A new approach to chemically modified carboxymethyl chitosan and study of its moisture-absorption and moisture-retention abilities

Carboxymethyl chitosan and octadecylamine-coated liposome-containing WPTS: design, optimization, and evaluation

Liposomes (LPs) are a delivery system for stabilizing pharmaceuticals with limited use due to their propensity to congregate and fuse. A proposed method of addressing these problems is polymer coating. In this study, the potential of octadecylamine (ODA)-coated liposomes and carboxymethyl chitosan (CMCS/ODA-LPs) for enhancing Wacao pentacyclic triterpene saponin (WPTS) transport capacity was investigated. CMCS/ODA-LPs were produced by electrostatic adsorption and thin-film hydration. Response surface methodology (RSM) was employed to enhance the process and encapsulation efficiency (EE) for optimum drug encapsulation efficiency. The synthesized WPTS-CMCS/ODA-LPs were uniformly dispersed in a circular shape, and during 14 days of storage at 4 °C, the particle size and morphology did not significantly change. Vesicle size, zeta potential, polydispersity index (PDI), and entrapment efficiency (%) were 179.1 ± 7.31 nm, -29.6 ± 1.35 mV, 0.188 ± 0.052, and 75.62 ± 0.43, respectively. The hemolysis test revealed that WPTS-CMCS/ODA-LPs were sufficiently biocompatible. Compared to WPTS-LPs, WPTS-CMCS/ODA-LPs consistently showed a much more significant cytotoxic effect on cancer cells. Early and WPTS-CMCS/ODA-LPs-induced apoptosis resulted in almost seven times more cell death than the control. Compared to physiological pH 7.3, the pH-sensitive CMCS coupled LPs increased drug release at acidic pH 6.5. These findings suggest the efficacy of pH-sensitive CMCS/ODA-LPs as a medication delivery method for WPTS.

Screening Additives for Amending Compacted Clay Covers to Enhance Diffusion Barrier Properties and Moisture Retention Performance

The cover systems in contaminated sites have some problems, including desiccation cracks, which would lead to degradation of the barrier performance. This study presented a systemic laboratory experimental investigation on the liquid–plastic limit, moisture retention, hydraulic conductivity (k), and gas diffusion barrier properties of amended compacted clay by attapulgite and diatomite for controlling desiccation cracks and migration of water and volatile organic compounds (VOCs). The results showed that the attapulgite could enhance the moisture retention and liquid limit of amended compacted clay. Diatomite could reduce the gas diffusion coefficient (Dθ) significantly. The compacted clay amended by the dual-additives component of attapulgite and diatomite could enhance the liquid limit, moisture retention percent, gas barrier property, and hydraulic performance compared with the unamended clay. Based on the experimental data obtained, the dosage of additives was targeted to be 5%. The moisture retention percent of dual-additives (attapulgite 4% and diatomite 1%) amended clay increased by 82%, the k decreased by 25%, and the Dθ decreased by 42% compared with unamended clay. Scanning electron microscopy (SEM), BET-specific surface area test method (BET), Mercury Intrusion Porosimetry (MIP), and thermogravimetric analysis (TGA) indicated the enhancement mechanism of additives-amended compacted clay.

Succinyl chitosan gold nanocomposite: Preparation, characterization, in vitro and in vivo anticandidal activity

Herein, we have successfully synthesized a novel N-Succinyl chitosan/gold nanocomposite (N-SuC/Au NC) using N-SuC and gold(III) chloride, and investigated the biocompatibility and antifungal activity. The synthesized N-SuC/Au NC was characterized by UV-visible spectroscopy, X-ray diffraction, field emission scanning electron microscope, and inductively coupled plasma atomic emission spectroscopy. The N-SuC/Au NC exhibited a strong inhibition effect towards pathogenic Candida albicans. Morphological analysis revealed the destruction of C. albicans cell membrane due to N-SuC/Au NC treatment. The in vitro and in vivo toxicity of N-SuC/Au NC was analyzed with HEK293T mammalian cells and zebrafish larvae, respectively. The synthesized N-SuC/Au NC demonstrated no cytotoxicity towards HEK293T cells up to 1200 μg/mL concentration. The survival rate of the zebrafish larvae at 120 hpf, was found as 100% up to 1200 μg/mL of N-SuC/Au NC exposure. The in vivo studies further confirmed the inhibitory effects of N-SuC/Au NC on the formation of C. albicans hyphae in infected zebrafish muscle tissue.

Sponges of Carboxymethyl Chitosan Grafted with Collagen Peptides for Wound Healing

Burns are physically debilitating and potentially fatal injuries. Two marine biomaterials, carboxymethyl chitosan (CMC) and collagen peptides (COP), have emerged as promising burn dressings. In this paper, sponges of carboxymethyl chitosan grafted with collagen peptide (CMC–COP) were prepared by covalent coupling and freeze drying. Scanning electron microscopy (SEM) and Fourier transform infrared (FTIR) spectroscopy were then used to characterize the prepared sponges. To evaluate the wound healing activity of the CMC–COP sponges, in vitro tests including cell viability scratch wound healing and scald wound healing experiments were performed in rabbits. Appearance studies revealed the porous nature of sponges and FTIR spectroscopy demonstrated the successful incorporation of COP into CMC. The in vitro scratch assay showed that treatment with CMC–COP sponges (at 100 μg/mL) had significant effects on scratch closure. For burn wounds treated with CMC–COP, regeneration of the epidermis and collagen fiber deposition was observed on day 7, with complete healing of the epidermis and wound on days 14 and 21, respectively. Based on the pathological examination by hematoxylin and eosinstaining, the CMC–COP group demonstrated pronounced wound healing efficiencies. These results confirmed that the CMC–COP treatment enhanced cell migration and promoted skin regeneration, thereby highlighting the potential application of these sponges in burn care.

Preparation and characterization of N-chitosan as a wound healing accelerator

Chitosan is insoluble in water due to its rigid crystalline structure, which has significantly restricted its application in wound healing. The objective of this study was to synthesize a water-soluble chitosan derivative, N-succinyl-chitosan (NSC), and evaluate its ability to accelerate the wound healing process. NSC was synthesized with succinic anhydride, hydrochloric acid, and alkaline chitosan under optimized conditions, and characterized using Fourier transform infrared, proton nuclear magnetic resonance, and X-ray diffraction spectroscopy; thermal gravimetric analysis; and a solubility test. The cytotoxicity of NSC was investigated in L929 cells, and its antibacterial activity was evaluated by the inhibition zone method and bacterial growth curves analysis. The results showed that the solubility of NSC was substantially improved compared to chitosan, and NSC was non-toxic with good antibacterial properties. An animal wound healing test indicated that NSC could significantly reduce the healing time compared to chitosan. Histopathological examination suggested that the underlying mechanisms of these effects were related to NSC's ability to promote the formation of granulation tissue and enhance epithelialization. Collectively, these results demonstrate the good potential for NSC to be applied as a wound dressing material.

Utilization of carboxymethyl chitosan in cosmetics

Carboxymethyl chitosan is a chitosan derivative of the most intensively investigated due to its water solubility in wider pH range compared with the parent compound, thus extended its use in various applications. In this review, different preparation conditions, which resulting in the N- and O-carboxylated chitosan, diverse degree of substitution and water solubility are recapitulated. Five important features of carboxymethyl chitosan from recent studies, which are moisture absorption-retention, anti-microbial properties, antioxidant capacities, delivery system and emulsion stabilization, have been centred and emphasized for cosmetic utilization. Additionally, cytotoxicity information has been inclusively incorporated to ensure its safety in application.

Synthesis and anticoagulant activity of the quaternary ammonium chitosan sulfates

Quaternary ammonium chitosan sulfates with diverse degrees of substitution (DS) ascribed to sulfate groups between 0.52 and 1.55 were synthesized by reacting quaternary ammonium chitosan with an uncommon sulfating agent (N(SO(3)Na)(3)) that was prepared from sodium bisulfite (NaHSO(3)) through reaction with sodium nitrite (NaNO(2)) in the aqueous system homogeneous. The structures of the derivatives were characterized by FTIR, (1)H NMR and (13)C NMR. The factors affecting DS of quaternary ammonium chitosan sulfates which included the molar ratio of NaNO(2) to quaternary ammonium chitosan, sulfated temperature, sulfated time and pH of sulfated reaction solution were investigated in detail. Its anticoagulation activity in vitro was determined by an activated partial thromboplastin time (APTT) assay, a thrombin time (TT) assay and a prothrombin time (PT) assay. Results of anticoagulation assays showed quaternary ammonium chitosan sulfates significantly prolonged APTT and TT, but not PT, and demonstrated that the introduction of sulfate groups into the quaternary ammonium chitosan structure improved its anticoagulant activity obviously. The study showed its anticoagulant properties strongly depended on its DS, concentration and molecular weight.

Synthesis and Properties of N,N-Dimethyl-O-Quaternary Ammonium Chitosan

N,N-dimethyl-O-quaternary ammonium chitosan(NNQAC) was synthesized from chitosan by N-dimethylation then quaternized by 2,3-epoxy propyl trimethyl ammonium chloride. The structure of NNQAC was characterized by FTIR. Properties of quaternary ammonium chitosans, including solubility, antimicrobial activity, water-absorption and water-retention ability, were investigated. The results showed that NNQAC was water–soluble in neutral and basic environments. The moisture-absorption and retention abilities of NNQAC were higher than that of chitosan and equivalent to hyaluronic acid. The antibacterial activities of NNQAC were tested against Bacillus subtilis, Escherichia coli and Staphylococcus aureus. In water medium, NNQAC exhibited MIC values in the range of 10 to 2.5 μg/mL.