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The development of long-wavelength emission carbon dots as a label-free sensing platform for the direct detection of glutathione (GSH) is still of great challenge. Herein, novel rose-red fluorescence carbon dots (wCDs) with a long-wavelength emission of 654 nm were successfully synthesized by a one-step microwave-solvothermal treatment of biomass Wedelia trilobata. The biomass-based wCDs could sensitively respond to copper ions (Cu2+) with a limit of detection (LOD) of 0.22 μM, which could be utilized as the fluorescence turn off–on sensor for the detection of GSH through recovering their fluorescence quenched by Cu2+. Moreover, the label-free wCDs with abundant active functional groups could be used to construct a direct quenching platform for the sensitive and selective detection of GSH by the dynamic quenching effect within 20 s without further modification, displaying a good linear range of 0–3.0 mM with a LOD of 35 μM that fits well with the GSH content in living cells (0.5–10 mM). Additionally, confocal imaging of living cells indicates that as-prepared wCDs with high photobleaching resistance and favorable biocompatibility possess the capacity for real-time monitoring of the variations of intracellular Cu2+ and GSH levels, and distinguishing cancerous cells from normal cells owing to the overexpression of GSH in cancerous cells. This study opens a new vision for developing an efficient and sensitive fluorescent sensor for the detection of GSH, and demonstrates the great prospects for wCDs in ion/molecule tracking, bioimaging and cancer diagnosis.

Cellulose acetate is one of the oldest synthetic thermoplastic polymers and has various applications including usage as films, fibers, and membrane products. Traditionally, cellulose acetate is pre...

Nanocomposites composed of Ag and γ-Fe2O3 nanoparticles within poly-γ-glutamic acid (γ-PGA) derived amorphous carbon nitride (a-CN) films (Ag + γ-Fe2O3@a-CN) were synthesized by a one-step facile pyrolysis strategy. Transmission electron microscopy analysis shows that Ag and γ-Fe2O3 nanoparticles were obtained in situ and homogeneously dispersed on the a-CN matrix. The average size of nanoparticles was 8.1 nm. The presence of γ-Fe2O3, Ag, and a-CN in the nanocomposite was confirmed by X-ray diffraction analysis, UV–visible absorption spectroscopy, Raman spectroscopy, and X-ray photoelectron spectroscopy. Ag + γ-Fe2O3@a-CN catalyzed the degradation of methyl orange. This catalyst was also recycled ten times by magnetic separation without any loss in efficiency. Ag + γ-Fe2O3@a-CN exhibited strong antibacterial activity against E. coli and S. aureus. It also exhibited excellent antibacterial activity even after 20 times magnetic recycling. This indicates that this is a promising recyclable antibacterial and catalyst for environmental applications.

Inspired by antimicrobial peptides (AMP) which could alleviate drug resistance pressure, antimicrobial peptide mimics (AMPMs) were designed timely. Here, carboxymethyl cellulose (CMC) -based AMPMs were constructed by introducing different diamines on CMC effectively. Firstly, CMC was degraded to be oligomers with different molecular weights, followed by amination reactions with different diamines respectively. After protonation, a series of AMPMs with different structures were synthesized successfully. Their antibacterial effect has been evaluated by dynamic growth curves and microdilution method. The images snapped by the confocal laser scanning microscope and transmission electron microscope have fully proved its great lethality. And the antibacterial mechanism measured by flow cytometry analysis and zeta potential detection demonstrated that the destruction of membrane potential leads to bacteria death. The excellent blood compatibility and negligible drug resistance has also been confirmed. In addition, the synthesis method is simple and environmental-friendly.

Antibiotic pollution has been a serious global public health concern in recent years, photodynamic inactivation is one of the most promising and innovative methods for antibacterial applications that avoids antibiotic abuse and minimizes risks of antibiotic resistance. However, limited by the weak interaction between the photosensitizers and Gram-negative bacteria, the effect of photodynamic inactivation cannot be fully exerted. Herein, photosensitizer chlorin e6-loaded polyethyleneimine-based micelle was constructed. The synergy of electrostatic and hydrophobic interactions between the nanoparticles and the bacterial surface promoted the anchoring of nanoparticles onto the bacteria, resulting in enhanced photoinactivation activities on Gram-negative bacteria. As expected, an eminent antibacterial effect was also observed on the Gram-positive bacteria Staphylococcus aureus. The cellular uptake results showed that photosensitizer was firmly anchored to the bacterial cell surface of Escherichia coli or Staphylococcus aureus by the introduction of branched polyethylenimine-containing nanoparticles. The light-triggered generation of reactive oxygen species, mainly singlet oxygen, from the membrane-bound nanoparticles caused irreversible damage to the bacterial outer membrane, achieving enhanced bactericidal efficiency than free photosensitizer. The study would provide an efficient and promising antimicrobial alternative to prevent overuse of antibiotics and have enormous potential for human healthcare and the environment remediation.

Many animals such as snails and Chinese giant salamanders can secrete mucus for moisturizing, eliminating swelling and inflammation, and promoting wound healing; this implies that high viscous bio-functional materials inspired by mucus may show potential for biomedical applications. Herein, we developed a maltose-like injectable nanocomposite via the combination of chitosan polysaccharide and clay rectorite for hemostasis. Through the hemostatic property of rectorite, the viscous nanocomposite decreased the in vitro clotting time by 43%. Moreover, an in vitro porcine skin model confirmed that the viscous nanocomposite can stably adhere on skin and impede blood bleeding successfully. Importantly, the internal structure of the nanocomposites, chitosan intercalating into rectorite interlayers, provided a physical cross-linked network to decrease the release of rectorite from the nanocomposite and its invasion into the blood. Therefore, this viscous injectable nanocomposite provided a concept for a facile and sustainable biomaterial for skin hemostasis.

Extracellular polymeric substances (EPS) are organic metabolic compounds excreted by microorganisms. They largely impact microbial aggregate structures and functions. Extracellular polysaccharides (EP) in EPS are responsible for the formation of microbial aggregates. In this work, we successfully separated and characterized EP from EPS of the bacterium Bacillus megaterium TF10. Extraction of EP from EPS was optimized using Sevag's reagent. Chemical characteristics, functional groups, and molecular weight (MW) distribution of EP were compared with the harvested EPS and soluble microbial products (SMP). We found that the polymers of lower MW and free proteins were successfully removed by Sevag's reagent. The higher MW components of EPS were predominantly polysaccharides, while the polymers of lower MW tended to secrete to the supernatant and were described as SMP. A part of the proteins in the EP was polysaccharide-bonded. Our results can be further used in elucidating the complex flocculation mechanisms in which EP play a major role.

Silver nanoparticles are excellent antibacterial materials with wide application. However, it is extremely unstable associated with easy aggregation and colour changes. Although a great number of carriers have been developed for stable silver nanoparticles, it is never ending to broaden silver carrier to meet varying applications. Herein, delaminated hectorite was developed as an alternative silver carrier. The structure of silver-loaded delaminated hectorite was confirmed by X-ray diffraction, X-ray photoelectron spectroscopy and scanning electron microscopy/energy-dispersive X-ray studies. Silver (8.69 wt%) was loaded onto the hectorite nanoparticles by cationic ionic change and surface coating. The silver-loaded hectorite showed fast bacterial killing ability (kill more than 94% Escherichia coli and 83% Staphylococcus aureus at 50 ppm within 1 h) by destroying bacterial cell wall.

In this study, nano-doped calcium phosphate cement delivery systems (poly (γ-glutamic acid)/β-tricalcium phosphate/calcium phosphate ceramics and nano (γ-glutamic acid)/β-tricalcium phosphate/calcium phosphate ceramic) were fabricated, and low doses (10 µg/g) of two growth factors, insulin-like growth factor-1 and bone morphogenetic protein-2, were encapsulated then sequentially released. We characterized the delivery systems using Fourier transform infrared spectroscopy and X-ray diffraction and measured washout resistance and compressive strength, and thus optimized the most appropriate proportioning of delivery systems for the two growth factors. One of the growth factors was absorbed by the nano-poly (γ-glutamic acid)/β-tricalcium phosphate, which was then mixed into the calcium phosphate ceramic solid phase to create a new solid phase calcium phosphate ceramic. Nano-poly (γ-glutamic acid)/β-tricalcium phosphate/calcium phosphate ceramic carriers were then prepared by blending the new calcium phosphate ceramic solid phase powder with a solution of the remaining growth factor. The effects of different release patterns (studying sequential behavior) of insulin-like growth factor-1 and bone morphogenetic protein-2 on osteogenic proliferation and differentiation of the MC3t3-E1 mouse osteoblast cell were investigated. This combinational delivery system provided a controlled release of the two growth factors, in which nano-doping significantly affected their release kinetics. The incorporation of dual growth factors could potentially stimulate bone healing and promoting bone ingrowth processes at a low dose.

Although both silver ions and silver nanoparticles (AgNPs) have perfect antibacterial activity, but it was assumed that AgNPs have stronger activity than that of silver ions. In this study, we make a comparative analysis of activity, dynamics, and effects of silver ions and two types of AgNPs against four bacterial strains. The minimum inhibitory concentrations (MICs) of silver ions, AgNPs (I) and AgNPs (II) were 0.5, 1 and 2 μg/mL against E. coli , 1, 2 and 8 μg/mL against P. aeruginosa , 1, 2 and 4 μg/mL against S. aureus , and 1, 2 and 2 μg/mL against S. epidermidis respectively. This experimental results showed that Ag + have stronger antibacterial activity than that of AgNPs (I) and AgNPs(II). Antibacterial dynamic curves revealed all the silver ions, AgNPs (I), and AgNPs (II) prolonged the growth lag phase of all four bacteria in a concentration-dependent manner. Furthermore, transmission electronic microscopy (TEM) observation showed that a major part of bacterial cells treated with 2 μg/mL of silver ion and AgNPs were destroyed within 5 h. The transmission electron microscopy (TEM) observation indicated that all the silver ions, AgNPs (I), and AgNPs (II) can induce severe damage in bacterial cells. The flagella of bacteria were damaged or even eliminated, which would cause movement disorders. Many holes or gaps were observed on cell surfaces, which would cause the leakage of cytoplasm and macromolecules, and leading to cell death at last. Our results suggested that silver ions have similar action mode and slightly better antibacterial activity than that of AgNPs against bacterial cells.

The use of aqueous ionic liquids as a pretreatment for enhancing enzymatic saccharification of lignocellulosic biomass is well-known, with a focus on lignin and hemicellulose removal. However, in-depth knowledge of changes in cellulose crystallinity during the pretreatment is limited. To this effect, detailed Fourier transform infrared (FT-IR) spectroscopy, cross-polarized magic angle spinning 13C nuclear magnetic resonance (CP/MAS 13C NMR), and X-ray diffraction (XRD) studies on sugar cane bagasse that has been pretreated with aqueous ionic liquids is presented. Secondary derivatives of FT-IR spectra and Gauss deconvolution of XRD patterns were applied to give a detailed understanding of the crystalline changes in sugar cane bagasse cellulose upon pretreatment. The results showed that aqueous ionic liquid pretreatment destroys the semicrystalline region of sugar cane bagasse cellulose, thus disordering the orientation of the cellulose crystallites.

The incorporation of metallic nanoparticles (NPs) into a biomass-based matrix has been intensively investigated because the obtained nanocomposites exhibited effective antibacterial activity to intractable resistance of bacteria. However, the nanocomposites present limitations, such as a multi-step preparation process and a low loading capacity of nanoparticles. A facile preparation route for the preparation of antibacterial metallic nanocomposites would be especially beneficial for industrial fabrication. In this study, we provided a facile strategy for the preparation of a rosin-derived biochar matrix loaded with silver nanoparticles (Ag NPs) as the fillers. The results demonstrated that the preparation of these rosin-derived biochar silver nanocomposites (Rc/Ag nanocomposites) was achieved by a rapid pyrolysis process and a large amount of Ag NPs were in-situ obtained and homogeneously dispersed on the matrix. More importantly, these materials exhibited satisfying antibacterial activities against E. coli and S. aureus. Thus, the Rc/Ag nanocomposites exhibit promising filler for wooden furniture against bacterial infection and could be used as a filter for indoor antibacterial air filtration.

Homogeneous esterification of lignocellulosic agro-forestry wastes is an efficient approach to transform the biomass into value-added biobased materials. However, the application of fatty acid anhydrides or acyl chlorides as esterified reagents would yield equivalent acids which lead to significant decomposition of lignocellulosic biomass. The present study proposed an alternative chemical approach to prepare bioplastics from lignicellulosic biomass. Sugar cane bagasse esters were prepared by transesterification with vinyl esters using 1-ethyl-3-methylimidazolium acetate as duel solvent and activator. Solution-stated NMR studies suggested that the polysacchirides were highly reactive during the homogeneous transesterification. The chemical mechanism of the transesterification was demonstrated to be a carbene mechanism, which subsequently transferred into the intermediate of 2-alkanoyl-dialkylimidazolium. The as-prepared sugar cane bagasse esters were found to be solvable in common solvents. Bioplastic fil...

Sugarcane bagasse, lignocellulosic residue from the sugar industry, is an abundant and renewable bioresource on the earth. The application of ionic liquids in sugarcane bagasse biorefinery is gaining increasing interest. The homogeneous modification of sugarcane bagasse by free radical initiated graft copolymerization of acrylate monomers using 1-allyl-3-methylimidazolium chloride as solvent was performed. A variety of sugarcane bagasse graft copolymers with different weight percent gain were prepared via adjusting the monomer dosage. FT-IR studies confirmed the success in attaching the poly(acrylate) side chains onto sugarcane bagasse. Oil absorbency studies suggested that the sugarcane bagasse graft copolymers were potential biobased materials for effective treatment of ester-based oils. SEM studies showed that the sugarcane bagasse graft copolymers displayed a dense morphology structure. Thermogravimetric analysis demonstrated that the thermal stability of sugarcane bagasse decreased after the homogeneous modification by the graft copolymerization. The present study provides an alternative strategy to convert sugarcane bagasse into a value-added functional biobased material.

Zwitterionic monomer methyacryloxyethyl sulfobetaine (MAES) copolymerized with hydroxyethyl methacrylate (HEMA) forming random copolymer with some block characteristics in a controlled manner. The polyzwitterionic copolymer P(MAESx-ran-HEMAy) (PMxHy, where x and y were the degrees of polymerization of MAES and HEMA, respectively), which bearing hydroxyl groups that served as both reducing and capping reagent for in situ AgNPs synthesis without exogenous additions. The in situ formed uniform AgNPs composites adopted a typical “core-shell” structure where AgNPs served as cores, and PMH were shells. The stability of the AgNPs composites was promoted by chelation of AgNPs core and the generated aldehyde on PMH during silver ions (Ag+ ions) reduction. Size of the AgNPs composites directly correlated with [MAES] to [HEMA] ratio in PMH and the highest yield of AgNPs composites was achieved when PM20H27 to AgNO3 weight ratio equaled 30%. The AgNPs composites originating from PM50H26 showed the most potent bactericidal activity through the membrane perturbation mechanism. Besides, the AgNPs composites confirmed safe for mammalian cells by hemolysis and cytotoxicity tests.

Cationic amphiphilic cellulose copolymers were prepared through grafting hydrophobic poly (p-dioxanone) (PPDO) chains onto hydrophilic quaternized cellulose derivatives (QC) via ring-opening polymerization (ROP) reaction, which was performed in 1-butyl-3-methylimidazolium chloride (BmimCl) and using 4-dimethylaminopyridine (DMAP) or 1,8-diazabicyclo (5.4.0) undec-7-ene (DBU) as catalyst. Their chemical structures and physical properties were confirmed by FT-IR, 1H-, 13C-, 2D HSQC-NMR, X-ray diffraction (XRD), and thermal stability (TGA) techniques, while self-assembly behavior was characterized by dynamic light scattering (DLS), transmission electron microscopy (TEM) and fluorescence techniques. Both of the sizes and critical micelle concentration (CMC) values of micelles were decreased with increasing grafting contents of PPDO in the copolymers, which were in the ranges of 110–246 nm and 64–253 μg/mL, respectively. The ζ-potentials of micelles were cationic andranged from 39.1 mV to 45.4 mV. The highest encapsulation efficiencyof paclitaxel (PTX) into the micelles was 61.8% and 92.0% of loaded PTX was continuously released from micelles in phosphate buffered saline medium for 36 h.

The use of chitosan natural polymers to replace synthetic polymers is of interest as part of the green materials movement. However, a major challenge of using chitosan material is its rigid and brittle nature associated primarily with its intra- and inter-molecular hydrogen bonds creating a hydrogen bond network. Plasticizers are able to make chitosan flexible, hypothetically by destroying its hydrogen bond networks. Herein, we showed the importance and complicated nature of the chitosan’s hydrogen bond network with respect to its flexibility, through a comparative study of glycerol and ionic liquids plasticizers. The results demonstrated that glycerol’s hydrogen bonding was able to disrupt the chitosan’s hydrogen bond network resulting in a flexible film, but ionic liquids, even with their very strong hydrogen bonding, were not able to plasticize chitosan. This result suggested that the plasticization phenomenon was more complicated than hydrogen bond disruption. A molecular level study by quantum chemistry calculation showed that the efficiency of glycerol as chitosan plasticizer was due to its single hydrogen bonding site, which breaks down the chitosan hydrogen bonding networks, and leave hydrophobic C-H ending groups to limit the formation of inter molecular hydrogen bonds.

Soluble microbial products (SMPs) are of significant concern in the natural environment and in engineered systems. In this work, poly-γ-glutamic acid (γ-PGA), which is predominantly produced by Bacillus sp., was investigated in terms of pH-induced conformational changes and molecular interactions in aqueous solutions; accordingly, its sedimentation coefficient distribution and viscosity were also elucidated. Experimental results indicate that pH has a significant impact on the structure and molecular interactions of γ-PGA. The conformation of the γ-PGA acid form (γ-PGA-H) is rod-like while that of the γ-PGA sodium form (γ-PGA-Na) is sphere-like. The transformation from α-helix to random coil in the γ-PGA secondary structure is primarily responsible for this shape variation. The intramolecular hydrogen bonds in the γ-PGA-H structure decrease and intramolecular electrostatic repulsion increases as pH increases; however, the sedimentation coefficient distributions of γ-PGA are dependent on intermolecular interactions rather than intramolecular interactions. Concentration has a more substantial effect on intermolecular electrostatic repulsion and chain entanglement at higher pH values. Consequently, the sedimentation coefficient distributions of γ-PGA shift significantly at pH 8.9 from 0.1 to 1.0 g/L, and the viscosity of γ-PGA (5% w/v) significantly increases as pH increases from 2.3 to 6.0.

To illuminate changes in the thermal stability of lignocellulosic biomass by homogeneous chemical modification in ionic liquids, sugarcane bagasse derivatives bearing carboxyl groups were prepared in ionic liquids. Fourier transform infrared (FT-IR) spectroscopy and solid-state nuclear magnetic resonance (NMR) confirmed the chemical structure of the derivatives. Sugarcane bagasse derivatives with degree of substituted OH as high as 9.93 mmol/g were achieved. The homogeneous esterification was demonstrated to be a more efficient approach than heterogeneous ones. Based on thermogravimetric analysis, the onset degradation temperature of sugarcane bagasse decreased dramatically to 185 °C, 160 °C and 140 °C, using succinic anhydride, maleic anhydride, and phthalic anhydride as reagent, respectively. A first-order degradation kinetic model was applied to obtain the degradation activation energies of sugarcane bagasse. The results showed that homogeneous chemical modification significantly decreased the thermal stability of sugarcane bagasse by reducing the onset degradation temperature and degradation activation energies.

A series biodegradable poly (γ-glutamic acid)/beta-tricalcium phosphate (γ-PGA/TCP) nanocomposites were prepared which were composed of poly-γ-glutamic acid polymerized in situ with β-tricalcium phosphate and physiochemically characterized as bone graft substitutes. The particle size via dynamic light scattering, the direct morphological characterization via transmission electron microscopy and field emission scanning electron microscope, which showed that γ-PGA and β-TCP were combined compactly at 80℃, and the γ-PGA/TCP nanocomposites had homogenous and nano-sized grains with narrow particle size distributions. The water uptake and retention abilities, in vitro degradation properties, cytotoxicity in the simulated medium, and protein release of these novel γ-PGA/TCP composites were investigated. Cell proliferation in composites was nearly twice than β-TCP when checked in vitro using MC3T3 cell line. We also envision the potential use of γ-PGA/TCP systems in bone growth factor or orthopedic drug delivery applications in future bone tissue engineering applications. These observations suggest that the γ-PGA/TCP are novel nanocomposites with great potential for application in the field of bone tissue engineering.