Hydrogels are three-dimensional porous polymeric networks prepared by physical or chemical cross-linking of hydrophilic molecules, which can be made into smart materials through judicious chemical ...

Hydrogel-Based Sensor Networks: Compositions, Properties, and Applications—A Review

Chitosan is one of the most studied cationic polysaccharides. Due to its unique characteristics of being water soluble, biocompatible, biodegradable, and non-toxic, this macromolecule is highly attractive for a broad range of applications. In addition, its complex behavior and the number of ways it interacts with different components in a system result in an astonishing variety of chitosan-based materials. Herein, we present recent advances in the field of chitosan-based materials from a physico-chemical perspective, with focus on aqueous mixtures with oppositely charged colloids, chitosan-based thin films, and nanocomposite systems. In this review, we focus our attention on the physico-chemical properties of chitosan-based materials, including solubility, mechanical resistance, barrier properties, and thermal behaviour, and provide a link to the chemical peculiarities of chitosan, such as its intrinsic low solubility, high rigidity, large charge separation, and strong tendency to form intra- and inter-molecular hydrogen bonds.

Chitosan-based smart hybrid materials: a physico-chemical perspective

Research progress of adsorption and removal of heavy metals by chitosan and its derivatives: A review.

Background As the only natural cationic polysaccharide, chitosan (CH) have several bioactivities. Moreover, CH was the ideal biomaterial for the preparation of hydrogels that have desirable biocompatibility and biodegradability. CH-based hydrogels have been extensively reported for their applications in delivery system and tissue engineering. Furthermore, CH-based hydrogels have shown great potential and attracted considerable attention in recent years for biosensors and packaging materials. Scope and approach This review aims to discuss the favorable properties and advantage of CH-based hydrogels through introducing different types of CH-based hydrogels, and extend these properties to their application in biosensors. Finally, combining the above-mentioned advantages and characteristics (excellent bioactivities, stimuli responsiveness, embedding ability, swelling, biodegradability, non-toxicity, and low-cost), the potential of CH-based hydrogels for application in intelligent food packaging systems is analyzed. Key findings and conclusions CH-based hydrogels, a hydrophilic, high-water content biomaterial, have a variety of applications, which are closely related to its excellent properties such as good swelling capacity and embedding ability. Different types of CH-based hydrogels have different working mechanism and extensive application prospect in delivery system and tissue engineering. Moreover, CH-based hydrogels can respond to external stimuli and convert environmental signal to a measurable signal output through its swelling behavior or embedding bioactive substance that can interact with an input element, which has been used as biosensors in various fields. Combining its favorable antibacterial, antioxidant activity and good biodegradability, CH-based hydrogels have great application potential in intelligent food packaging system.

Advanced applications of chitosan-based hydrogels: From biosensors to intelligent food packaging system

In this study, natural polymer material chitosan (CS) and graphene oxide (GO) with large specific surface area were used to prepare a new CS/RGO-based composite hydrogel by using glutaraldehyde (GA) as cross-linking agent. In addition, a CS/GA/RGO/Pd composite hydrogel was prepared by loading palladium nanoparticles (Pd NPs). The morphologies and microstructures of the prepared hydrogels were characterized by SEM, TEM, XRD, TG, and BET. The catalytic performance of the CS/GA/RGO/Pd composite hydrogel was analyzed, and the experimental results showed that the CS/GA/RGO/Pd composite hydrogel had good catalytic performance for degradation of p-nitrophenol (4-NP) and o-nitroaniline (2-NA). Therefore, this study has potential application prospect in wastewater treatment and provides new information for composite hydrogel design.

https://pubs.rsc.org/en/content/articlepdf/2020/ra/d0ra01884h

Fabrication of CS/GA/RGO/Pd composite hydrogels for highly efficient catalytic reduction of organic pollutants

Quaternary ammonium salts of chitosan. A critical overview on the synthesis and properties generated by quaternization

Fluorescent chitosan hydrogel for highly and selectively sensing of p-nitrophenol and 2, 4, 6-trinitrophenol.

Detection of heavy metals with high sensitivity and selectivity is of vital importance. In this study, we report the synthesis of small molecular chemosensors and the fabrication of corresponding macromolecular fluorescent chemosensors. Boron dipyrrole methane (BODIPY)-derived chemosensors, BE and BB, were designed and synthesized first. Then, they were incorporated into polymeric derivatives to prepare macromolecular fluorescent chemosensors. The small molecular sensors were highly sensitive and selective to Hg2+. Other ions and albumin did not exhibit clear interference to the sensing of Hg2+ ions. Once the macromolecular chemosensors were formed, the recognition ability was preserved; moreover, the sensitivity was even enhanced by the “molecular wire” mechanism. The minimum detection limits of four macromolecular chemosensors, PBEP, PBEB, PBBP and PBBB, for Hg2+ reached 2.05 μM, 0.23 μM, 4.23 μM, and 0.15 μM, respectively. Under natural light, the addition of Hg2+ led to significant color changes; also, they can be used as Hg2+-sensitive “naked eye” indicators in the natural environment.

Xinjian Cheng

Papers

Quaternary ammonium salts of chitosan. A critical overview on the synthesis and properties generated by quaternization

Fluorescent chitosan hydrogel for highly and selectively sensing of p-nitrophenol and 2, 4, 6-trinitrophenol.

Bodipy-based chemosensors for highly sensitive and selective detection of Hg2+ ions

A novel coumarin-chitosan fluorescent hydrogel for the selective identification of Fe2+ in aqueous systems

Phenothiazine-chitosan based eco-adsorbents: A special design for mercury removal and fast naked eye detection.