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To fabricate multifunctional nanoparticles (NPs) based on chitosan (CS) derivative, we first prepared quaternized CS (2-hydroxypropyltrimethyl ammonium chloride CS, HTCC) via a one-step approach, then synthesized p-coumaric acid (p-CA) modified HTCC (HTCC-CA) for the first time through amide reaction, and finally fabricated a series of NPs (HTCC-CA NPs) using HTCC-CAs with different substitution degrees and sodium tripolyphosphate (TPP) by ionic gelation. Newly-prepared HTCC and HTCC-CAs were characterized by FT-IR, 1 H NMR, elemental analysis (EA), full-wavelength UV scanning, silver nitrate titration, and Folin-Ciocalteu methods. DLS and TEM results demonstrated that three selected HTCC-CA NPs had moderate size (< 350 nm), good dispersion (PDI < 0.4), and positive zeta potential (11-20 mV). The HTCC-CA NPs had high antibacterial activity against six bacterial strains, and the minimum inhibitory concentration (MIC) values were almost the same as the minimum bactericidal concentration (MBC) values (250-1000 μg/mL). Also, the HTCC-CA NPs had good antioxidation (radical scavenging ratio > 65 %) and low cytotoxicity (relative cell viability >80 %) to the tested cells. Totally, HTCC-CA NPs with high antibacterial activity, great antioxidation, and low cytotoxicity might serve as new biomedical materials for promoting skin wound healing., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)

In this study, porous hemostatic sponges (CGS1, CGS2 and CGS3) with proper absorption (38-43×) and air permeability (2214 g/m 2 ·day) were prepared from l-glutamine-modified chitosan (CG), tannic acid-modified gelatin (GTA), and oxidized dextran (ODEX) by Schiff base crosslinking reaction. Among them, CGS2 was proved to have high porosity (88.98 %), durable water retention (>6 h), strong antibacterial activity, proper mechanical quality, and suitable tissue adhesion. In addition, CGS2 had good biocompatibility, mainly manifested in low hemolysis rate (<0.4 %), low cytotoxicity (relative cell activity>90 %), and good biodegradability in vitro. The hemostatic time and blood loss in CGS2 group were much lower than those in commercial gelatin sponge group in three animal injury models. Moreover, the activated partial thromboplastin time (APTT) and the prothrombin time (PT) results indicated that CGS2 promoted coagulation by activating the endogenous coagulation pathway. These results suggested that CGS2 had great potential for rapid hemostasis and avoidance of wound infection., Competing Interests: Declaration of competing interest The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article., (Copyright © 2023 Elsevier B.V. All rights reserved.)

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., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

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, 1 H 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., (Copyright © 2019 Elsevier B.V. All rights reserved.)

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 C3OH and C6OH 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 25mg/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., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

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 144nm and a polydispersity index of 0.11. PICMCS nanoparticles exhibited excellent physical stability after storage at 25°C for 30days, 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., (Copyright © 2017 Elsevier B.V. All rights reserved.)

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., (Copyright © 2017 Elsevier B.V. All rights reserved.)

DNA/chitosan co-assemblies were initially used as nanocarriers for efficient astaxanthin encapsulation and delivery. The obtained astaxanthin-loaded DNA/chitosan (ADC) colloidal system was transparent and homogenous, with astaxanthin content up to 65μg/ml. Compared to free astaxanthin, ADC nanoparticles with an astaxanthin concentration as low as 3.35nM still showed a more powerful cytoprotective effect on H 2 O 2 -induced oxidative cell damage, and improved cell viability from 49.9% to 61.9%. The ROS scavenging efficiency of ADC nanoparticles was as high as 54.3%, which was 2-fold higher than that of free astaxanthin. Besides this, ADC nanoparticles were easily engulfed by Caco-2 cells in a short time, indicating that the encapsulated astaxanthin could be absorbed through endocytosis by intestinal epithelial cells. The improved antioxidation capability and facilitated cellular uptake enabled the ADC nanoparticles to be good candidates for efficient delivery and absorption of astaxanthin., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

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., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

A novel chitosan derivative, 3,6-O-[N-(2-aminoethyl)-acetamide-yl]-chitosan (AACS), was successfully prepared to improve water solubility and antibacterial activity of chitosan. AACS had good antibacterial activity, with minimum inhibitory concentrations of 0.25mg/mL, against Escherichia coli and Staphylococcus aureus. Cell membrane integrity, electric conductivity and NPN uptake tests showed that AACS caused quickly increasing the release of intracellular nucleic acids, the uptake of NPN, and the electric conductivity by damaging membrane integrity. On the other hand, hydrophobicity, cell viability and SDS-PAGE experiments indicated that AACS was able to reduce the surface hydrophobicity, the cell viability and the intracellular proteins through increasing membrane permeability. SEM observation further confirmed that AACS could kill bacteria via disrupting their membranes. All results above verified that AACS mainly exerted antibacterial activity by a membrane damage mechanism, and it was expected to be a new food preservative., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

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 SOCl2. 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., (Copyright © 2015 Elsevier B.V. All rights reserved.)

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., (Copyright © 2015 Elsevier B.V. All rights reserved.)

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]

Adipic acid dihydrazide (ADH) was used to cross-link carboxymethyl chitosan (CMCS) microspheres for Cu 2+ removal from aqueous solution. SEM, FTIR, XPS and BET techniques were performed to characterize the ADH cross-linked CMCS (ADH-CMCS) microspheres. The effects on adsorption capacities of pH value, adsorption time, and initial Cu 2+ concentration were investigated. The adsorption experiments demonstrated ADH-CMCS microspheres had high adsorption capacity for Cu 2+ removal. Furthermore, in order to investigate the effect of ADH in ADH-CMCS microspheres on Cu 2+ adsorption, cross-linking experiments and XPS tests were carried out to reveal the adsorption mechanism. The results suggested that ADH in ADH-CMCS microspheres had a compensation action on its consumption of binding sites for Cu 2+ adsorption. The XPS etching results showed cross-linking reaction occurred mainly on the surfaces of the microspheres. The kinetics of Cu 2+ adsorption on ADH-CMCS microspheres complied with the pseudo-second-order model, indicating a chemical reaction process. The adsorption data analysis using three different adsorption isotherm models indicated that ADH-CMCS microspheres were of heterogeneity surfaces. Moreover, the ADH-CMCS microspheres still exhibited good adsorption performances after the fifth adsorption-desorption cycle. [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]

This work aims to fabricate multifunctional hemostatic sponges (C-ODs). Porous C-ODs were first constructed by using capric acid-modified chitosan (CSCA) and oxidized dextrans (ODs) with different oxidation degrees. Batches of experiments showed that (i) CSCA (33.39% of grafting degree), ODs, and C-ODs (100–200 μm in pore size) were synthesized, evidenced by FT-IR, 1H NMR, elemental analysis, hydroxylamine hydrochloride titration, and SEM results; (ii) among C-ODs, C-OD 2 had appropriate porosity (85.0%), swelling (20 times its dry weight), absorption, water retention, water vapor transmission, and mechanical properties; (iii) C-OD 2 possessed low toxicity (relative cell viability > 86%), low hemolysis rate (0.65%), suitable tissue adhesion (4.74 kPa), and strong antibacterial efficacy (five strains); and (iv) C-OD 2 's dynamic blood clotting was within 30 s. In three animal injury models, C-OD 2 's hemostasis time and blood loss were fairly lower than commercial gelatin sponge. Totally, C-OD 2 might serve as an ideal hemostatic dressing. [Display omitted] [ABSTRACT FROM AUTHOR]

Glutaraldehyde-crosslinked chitosan microparticles (CGP) prepared via the inversed-phase emulsification were successively modified by epichlorohydrin (ECH) and amidinothiourea (AT) as novel adsorbent (CGPET) for selective removal of Hg(II) in solution. FTIR, EA, XPS, SEM-EDX, TG, DTG, and XRD results indicated that CGPET had ample −NH 2 and C S, relative rough surface, mean diameter of ~40 μm, great thermal stability, and crystalline degree of 2.4%, beneficial to the uptake of Hg(II). The optimum parameters (pH 5, dosage 1 g/L, contact time 4 h, and initial concentration 150 mg/L) were acquired via batches of adsorption experiments. Adsorption behavior was well described by the Liu isothermal and pseudo-second-order kinetics models, and the maximum adsorption capacity was 322.51 mg/g, surpassing many reported adsorbents. Regeneration and coexisting-ion tests demonstrated that CGPET had outstanding reusability (R r > 86.89% at the fifth cycle) and selectivity (R s > 93%). Besides, its potential adsorption sites and mechanisms were proposed. [Display omitted] • Chitosan-based microparticles (CGPET) were first fabricated via two-step grafting. • CGPET of 40 μm in size had good thermal stability and relative rough spherical surface. • CGPET had sound reusability and outstanding selectivity for Hg(II). • Adsorption capacity for Hg(II) was higher than the counterparts reported. [ABSTRACT FROM AUTHOR]