Multiple chiroptical switches and logic circuit based on salicyl‒ imine‒chitosan hydrogel

Salicylaldehydediol Grafted onto Chitosan: Characterization and Their Film Properties

The concentrations of linker group effect different physicochemical features of the biopolymer, including thermal stability, shape, swelling, and water solubility. Herein, three novel chitosan (CH) based films (CHSD1-3) have been prepared by a facile method for their film characteristics. Thus, amphiphilic salicylaldehydediol (SD) was synthesized from hydrophilic glycidol and salicylaldehyde in high yield and regioselectivity. CHSD1-3 films were prepared by the imine condensation reaction of polymeric chitosan backbone and various ratios of SD linker. The reaction takes place with high conversation and amazingly mechanically resistant thickness films without using any plasticizer that exhibits low water solubility and low swelling ratios at pH > 3, which can be suggested as thin layer protecting systems for medical devices. Chitosan-salicylaldehydediol biopolymer films were characterized by Fourier transform infrared (FT-IR) spectroscopy, differential scanning calorimetry (DSC), and X-ray diffraction (XRD) methods. The FT-IR, DSC, and XRD results show a clear linkage of the SD group to the chitosan backbone, high thermal stability of the films, and a change in the original nature of chitosan, respectively. Scanning Electron Microscopy (SEM) observations have also supported the successful grafting of the SD group onto the chitosan.

Chitosan-salicylide Schiff base with aggregation-induced emission property and its multiple applications

Aggregation-induced emission (AIE) active compounds are fascinated due to their unique properties of limiting intramolecular rotation, and they have been developed in the biomedical fields. In this work, AIE material based on the Schiff base compound of chitosan (Cs) and salicylaldehyde (SA) was designed and synthesized. Cs-SA emits weak light in dilute aqueous solution, and emits bright light in concentrated solution and solid, showing obvious AIE performance. In addition, Cs-SA can also be used as a biosensor to detect Fe³⁺, and Cu²⁺, it has good bioimaging behavior. In addition, it can also be used as biosensor to quantitatively detect gram-positive bacteria and gram-negative bacteria, Moreover, Cs-SA shows excellent broad spectrum antibacterial performance in inhibiting E. coli and S. aureus.

Carboxyalkylchitosan-based hydrogels with "imine clip": Enhanced stability and amino acids-induced disassembly under physiological conditions

Here we report on the properties of hydrogels of carboxyalkylchitosans-salicylimines depending on the salicylaldehyde (SA) grafting density, type of carboxyalkyl substitution, pH, and presence of amino acids. The mechanism of SA grafting has been investigated using ¹³C NMR and FT-IR spectroscopy and elemental analysis. We have found that, despite lower SA grafting density to carboxyalkylchitosans, gelation in these solutions occurred at much lower SA:polymer molar ratios than for chitosan-salicylimines, being the highest for a N-carboxyethylchitosan with a medium substitution degree. Controlled disassembly of supramolecular architecture of hydrogel of N-carboxyethylchitosan-salicylimine at physiological pH was achieved via the transimination reaction in the presence of amino acids with the efficiency decreased in the order: lysine > arginine ≥ serine. Application of carboxyalkylchitosans opens a new window for development of salicylimine-based hydrogels with lower SA grafting density, better mechanical properties, and reversibility in a broader pH range than it was earlier known for chitosan-based biodynamers.