Carboxymethyl chitosan and carboxymethyl cellulose based self-healing hydrogel for accelerating diabetic wound healing.

In this study, a new type of biodegradable, injectable, self-healing, and low-toxic CMCSH, formed by N, O-carboxymethyl chitosan-heparin (CMCS-Hep) and carboxymethyl cellulose-aldehyde (CMC-A), was designed to deliver drug for promoting the progress of the diabetic wound healing. CMCS was modified with Hep for the first time to synthesize CMCS-Hep, and CMC-A was synthesized by the periodate oxidation method. First, SOD encapsulated in the CMCSH was applied to the diabetic wound bed to moderate the microenvironment, then rhEGF retained in the CMCSH was sustainedly released to the wound area. These results indicated that the dual-drug delivery system had the ability to improve drug availability, promote cell migration and proliferation, reduce DNA damage, shorten the inflammatory period, and accelerate the deposition of collagen fibers and the formation of blood vessels in the model with diabetic skin injury, suggesting that CMCSH as drug carriers had positive effects on diabetic wound healing.

Cr(VI) and Pb(II) capture on pH-responsive polyethyleneimine and chloroacetic acid functionalized chitosan microspheres.

PEI-ECH-CMCS microspheres (MPs) were first constructed via elaborately programmed procedures. Fourier transform infrared spectroscopy, conductometric titration, Brunauer-Emmett-Teller, X-ray diffraction, pH at zero point of charge (pHzpc), scanning electron microscopy, X-ray photoelectron spectroscopy, and swelling results demonstrated that chitosan-based adsorbent had ample -NH2 and -COOH, specific surface area of 29.040 m2/g, porous 3D architectures, pHzpc of 4.2, uniform spherical surfaces, narrow size distribution (19-33 µm), and pH-responsive swelling features, advantageous to Cr(VI) and Pb(II) capture. Adsorption parameters were obtained from batch experiments and pH 3 and 5 were chosen for Cr(VI) and Pb(II) capture. Pseudo-second-order kinetic and Liu isotherm models well interpreted adsorption behavior, and thermodynamic, isotherm, and kinetic studies revealed an exothermic, spontaneous, monolayer, and chemical adsorption process. Maximum adsorption capacity for Cr(VI) or Pb(II) was 331.32 or 302.56 mg/g, exceeding CS-based adsorbents reported. Excellent reusability and feasibility were evidenced by adsorption capacity loss < 12.10% and high removal efficiency for Cr(VI) (95.79%) and Pb(II) (91.40%) in synthetic effluents. Finally, potential adsorption mechanisms were proposed.

Characterization and antibacterial mechanism of poly(aminoethyl) modified chitin synthesized via a facile one-step pathway.

This work aims to synthesize poly(aminoethyl) modified chitin (PAEMC) and ascertain its antibacterial activity and mechanism. FTIR and 1H NMR results proved aminoethyl moieties were grafted to C6OH and C3OH 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.