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In this study, three series of chitosan derivatives bearing imidazole rings, including the Schiff‐bases of chitosan, N‐substituted chitosan, and quaternized chitosan are designed and synthesized. The structures of these chitosan derivatives are verified by FT‐IR and 1H NMR, and their antioxidant, antibacterial, and antifungal activities are tested. The Schiff‐bases of chitosan and N‐substituted chitosan have similar biological properties compared with chitosan. Derivatives 2IMTMC, 4IMTMC, MIMTMC, and BIMTMC exhibit significant antioxidant ability and antifungal activity, especially derivative BIMTMC. All the quaternized chitosan remarkably inhibits Escherichia coli, Staphylococcus aureus, and Vibrio harvey, especially derivative BIMTMC, whose minimum inhibitory concentration values are 0.03125, 0.0625, and 0.03125 mg mL−1, respectively. The results indicated that quaternized chitosan are synergistic with imidazole groups and have the better antioxidant, antifungal, and antibacterial properties than chitosan, which can be used as drug materials for antioxididant and antimicrobial purposes. [ABSTRACT FROM AUTHOR]

pH-responsive nanogels have played an increasingly momentous role in tumor treatment. The focus of this study is to design and develop pH-responsive benzimidazole-chitosan quaternary ammonium salt (BIMIXHAC) nanogels for the controlled release of doxorubicin hydrochloride (DOX) while enhancing its hydrophilicity. BIMIXHAC is crosslinked with carboxymethyl chitosan (CMC), hyaluronic acid sodium salt (HA), and sodium alginates (SA) using an ion crosslinking method. The chemical structure of chitosan derivatives was verified by 1H NMR and FT-IR techniques. Compared to hydroxypropyl trimethyl ammonium chloride chitosan (HACC)-based nanogels, BIMIXHAC-based nanogels exhibit better drug encapsulation efficiency and loading capacity (BIMIXHAC-D-HA 91.76 %, and 32.23 %), with pH-responsive release profiles and accelerated release in vitro. The series of nanogels formed by crosslinking with three different polyanionic crosslinkers have different particle size potentials and antioxidant properties. BIMIXHAC-HA, BIMIXHAC-SA and BIMIXHAC-CMC demonstrate favorable antioxidant capability. In addition, cytotoxicity tests showed that BIMIXHAC-based nanogels have high biocompatibility. BIMIXHAC-based nanogels exhibit preferable anticancer effects on MCF-7 and A549 cells. Furthermore, the BIMIXHAC-D-HA nanogel was 2.62 times less toxic than DOX to L929 cells. These results suggest that BIMIXHAC-based nanogels can serve as pH-responsive nanoplatforms for the delivery of anticancer drugs. [ABSTRACT FROM AUTHOR]

Herein, imidazole acids grafted chitosan derivatives were synthesized, including HACC, HACC derivatives, TMC, TMC derivatives, amidated chitosan and amidated chitosan bearing imidazolium salts. The prepared chitosan derivatives were characterized by FT-IR and 1H NMR. The tests evaluated the biological antioxidant, antibacterial, and cytotoxic activities of chitosan derivatives. The antioxidant capacity (DPPH radical, superoxide anion radical and hydroxyl radical) of chitosan derivatives was 2.4–8.3 times higher than that of chitosan. The antibacterial capacity against E. coli and S. aureus of cationic derivatives (HACC derivatives, TMC derivatives, and amidated chitosan bearing imidazolium salts) was more active than only imidazole-chitosan (amidated chitosan). In particular, the inhibition effect of HACC derivatives on E. coli was 15.625 μg/mL. Moreover, the series of chitosan derivatives bearing imidazole acids showed certain activity against MCF-7 and A549 cells. The present results suggest that the chitosan derivatives in this paper seem to be promising carrier materials for use in drug delivery systems. [Display omitted] [ABSTRACT FROM AUTHOR]