Search Results (5)

In this study, self-healing hydrogels were created using oxidized hydroxybutanoyl glycan (OHbG) and quaternized carboxymethyl chitosan (QCMCS), displaying antioxidant and antibacterial properties for pH-responsive drug delivery. The structures of the modified polysaccharides were confirmed through ¹H NMR analysis. Double crosslinking in the hydrogel occurred via imine bonds (between the aldehyde group of OHbG and the amine group of QCMCS) and ionic interactions (between the carboxyl group of OHbG and the quaternized group of QCMCS). The hydrogel exhibited self-healing properties and improved thermal stability with an increase in OHbG concentration. The OHbG/QCMCS hydrogel demonstrated high compressive strength, significant swelling, and large pore size. Drug release profiles varied between pH 2.0 (96.57%) and pH 7.4 (63.22%). Additionally, the hydrogel displayed antioxidant and antibacterial effects without compromising the polysaccharides’ inherent characteristics. No cytotoxicity was observed in any hydrogel samples. These findings indicate that the OHbG/QCMCS hydrogel is a biocompatible and stimuli-responsive drug carrier, with potential for various pharmaceutical, biomedical, and biotechnological applications. Full article

The azide transfer reaction and copper(I)-catalyzed alkyne-azide cycloaddition (CuAAC) can be used to convert the amino groups in chitosan to triazole 1,2,3-moieties. The resulting polymer has been named chitotriazolan. This synthesis was performed with six different quaternary ammonium alkynes and three amine alkynes to obtain a series of nine water-soluble chitotriazolan derivatives. The structure and complete conversion of the azide were confirmed by FT-IR and proton NMR spectroscopy. The derivatives were investigated for antibacterial activity against S. aureus, E. faecalis, E. coli, and P. aeruginosa. The activity of the quaternized chitotriazolan derivatives varied depending on the structure of the quaternary moiety and the species of bacteria. The basic protonable derivatives were less active or inactive against the bacteria. Full article

An effective drug nanocarrier was developed on the basis of a quaternized aminated chitosan (Q-AmCs) derivative for the efficient encapsulation and slow release of the curcumin (Cur)-drug. A simple ionic gelation method was conducted to formulate Q-AmCs nanoparticles (NPs), using different ratios of sodium tripolyphosphate (TPP) as an ionic crosslinker. Various characterization tools were employed to investigate the structure, surface morphology, and thermal properties of the formulated nanoparticles. The formulated Q-AmCs NPs displayed a smaller particle size of 162 ± 9.10 nm, and higher surface positive charges, with a maximum potential of +48.3 mV, compared to native aminated chitosan (AmCs) NPs (231 ± 7.14 nm, +32.8 mV). The Cur-drug encapsulation efficiency was greatly improved and reached a maximum value of 94.4 ± 0.91%, compared to 75.0 ± 1.13% for AmCs NPs. Moreover, the in vitro Cur-release profile was investigated under the conditions of simulated gastric fluid [SGF; pH 1.2] and simulated colon fluid [SCF; pH 7.4]. For Q-AmCs NPs, the Cur-release rate was meaningfully decreased, and recorded a cumulative release value of 54.0% at pH 7.4, compared to 73.0% for AmCs NPs. The formulated nanoparticles exhibited acceptable biocompatibility and biodegradability. These findings emphasize that Q-AmCs NPs have an outstanding potential for the delivery and slow release of anticancer drugs. Full article

In order to improve the bioactivity of chitosan, we synthesized a novel series of chitosan derivatives: firstly, chitosan was reacted with methylclhlorofonmate obtaining N-methoxyformylated chitosan (1), which was then converted into N-pyridylurea chitosan derivatives (2a-2c) by amine-ester exchange reaction. In addition, N-pyridylurea chitosan derivatives were conducted by reacting with iodomethane to obtain quaternized N-pyridylurea chitosan derivatives (3a-3c). The structural characteristics of as-prepared chitosan derivatives were confirmed by fourier transform infrared (FT-IR), ¹H nuclear magnetic resonance (¹H NMR), elemental analysis, and scanning electron microscope (SEM). Meanwhile, the antioxidant activity of the chitosan derivatives was assessed in vitro. As shown in this paper, the antioxidant activity decreased in the order: c > b > a. Moreover, after the quaternization with iodomethane, quaternized N-pyridylurea chitosan derivatives immediately exhibited enhanced antioxidant capacity compared with N-pyridylurea chitosan derivatives. For example, in 1,1-Diphenyl-2-picrylhydrazyl (DPPH) radical scavenging assay, the scavenging activities of 3a-3c were 91.75%, 93.63%, and 97.63% while 2a-2c were 42.32%, 42.97%, and 43.07% at 0.4 mg/mL. L929 cells were also adopted for cytotoxicity test of chitosan and synthesized derivatives by CCK-8 assay and all samples showed decreased cytotoxicity. These results suggested that the novel pyridylurea-functionalized chitosan derivatives could be an ideal biomaterial. Full article

Chitosan, which is derived from a deacetylation reaction of chitin, has attractive antimicrobial activity. However, chitosan applications as a biocide are only effective in acidic medium due to its low solubility in neutral and basic conditions. Also, the positive charges carried by the protonated amine groups of chitosan (in acidic conditions) that are the driving force for its solubilization are also associated with its antimicrobial activity. Therefore, chemical modifications of chitosan are required to enhance its solubility and broaden the spectrum of its applications, including as biocide. Quaternization on the nitrogen atom of chitosan is the most used route to render water-soluble chitosan-derivatives, especially at physiological pH conditions. Recent reports in the literature demonstrate that such chitosan-derivatives present excellent antimicrobial activity due to permanent positive charge on nitrogen atoms side-bonded to the polymer backbone. This review presents some relevant work regarding the use of quaternized chitosan-derivatives obtained by different synthetic paths in applications as antimicrobial agents. Full article