A sodium alginate/carboxymethyl chitosan dual-crosslinked injectable hydrogel scaffold with tunable softness/hardness for bone regeneration.

Recently, injectable dual-crosslinked (DC) hydrogel scaffolds have attracted many attentions as a class of excellent bone regeneration biomaterials with in-situ tunable functions. However, the design of injectable DC hydrogels with cell behavior-compatible network structure and mechanical property remains a bottleneck. Herein, based on the in-situ gelling method, we constructed an injectable CMCS/PEG+SA/CaCl2 (CPSC) chemical/physical DC hydrogel scaffold with tunable softness/hardness mechanical properties and good biocompatibility. The formation mechanism and properties of the CPSC hydrogel scaffold were investigated by FTIR, XRD, rheometry, and mechanical testing. It is found that proper softness/hardness mechanical properties can be obtained by adjusting the secondary network structure of the hydrogel. The CPSC hydrogel scaffold prepared under optimal conditions can effectively promote cell infiltration, nutrient transport, and the osteogenic differentiation of rat bone mesenchymal stem cells (rBMSCs). The in vivo experiments show that the rBMSCs-loaded injectable CPSC hydrogels with appropriate mechanical properties can effectively promote bone reconstruction. This study has provided important guidance for the construction of injectable DC hydrogels with adjustable softness/hardness to promote osteogenesis for bone defect repair.

A natural polymer-based hydrogel with shape controllability and high toughness and its application to efficient osteochondral regeneration.

Hydrogels prepared from sustainable natural polymers have broad prospects in the biological field. However, their poor mechanical properties and challenges in achieving shape control have limited their application. Herein, a novel preforming dual-effect post-enhancing method is proposed to address these issues. The method utilizes the hydrogen bonding of agar to obtain a shape-controllable preformed hydrogel at low polymer concentrations using casting, injection, or 3D printing techniques. Subsequently, the preformed hydrogel was subjected to a permeation process to form a post-enhanced multi-network (PEMN) hydrogel with hierarchical chain entanglements to ensure its high toughness, which exhibits tensile and compressive strengths of up to 0.51 MPa and 1.26 MPa with solely physically crosslinking networks. The excellent biocompatibility of the PEMN hydrogel prepared without the need for additional initiator agents under mild conditions was confirmed by both in vitro and in vivo experiments. Furthermore, the adaptability for irregular defects, suitable toughness, adhesive properties, and degradability of PEMN hydrogels are beneficial to provide mechanical support, induce endogenous cell mineralization, and accelerate the regeneration of cartilage and subchondral bone with more than 40% bone regeneration in 12 weeks. Our work has provided a novel solution to simultaneously achieve shape controllability and high toughness based on natural polymers among the already well-explored strategies for osteochondral regeneration.

Green Conductive Hydrogel Electrolyte with Self-Healing Ability and Temperature Adaptability for Flexible Supercapacitors.

Conductive hydrogels (CHs) are ideal electrolyte materials for the preparation of flexible supercapacitors (FSCs) due to their excellent electrochemical properties, mechanical properties, and deformation restorability. However, most of the reported CHs are prepared by the chemical crosslinking of synthetic polymers and thus usually display the disadvantages of poor self-healing abilities and nonadaptability at environmental temperatures, which greatly limits their application. To overcome these problems, in the present work, we constructed a sodium alginate-borax/gelatin double-network conductive hydrogel (CH) by a dynamic crosslinking between sodium alginate (SA) and borax via borate bonds and hydrogen bonding between amino acids in gelatin and SA chains. The CH displays an excellent elongation of 305.7% and fast self-healing behavior in 60 s. Furthermore, a phase-change material (PCM), Na2SO4·10H2O, was introduced into the CH, which, combined with the nucleation effect of borax, improved the ionic conductivity and temperature adaptability of the CH. The flexible supercapacitor (FSC) assembled with the obtained CH as the electrolyte exhibits a high specific capacitance of 185.3 F·g-1 at a current density of 0.25 A·g-1 and good stability with 84% capacitance retention after 10 000 cycles and excellent temperature tolerance with a resistance variation of 2.11 Ω in the temperature range of -20-60 °C. This green CH shows great application potential as an electrolyte for FSCs, and the preparation method can be potentially expanded to the fabrication of self-repairing FSCs with good temperature adaptabilities.

Preparation of chitosan/sodium alginate conductive hydrogels with high salt contents and their application in flexible supercapacitors.

Conductive hydrogels (CHs) are a potential material for flexible electronics. However, most of CHs display disadvantages of low ionic conductivities and intolerance to low temperatures. Herein, a novel physical CHs with salt contents as high as 30 wt% was prepared with chitosan (CTS) and sodium alginate (SA) by combining the anti-polyelectrolyte effect and semi-dissolution acidification sol-gel transition (SD-A-SGT) method. The obtained hydrogels show extremely high ionic conductivities up to 2.96 × 10-1 S·cm-1 at room temperature and 4.9 × 10-2 S·cm-1 at -20 °C. The effects of different salts on the ion mobility and electrochemical properties of CTS/SA CHs were predicted and analyzed. The flexible supercapacitor assembled using CTS/SA CHs as the electrolyte exhibits the specific capacitance as high as 405 F·g-1 at the current density of 0.25 A·g-1 and satisfying electrochemical stability with 74.91% capacitance retention in 1000 cycles. Our work has provided a new strategy for constructing green CHs with high ionic conductivities.

Construction of a physically cross-linked carrageenan/chitosan/calcium ion double-network hydrogel for 3-Nitro-1, 2, 4-triazole-5-one removal.

3-Nitro-1, 2, 4-triazole-5-one (NTO) is an important insensitive explosive. The discharge of NTO wastewater not only pollutes the environment but also causes the economic loss of the valuable explosive. Currently, the NTO wastewater in industrial production is often treated with activated carbon adsorbents. There are no green, efficient and specific adsorption materials for the NTO treatment yet. In the present work, polymer materials suitable for NTO adsorption were screened by molecular dynamics simulation. With the optimized materials, a carrageenan/chitosan/calcium ion physically cross-linked double network hydrogel (KC/CTS/Ca2+ PCDNH) was successfully prepared by the semi-soluble-acidified sol-gel conversion method. The structure and NTO adsorption performance of the hydrogel were investigated by scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS). The NTO adsorption kinetics, isotherm, and thermodynamics were further studied to understand the adsorption behavior and mechanism. In addition, the adsorbed NTO was successfully released and recovered by soaking the hydrogel in NaOH solution. Our work has provided an environmentally friendly and targeted preparation method of NTO adsorbent materials for NTO wastewater treatment.

Design, synthesis and evaluation of novel ferulic acid-memoquin hybrids as potential multifunctional agents for the treatment of Alzheimer's disease.

A novel series of ferulic acid-memoquin hybrids were designed, synthesized and evaluated as multifunctional agents for the treatment of Alzheimer's disease (AD). The in vitro studies showed that most of the compounds exhibited a significant ability to inhibit acetylcholinesterase (AChE) (IC50 of 3.2-34.7µM) and self-induced ß-amyloid (Aß1-42) aggregation (30.8-39.1%, 25µM), to act as potential antioxidants (ORAC-FL value of 0.9-1.3). In particular, compound 17d had the greatest ability to inhibit AChE (IC50=3.2µM), and Aß1-42 aggregation (30.8%) was also an excellent antioxidant and neuroprotectant. Moreover, it is capable of disaggregating self-induced Aß aggregation. Furthermore, 17d could cross the blood-brain barrier (BBB) in vitro. The results showed that compound 17d is a potential multifunctional agent for the treatment of AD.