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A new nanodevice based on gold nanoparticles (AuNPs) capped with poly(diethylvinylphosphonate) (PDEVP) has been synthesized, showing interesting photophysical and thermoresponsive properties. The synthesis involves a properly designed Yttriocene catalyst coordinating the vinyl-lutidine (VL) initiator active in diethyl vinyl phosphonate polymerization. The unsaturated PDEVP chain ending was thioacetylated, deacetylated, and reacted with tetrachloroauric acid and sodium borohydride to form PDEVP-VL-capped AuNPs. The NMR, UV–Vis, and ESI-MS characterization of the metal nanoparticles confirmed the formation of the synthetic intermediates and the expected colloidal systems. AuNPs of subnanometric size were determined by WAXD and UV–Vis analysis. UV–Vis and fluorescence analysis confirmed the effective anchoring of the thiolated PDEVP to AuNPs. The formation of 50–200 nm globular structures was assessed by SEM and AFM microscopy in solid state and confirmed by DLS in aqueous dispersion. Hydrodynamic radius studies showed colloidal contraction with temperature, demonstrating thermoresponsive behavior. These properties suggest potential biomedical applications for the photoablation of malignant cells or controlled drug delivery induced by light or heat for the novel PDEVP-capped AuNP systems. [ABSTRACT FROM AUTHOR]

Theranostics is a growing field that matches diagnostics and therapeutics. In this approach, drugs and techniques are uniquely coupled to diagnose and treat medical conditions synergically or sequentially. By integrating diagnostic and treatment functions in a single platform, the aim of theranostics is to improve precision medicine by tailoring treatments based on real-time information. In this context, lipid-based nanocarriers have attracted great scientific attention due to their biodegradability, biocompatibility, and targeting capabilities. The present review highlights the latest research advances in the field of lipid-based nanocarriers for cancer theranostics, exploring several ways of improving in vivo performance and addressing associated challenges. These nanocarriers have significant potential to create new perspectives in the field of nanomedicine and offer promise for a significant step towards more personalized and precise medicine, reducing side effects and improving clinical outcomes for patients. This review also presents the actual barriers to and the possible challenges in the use of nanoparticles in the theranostic field, such as regulatory hurdles, high costs, and technological integration. Addressing these issues through a multidisciplinary and collaborative approach among institutions could be essential for advancing lipid nanocarriers in the theranostic field. Such collaborations can leverage diverse expertise and resources, fostering innovation and overcoming the complex challenges associated with clinical translation. This approach will be crucial for realizing the full potential of lipid-based nanocarriers in precision medicine. [ABSTRACT FROM AUTHOR]

Cannabigerol's (CBG) therapeutic effects are limited by its poor water solubility and low dissolution rate. To improve these properties, supercritical CO2-assisted atomization (SAA) was applied to produce coprecipitates, i.e., CBG nanoparticles coprecipitated in polyvinylpyrrolidone (PVP) microparticles. The experiments were performed by varying the CBG/PVP mass ratio (R) and the overall concentration of solutes CBG+PVP to study the influence of these parameters on particle morphology, particle size, and size distribution. Periodic dynamic light scattering (DLS) analysis was performed at regular time intervals to measure the size of CBG nanoparticles in PVP microparticles. It showed that CBG nanoparticles down to 105 nm were successfully produced through SAA. Dissolution tests were used to verify that a reduction of CBG particle size significantly increased its dissolution rate. In the liquid medium adopted, untreated CBG powder was released in 210 min, whereas CBG nanoparticles of 105 nm were completely dissolved in only 15 min. [ABSTRACT FROM AUTHOR]

Bone tissue engineering (BTE) is the most promising strategy to repair bones injuries and defects. It relies on the utilization of a temporary support to host the cells and promote nutrient exchange (i.e., the scaffold). Supercritical CO2 assisted drying can preserve scaffold nanostructure, crucial for cell attachment and proliferation. In this work, agarose aerogels, loaded with hydroxyapatite were produced in view of BTE applications. Different combinations of agarose concentration and hydroxyapatite loadings were tested. FESEM and EDX analyses showed that scaffold structure suffered from partial closure when increasing filler concentration; hydroxyapatite distribution was homogenous, and Young's modulus improved. Looking at BTE applications, the optimal combination of agarose and hydroxyapatite resulted to be 1% w/w and 10% w/v, respectively. Mechanical properties showed that the produced composites could be eligible as starting scaffold for BTE, with a Young's Modulus larger than 100 kPa for every blend. [ABSTRACT FROM AUTHOR]

The text discusses the use of nanosomes in precision nanomedicine to deliver drugs to specific cells or tissues, improving efficacy and safety. Various types of nanosomes, such as niosomes and transfersomes, are explored for drug delivery applications. Researchers have developed innovative methods and materials, like Fe-N-C nanozymes and polydopamine, to enhance drug delivery and treatment outcomes. The field of nanomedicine is rapidly expanding, with a focus on personalized medicine and reducing side effects for patients worldwide. [Extracted from the article]

Niosomes are arousing significant interest thanks to their low cost, high biocompatibility, and negligible toxicity. In this work, a supercritical CO2-assisted process was performed at 100 bar and 40 °C to produce niosomes at different Span 80/Tween 80 weight ratios. The formulation of cholesterol and 80:20 Span 80/Tween 80 was selected to encapsulate vancomycin, used as a model active compound, to perform a drug release rate comparison between PEGylated and non-PEGylated niosomes. In both cases, nanometric vesicles were obtained, i.e., 214 ± 59 nm and 254 ± 73 nm for non-PEGylated and PEGylated niosomes, respectively, that were characterized by a high drug encapsulation efficiency (95% for non-PEGylated and 98% for PEGylated niosomes). However, only PEGylated niosomes were able to prolong the vancomycin release time up to 20-fold with respect to untreated drug powder, resulting in a powerful strategy to control the drug release rate. [ABSTRACT FROM AUTHOR]

In recent years, scientific research has faced the numerous problems deriving from the presence of active ingredients in surface and groundwater. Traditional removal methods, such as adsorption and bioremediation, have several disadvantages; thus, in this work, membranes based on cellulose acetate loaded with Fe-N-TiO2, were tested for the photocatalytic degradation of Ceftriaxone Sodium from aqueous solution. The immobilization of the photocatalyst allows to overcome the limits of the photocatalytic process in suspension, which requires expensive and time-consuming post-treatments. Membranes were obtained by supercritical CO2 phase inversion process and were subjected to characterizations such as EDX, TGA, FT-IR, Raman spectroscopy and, subsequently, tested in adsorption tests in the dark and in the presence of visible light, to evaluate their photocatalytic activity. The variations in the concentration of the antibiotic, during the tests conducted, were monitored by HPLC chromatographic analysis. Samples with 10% and 30% by weight of Fe-N-TiO2 demonstrated relatively low adsorption efficiencies of the target contaminant, respectively equal to 22% and 18% in 180 minutes, for reasons related both to the morphology of the samples products, which changes from cellular to finger-like as the photocatalyst load increases, and to the quality of the dispersion. The membrane loaded with 20% by weight of Fe-N-TiO2 allowed a degradation of the model pollutant of 35% in 180 minutes; moreover, the reusability of the membranes was verified. The photocatalytic tests showed that the photocatalytic efficiency was highly correlated to the dispersion of the photocatalyst nanoparticles and to its loading in the polymeric membranes. [ABSTRACT FROM AUTHOR]

One of the most effective strategies to fight viruses and handle health diseases is vaccination. Recent studies and current applications are moving on antigen, DNA and RNA-based vaccines to overcome the limitations related to the conventional vaccination strategies, such as low safety, necessity of multiple injection, and side effects. However, due to the instability of pristine antigen, RNA and DNA molecules, the use of nanocarriers is required. Among the different nanocarriers proposed for vaccinal applications, three types of nanovesicles were selected and analysed in this review: liposomes, transfersomes and niosomes. PubMed, Scopus and Google Scholar databases were used for searching recent papers on the most frequently used conventional and innovative methods of production of these nanovesicles. Weaknesses and limitations of conventional methods (i.e., multiple post-processing, solvent residue, batch-mode processes) can be overcome using innovative methods, in particular, the ones assisted by supercritical carbon dioxide. SuperSomes process emerged as a promising production technique of solvent-free nanovesicles, since it can be easily scaled-up, works in continuous-mode, and does not require further post-processing steps to obtain the desired products. As a result of the literature analysis, supercritical carbon dioxide assisted methods attracted a lot of interest for nanovesicles production in the vaccinal field. However, despite their numerous advantages, supercritical processes require further studies for the production of liposomes, transfersomes and niosomes with the aim of reaching well-defined technologies suitable for industrial applications and mass production of vaccines. [ABSTRACT FROM AUTHOR]

The presence of organic dyes in wastewater raises significant environmental and human health concerns, owing to their high toxicity. In light of this, a novel adsorbent material with porous cryogel architecture was developed and employed for the effective removal of organic dyes from an aqueous solution. Initially, a titanium dioxide nanowire doped with zirconium HZTO was synthesized by the hydrothermal process. Subsequently, the beads (SA/HZTO) of sodium alginate and HZTO were successfully prepared through a cross-linking process, employing Ca2+ ions as the crosslinking agent. Structural analysis of SA/ HZTO beads was performed using FTIR, SEM, and EDX techniques. We systematically examined the impact of different conditions, including the initial dye concentration, pH, contact time, and adsorbent dosage, on the adsorption process. Batch experiments, both in signal and binary systems, were conducted to rigorously assess the dye adsorption capabilities. Kinetic modeling revealed that the adsorption process adhered to the pseudo-second-order kinetic model. Remarkably, the prepared beads exhibited impressive adsorption capacities of 26 and 29 mg/g toward methylene blue (MB) and safranin (SF), respectively. SA/ HZTO beads have demonstrated excellent adsorption properties, offering a promising avenue for the development of low-cost, efficient, and reusable adsorbent to remove dyes from wastewater. [ABSTRACT FROM AUTHOR]

Exopolysaccharides, obtained from microorganisms as fermentation products, are interesting candidates for biomedical applications as scaffolds: they are biocompatible, nontoxic, antimicrobial, antitumor materials. To produce exopolysaccharide-based scaffolds, sol–gel technology could be used, which ends with the removal of the liquid phase from the polymeric network (i.e., the drying step). The aim of this review is to point out the most relevant strengths and weaknesses of the different drying techniques, focusing attention on the production of exopolysaccharide-based porous structures. Among these drying processes, supercritical carbon dioxide-assisted drying is the most promising strategy to obtain dried gels to use in the biomedical field: it produces highly porous and lightweight devices with outstanding surface areas and regular microstructure and nanostructure (i.e., aerogels). As a result of the analysis carried out in the present work, it emerged that supercritical technologies should be further explored and applied to the production of exopolysaccharide-based nanostructured scaffolds. Moving research towards this direction, exopolysaccharide utilization could be intensified and extended to the production of high added-value devices. [ABSTRACT FROM AUTHOR]

Supercritical CO2 (SC-CO2)-assisted electrospray has been successfully performed to obtain a sustained release of ceftriaxone sodium (CFX) from polylactic acid (PLA) nanoparticles. PLA nanoparticles ranged from 270 ± 70 to 310 ± 80 nm, when produced at 140 bar. CFX release in a phosphate-buffered solution ranged from about 5 min, when the pure antibiotic was tested, to a maximum of 1200 min when 140 bar and 4 wt% of PLA + CFX nanoparticles was used: operating at these process conditions, an increase of 240 times of the release time was observed and no interactions were produced between PLA and the antibiotic. The release curves were explained hypothesizing a two-step mass transfer mechanism consisting of polymer swelling and PLA ester bond cleavage. [ABSTRACT FROM AUTHOR]

Vesicles are intriguing candidates for the topical administration of cosmetics as they can act as skin penetration stimulators, the individual components of the vesicles can impart additional desired properties to cosmetics, and are biodegradable and minimally toxic. Among the vesicular systems proposed for this application, liposomes are widely investigated. They are constituted of an inner aqueous core and an outer lipid bilayer. This configuration allows the encapsulation of both lipophilic and hydrophilic bioactive drugs. However, the traditional processes proposed for the production of these vesicles suffer from several limits: they are batch and time-consuming techniques, require post-treatments for the purification of vesicles from organic solvent residues and/or for reducing their mean size, do not favour a high encapsulation efficiency of drugs. In this work, SuperSomes, a sustainable and continuous process assisted by supercritical CO2, was used to produce nanometric liposomes loaded with ascorbic acid for cosmetic applications. Operating at 100 bar and 40 °C, stable liposomes characterized by a spherical morphology and a mean diameter lower than 250 nm, were obtained. An ascorbic acid encapsulation efficiency of 85% was measured and the supercritical process preserved the antioxidant activity of the drug. [ABSTRACT FROM AUTHOR]

Transfersomes are deformable vesicles that can transport drugs across difficult-to-permeate barriers in human tissues. In this work, nano-transfersomes were produced for the first time by a supercritical CO2 assisted process. Operating at 100 bar and 40 °C, different amounts of phosphatidylcholine (2000 and 3000 mg), kinds of edge activators (Span® 80 and Tween® 80), and phosphatidylcholine to edge activator weight ratio (95:5, 90:10, 80:20) were tested. Formulations prepared using Span® 80 and phosphatidylcholine at an 80:20 weight ratio produced stable transfersomes (−30.4 ± 2.4 mV ζ-potential) that were characterized by a mean diameter of 138 ± 55 nm. A prolonged ascorbic acid release of up to 5 h was recorded when the largest amount of phosphatidylcholine (3000 mg) was used. Moreover, a 96% ascorbic acid encapsulation efficiency and a quasi-100% DPPH radical scavenging activity of transfersomes were measured after supercritical processing. [ABSTRACT FROM AUTHOR]

Marigold oil is a product of great industrial interest thanks to its wide range of medicinal and wound-healing properties. In this work, supercritical carbon dioxide was used to recover marigold essential oil from the hexane solvent extract of marigold flowers, the floral "concrete". This starting material was mixed with synthetic paraffinic waxes to heighten its melting point and viscosity, thus, improving material processability. Supercritical fluid extraction and fractionation of the modified marigold "concrete" was carried out, and the effect of pressure and CO2 mass flow rate was studied. The pressure was varied from 80 to 180 bar, keeping the temperature constant at 40 °C: the higher the pressure, the larger the CO2 solvent power and extraction yield (up to 9.40% w/w). Nevertheless, the optimum between productivity and process selectivity was found at 100 bar. By changing the CO2 mass flow rate (from 1.20 to 1.50 kg/h), we noted that mass transfer resistance was located externally. GC-MS analysis showed that the most abundant compounds in the oil were δ-cadinene (25%), γ-cadinene (16%), τ-muurolol (6.5%), and α-muurolene (6%). Moreover, the traces of oil and waxes showed no mutual contamination between lighter species and waxes, meaning that the fractionation step was successful. [ABSTRACT FROM AUTHOR]

Clary Sage extracts are of industrial interest: in particular, sclareol shows a strong pharmaceutical potential. Supercritical fluid extraction was used to recover compounds of interest from a Salvia sclarea L. waxy n-hexane extract ("concrete"), using semi-continuous fractionation and a multi-step extraction strategy. Multi-step extraction experiments were carried out in two phases: the first one operated at 90 bar and 50 °C; the second one at 100 bar and 40 °C. GC-MS traces showed that during the first extraction step, only lighter compounds (e.g., monoterpenes, sesquiterpenes, and derivatives) were collected, whereas, in the second step, only sclareol and related compounds were recovered. By adjusting operating conditions (temperature and pressure), selective extraction of different families of compounds was accomplished, with no further need for post-processing of the products. Moreover, using two separators in series, the compounds of interest were fractionated from paraffins and, by changing the operating conditions, the extraction yield increased from about 6.0% to 9.3% w/w as CO2 density increased. [ABSTRACT FROM AUTHOR]

Liposomes have been used for several decades for the encapsulation of drugs and bioactives in cosmetics and cosmeceuticals. On the other hand, the use of these phospholipid vesicles in food applications is more recent and is increasing significantly in the last ten years. Although in different stages of technological maturity—in the case of cosmetics, many products are on the market—processes to obtain liposomes suitable for the encapsulation and delivery of bioactives are highly expensive, especially those aiming at scaling up. Among the bioactives proposed for cosmetics and food applications, vitamins are the most frequently used. Despite the differences between the administration routes (oral for food and mainly dermal for cosmetics), some challenges are very similar (e.g., stability, bioactive load, average size, increase in drug bioaccessibility and bioavailability). In the present work, a systematic review of the technological advancements in the nanoencapsulation of vitamins using liposomes and related processes was performed; challenges and future perspectives were also discussed in order to underline the advantages of these drug-loaded biocompatible nanocarriers for cosmetics and food applications. [ABSTRACT FROM AUTHOR]

Supercritical CO2 phase inversion is one of the most promising techniques to generate polymeric membranes. In recent years, it has been also tested to generate loaded membranes to be used in several applications such as controlled release, catalysis, tissue engineering, water purification, etc. In this work, membranes of cellulose acetate were generated, loaded with a highly hydrophobic drug with antifungal properties, i.e., quercetin. Different process parameters were tested to verify their effect on the final morphology of the membranes and on the drug distribution along the membranes. In particular, polymer concentration in the starting polymeric solution was varied from 5 to 15% w/w, operative pressure ranged between 100 and 200 bar, operative temperature from 45 to 55 °C. Different membranes structures were obtained: finger-like and cellular-like; the effect of these different morphologies on quercetin release was also analyzed, finding as finger-like structure promoted a faster drug release (i.e., less than 200 min) with respect to cellular structures (i.e., up to 1400 min). Results confirmed the capability of supercritical CO2 phase inversion process to generate loaded polymeric membranes and the high versatility of this process that allowed to generate different morphologies capable to control the drug release rate [ABSTRACT FROM AUTHOR]

TiO2-loaded poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-coHFP) membranes were produced by supercritical CO2-assisted phase inversion. Three different TiO2 loadings were tested: 10, 20, and 30 wt% with respect to the polymer. Increasing the TiO2 amount from 10 wt% to 20 wt% in the starting solution, the transition from leafy-like to leafy-cellular morphology was observed in the section of the membrane. When 30 wt% TiO2 was used, the entire membrane section showed agglomerates of TiO2 nanoparticles. These polymeric membranes were tested to remove Sudan Blue II (SB) dye from aqueous solutions. The adsorption/photocatalytic processes revealed that membrane morphology and TiO2 cluster size were the parameters that mainly affected the dye removal efficiency. Moreover, after five cycles of exposure of these membranes to UV light, SB removal was higher than 85%. [ABSTRACT FROM AUTHOR]

Alginate-based microparticles were produced via supercritical assisted atomization (SAA) with the aim of obtaining a biocompatible and low-cost carrier for the delivery of active compounds in cosmetic applications. Salicylic acid was selected as an active model compound, and it was co-precipitated with alginate via SAA, operating at 82 bar and 80 °C. In particular, the drug-to-polymer weight ratio was fixed at 1/4, whereas polymer concentration was varied from 5 to 20 mg/mL in the starting aqueous solution. Operating in this way, alginate-salicylic acid microparticles were characterized by a mean diameter of 0.72 ± 0.25 µm, and the active compound became amorphous after processing. A salicylic acid encapsulation efficiency close to 100% was reached, and the drug release time from the biopolymeric microparticles was prolonged up to nine times with respect to untreated salicylic acid powder. [ABSTRACT FROM AUTHOR]

This work proposes an improvement of the traditional electrospraying process, in which supercritical carbon dioxide (SC-CO2) is used to produce poly(lactic-co-glycolic acid) (PLGA) nanoparticles. The experiments were performed at different PLGA concentrations (1, 3 and 5% w/w), applied voltages (10 and 30 kV) and operating pressures (80, 120 and 140 bar). It was found that working at 140 bar and 30 kV, spherical nanoparticles, with mean diameters of 101 ± 13 nm and 151 ± 45 nm, were obtained, when solutions at 1% w/w and 3% w/w PLGA were electrosprayed, respectively. Increasing PLGA concentration up to 5% w/w, a mixture of fibers and particles was observed, indicating the transition to the electrospinning regime. [ABSTRACT FROM AUTHOR]

Abdel-Kader et al. [[4]] designed a reverse-phase high-performance thin-layer chromatography (RP-HPTLC) protocol for the simultaneous determination of bioactive sesquiterpene coumarins feselol and samarcandin in the methanol extract of five I Ferula i species. The extraction of active ingredients from vegetable matter is one of the most attractive research fields in the literature. 10.3390/separations9100283 3 Althurwi H.N., Salkini M.A.A., Soliman G.A., Ansari M.N., Ibnouf E.O., Abdel-Kader M.S. Wound Healing Potential of Commiphora gileadensis Stems Essential Oil and Chloroform Extract. [Extracted from the article]

Supercritical-CO2 assisted electrospray is a new process used to produce polymeric micro- and nanoparticles characterized by tunable and regular morphologies. The major innovation consists of the addition of supercritical CO2 to the polymeric solution, obtaining a gas expanded liquid having reduced values of viscosity and surface tension. Due to its biodegradability and biocompatibility, cellulose acetate (CA) was selected as polymeric carrier for microparticles production, that can be used for drug delivery applications. Indeed, CA solutions were loaded with a poorly-water soluble compound, rutin (RUT), to improve its bioavailability. The experiments were performed at different CA concentrations (0.5 and 1 wt%) and different RUT concentration, that was varied from 2.5 to 7.5 wt% with respect to CA; the applied voltage was set at 30 kV. CA/RUT microparticles were successfully produced; working at 140 bar and 30 kV, particles characterized by an average diameter of 980±120 nm and networked fibers were obtained, processing 1 wt% CA solution and using a RUT concentration of 7.5 wt% with respect to CA. IR spectroscopy revealed the physical dispersion of RUT into CA particles. [ABSTRACT FROM AUTHOR]

Traditional and supercritical CO2 assisted processes are frequently used to produce microparticles formed by a biopolymer containing an active principle to improve the bioavailability of the active principle. However, information about the internal organization of these microparticles is still scarce. In this work, a suspension of dextran + Fe3O4 nanoparticles (model system) and a solution of polyvinylpyrrolidone (PVP) + curcumin were used to produce spherical microparticles by supercritical CO2 processing. Periodic dynamic light scattering measurements were used to analyze the evolution of the microparticles dissolution, size, and size distribution of the guest active principle in the polymeric matrix. It was found that curcumin was dispersed in the form of nanoparticles in the PVP microparticles, whose size largely depended on its relative concentration. These results were validated by transmission electron microscopy and scanning electron microscopy of the PVP microparticles and curcumin nanoparticles, before and after the dissolution tests. [ABSTRACT FROM AUTHOR]

Cuticular waxes can be used in high-value applications, including cosmetics, foods and nutraceuticals, among the others. The extraction process determines their quality and purity that are of particular interest when biocompatibility, biodegradability, flavor and fragrance are the main features required for the final formulations. This study demonstrated that supercritical fluid extraction coupled with fractional separation can represent a suitable alternative to isolate cuticular waxes from vegetable matter that preserve their natural properties and composition, without contamination of organic solvent residues. Operating in this way, cuticular waxes can be considered as a fingerprint of the vegetable matter, where C27, C29 and C31 are the most abundant compounds that characterize the material; the differences are mainly due to their relative proportions and the presence of hydrocarbon compounds possessing other functional groups, such as alcohols, aldehydes or acids. Therefore, selectivity of supercritical fluid extraction towards non-polar or slightly polar compounds opens the way for a possible industrial approach to produce extracts that do not require further purification steps. [ABSTRACT FROM AUTHOR]

The main techniques used for organic pollutant removal from water are adsorption, reductive and oxidative processes, phytoremediation, bioremediation, separation by membranes and liquid-liquid extraction. In this review, strengths and weaknesses of the different purification techniques are discussed, with particular attention to the newest results published in the scientific literature. This study highlighted that adsorption is the most frequently used method for water purification, since it can balance high organic pollutants removal efficiency, it has the possibility to treat a large quantity of water in semi-continuous way and has acceptable costs. [ABSTRACT FROM AUTHOR]

Supercritical assisted electrospray is an emerging process used for the production of polymeric micro- and nanoparticles of controlled size and distribution. The main innovation consists of the addition of supercritical CO2 to the polymeric solution, with the aim of obtaining an expanded liquid, characterized by reduced viscosity and surface tension. Cellulose acetate (CA) was selected as the model polymer, thanks to its peculiarities, such as low cost, biodegradability and biocompatibility. The experiments were performed at different pressures (from 80 bar to 140 bar) and polymer concentrations (from 0.2% to 1% w/w). CA nanoparticles were successfully produced; working at 140 bar and 30 kV, particles characterized by a mean diameter in the range from 266.7±145 nm to 343.9±120 nm were obtained, processing 0.2% w/w and 1% w/w CA solutions, respectively. These results open the way to the production of biopolymeric sub-microcarriers that, loaded with active molecules, can be used in nutraceuticals. [ABSTRACT FROM AUTHOR]

In the last years, biolpolymeric porous structures have acquired an increasing importance in different fields of engineering, ranging from chemical engineering to tissue engineering. Until now, various processes have been implemented for the generation of porous structures, but they are all characterized by several limits, such as long processing times, traces of organic solvents in the final products, low versatility, etc. In this work, we tested a green process assisted by supercritical fluids for the generation of biopolymeric porous structures: the supercritical phase inversion process. We processed different biopolymers such as Polysulfone, Polymethylmethacrylate and Polyvinyl alcohol, and analyzed the effect of process parameters (pressure, temperature, polymer concentration, kind of solvents) on the final morphology. The results confirmed the advantages of the supercritical fluids assisted process with respect to the traditional ones: indeed, dry porous structures were obtained in few hours; moreover, changing the parameters, it was possible to control the kind of structures obtained (from cellular one to bicontinuous) and the size of the pores and porosity (from 70 to 90%); finally, the structures were characterized by residual solvents amount lower than 5 ppm. [ABSTRACT FROM AUTHOR]

Supercritical CO2 (SC‐CO2) extraction is commonly used to eliminate caffeine from coffee beans. In this work, the feasibility of tryptamine elimination is considered as a further objective of the process. SC‐CO2 extraction process parameters (eg, pressure, CO2 flow rate, water content) were studied to obtain tryptamine reduction, starting from those used in supercritical decaffeination. A good compromise, in terms of tryptamine residue in coffee beans, and process feasibility and selectivity, was found operating at 280 bar and 0.8 kg/h CO2, at a starting H2O content in coffee beans of 20% w/w. Using these process conditions, a tryptamine residue of 218 ppm (ppm) was measured in coffee beans after 18 hours of processing. A negligible effect on process selectivity and tryptamine yield was obtained by changing the CO2 flow rate and the initial water content. However, working at an initial water content of 30% w/w and using wet CO2 (CO2 plus 3% w/w water), a tryptamine residue of 107 ppm in coffee beans was obtained, but industrial complexity and costs increased. [ABSTRACT FROM AUTHOR]

In this work Poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) aerogels loaded with curcumin were produced by a supercritical CO2 assisted process. The aim was to create controlled release systems for wound healing applications. Performing the supercritical gel drying at suitable operating conditions (200 bar and 45°C), PVDF-HFP aerogels were generated starting from gels at 5, 10 and 12% w/w PVDF-HFP. They presented interesting morphologies: nanoporous, homogeneous and regular. Then, PVDF-HFP gels were loaded at 3% w/w of curcumin with respect to the polymer and, subsequently, dried by SC-CO2 at the same operative conditions previously tested. Curcumin release tests and DPPH tests were performed on the composite systems, for the determination of the curcumin antioxidant activity. The release test showed that the PVDF-HFP aerogels allowed to obtain a regular and prolonged release of curcumin, up to 45 h; furthermore, DPPH tests confirmed that curcumin still presented an high antioxidant activity (about 77%). All the samples produced were also characterized from a chemical and physical point of view: from the results of DSC and XRD analyses, it was observed that the gel drying process assisted by SC-CO2 did not lead to any change in the properties of the polymer (PVDF-HFP) and of the active agent (curcumin). [ABSTRACT FROM AUTHOR]

In this work, polycaprolactone (PCL) foams were generated by a supercritical CO2 (SC-CO2) assisted process. These foams can find application in tissue engineering as scaffolds, which require specific biological and morphological properties. SC-CO2 foaming process was carried out under different pressure and temperature conditions, in order to study the influence of these operating parameters on the final samples morphology. These polymeric foams were then analyzed by scanning electron microscope (FE-SEM) in order to observe their internal structure. The performed analyses showed the influence of pressure and temperature on the external shape and on the morphology of these polymeric foams, in particular on the pore size. Pressures of 100, 150, 200 and 250 bar and temperatures of 40 and 60°C were tested as operating variables. The PCL foams obtained at 40°C and 200 bar presented the lowest value of the average pores diameter (i.e., 85 ± 24 µm); this value was about 7 times lower than that of the foams produced operating at 40°C and 100 bar (622 ± 62 µm). These results confirmed the high versatility of the SC-CO2 foaming that allowed to generate PCL foams with tunable morphological characteristics. [ABSTRACT FROM AUTHOR]

A supercritical CO2 (SC-CO2) assisted phase inversion process was tested to load a fructose exopolysaccharide with amphiphilic properties (i.e., levan) in membranes of polyvinylidenefluoride-cohexafluoropropylene (PVDF-HFP). The aim was to investigate the effect of levan on the morphological and biological properties of PVDF-HFP membranes. Different loadings of levan from 0 to 50% w/w were tested: PVDF-HFP + levan membranes characterized by a foam-like structure were generated, with an increase of overall porosity from 75 to 90%. The effect of levan addition on mechanical and biological characteristics of PVDF-HFP membranes was also studied: a decrease of the mechanical resistance from 12 to 1 MPa and an increase of cells (colon cancer cell line HTC-116) adhesion from 8% to 35% were measured. In conclusion, SC-CO2 assisted process was able to generate composite structures potentially useful for biological applications, characterized by a homogeneous distribution of levan and by improved biological properties. [ABSTRACT FROM AUTHOR]

Supercritical phase inversion process was successfully implemented to produce loaded polymeric membranes of cellulose acetate with a synthetic clay mineral (i.e., laponite), to enhance both their mechanical and biological properties. The generated structures presented a microporous structure with a pore size ranging from 8.7 to 12.6 µm, depending on the laponite concentration: the addition of a solid in the starting solution caused a phase separation delay and a consequent pores size increasing. At the same time, the addition of laponite in form of nanodisks improved the mechanical characteristics of the material in terms of Young modulus up to 4.2 MPa. Furthermore, a relevant increase up to 80.9% on cellular adhesion (cell line BT474) was found thanks to the incorporation of laponite inside these membranes. This phenomenon can be attributed to the high surface area and the mineral properties of this clay; therefore, the inclusion of laponite in cellulose acetate membranes produced by supercritical phase inversion, drastically transformed this polymer into a suitable material for tissue engineering applications. [ABSTRACT FROM AUTHOR]

In this work, poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) membranes for water purification were produced by supercritical phase inversion using a mixture of supercritical CO2 (SC-CO2) and ethanol as non-solvent. Different polymer concentrations (from 10 to 20% w/w) and ethanol amount by volume (from 1 to 50% v/v) with respect to SC-CO2 flow rate, were tested in order to study their influence on membranes morphology, surface area and porosity; supercritical processing was performed at a pressure of 200 bar and a temperature of 45 °C. Membranes characterized by a cellular morphology with a nanoporous substructure and/or by an homogeneous nanoporous morphology were obtained, changing the starting polymer concentration and the ethanol amount during the process. In particular, increasing the amount of ethanol from 1 to 50% v/v, an increase of membranes porosity and surface areas was obtained, and the membranes morphology changed from microporous with nanoporous cell walls to completely nanoporous, due to an increase of the non-solvent power that improved the in-situ gelification mechanism during the supercritical phase separation. [ABSTRACT FROM AUTHOR]

BACKGROUND Silver‐loaded hydroxyapatite nanoparticles were incorporated into poly(vinyl alcohol) (PVA) membranes obtained by supercritical CO2 (SC‐CO2) assisted phase inversion. Ag3PO4 crystals of 2.2 ± 0.6 nm were dispersed in synthesized needle‐like hydroxyapatite nanoparticles (20 × 65 nm) and were uniformly deposited on the internal surfaces of the PVA membranes. Operative conditions to produce membranes by SC‐CO2, PVA concentration and the effect on membrane porosity and morphology were studied. RESULTS: Solutions at 20% w/w PVA produced membranes with cellular morphology and nanoporous walls, whereas 30% and 50% w/w solutions produced nanostructured membranes. Silver ions were released from PVA membranes mainly by diffusion according to the Peppas–Sahlin model. Membranes obtained at 20% w/w PVA showed a significant E. coli inhibition at an Ag concentration of 9 ppm, reaching the minimal inhibitory concentration (MIC) and improving the bactericidal activity of the nanoparticles. CONCLUSION: A concentration of Ag3PO4 crystals of about 22 ppm was calculated as being capable of completely destroying these bacteria, reaching the minimum bactericidal concentration (MBC). © 2018 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

BACKGROUND: Supercritical (SC)‐CO2 extraction of rotenoids from Derris elliptica roots was proposed using fractional separation of the extracts and operating at increasing pressure. RESULTS: The best processing conditions were found at 200 bar, 40 °C and 1.2 kg h−1 SC‐CO2 flow rate, obtaining a final product with a concentration of 93% w/w of rotenone and rotenoids, and a yield of active principles of 6.70% w/w with respect to the vegetable matrix. Very small quantities of waxes were found, up to 0.05% w/w; this result can be explained considering the reduced surface‐to‐volume ratio of this vegetable material. CONCLUSION: Extraction kinetics data confirmed that, in this case, the extraction process was controlled by solubility limitation of the active compounds in the supercritical solvent. © 2018 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

BACKGROUND Artemisia annua L. extraction is traditionally performed using hexane; the process is simple, but not selective. In this work, a strategy to concentrate artemisinin and the other similar active principles in the final extract is proposed, combining cheapness of maceration and selectivity of SC‐CO2 processing. RESULTS: Hexane extraction produced a solid, waxy extract with a yield of 3.3% w/w with respect to the starting vegetable material. Then, SC‐CO2 processing of this solid extract was performed operating at 0.8 kg h−1 SC‐CO2 flow rate and at different operative parameters. Very selective conditions were found operating at 90 bar and 50°C, obtaining a final product containing more than 71% w/w of active compounds (artemisinin, artemisin and dehydroartemisinin). CONCLUSION: Using this approach, a product more than 2.6 times richer in artemisinin than the one obtained by conventional techniques and about 2 times richer than direct CO2 extraction, was obtained. Another relevant result is that the overall process scheme is cheaper than direct CO2 extraction, since a high pressure extractor about 20 times smaller can be used, to process the waxy product obtained by hexane extraction. © 2018 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

In this work, chitosan/gelatin (Ch/G) aerogels with a network organization were produced by supercritical gel drying. Ch structure was characterized by a cellular morphology with smooth pore walls, with a mean pore size of about 20 µm. The morphology of G aerogel was, instead, nanofibrous with a mean fiber size lower than 100 nm. The mixture between Ch and G favored Ch gelification, due to the chemical interaction among the cationic Ch and negatively charged molecules of G. Ch/G hybrid aerogels formed an interpenetrated polymer network, with enhanced mechanical properties with respect to the starting single biopolymers, achieving a Young modulus up to 181 kPa, suitable for bone tissue engineering. Moreover, high surface area (≈250 m2 g−1) and negligible glutaraldehyde (GTA) residues were found after supercritical processing; in particular, the GTA residues in the aerogels were lower than 3 ppm, also in the worst case (i.e., 2.3 ppm of released GTA for the Ch/G 4/1 aerogel), making them useful for potential nanomedicine applications. POLYM. ENG. SCI., 58:1494–1499, 2018. © 2017 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

Natural polymers, such as alginate and gelatin, can be used to produce scaffolds for tissue engineering applications; but, their mechanical and biochemical performance should be improved. A possible solution to obtain this result, is the generation of multi-component scaffolds, by blending two or more polymers. One way to realize it, is the formation of an interpenetrating polymer network (IPN). In this work, the interpenetration of alginate and gelatin hydrogels has been successfully obtained and preserved by supercritical CO2 (SC-CO2) drying performed at 200 bar and 35 °C, using different blend compositions: from alginate/gelatin = 20:80 v/v to alginate/gelatin = 80:20 v/v. The process allowed modulation of morphology and mechanical properties of these blends. The overall result was made possible by the supercritical drying process that, working at zero surface tension, allows preserving the hydrogels nanostructure in the corresponding aerogels. [ABSTRACT FROM AUTHOR]

Introduction: The complex structure of the bone-tendon and muscle-tendon junctions makes their reproduction for tissue engineering applications very difficult. Relatively few studies have investigated the characteristics of these regions from a tissue engineering view point. Sources of data: PubMed, Thomson Reuters, Scopus and Google Scholar databases were searched using various combinations of the keywords 'Tendon', 'Myotendinous junction', 'Osteotendinous junction', 'Tissue engineering' and 'Scaffold'. Areas of agreement: The available studies can be divided according to whether the objective is to build an entire composite tissue unit or to assist the recreation of interfaces, such as improving integration of autografts with the surrounding bone or with the muscle. The most used techniques are based on the electrospinning and the self-reorganized constructs process, which were applied to both bone-to-tendon junction (BTJ) and muscle-to-tendon junction (MTJ) regeneration. The use of nanofibers that mimic the hierarchical structure of the extracellular matrix (ECM), eventually functionalized by encapsulation of bioactive components, allowed cell attachment and differentiation. Areas of controversy: There have been no translational investigations. Growing points: There is a need to devise suitable techniques that allow suitable tissue engineering of BTJ and MTJ. Areas timely for developing research: Appropriately planned studies are needed to translate tissue engineering from a scientific challenge to a clinically applicable technique. [ABSTRACT FROM AUTHOR]

A supercritical CO2 drying process was used to prepare an innovative nanocomposite, formed by a poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF HFP) aerogel loaded with RuO2 nanoparticles. The produced nanocomposites, at 10% and 60% w/w of RuO2, were tested for the electrochemical oxidation of model tannery wastewaters. The effect of the electrochemical oxidation parameters, like pH, temperature, and current density, on tannic acid, intermediates, and chemical oxygen demand (COD) removal, was investigated. In particular, the electrolysis of a simulated real tannery wastewater, using PVDF HFP_RuO2 60, was optimized working at pH 10, 40 °C, and setting the current density at 600 A/m2. Operating in this way, surfactants, sulfides, and tannins oxidation was achieved in about 2.5 h, ammonium nitrogen oxidation in 3 h, and COD removal in 5 h. When chloride-containing solutions were tested, the purification was due to indirect electrolysis, related to surface redox reactions generating active chlorine. Moreover, sulfide ions were converted into sulfates and ammonium nitrogen in gaseous N2. [ABSTRACT FROM AUTHOR]

Poly(ʟ-lactide) (PLLA) films, even of high thickness, exhibiting co-crystalline and crystalline α phases with their chain axes preferentially perpendicular to the film plane (c⊥ orientation) have been obtained. This c⊥ orientation, unprecedented for PLLA films, can be achieved by the crystallization of amorphous films as induced by low-temperature sorption of molecules being suitable as guests of PLLA co-crystalline forms, such as N,N-dimethylformamide, cyclopentanone or 1,3-dioxolane. This kind of orientation is shown and quantified by two-dimensional wide-angle X-ray diffraction (2D-WAXD) patterns, as taken with the X-ray beam parallel to the film plane (EDGE patterns), which present all the hk0 arcs centered on the meridian. PLLA α-form films, as obtained by low-temperature guest-induced crystallization, also exhibit high transparency, being not far from those of the starting amorphous films. [ABSTRACT FROM AUTHOR]

In this work, Class 2 and Class 3 solvents contained in two corticosteroids, flunisolide (Fluni) and fluticasone propionate (Fluti), were reduced to a few ppm by supercritical CO2 extraction. The process was carried out at pressures from 80 to 200 bar, temperatures of 40 °C and 80 °C, and at a fixed CO2 flow rate of 0.7 kg/h. The results demonstrated that CO2 density is the key parameter influencing the extraction kinetics and the solvent final residue. In particular, in the range investigated, optimal pressure and temperature conditions for the extraction of residual organic solvents were found working at 200 bar and 40 °C, which corresponds to a CO2 density of 0.840 g/cm3. Operating in this way, total organic solvent residues were reduced from 13,671 ppm and 326 ppm to 12 ppm and 10 ppm for Fluni and Fluti, respectively. [ABSTRACT FROM AUTHOR]

A comparative analysis concerning bio-based gels production, to be used for tissue regeneration, has been performed in this review. These gels are generally applied as scaffolds in the biomedical field, thanks to their morphology, low cytotoxicity, and high biocompatibility. Focusing on the time interval 2015–2020, the production of 3D scaffolds of alginate, chitosan and agarose, for skin and bone regeneration, has mainly been investigated. Traditional techniques are critically reviewed to understand their limitations and how supercritical CO2-assisted processes could overcome these drawbacks. In particular, even if freeze-drying represents the most widespread drying technique used to produce polysaccharide-based cryogels, supercritical CO2-assisted drying effectively allows preservation of the nanoporous aerogel structure and removes the organic solvent used for gel preparation. These characteristics are essential for cell adhesion and proliferation. [ABSTRACT FROM AUTHOR]

Wendita calysina (commonly known as burrito) is an indigenous Paraguayan medical plat, whose essential oil (EO) is characterized by some pharmaceutical properties. In particular, the main component is D-carvone, with anticancer action and antimicrobial properties against various microorganisms. In this work, supercritical CO2 (SC-CO2) was used for the extraction of volatile compounds from this plant, selecting different operative conditions to optimize the extract yield and purity. Pressure was varied from 80 to 250 bar, and two CO2 flow rates (0.8 kg/h and 1.2 kg/h) were tested. The highest EO percentage in the extract was obtained operating at 100 bar and 40 °C, using ground Wendita calysina leaves of 250 µm. CO2 flow rate did not influence the extraction yield, indicating that an internal mass transfer resistance governs this process. The largely prevailing compound identified in the extract was D-carvone, with a mean percentage up to 90% w/w. [ABSTRACT FROM AUTHOR]

Antimicrobial composite membranes, formed by cellulose acetate loaded with AgNO3 particles, were produced by supercritical phase inversion. Different cellulose acetate concentrations were tested (15%, 20%, 30%(w/w)), whereas the active agent (i.e., silver nitrate) concentration was fixed at 0.1%(w/w) with respect to the quantity of polymer used. To determine the influence of the process parameters on membranes morphology, the pressure and temperature were varied from 150 to 250 bar and from 55 to 35 °C, respectively. In all cases, regularly porous membranes were produced with a uniform AgNO3 distribution in the membrane matrix. Silver release rate depended on membrane pore size, covering a time interval from 8 to 75 h. [ABSTRACT FROM AUTHOR]

This work proposes a modeling of the mechanical properties of porous polymers processed by scCO2, using a phenomenological approach. Tensile and compression tests of alginate/gelatin and cellulose acetate/graphene oxide were modeled using three hyperelastic equations, derived from strain energy functions. The proposed hyperelastic equations provide a fair good fit for mechanical behavior of the nanofibrous system alginate/gelatin (deviations lower than 10%); whereas, due to the presence of the solid in the polymer network, a four-parameter model must be used to fit the composite cellulose acetate/graphene oxide behavior. Larger deviations from the experimental data were observed for the system cellulose acetate/graphene oxide because of its microporous structure. A finite element method was, then, proposed to model both systems; it allowed a realistic description of observable displacements and effective stresses. The results indicate that materials processed using scCO2, when submitted to large stresses, do not obey Hooke´s law and must be considered as hyperelastic. [ABSTRACT FROM AUTHOR]

A new process is proposed that can largely improve classical electrospray (ESPR) atomization, thanks to the addition of supercritical CO2 (SC-CO2) to the liquid mixture, in which a polymer is dissolved, forming an expanded liquid. The consequent reduction of surface tension and viscosity allows the production of micrometric or nanometric particles of controlled size and distribution at a production rate up to one hundred times that of the traditional process. The new process was applied to particle generation from a very high molecular weight polyvinylpyrrolidone (PVP) and tested at different polymer percentages by weight and at different pressures. Repeatable microparticle diameters and distributions were obtained, ranging between 0.55 and 2.25 µm at PVP concentrations from 1 to 5% w/w and pressures between 80 and 120 bar. [ABSTRACT FROM AUTHOR]