses on synthesizing PHB from microbial sources as cell factories. From distinct natural sources two novel bacterial isolates, Bacillus pacificus NAA2 (NAA2) and Klebsiella quasipneumonia NAA4 (NAA4) were screened based on their high PHB synthesizing abilities. To improve the PHB levels, a series of process optimization studies were conducted. The process conditions such as different carbon and nitrogen sources, concentrations, pH levels, temperatures, and incubation periods have been explored and optimized. Under optimized conditions, NAA2 produced 2.92 g/L of PHB (79 %) with glycerol and peptone as carbon and nitrogen sources respectively at pH 7.5 and 35 °C at 48 h. The other isolate, NAA4, produced 2.89 g/L of PHB (73 %) from xylose and urea as equivalent carbon and nitrogen sources respectively with the same pH and temperature after 36 h of incubation. In addition, the replacement of conventional carbohydrates (glucose and/or xylose) with seaweed hydrolysate exhibited almost equivalent levels of PHB 72.7 and 70.7 % of PHB in NAA2 and NAA4 respectively. Fourier Transform Infrared (FTIR) spectroscopy and FE-SEM analysis confirmed the production of a polymer. Though there are several studies reported with other Bacillus sp and Klebsiella sp., this is the only study that used novel strains Bacillus pacificus (NAA2) and Klebsiella quasipneumonia (NAA4) as the microbial cell factories for the effective synthesis of PHB using seaweed as a substrate. Thus, the technology for bioconversion of harmful and waste seaweed biomass into PHB with dual sustainability was developed. [Display omitted] [ABSTRACT FROM AUTHOR]

As an energy-storage substance of microorganisms, polyhydroxybutyrate (PHB) is a promising alternative to petrochemical polymers. Under appropriate fermentation conditions, PHB-producing strains with metabolic diversity can efficiently synthesize PHB using various carbon sources. Carbon-rich wastes may serve as alternatives to pure sugar substrates to reduce the cost of PHB production. Genetic engineering strategies can further improve the efficiency of substrate assimilation and PHB synthesis. In the downstream link, PHB recycling strategies based on green chemistry concepts can replace PHB extraction using chlorinated solvents to enhance the economics of PHB production and reduce the potential risks of environmental pollution and health damage. To avoid carbon loss caused by biodegradation in the traditional sense, various strategies have been developed to degrade PHB waste into monomers. These monomers can serve as platform chemicals to synthesize other functional compounds or as substrates for PHB reproduction. The sustainable potential and cycling value of PHB are thus reflected. This review summarized the recent progress of strains, substrates, and fermentation approaches for microbial PHB production. Analyses of available strategies for sustainable PHB recycling were also included. Furthermore, it discussed feasible pathways for PHB waste valorization. These contents may provide insights for constructing PHB-based comprehensive biorefinery systems. • PHB-producing strains each have their advantages due to different characteristics. • Various carbon-rich wastes are available for PHB production. • "Green" solvents and mild cell lysis agents enable sustainable PHB recycling. • Chemical and enzymatic treatments degrade PHB into platform monomers instead of CO 2. • PHB-derived products can be used for PHB reproduction and recovery. [ABSTRACT FROM AUTHOR]

We report the synthesis of a novel electrochemical biosensor comprising of cupric oxide (CuO) nanoparticles (NPs) mediated poly(hydroxybutyrate) (PHB) composite film with polyvinyl alcohol (PVA) as a binder/template support using the solution casting method for the detection of a biomolecule i.e., ascorbic acid (AA). The specimens were characterized for surface, chemical, mechanical, optical, and electrochemical attributes. The results expressed regular mediation of CuO NPs in the PHB/PVA matrix towards nanobiocomposite formation with enhanced crystallinity, inter-molecular interactions, mechanical, and electrochemical attributes, and decreased hydrophilicity and bandgap, thus being useful in potential optoelectronic devices. The synthesized biocomposite film exhibited a tensile strength of 86.24 ± 4.10 N which might be due to reinforcement/uniform dispersion of the CuO nanofiller in the PHB-based matrix. The PHB/CuO composite, then, deposited on a glassy carbon electrode surface exhibited good electrocatalytic activity towards the AA in the aqueous media even at low analyte concentrations. Such modified electrode surfaces with metal/biopolymer complex could find possible applications in the detection of other bioactive molecules. • We present the synthesis of CuO nanoparticles (NPs) mediation in poly(hydroxybutyrate) (PHB)-based composite. • The nanocomposite films were thermally stable and less hydrophilic as compared to the control. • The nanobiocomposite was deposited on a glassy carbon electrode for biosensing application. • Such modified electrode surfaces may find potential applications in the detection of bioactive molecules. [ABSTRACT FROM AUTHOR]

The parameters used in the preparation of polymeric nanoparticles can influence its ability to photooxidate biomolecules. This work evaluated the effects of four parameter to prepare Poly(3-hydroxybutyrate) (PHB) nanoparticle loaded with aluminum and indium phthalocyanine (AlPc and InPc), together with iron oxide nanoparticles, assessing their influence on the size, the entrapment efficiency, and the nanoparticles recovery efficacy. The capability of free, and encapsulated, AlPc and InPc in photooxidating the bovine serum albumin (BSA) and tryptophan (Trp) was monitored by fluorescence. The AlPc-loaded nanoparticles had a larger size and a greater entrapment efficiency than that obtained by InPc-loaded nanoparticles. The free InPc was more efficient than the free AlPc to photooxidize the BSA and Trp; whereas the encapsulated AlPc was more efficient than encapsulated InPc to photooxidize the biomolecules. The higher hydrophobicity of the AlPc, combined with the greater aggregation state and the major interaction with the BSA, quenching the capacity of the free AlPc to photooxidate the biomolecules; whereas the greater interaction of the AlPc with PHB reduce the aggregation effect on the free molecules in the aqueous phase and increase the entrapment efficiency, resulting in an improving of the photodynamic efficiency and an increase of the photooxidation rate constant. • The change of Al by In on the phthalocyanine structure influenced the PHB nanoparticle size and entrapment efficiency • The stronger interaction of the phthalocyanine with the PHB favors a better entrapment efficiency • A stronger interaction between BSA and the free AlPc hamper the generation of the singlet oxygen • The lower interaction strength of the InPc with the PHB favored its aggregation into the nanoparticulate matrix • Only the encapsulation of a photosensitizer does not always improve its efficiency in photooxidizing biomolecules [ABSTRACT FROM AUTHOR]

Poly (3-hydroxybutyrate) (PHB) is a valuable bio-based and biodegradable polymer that may substitute common polymers in packaging and biomedical applications provided that the production cost is reduced and some properties improved. Blending PHB with other biodegradable polymers is the most simple and accessible route to reduce costs and to improve properties. This review provides a comprehensive overview on the preparation, properties and application of the PHB blends with other biodegradable polyesters such as medium-chain-length polyhydroxyalkanoates, poly(ε-caprolactone), poly(lactic acid), poly(butylene succinate), poly(propylene carbonate) and poly (butylene adipate- co -terephthalate) or polysaccharides and their derivatives. A special attention has been paid to the miscibility of PHB with these polymers and the compatibilizing methods used to improve the dispersion and interface. The changes in the PHB morphology, thermal, mechanical and barrier properties induced by the second polymer have been critically analyzed in view of industrial application. The biodegradability and recyclability strategies of the PHB blends were summarized along with the processing techniques adapted to the intended application. This review provides the tools for a better understanding of the relation between the micro/nanostructure of PHB blends and their properties for the further development of PHB blends as solutions for biodegradable packaging. [ABSTRACT FROM AUTHOR]

Polyhydroxybutyrate (PHB) is a non-toxic polyhydroxyalkanoate polymer produced by several microorganisms, widely used as a biological substitute for plastics derived from fossil hydrocarbons. In this work, PHB polymer has been tested in an animal model for colorectal cancer. In the animal model, PHB has been able to reduce the number of polyps by 48,1%, and the tumoral extension area by 58,1%. Also, PHB induces a selective increase in beneficial gut bacterial taxons in this animal model, and a selective reduction in pro-inflammatory taxons, demonstrating its value as a nutraceutical compound. This antitumor effect is caused by gut production of 3-hydroxybutyrate and butyrate. In this animal model, 3-hydroxybutyrate is also observed in plasma and in brain tissue, after PHB consumption, making PHB supplementation interesting as a bioactive compound in other extraintestinal conditions, as 3-hydroxybutyrate has been reported to enhance brain and cognitive function, cardiac performance, appetite suppression and diabetes. Therefore, PHB could be postulated as an interesting non-polysaccharide antitumor prebiotic, paving the way towards its future use in functional foods. [ABSTRACT FROM AUTHOR]

Polyhydroxyalkanoates (PHAs) and their derivatives are biopolymers that have the potential of replacing petroleum-based plastics and can be produced and degraded via bacterial metabolism. However, there are only a few studies on polyhydroxybutyrate (PHB) production using lactate, one of the major waste organic acids that could be implemented in the production of polylactic acid (PLA). Herein, we screened and characterized the PHA-producing microbial strains isolated from saltern soil from Docho Island (South Korea). Among the 24 identified microorganisms that can use lactate as a carbon source, Bacillus sp. YHY22, a newly reported strain, produced the highest amount of PHB: 4.05 g/L with 6.25 g/L dry cell weight, which is 64.7% PHB content under optimal production conditions. Bacillus sp. YHY22 could form the poly(3-hydroxybutyrate- co -3-hydroxyvalerate) copolymer with propionate addition. Moreover, Bacillus sp. YHY22 produced PHB in non-sterilized 2% lactate and 8% NaCl marine broth culture medium, suggesting that its production can occur in high salinity media without additional sterilization steps, rendering fermentation cost- and time-efficient. [ABSTRACT FROM AUTHOR]

In this work, the use of potato fruit juice (PFJ) in combination with poly(3-hydroxybutyrate) (PHB) was explored as a biobased barrier coating on paperboard. A two-layer and three-layer solution were explored. In the two-layer structure, the PFJ layer was rod-coated on pigment-coated paperboard, followed by extrusion coating of PHB on top. In the three-layered coating, paperboard without pigment coating was extrusion-coated with PHB, followed by rod coating of PFJ, and finally, extrusion-coated with PHB. The specific water vapour transmission rate was reduced by approximately 95 % and 90 % for the two- and three-layer coatings, respectively, relative to the uncoated paperboard. Besides contributing to barrier properties, the PFJ increased the bonding strength between the PHB and the paperboard. Although the three-layer coated paperboards showed better oxygen barrier properties than the two-layered coatings, the oxygen permeability was still high. Three-layer coatings exhibited moderate peeling strength, and better creasing and grease barrier properties compared to two-layered coated paperboards. [Display omitted] [ABSTRACT FROM AUTHOR]

Cynara cardunculus , cardoon, is a biorefinery crop with an overwhelming role in the bioplastic scenario. This work explored the use of inulin extracted from cardoon roots as a feedstock for polyhydroxyalkanoates (PHA) production. Cardoon roots from both spring and winter seasons were subjected to two protocols consisting of an autoclave extraction followed by i) an ethanol precipitation and further lyophilization or ii) lyophilization directly. The resulting extracts were characterized for recovery yield (from 11.6 to 16 g of inulin per 100 g of roots), purity grade (from 64% to 97%) and molecular weight distribution, the latter being affected by both seasonal variability and the extraction method. The performances of two PHA producers, Cupriavidus necator and Burkholderia cepacia , were compared in Simultaneous Saccharification and Fermentation of spring inulin extracts obtained with the two protocols, exploring the effect of controlled addition of fungal inulinase PlaI. Up to 2 g/L of polyhydoxybutyrate (PHB) polymer was produced in the best feeding condition, with both strains found able to metabolize the main phenolic acids coextracted with inulin. Diversity in polymer yields were observed, with evidence of the synthesis of PHB polymers characterized by different molecular weight distributions depending on the type of feeding and microorganism employed. The proposed processes are placed in the frame of the circular economy approaches applied to the valorization of cardoon biomass in the bioplastic field. [Display omitted] • Roots of Cynara cardunculus proved to be a valid source of high purity inulin. • Inulin varied in molecular weight distributions according to harvest seasons. • Polyhydroxyalkanoates were obtained from inulin saccharification and fermentation. • Efficient feeding strategies were defined for C. necator and B. cepacia strains. • Polyhydroxyalkanoates properties varied in relation to strains and feedings. [ABSTRACT FROM AUTHOR]

[Display omitted] • Methanotrophs concurrently incorporated CH 4 and CO 2 into polyhydroxybutyrate. • CO 2 supplement enhanced polyhydroxybutyrate production in methanotrophs. • More than 40 % of PHB was come from CO 2. Methane (CH 4) and carbon dioxide (CO 2) are the dominant greenhouse gases (GHGs) that are increasing at an alarming rate. Methanotrophs have emerged as potential CH 4 and CO 2 biorefineries. This study demonstrated the synchronous incorporation of CH 4 and CO 2 into polyhydroxybutyrate (PHB) for the first time using 13C-labeling experiments in methanotrophs. By supplying substantial amounts of CO 2 , PHB content was enhanced in all investigated type II methanotrophic strains by 140 %, 146 %, and 162 %. The highest content of PHB from CH 4 and CO 2 in flask-scale cultivation reached 38 % dry cell weight in Methylocystis sp. MJC1, in which carbon percentage in PHB from CO 2 was 45 %. Flux balance analysis predicted the critical roles of crotonyl-CoA carboxylase/reductase and phosphoenolpyruvate carboxylase in CO 2 recycling. This study provided proof of the conversion of GHGs into a valuable and practical product using methanotrophic bacteria, contributing to addressing GHG emissions. [ABSTRACT FROM AUTHOR]

[Display omitted] • Sustainable and eco-friendly method for synthesizing castor oil-based fillers is explored. • The castor oil-based fillers exhibit promising properties for toughening PHB. • The resultant PHB composites have improved mechanical properties. • Fibrillation and shear yielding are the proposed toughening mechanisms for the resultant PHB composites. Poly(3-hydroxybutyrate) (PHB) faces a significant challenge of intrinsic brittleness, thus limiting its widespread applicability. This challenge can be surmounted by incorporating various nanofillers into the PHB matrix to tune the mechanical performance. However, many of these fillers are produced using unsustainable, non-environmentally friendly methods. Herein, we employed a green process to develop castor-oil-based fillers, CO- g -DLA, and CO-P(CL- co -DLA)-PDLA (CO- r -DLA), for the toughening of the PHB matrix. Impressively, the addition of 20% of these fillers increases the elongation at the break by 13-fold through forming elongated fibril structures and enhanced interfacial interactions between fillers and the matrix, accompanying by a substantial reduction on the PHB's brittleness through shear yielding and fibrillation. These are confirmed by Small-Angle X-ray Scattering (SAXS) results, showing significant copolymer-induced microstructural changes in the matrix. The biodegradable PHB biocomposite developed in this study offers a promising green alternative to conventional plastics, especially in sustainable packaging. [ABSTRACT FROM AUTHOR]

• Portable SPME-PSS coupled with UV–Vis spectrometry for methylene blue determination. • CCD was applied to optimize the different variables used in the P- SPME-PS system. • The values of G° −3.709 and H° 4.4039 designate an endothermic adsorption process. • And about 169 mg/g monolayer adsorption capacity was determined. A novel material based on Poly (3-hydroxy butyrate)-Polyricinoleic acid-Ag nanocomposite (PHB-AgPrici) is prepared and used for removing methyl blue (MB) from water. Solid phase micro-extraction (SPME) in portable syringe systems was established in this work. Silver nanoparticles were induced from AgNO 3 in ricinoleic acid under atmospheric autoxidation conditions at room temperature leading to peroxidized polyricinoleic acid (AgPrici). Methacrylate poly (3-hydroxy butyrate) (PHB-MA) was reacted with AgPrici to obtain PHB-poly ricinoleic acid containing silver nanoparticles (PHB-AgPrici). The obtained nanocomposite was characterized using 1H NMR, SEM-EDX, DSC, and FT-IR. Using studies of isotherms, kinetics, and thermodynamics, the adsorption mechanisms of MB over PHB-AgPrici were examined. About 169 mg/g maximum monolayer adsorption capacity was determined and the percentage efficiency was reached to 99.5 %. Moreover, the percentage recovery was recorded at 99.0 % for wastewater and 99.5 % in drinking water which reached 99.7 % in river water. The values of G° −3.709 KJ mol−1 and H° 4.4039 KJ mol−1 designate an endothermic adsorption process. The obtained results indicated that the prepared material is very promising to be used to remove pollutants from industrial wastewater. [ABSTRACT FROM AUTHOR]

Gas-transfer membranes have been successfully deployed as efficient aeration devices in wastewater treatment. There is an increasing interest in using such membrane technology in industrial biotechnology. This study proposes membrane bioreactors as a novel bioreactor setup for polyhydroxybutyrate (PHB) production using Cupriavidus necator , whereby gas-transfer membranes are used for aeration. A proof-of-concept membrane bioreactor was built by combining a 50 ml centrifuge tube with hollow fiber membrane bundles. Different numbers and length of polydimethylsiloxane (PDMS) hollow fiber membranes were used to create membrane bundles with varying specific surface areas for oxygen transfer. In batch mode, a maximum biomass concentration of 10.3 g/L, which corresponds to a yield of 0.67 g biomass/g substrate, was achieved with 250 m2/m3 as the specific surface area of the membranes and 40 rpm as the liquid recirculation rate. Two different fed-batch modes were investigated to induce PHB production by applying nitrogen source limitation via fill-and-draw and two-step feeding strategies. A PHB level of 22% was obtained with fill-and-draw feeding by supplying 0.25 g/L NH 4 Cl after initial cultivation. Results indicate that membrane bioreactors are promising for C. necator cultivation, but further research is needed to enhance the PHB productivity. • A novel gas-transfer membrane bioreactor was developed for microbial fermentation. • Various operating parameters were tested in batch for maximizing microbial growth. • Two different fed-batch operation modes were investigated for PHB production. • Membrane bioreactors has shown promising results to cultivate Cupriavidus necator. [ABSTRACT FROM AUTHOR]

The production of poly-3-hydroxybutyrate (PHB) on an industrial scale remains a major challenge due to its higher production cost compared to petroleum-based plastics. As a result, it is necessary to develop efficient fermentative processes using low-cost substrates and identify high-value-added applications where biodegradability and biocompatibility properties are of fundamental importance. In this study, grape residues, mainly grape skins, were used as the sole carbon source in Azotobacter vinelandii OP cultures for PHB production and subsequent nanoparticle synthesis based on the extracted polymer. The grape residue pretreatment showed a high rate of conversion into reducing sugars (fructose and glucose), achieving up to 43.3 % w w−1 without the use of acid or external heat. The cultures were grown in shake flasks, obtaining a biomass concentration of 2.9 g L−1 and a PHB accumulation of up to 37.7 % w w−1. PHB was characterized using techniques such as Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). The formation of emulsified PHB nanoparticles showed high stability, with a particle size between 210 and 240 nm and a zeta potential between −12 and − 15 mV over 72 h. Owing to these properties, the produced PHB nanoparticles hold significant potential for applications in drug delivery. [ABSTRACT FROM AUTHOR]

The search for eco-friendly substitutes for traditional plastics has led to the production of biodegradable bioplastics. However, concerns have been raised about the impact of bioplastic biodegradation on soil health. Despite these concerns, the potential negative consequences of bioplastics during various stages of biodegradation remain underexplored. Therefore, this study aims to investigate the impact of micro-bioplastics made of poly-3-hydroxybutyrate (P3HB) on the properties of three different soils. In our ten-month experiment, we investigated the impact of poly-3-hydroxybutyrate (P3HB) on Chernozem, Cambisol, and Phaeozem soils. Our study focused on changes in soil organic matter (SOM), microbial activity, and the level of soil carbon and nitrogen. The observed changes indicated an excessive level of biodegradation of SOM after the soils were enriched with micro-particles of P3HB, with concentrations ranging from 0.1% to 3%. The thermogravimetric analysis confirmed the presence of residual P3HB (particularly in the 3% treatment) and underscored the heightened biodegradation of SOM, especially in the more stable SOM fractions. This was notably evident in Phaeozem soils, where even the stable SOM pool was affected. Elemental analysis revealed changes in soil organic carbon content following P3HB degradation, although nitrogen levels remained constant. Enzymatic activity was found to vary with soil type and responded differently across P3HB concentration levels. Our findings confirmed that P3HB acts as a bioavailable carbon source. Its biodegradation stimulates the production of enzymes, which in turn affects various soil elements, indicating complex interactions within the soil ecosystem. [Display omitted] • Biodegradation of P3HB caused degradation of soil organic matter. • P3HB represents a preferable substrate for soil microorganisms. • Biodegradation of P3HB influenced SOC but not soil nitrogen. • Elevated enzymes content decreased after P3HB biodegradation. [ABSTRACT FROM AUTHOR]

Electrospun biomimetic materials based on polyester of natural origin poly-3-hudroxybutyrate (PHB) modified with hemin (Hmi) and fibrinogen (Fbg) represent a great interest and are potentially applicable in various fields. Here, we describe formulation of the new fibrous PHB-Fbg and PHB-Hmi-Fbg materials with complex structure for biomedical application. The average diameter of the fibers was 3.5 μm and 1.8 μm respectively. Hmi presence increased porosity from 80 % to 94 %, significantly reduced the number of defects, ensured the formation of a larger number of open pores, and improved mechanical properties. Hmi presence significantly improved the molding properties of the material. Hmi facilitated effective Fbg adsorption on the of the PHB wound-healing material, ensuring uniform localization of the protein on the surface of the fibers. Next, we evaluated cytocompatibility, cell behavior, and open wound healing in mice. The results demonstrated that PHB-Fbg and PHB-Hmi-Fbg electrospun materials had pronounced properties and may be promising for early-stage wound healing - the PHB-Hmi-Fbg sample accelerated wound closure by 35 % on the 3rd day, and PHB-Hmi showed 45 % more effective wound closure on the 15th day. [ABSTRACT FROM AUTHOR]

[Display omitted] • First report on the use of herb residue as a fermentation carbon source. • The newly isolated Bacillus altitudinis utilized herb residues to produce PHB. • The highest concentration of PHB was obtained in a 5-L fermentor by Bacillus sp. Traditional Chinese medicine residue (TCMR) was utilized as an inexpensive carbon source for the production of poly(3-hydroxybutyrate) (PHB) using the newly isolated Bacillus altitudinis HBU-SI7. The results showed that Yu Ping Feng TCMR could be directly hydrolysed by cellulase to obtain a high proportion of glucose (99 % of total sugar) without pretreatment, achieving an enzymatic hydrolysis rate of up to 89.2 %. B. altitudinis could grow and produce PHB when using enzymatically hydrolysed TCMR in a 5-L fermenter. After 20 h of fermentation, the maximum concentration of PHB was 11.2 g/L, and the highest cell dry weight (CDW) was 15.4 g/L, with 72.7 % of the PHB fraction in CDW. Moreover, this strain could utilize enzymatic hydrolysates from various herbal formulas to produce high levels of PHB. This novel approach aims to accumulate PHB from TCMR hydrolysates, offering an effective and environmentally friendly method to reduce production costs and achieve mass production. [ABSTRACT FROM AUTHOR]

Synthetic biodegradable and bio-based polymers have emerged as sustainable alternatives to nonrenewable petroleum-derived polymers which cause serious environmental issues. In particular, polyhydroxyalkanoates (PHA) are promising biopolymers owing to their outstanding biodegradability and biocompatibility. The production of the homopolymer poly(3-hydroxybutyrate) (PHB) and copolymer poly(3-hydroxybutyrate- co -3-hydroxyvalerate) (PHBV) from type II methanotrophs via microbial fermentation was presented. For the efficient extraction and recovery of intracellular PHA from methanotrophs, different extraction approaches were investigated including solvent extraction using 1,3-dioxolane as a green solvent, integrated cell lysis and solvent extraction, and cell digestion without the use of organic solvents. Among various extraction approaches, the integrated method exhibited the highest extraction performance, with PHA recovery and purity exceeding 91 % and 93 %, respectively, even when the PHA content of the cells was low. Furthermore, the molecular weight, thermal stability, and mechanical properties of the recovered PHA were comprehensively analyzed to suggest its suitable practical applications. The obtained properties were comparable to that of the commercial PHA products and PHA produced from other microbial species, indicating an efficient recovery of high-quality PHA produced from methanotrophs. • Bio-based and biodegradable PHB and PHBV were produced from type II methanotrophs. • Various extraction methods were applied to separate PHB and PHBV from dried cells. • Integrated cell lysis and PHA extraction using sodium hypochlorite and 1,3-dioxolane • PHA recovery and purity of 91 %–93 % was obtained from the integrated extraction. • PHA properties were comprehensively characterized using diverse analytical methods. [ABSTRACT FROM AUTHOR]

• CoP-Fe2O3/g-C3N4 improve photogenerated electron–hole separation efficiency. • CoP-Fe2O3/g-C3N4 decrease ROS generation in MES. • CoP-Fe2O3/g-C3N4 provide more reducing force to improve MES performance. • CoP-Fe2O3/g-C3N4 facilitated the enrichment of microorganisms. • 142.20 mg/L PHB can be obtained on 7-day MES reaction. The hydrogen energy and CO 2 reduction in-situ recombination has drawn increasing attention. Microbial electrosynthesis (MES) integrated with photocatalytic materials is a novel technology for CO 2 utilization. Here, MES with the photocathode CoP-Fe 2 O 3 /g-C 3 N 4 was constructed using Ralstonia eutropha as biocatalyst to generate polyhydroxybutyrate (PHB). The integration of CoP and Fe 2 O 3 /g-C 3 N 4 facilitated electron–hole pair separation and electron transfer, which enhanced hydrogen evolution reaction and provided additional reducing power for CO 2 conversion. Simultaneously, the concentration of reactive oxygen species was also considerably reduced, increasing the production of PHB. In particular, 87.54 mg/L of PHB was obtained in CoP-Fe 2 O 3 /g-C 3 N 4 at − 1.05 V, which is about three times higher than that in carbon felt. At − 0.9 V, PHB concentration further increased to 142.20 mg/L. This study provides a new approach for converting CO 2 into multicarbon compounds in situ electrolysis of water under visible light. [ABSTRACT FROM AUTHOR]

Several species of novel marine bacteria from the genus Marinobacterium , including M. nitratireducens , M. sediminicola , and M. zhoushanense were found to be capable of producing polyhydroxyalkanoates (PHA) using sugars and volatile fatty acids (VFAs) as the carbon source. M. zhoushanense produced poly-3-hydroxybutytate (PHB) from sucrose, achieving a product titer and PHB content of 2.89 g/L and 64.05 wt%, respectively. By contrast, M. nitratireducens accumulated 3.38 g/L PHB and 66.80 wt% polymer content using butyrate as the substrate. A third species, M. sediminicola showed favorable tolerance to propionate, butyrate, and valerate. The use of 10 g/L valerate yielded 3.37 g/L poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), with a 3-hydroxyvalerate (3 HV) monomer content of 94.75 mol%. Moreover, M. sediminicola could be manipulated to produce PHBV with changeable polymer compositions by feeding different mixtures of VFAs. Our results indicate that M. sediminicola is a promising halophilic bacterium for the production of PHA. • Three strains of Marinobacterium were firstly employed to produce PHA. • M. sediminicola grew well at butyrate concentrations up to 40 g/L. • PHBV titer reached 5.06 g/L in shake flasks using VFA mixtures. • PHBV with high 3 HV content (over 94 mol%) was produced using valerate. [ABSTRACT FROM AUTHOR]

Over the past decade, formic acid and acetic acid have gained increasing attention as alternative feedstocks for poly-3-hydroxybutyrate (PHB) production as these potentially CO 2 -derived molecules are naturally assimilated by Cupriavidus necator. Both organic acids were individually evaluated in fed-batch fermentations at bioreactor scale. Acetic acid was revealed as the most promising carbon source yielding 42.3 g L−1 PHB, whereas no significant amount of PHB was produced from formic acid. Hence, acetic acid was further used as the substrate during process intensification. Key performance characteristics, including process stability, PHB titer, and productivity were optimized by introducing NH 4 -acetate as the nitrogen source, extending the growth phase, and implementing a repeated fed-batch procedure, respectively. These advanced fermentation strategies resulted in the establishment of a stable fermentation process reaching 58.5 g L−1 PHB, while doubling the productivity to 0.93 g L−1 h−1 PHB. [Display omitted] • Acetic acid was revealed as most promising CO 2 -derived feedstock over formic acid. • Ammonium acetate as nitrogen source enables stable pH-static feeding of acetic acid. • Extension of the growth phase by linear feeding increases final PHB concentration. • Repeated fed-batch strategy enhances PHB productivity. • 58.5 g L−1 PHB was produced with a productivity of 0.93 g L−1 h−1 PHB. [ABSTRACT FROM AUTHOR]

In this study, a phaC R gene encoding PHA synthase was identified in Rhodoligotrophos defluvii which was adjacent to β-ketothiolase encoded by phaA R gene and acetoacetyl-CoA reductase encoded by phaB R gene. Amino acid comparison of PhaC R showed the highest homology of 65.98% with PhaC of R. appendicifer , while its homology with typical class I PHA synthase in Cupriavidus necator was only 42.54%. PHA synthesis genes were then transformed into E. coli harboring phaCAB R and phaC R AB C which were cultured with 15 g/L glucose respectively, and 20.46 wt% and 16.95 wt% of CDW for poly(3-hydroxybutyrate) (PHB) were accumulated respectively. To further explore the effect of substrate specificity for PHA production, the ptsG gene was then deleted and 15 g/L glucose and 1.5 g/L propionate were co-employed as carbon sources, which enabled the synthesis of poly(3HB- co -3HV) copolymer. As a result, poly(3HB-co-3HV) was accumulated up to 24.74 wt% of CDW, and the highest content of 3-hydroxyvalerate (3HV) was 10.86 mol%. The T d5 was 260 °C, which implied that it possessed good thermal stability, and the M w of GPC in recombinant strains were between 22 and 26 × 104 g/mol, and the highest PDI was 3.771. The structure of poly (3HB- co -3HV) copolymer was determined through 1H NMR analysis. [ABSTRACT FROM AUTHOR]

In this work we investigated tenogenic differentiation of adipose-derived mesenchymal stem cells (AdMSCs), which were seeded onto silk fibroin/poly-3-hydroxybutyrate (SF/P3HB) scaffolds with aligned topography, and high mechanical strength. The electrospinning process was optimized by using the response surface method (RSM) and SF/P3HB nanofibrous matrices with a total polymer concentration of 5% (SF: PHB = 3: 1), flow rate 1 mL/h, collector rotation speed 2000 rpm, applied voltage 14 kV, and collector distance 25 cm were obtained. The average fiber diameter was 699 ± 203 nm and 80% of the nanofibers were aligned within the ±15o range. SF reinforcement reduced the crystallinity of P3HB, and the elastic modulus was found to be 197.0 ± 7.7 MPa. The scaffolds showed bacteriostatic effect. A 21-day of cell culture study was performed with rat rAdMSCs in the absence and presence of tenogenic differentiation factor-5 (GDF-5). The results demonstrated that SF/P3HB scaffolds allow the cells to proliferate and differentiate to the tenocytes. However, no significant effect of GDF-5 on the differentiation of cells was observed. These findings indicated that our aligned SF/P3HB scaffolds have a significant potential to be used for tendon tissue engineering. [ABSTRACT FROM AUTHOR]

Poly(3-hydroxybutyrate) (PHB) is a promising substitute to petroleum-based polymers in packaging and biomedical applications provided that its melt processability and degradability are improved. A new method to control the properties of PHB by using cheap calcium stearate (CS) as a lubricant and decomposition catalyst in melt-mixed PHB-CS compounds was first used. CS is composed of a metallic cation, which promotes PHB degradation, and a hydrophobic anion that improves the compatibility with PHB and processability. An environmentally friendly melt mixing technique was employed to obtain the PHB-CS compounds. Incorporation of 0.5 or 5 wt% CS reduced the melt viscosity and molecular weight of PHB, decreased the melting temperature with up to 5 °C, the crystallization temperature with more than 25 °C, and the degradation temperature with 15 and 40 °C, respectively. In small amounts (0.05 wt%), CS improved the processability and mechanical properties of PHB. In higher amount (0.5 wt%), CS slightly improved the Young's modulus, reduced the tensile strength and enhanced degradation. A better control of thermal and mechanical properties of PHB is, thus, possible by using different CS amount and processing conditions. These results are relevant for PHB application in the context of the global transition to biodegradable packaging. [ABSTRACT FROM AUTHOR]

Methanotrophic biotechnologies for methane mitigation and nitrogen removal are becoming more apparent. However, the sludge produced during these processes is often underutilized and instead can be applied for resources recovery. Fortunately, methanotrophic bacteria can utilize methane while also producing poly-hydroxy-butyrate (PHB), bioplastics, under nutrients deficient conditions. Bioplastics are increasing in popularity and can be produced from unexploited resources, such as methane and carbon dioxide, within wastewater facilities. This research demonstrates that methanotrophic sludge generated during a methanotrophic-based nitrogen removal process, which has been recently suggested, can be directly utilized for PHB production. It was found that the PHB storage response of the methanotrophic driven mixed culture was greatest when methane and oxygen were supplied in equal volume to volume ratios. In addition, the PHB response due to imposing feast-like conditions along with nitrogen or phosphorus deprivation were assessed. The highest PHB storage achieved was 21 ± 1.31% after one cycle under methane sufficient and nitrogen limited conditions. Whereas, only applying feast-like conditions demonstrated a PHB storage of 15 ± 0.67% while simultaneously removing nitrate. Finally, further optimization and continued feast- and famine-like cycles can lead to a greater PHB storage response by the culture. • The methanotrophic culture was enriched in a novel bioreactor for nitrogen removal. • Feast and famine-like conditions were applied based on methane availability. • Achieved a maximum PHB capacity of 21 ± 1.31% in a mixed methanotrophic culture. • Feast and famine conditions and nitrogen limitation led to the greatest capacity. [ABSTRACT FROM AUTHOR]

Waste straw bio-transformation of high value-added macromolecule polyhydroxyalkanoates (PHAs) was significance to environmental sustainable development. As a member of the PHA family, poly-β-hydroxybutyrate (PHB) could be synthesized by Halomonas elongata A1 with maximal yields of 22.8% and 11.8% of bacterial weights using glucose and carboxymethyl cellulose as carbon sources, respectively. To improve PHB production, we generated three recombinant strains, the H. elongata P2 with highest PHB biosynthesis ability. When wheat straw, mixed substrate and oleic acid were individually used as single carbon source, the maximal PHA polymer accumulation in the H. elongata P2 reached 5.2%, 16.5% and 27.5%, respectively, after 84 h of cultivation. This hardness, toughness and crystallization properties of the PHA macromolecule altered dependent on starting substrates, when analyzed by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC). In terms of the hardness and roughness, the PHA produced from mixed substrates was much softer than that from wheat straw but harder than that from oleic acid. The long-chain carbon improved the softness and strength of the produced PHA. Our data indicate that economical substrates, such as straw and waste oil, can be used in the synthesis of multi-functional plastic products with biodegradable properties. [Display omitted] • Wild type and recombinant H. elongata A1 synthesized 22.81% and 90.76% PHB respectively, using glucose. • The number of porin promoters in recombinant strain affected phaCAB gene expression. • H. elongata P2 used straw and oleic acid to synthesize 5.19% and 31.42% PHA polymer, respectively. • SEM, FTIR and DSC showed that synthetic materials differ from straw to oleic acid. [ABSTRACT FROM AUTHOR]

Marine microorganisms are reported to produce polyhydroxybutyrate (PHB) that has wide range of medical and industrial applications with the advantage of biodegradability. PHBs are synthesized as an energy and carbon storage element under metabolic pressure. The scope of this work is enhancing PHB production using marine microbial isolate, Micrococcus luteus by selectively optimizing various growth conditions such as different media components and growth parameters that influence the cell growth and PHB production were sampled. Micrococcus luteus produced 7.54 g/L of PHB utilizing glucose as a carbon source and ammonium sulphate as a nitrogen source with maximum efficiency. The same optimized operational conditions were further employed in batch fermentation over a time span of 72 h. Interestingly higher cell dry weight of 21.52 g/L with PHB yield of 12.18 g/L and 56.59% polymer content was observed in batch fermentation studies at 64 h. The chemical nature of the extracted polymer was validated with physio-chemical experiments and was at par with the commercially available PHB. This study will spotlight M. luteus as a potential source for large-scale industrial production of PHB with reducing environmental pollutions. • PHB producing bacteria Micrococcus luteus was isolated from the marine environment. • Diverse growth parameters were optimized to produce the maximum quantity of PHB. • Under optimized conditions, 12.18 g/L of PHB was produced from batch fermentation. • Structural characterizations showed that extracted polymer was PHB. [ABSTRACT FROM AUTHOR]

The use of antioxidants such as curcumin (Cur) or quercetin (Que) in biomedical and biotechnological applications has been studied owing to their capability to prevent oxidative stress and inhibit free radicals. Using polyhydroxybutyrate (PHB) electrospun fibers is presented as a proper option to encapsulate curcumin and quercetin due to its biocompatibility and biodegradability characteristics. Electrospun fibers were obtained dissolving commercial PHB in chloroform: N , N -dimethylformamide (DMF) (4:1) at 7% m/V, and adding two different concentrations of antioxidant (Cur, and Que) 1%m/m, and 7% m/m. These polymeric solutions were electrospun at different conditions and the obtained fibers were characterized by scanning electron microscopy (SEM), thermogravimetric (TGA) analysis, and Fourier transform infrared spectroscopy (FT-IR). The curcumin and quercetin releases into phosphate buffer saline (PBS) at pH 7.4 were obtained in vitro and measured by spectrophotometry. Antioxidant activities were measured by spectrophotometry in a microplate reader using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) method. Fibers obtained with different formulations presented a chemical composition in accordance with PHB according to FTIR spectra, the diameters fluctuate between 0.761 ± 0.123 and 1.803 ± 0.557 μm, with qualities over 0.95 according to their morphology, and the melting temperature resulted near 178 °C according to the bibliography. The crystallinity of fibers decreases while curcumin or quercetin concentration increases for the studied interval, indeed, quercetin showed a higher impact on the relative crystallinity of fibers. Antioxidant activity of active compounds is maintained after encapsulation in PHB electrospun fibers, and quercetin resulted in near four times antioxidant activity compared to curcumin according to DPPH analysis. • PHB is suitable for carrying quercetin and curcumin. • High quality and solvent-free microfibers are produced with PHB and antioxidants. • Antioxidant characteristics are maintained for the new material. [ABSTRACT FROM AUTHOR]

• Organic acid sources for P3HB production by marine bacterium Rhodovulum sulfidophilum DSM-1374. • Either batch or semi-continuous growth procedures in photo-fermentative processes. • Specific nutrient deficiency to increase cumulative poly-3-hydroxybutyrate in cells. • Novel 4 L working-volume photobioreactor for parallel production of H 2 and bioplastic. In the present study, the ability of the marine bacterium Rhodovulum sulfidophilum DSM-1374 to convert, via photo-fermentative process, certain organic acids such as single carbon source (acetate, lactate, malate and succinate) into polyhydroxyalkanoate accumulations within bacterial cells is evaluated. The main goal of the investigation was poly-3-hydroxybutyrate (P3HB) synthesis by a photo-fermentative process. Of the four carbon sources, only succinate simultaneously produced P3HB and H 2 (268 mg/L and 1085 mL/L respectively). Malate was the least productive source for P3HB; the other carbon sources (acetate and lactate) produced a significant amount of polymer (596 mg P3HB/L for acetate and 716 mg P3HB/L for lactate) when R. sulfidophilum was cultured in batch growth conditions. Cumulative P3HB increased significantly when the bacterium was grown under two steps: nutrient sufficient conditions (step 1) followed by macronutrient deficient conditions (step 2). The highest cumulative P3HB was observed at the end of step 2 (1000 mg/L) when R. sulfidophilum was fed with lactate under phosphorus starvation. When grown over 1200 h, under a semi-continuous regimen, the harvested dry-biomass reached a constant content of P3HB (39.1 ± 1.6 % of cell dry-weight), in the semi-steady state condition. Since lactate is an abundant byproduct of world industries, it can be used to mitigate the environmental impact in a modern circular bio-economy. [ABSTRACT FROM AUTHOR]

The increasing prevalence of multi-drug resistant bacteria poses a significant threat to public health, especially in wound infections. Developing new bactericidal agents and treatment strategies is crucial to address this issue. In this study, biopolymeric nanofibrous scaffolds containing green-synthesized silver nanoparticles (AgNPs) with curcumin (CUR) were evaluated as antimicrobial materials for wound healing therapy. Firstly, CUR was utilized to synthesize AgNPs, which were then analyzed using various analytical methods. The microstructural analysis revealed that the biogenic AgNPs, which had a spherical shape and an average size of 19.83 nm, were uniformly anchored on PHB/CTS nanofibers. Then, the AgNPs with various content (0.25–1%wt) were incorporated into PHB/CTS matrix to enhance its wettability, thermal and bactericidal behaviors. The nanofibrous scaffolds were characterized by FT-IR, FE-SEM, TGA analysis and water contact angle measurement. Overall, the addition of CUR-AgNPs to the PHB/CTS matrix led to a reduction in fiber diameter, enhanced hydrophilicity and improved thermal properties. Additionally, antibacterial activity against Staphylococcus aureus and Escherichia coli was performed on samples of AgNPS and PHB/CTS/CUR-Ag. The synthesized AgNPs showed antibacterial activity against both microorganisms, especially against S. aureus. Higher concentrations of AgNPs in nanofibers led to a significant reduction in bacterial colony formation. The results displayed that PHB/CTS/CUR-AgNPs nanofibrous scaffolds could be a promising material for the biomedical applications such as wound healing. [Display omitted] • Biogenic AgNPs synthesized using curcumin successfully added to biopolymeric nanofibrous scaffolds made of PHB/CTS. • Characterization studies showed that thermal properties and surface wettability of the PHB/CTS/CUR-AgNPs samples improved. • The synthesized AgNPs were uniformly dispersed within the PHB/CTS, with an average size of 19.83 nm and a spherical shape. • AgNPs exhibited significant antibacterial activity against the Gram-positive bacteria S. aureus. • The synergistic effects of chitosan and AgNPs combined with PHB fibers increased antibacterial effectiveness. [ABSTRACT FROM AUTHOR]

Polyhydroxyalkanoates (PHA) are bioplastics which are well known as intracellular energy storage compounds and are produced in a large number of prokaryotic species. These bio-based inclusions are biodegradable, biocompatible and environmental friendly. Industrial production of, short chain and medium chain length PHA, involves the use of microorganisms and their enzymes. Priestia megaterium previously known as Bacillus megaterium is a well-recognized bacterium for producing short chain length PHA. This study focuses to characterize this bacterium for the production of medium chain length PHA, and a novel blend of both types of monomers having enhanced properties and versatile applications. Statistical analyses and simulations were used to demonstrate that cell dry weight can be derived as a function of OD 600 and PHA content. Optimization of growth conditions resulted in the maximum PHA production as: 0. 05 g. g-x. H−1, where the rate of PHA production was 0.28 g L−1. H−1 and PHA concentration was 4.94 g. L−1. This study also demonstrated FTIR to be a semi quantitative tool for PHA production. Moreover, conversion of scl-PHA to mcl-PHA with reference to time intermissions using GC-FID are shown. • Priestia megaterium showed metabolic shift in PHA production by converting PHB into mcl-PHA using two different media. • Statistical analysis optimized the C/N ratio, and concentrations of growth constituents to enhance the mcl-PHA production. • Electron microscopy evaluated the size, structure and shape of PHA granules with respect to time intervals. [ABSTRACT FROM AUTHOR]

The current processes for producing polyhydroxyalkanoates (PHAs) are costly, owing to the high cost of cultivation feedstocks, and the need to sterilise the growth medium, which is energy-intensive. PHA has been identified as a promising biomaterial with a wide range of potential applications and its functionalization from waste streams has made significant advances recently, which can help foster the growth of a circular economy and waste reduction. Recent developments and novel approaches in the functionalization of PHAs derived from various waste streams offer opportunities for addressing these issues. This study focuses on the development of sustainable, efficient, and cutting-edge methods, such as advanced bioprocess engineering, novel catalysts, and advances in materials science. Chemical techniques, such as epoxidation, oxidation, and esterification, have been employed for PHA functionalization, while enzymatic and microbial methods have indicated promise. PHB/polylactic acid blends with cellulose fibers showed improved tensile strength by 24.45-32.08 % and decreased water vapor and oxygen transmission rates while PHB/Polycaprolactone blends with a 1:1 ratio demonstrated an elongation at break four to six times higher than pure PHB, without altering tensile strength or elastic modulus. Moreover, PHB films blended with both polyethylene glycol and esterified sodium alginate showed improvements in crystallinity and decreased hydrophobicity. [Display omitted] • PHAs are tailored to meet optimization issues in definite functions. • Blending creates a new polymer combination with unique characteristics. • Surface modifications can improve thermal stability. [ABSTRACT FROM AUTHOR]

Materials and fabrication methods significantly influence the scaffold's final features in tissue engineering. This study aimed to blend zein with polyhydroxybutyrate (PHB) at 5, 10, and 15 wt%, fabricate scaffolds using electrospinning, and then characterize them. SEM and mechanical analyses identified the scaffold with 10 wt% zein (PHB-10Z) as the optimal sample. Incorporating 10 wt% zein reduced fiber diameter from 894 ± 122 to 531 ± 42 nm while increasing ultimate tensile strength and elongation at break by approximately 53 % and 70 %, respectively. FTIR proved zein's presence in the scaffolds and possible hydrogen bonding with PHB. TGA confirmed the miscibility of polymers. DSC and XRD analyses indicated lower crystallinity for the PHB-10Z than for PHB. AFM evaluation indicated a rougher surface for the PHB-10Z in comparison to PHB. The PHB-10Z demonstrated a more hydrophobic surface and less weight loss after 100 days of degradation in PBS than PHB. The free radical scavenging assay exhibited antioxidant activity for the zein-containing scaffold. Eventually, enhanced cell attachment, viability, and differentiation in the PHB-10Z scaffold drawn from SEM, MTT, ALP activity, and Alizarin red staining of MG-63 cells confirmed that PHB-zein electrospun scaffold is a potent candidate for bone tissue engineering applications. [ABSTRACT FROM AUTHOR]