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Skin wound dressing materials, which can accelerate wound healing and have the synthetic advantages of simplicity, environmental safety, and resource abundance, are becoming a hot topic of research now. Following such a research trend, we prepared novel decanoic acid functionalized chitosan (CSDA) with good solubility by acylation via a facile one-step method. FTIR, 1H NMR, and UV–Vis results demonstrated that alkyl chains were successfully grafted onto C2 positions of chitosan (CS) skeleton through acylation. XRD patterns implied that the crystallinity of CSDA greatly declined due to the introduction of alkyl moieties, favorable for improving water solubility. Conductometric titration results showed that the degrees of substitution of CSDA, CSDA1, and CSDA2 were 41.42, 26.12, and 23.17%, respectively. MTT assay and hemolysis experiments illustrated that all the CSDA samples tested in this work possessed good hemocompatibility (hemolysis rate < 2%) and excellent cytocompatibility (relative cell viability >75%) toward L929 cells. Moreover, CSDA-soaked gauze dressings and full-thickness excisional wound models were employed to estimate the feasibility of CSDA as wound dressing material, and the results displayed that CSDA with the degree of substitution of 41.42% could enhance the wound healing rate to 100% on day 16. Altogether, CSDA might be potential material used as wound dressing. • Decanoic acid functionalized chitosan (CSDA) was prepared via a one-step method. • CSDA with a substitution degree of 41.42% had better solubility than chitosan (CS). • CSDA possessed excellent hemocompatibility and good cytocompatibility toward L929. • CSDA-loaded gauze used as wound dressing greatly promoted wound healing in rats. [ABSTRACT FROM AUTHOR]

This work aims to synthesize poly(aminoethyl) modified chitin (PAEMC) and ascertain its antibacterial activity and mechanism. FTIR and 1 H NMR results proved aminoethyl moieties were grafted to C6 OH and C3 OH on chitin backbone in the form of polymerization. XRD and TG/DTG analyses manifested its well-defined crystallinity and thermostability. PAEMC, with average molecular weight (MW) of 851.0 kDa, degree of deacetylation (DD) of 27.95%, and degree of substitution (DS) of 1.77, had good solubility in aqueous solutions over the pH range of 3–12, and also possessed high antimicrobial activity against Staphylococcus epidermidis , Staphylococcus aureus , Pseudomonas aeruginosa , Escherichia coli , Bacillus proteus , and Klebsiella pneumoniae , commonly causing chronic wound infections. Nucleic acid release, protein leakage, increased inner membrane permeability, and decreased cell surface hydrophobicity implied bacterial cytomembranes were substantially compromised in the presence of PAEMC. Microscopically, PAEMC visually perturbed bacteria, illustrating deformed and even collapsed morphologies. Overall, PAEMC possessed good solubility, effectively destroyed bacteria via a membrane damage mechanism, and might serve as an antibacterial agent for treatments of chronic wound infections. [ABSTRACT FROM AUTHOR]

This work aims to prepare 3,6- O - N -acetylethylenediamine modified chitosan (AEDMCS) and evaluate its potential use as an antimicrobial wound dressing material. UV, FTIR, and 1 H NMR results demonstrated N -acetylethylenediamine groups were successfully grafted to C3 OH and C6 OH on polysaccharide skeletons. TGA, XRD, and solubility tests indicated that as compared with chitosan, AEDMCS had diminished thermostability, decreased crystallinity, and greatly improved solubility. AEDMCS, with degrees of deacetylation and substitution being respectively 90.3% and 0.72, exhibited higher antibacterial activity than chitosan against six bacteria generally causing wound infections. Meanwhile, AEDMCS had permissible hemolysis and cytotoxicity and low BSA adsorption even at a AEDMCS concentration of 25 mg/mL. Acute toxicity tests showed AEDMCS was nontoxic. Moreover, the wound healing property was preliminarily evaluated, illustrating that AEDMCS enhanced wound healing rates as expected and had no significant differences as compared with chitosan. These results suggested AEDMCS might be a potential material used as antibacterial wound dressings. [ABSTRACT FROM AUTHOR]

A novel adsorbent, composed of poly(maleic acid)-grafted cross-linked chitosan microspheres (PMACCMs), was prepared via cross-linking with glutaraldehyde and modification by grafting maleic acid. FTIR, zeta potential, elemental analysis, 13 C NMR, DTG, laser particle size analysis, SEM, and BET methods were applied to characterize PMACCMs, exhibiting a successful fabrication, good thermostability, and well-defined surface microstructure beneficial to Cd(II) adsorption. The effects of pH, contact time, and initial concentration on Cd(II) adsorption were also investigated, and the maximum adsorption capacity was 39.2 mg g −1 , indicating a great improvement as compared with that (14.5 mg g −1 ) of cross-linked chitosan microspheres. The experimental data were well fitted with pseudo-second-order kinetic and Langmuir isotherm models. Five-cycle reusability tests demonstrated PMACCMs could be repeatedly used with a small adsorption capacity loss (<15%). Additionally, the adsorption mechanism was proposed. All the results confirmed that PMACCMs, which presented outstanding adsorption capability and reusability, could be a good candidate for wastewater purification. [ABSTRACT FROM AUTHOR]

This study aims to develop new antibacterial hydrogel wound dressings composed of poly(aminoethyl) modified chitosan (PAEMCS). FTIR, 1 H NMR, and elemental analysis demonstrated that PAEMCS was successfully synthesized via grafting poly(aminoethyl) groups onto hydroxyl groups on chitin first, and removing acetyl groups from the grafted polymer afterward. XRD and TGA implied its well-defined crystallinity and thermostability. Furthermore, a series of hydrogels were fabricated under the participation of dipotassium hydrogen phosphate (DHP). The gelation tests suggested that the higher concentration of PAEMCS or DHP was beneficial to the formation of hydrogels. The pH values of hydrogels at 37 °C were all in the range of 7.12–7.50. The rheological tests indicated that PAEMCS-based hydrogels were of lower DHP addition and higher elasticity than CS-based hydrogels to achieve the same gelation temperature under the same polymer’s concentration. Additionally, the swelling, anti-bacteria, and cytotoxicity experiments showed that PAEMCS-based hydrogels possessed excellent hygroscopicity, high antibacterial activity against E. coli , S. aureus , or S. epidermidis , and good cytocompatibility toward L929 cells or HUVECs, respectively. All the results implied that PAEMCS-based hydrogels not only maintained inherent multiple properties of chitosan but also possessed excellent antibacterial activity, and might be promising antibacterial hydrogel dressings used in wound therapy. [ABSTRACT FROM AUTHOR]

This work aims to synthesize a novel itaconic acid (IA) grafted carboxymethyl chitosan (PICMCS), and further fabricate its nanoparticles for potential biomedical applications. First, PICMCS was prepared via free-radical polymerization of IA monomer, in the presence of ammonium persulfate as an initiator and nitrogen as a protector. Its chemical structure was confirmed by FTIR and 1 H NMR. The IA substitution degree calculated by elemental analysis data was 1.85, implying that IA was successfully grafted to carboxymethyl chitosan (CMCS). XRD and TGA patterns illustrated its well-defined crystallinity and thermostability. Second, PICMCS nanoparticles were fabricated by electrostatic attraction between carboxyl and amino groups in the absence of any additional agent, which were of obvious core-shell structures with an average particle size of 144 nm and a polydispersity index of 0.11. PICMCS nanoparticles exhibited excellent physical stability after storage at 25 °C for 30 days, without any aggregation. PICMCS nanoparticles with high negative surface charge also indicated the good stability, especially in neutral or alkaline media. Additionally, the cytotoxicity experiments showed that either PICMCS or its nanoparticles had better cytocompatibility toward L929 cells than CMCS. These findings above suggested that PICMCS was a kind of promising material for preparing nanoparticles used in biomedical field. [ABSTRACT FROM AUTHOR]

Thermosensitive hydrogels whose physiological properties are similar to extracellular matrix have been extensively used for tissue regeneration. Polysaccharides and proteins, as biocompatible substrates similar to bio-macromolecules that could be recognized by human body, are two preferred polymers for fabrication of such hydrogels. A series of novel thermosensitive hydrogels (CS-ASC-HGs) containing chitosan (CS) and acid-soluble collagen (ASC) were thus prepared, in the presence of α, β-glycerophosphate, to mimic extracellular microenvironment for tissue regeneration. Rheological measurements demonstrated excellent thermosensitivity. FT-IR and SEM indicated CS-ASC-HGs possessed 3D porous architectures with fibrous ASC, and the molecular structure of ASC was well-maintained in hydrogels. Hemolysis, acute toxicity, and cytotoxicity tests suggested CS-ASC-HGs were of good biocompatibility. CS-ASC-HGs were able to support the survival and proliferation of L929 cells encapsulated in them. Moreover, CS-ASC-HGs had better pH stability and biocompatibility than pure CS hydrogel. These results suggested that CS-ASC-HGs could serve as promising scaffolds for tissue regeneration. [ABSTRACT FROM AUTHOR]

Injectable thermosensitive hydrogels have widely been studied as drug delivery systems for their minimally invasive administration and localized drug release. However, burst drug release limits clinical applications of such hydrogels. A double-component injectable formulation (microspheres-loaded hydrogel, CMs-CS-HG) was thus fabricated to eliminate the limitation. Gelation temperature, gelation time, complex viscosity and syringeability tests for CMs-CS-HG demonstrated excellent injectability. After injection, the drug-loaded chitosan-based microspheres (CMs) were localized within the hydrogel, leading to localized drug release. Moreover, CMs-CS-HG had good hemocompatibility and histocompatibility, and had non-genotoxicity and non-cytotoxicity to Kunming mice. In addition, both in vitro and in vivo methotrexate (MTX) releasing efficiencies were evaluated, demonstrating long-term sustained MTX release from MTX-loaded CMs-CS-HG. These results showed the double-component CMs-CS-HG not only maintained good injectability and biocompatibility but also prolonged drug-releasing time in comparison with the single-component CS-HG or CMs, suggesting that CMs-CS-HG may be a promising drug delivery system. [ABSTRACT FROM AUTHOR]

The present work aimed to develop two kinds of novel adsorbents, carboxylated chitosan magnetic microspheres (EDCMM) and submicrospheres (EDCMSM), for comparative study of Pb 2+ removal. Several techniques, including SEM, TEM, FTIR, BET and VSM, were applied to characterize the adsorbents. Batches of tests were conducted to investigate the Pb 2+ adsorption at different pH values, contact time, initial Pb 2+ concentrations and temperatures. EDCMSM with higher specific surface area and a lower content of carboxyl had faster initial absorbing rate but lower adsorption capacity for Pb 2+ than that of EDCMM. The adsorption processes for both EDCMM and EDCMSM fitted well with pseudo-second-order model and were dominated by chemical reaction process. The isotherm data for both adsorbents were well described by the Langmuir model, which suggested monolayer adsorptions. Thermodynamics analysis suggested that the adsorption processes of both EDCMM and EDCMSM were endothermic and spontaneous in nature. Both adsorbents still exhibited good adsorption performances after the fifth adsorption–regeneration cycle. All these results indicated that both EDCMM and EDCMSM might be promising adsorbents for the Pb 2+ removal. [ABSTRACT FROM AUTHOR]

Chitosan- N -2-hydroxypropyl trimethyl ammonium chloride (QTS) was prepared by reaction of chitosan (CS) and glycidyl trimethylammonium chloride. Later, O -acetyl-chitosan- N -2-hydroxypropyl trimethyl ammonium chloride (AQTS) was synthesized by reaction of QTS with acetic acid in the presence of SOCl 2 . Both derivatives were characterized by FTIR, 1 H NMR, TGA, and XRD techniques. The degree of quaternization of QTS was 85.5%, and the degree of acetyl (DA) of AQTS was from 1.63 to 2.31. Compared with CS, the solubility of QTS and AQTS was improved at different levels, especially AQTS, it could be dissolved in many organic solvents, water, and aqueous solution. Notably, the solubility of AQTS in organic solvents increased as DA increased, while the solubility in water was reversed. The results of CS, QTS, and AQTS against Escherichia coli and Staphylococcus aureus showed that QTS and AQTS exhibited higher antibacterial activity than CS, and the antibacterial activity of AQTS decreased with increased DA. Moreover, the inhibition effect was AQTS1 (DA 1.63) > AQTS2 (DA 2.02) > QTS > AQTS3 (DA 2.31). On the basis of the results of the present study, it could be emphasized that hydrophobicity and positive charge density might strongly affect the antibacterial activity of quaternary ammonium chitosan derivatives. [ABSTRACT FROM AUTHOR]

A novel amphipathic chitosan derivative, N -benzoyl- O -acetyl-chitosan (BACS), was prepared by using the selective partial acylation of chitosan (CS), benzoyl chloride, and acetic acid under high-intensity ultrasound. The chemical structure and physical properties of BACS were characterized by FTIR, 1 H NMR, TGA, and XRD techniques. The degrees of substitution of benzoyl and acetyl for the chitosan derivatives were 0.26 and 1.15, respectively, which were calculated from the peak areas in NMR spectra by using the combined integral methods. The foaming properties of CS and BACS were determined and the results suggested BACS had better foam capacity and stability than those of chitosan. In addition, the antimicrobial activities of CS and BACS were also investigated against two species of bacteria ( Escherichia coli and Staphylococcus aureus ) and a fungus ( Aspergillus niger ), the results indicated that the antibacterial and antifungal activities of BACS were much stronger than those of the parent chitosan. These findings suggested that BACS was preferable for use as a food additive with a dual role of both foaming agent and food preservative. [ABSTRACT FROM AUTHOR]