Photopatterned salecan composite hydrogel reinforced with α-Mo2C nanoparticles for cell adhesion

Chlorogenic acid/carboxymethyl chitosan nanoparticle-assisted biomultifunctional hyaluronic acid-based hydrogel scaffolds for burn skin repair

Burns are a prevalent type of injury worldwide, affecting tens of millions of people each year and significantly impacting the physical and psychological well-being of patients. Consequently, prompt treatment of burn wounds is imperative, with oxidative stress and excessive inflammation identified as primary factors contributing to delayed healing. In recent years, there has been growing interest in in situ crosslinked multifunctional hydrogels as a minimally invasive approach for personalized treatment delivery. To address these, a photocrosslinkable methacryloyl hyaluronic acid hydrogel scaffold embedded with chlorogenic acid/carboxymethyl chitosan nanoparticles (CGA/CMCS-HAMA, CCH), was developed for the treatment of burn wounds. The hydrogel prepared degraded by over 50 % by day 20, demonstrating stability and meeting the therapeutic requirements for burn wounds. Leveraging the extracellular matrix-like properties of HAMA and the antioxidant capabilities of CGA/CMCS NPs, this hydrogel demonstrates the ability to locally and continuously scavenge ROS and inhibit lipid peroxidation, inhibiting ferroptosis. Moreover, hydrogels well modulate the expression of macrophage- and fibroblast-associated inflammatory factors. Additionally, the hydrogel promotes cell adhesion and migration, further supporting the healing process. Overall, this innovative approach offers a safe and promising solution for burn wound treatment, addressing drug breakthrough and safety concerns while being adaptable to various irregular wound types.

Photo-degradable salecan/xanthan gum ionic gel induced by iron (III) coordination for organic dye decontamination

As dye adsorbents with great potential, polysaccharide-based hydrogels are significantly hampered in practical application owing to intricate preparation methods, low absorption, and bad degradability. Salecan is a water-soluble extracellular polysaccharide with excellent physicochemical and biological properties. Here, salecan and xanthan gum were first used as a dual-precursors system, their mixed solution was crosslinked by Fe³⁺ to assemble a photo-degradable ionic gel for malachite green (MG) adsorption. Photo-degradation was done using visible light under very mild conditions, which gave rise to gel network dissolution and homogeneous solution formation. Extensive dynamic coordinate interactions between Fe³⁺ and polysaccharides maintained gel matrix stability and were systematically investigated. The control of water uptake, micro-structure, and rheology can be facilely implemented by tuning salecan/xanthan gum ratios. Furthermore, various parameters such as polysaccharide ratios, pHs, MG concentrations, and contact time affecting adsorption were optimized using batch experiments. Adsorption process accurately adhered to pseudo-second-order kinetic and Langmuir isotherm model, with the maximum adsorption capacity of 463.0 mg/g. Such mechanism implied monolayer chemisorptive characteristics. The gel exhibited satisfactory reusability and was recycled five times without apparent decrease in adsorption capacity. From these results, the photo-degradable Fe³⁺-induced salecan/xanthan gum ionic gel is an alternative and sustainable absorbent for MG removal.

Ion-imprinted sponge produced by ice template-assisted freeze drying of salecan and graphene oxide nanosheets for highly selective adsorption of mercury (II) ion

As a kind of potential heavy metal absorbent, polysaccharide-based materials are limited by the complicated preparation method and bad selectivity toward targeted ion. Here, a fantastic sponge was produced by combining salecan and graphene oxide (GO) nanosheets via ice template-assisted freeze drying and ion-imprinting technologies. The intense intermolecular interactions between salecan and GO gave the sponge high stability. The swelling, morphology, and mechanical stiffness of the material showed highly dependent on the salecan content. Additionally, the influence of salecan content, pH, initial ion concentration, and contact time on Hg²⁺ adsorption was extensively investigated. Adsorption kinetics and equilibrium isotherms perfectly fitted in the pseudo-second-order and Freundlich models, reflecting the multilayer chemical-adsorption mediated mechanism. Most strikingly, the ion-imprinted sponge exhibited strong selectivity toward Hg²⁺ and outstanding stability with recyclability over usage of five times. These investigations provide the guidance for the construction of promising polysaccharide-based adsorbents for the remediation of Hg²⁺-polluted water.

Photopolymerized Porous Hydrogels

Hydrogels are polymeric networks highly swollen with water. Because of their versatility and properties mimicking biological tissues, they are very interesting for biomedical applications. In this aim, the control of porosity is of crucial importance since it governs the transport properties and influences the fate of cells cultured onto or into the hydrogels. Among the techniques allowing for the elaboration of hydrogels, photopolymerization or photo-cross-linking are probably the most powerful and versatile synthetic routes. This Review aims at giving an overview of the literature dealing with photopolymerized hydrogels for which the generation or characterization of porosity is studied. First, the materials (polymers and photoinitiating systems) used for synthesizing hydrogels are presented. The different ways for generating porosity in the photopolymerized hydrogels are explained, and the characterization techniques allowing adequate study of the porosity are presented. Finally, some applications in the field of controlled release and tissue engineering are reviewed.

Thermo-Tunable Pores and Antibiotic Gating Properties of Bovine Skin Gelatin Gels Prepared with Poly(n-isopropylacrylamide) Network

Polystyrene nanospheres (PNs) were embedded in bovine skin gelatin gels with a poly(N-isopropylacrylamide) (PNIPAAm) network, which were denoted as NGHHs, to generate thermoresponsive behavior. When 265 nm PNs were exploited to generate the pores, bovine skin gelatin extended to completely occupy the pores left by PNs below the lower critical solution temperature (LCST), forming a pore-less structure. Contrarily, above the LCST, the collapse of hydrogen bonding between bovine skin gelatin and PNIPAAm occurred, resulting in pores in the NGHH. The behavior of pore closing and opening below and above the LCST, respectively, indicates the excellent drug gating efficiency. Amoxicillin (AMX) was loaded into the NGHHs as smart antibiotic gating due to the pore closing and opening behavior. Accordingly, E. coli. and S. aureus were exploited to test the bacteria inhibition ratio (BIR) of the AMX-loaded NGHHs. BIRs of NGHH without pores were 48% to 46.7% at 25 and 37 °C, respectively, for E. coli during 12 h of incubation time. The BIRs of nanoporous NGHH could be enhanced from 61.5% to 90.4% providing a smart antibiotic gate of bovine skin gelatin gels against inflammation from infection or injury inflammation.

Design Rationale for Stimuli-Responsive, Semi-interpenetrating Polymer Network Hydrogels-A Quantitative Approach

Stimuli-responsive semi-interpenetrating polymer network (semi-IPN) hydrogels form an important class of polymers for their tunable properties via molecular design. They are widely investigated for a diverse range of applications including drug delivery, sensors, actuators, and osmotic agents. However, in-depth studies on some of the critical design principles affecting diffusion/leaching of linear polymer from semi-IPN hydrogels are lacking. Herein, for the first time, by preparing a series of model semi-IPN hydrogels based on thermally responsive poly (N-isopropyl acrylamide) (PNIPAM) network and linear poly(sodium acrylate) (PSA), a systematic and quantitative study concerning linear polymer chain retention and swelling/deswelling kinetics is reported. The study shows that PSA retention is significantly affected not only by PSA molecular weight and concentration, but also by polymerization temperature, which could be linked to homogeneity and internal morphology of the hydrogel. Surprisingly, there is no obvious influence of crosslinking density of PNIPAM network toward PSA retention, while faster swelling and deswelling at higher crosslinking density are observed in terms of swelling rate constant and deswelling activation energy. These findings offer new insights on the factors affecting structural and physicochemical properties of such semi-IPN hydrogels, which should in turn serve as a general guideline for materials design.

Allylated chitosan-poly(N-isopropylacrylamide) hydrogel based on a functionalized double network for controlled drug release

Smart hydrogels with dual network were presented since a new allylated chitosan was conceived. As a double network hydrogel, its first network consisted of poly(N-isopropylacrylamide) worked as the gel matrix, and its second network with Schiff base bond enabled itself function as a molecular switch through the formation and break of the bond. When only the intestinal fluid was used, the second network could provide efficient protection for the loaded drug, and the drug release mechanism conformed to the non-Fickian type diffusion. While pre-treated with simulated gastric fluid, the switch would be opened and the mechanism was the Fickian type, which increased the cumulative percentage of drug release by about 25% and the release time by about 300 min. Besides, the hydrogel was characterized by ¹H NMR, FT-IR and SEM. The effects of allylated chitosan, pH and crosslinker on the swelling ratio and morphology of hydrogel were also studied.

Design of photoinitiator-functionalized hydrophilic nanogels with uniform size and excellent biocompatibility

Three well-controlled biocompatible hydrophilic nanogels were synthesized, and they can effectively initiate photopolymerization and improve the mechanical properties of polymers.