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• Hyaluronate-alginate hybrid (HAH) can be synthesized using various linkers. • The types of linkers control the mechanical stiffness of HAH hydrogels. • The mechanical stiffness of HAH hydrogel regulates chondrogenic differentiation. Tissue engineering typically requires a use of scaffolds when delivering tissue-specific cells to be engineered. Hydrogels are frequently used as scaffolds, because their composition, structure, and function resemble the natural tissue extracellular matrix. In this study, hyaluronate-alginate hybrid (HAH) was synthesized by conjugating alginate (ALG) with the hyaluronate (HA) backbone using various types of linkers. HAH hydrogel was prepared by physically cross-linking the HAH polymer in the presence of calcium ions without chemical cross-linkers. The mechanical stiffness of HAH hydrogel was significantly affected by changing the type of a linker between HA and ALG. The mechanical stiffness increased with increasing linker length, likely due to enhanced intermolecular reactions between HA and ALG. This enables controlling the mechanical properties of HAH hydrogels. The types of linkers used to synthesize HAHs also influenced the chondrogenic differentiation of ATDC5 cells cultured in HAH hydrogel in vitro. This hybrid system that can change the mechanical stiffness by varying the linker type while maintaining the cross-linking density may be useful to design and fabricate scaffolds for tissue engineering applications, including cartilage regeneration. [ABSTRACT FROM AUTHOR]

This work aimed to develop a novel chitosan based metal-organic polyhedrons (MOPs)/enzyme hybrid hydrogel with superior antimicrobial properties in wound healing treatment. Hybrid hydrogel was prepared by crosslinking glucose oxidase (GOx), vanadium metal-organic polyhedrons (VMOP-2) and chitosan using glutaraldehyde as crosslinker. The formed GVCS hydrogel was characterized by using various techniques, including FTIR, SEM, XPS, TGA and EDX. Data show that GVCS hydrogel was successfully obtained with uniform distribution of GOx and VMOP-2 in the hydrogel structure. Antibacterial tests show that GVCS hydrogel exhibits better bactericidal effect on both gram-negative bacteria (S. aureus) and gram-positive bacteria (E. coli) compared to other hydrogel samples because of its hydroxyl radicals generation capacity in the presence of glucose. MTT assay shows that the hydrogel presents good cell compatibility. In vivo experiments using an infected wound model indicate that GVCS hydrogel can effectively facilitate wound healing. Therefore, chitosan based MOPs/enzyme hybrid hydrogel could be most promising for antibacterial therapy in clinical applications. [Display omitted] [ABSTRACT FROM AUTHOR]

Abstract: Novel hybrid hydrogels were prepared by introducing nano-hydroxyapatite (nHAp) into chitin solution dissolved in NaOH/urea aqueous solution at low temperature, and then by cross-linking with epichlorohydrin (ECH). Their structure and morphology were characterized by FTIR spectra, wide-angle X-ray diffraction (WAXD), thermo-gravimetric analysis (TGA), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Our findings revealed that hydroxyapatite nano-particles were uniformly dispersed in chitin hydrogel networks. The chitin/nHAP hybrid hydrogel (Gel2) exhibited about 10 times higher mechanical properties (compressive strength: 274kPa) than that of chitin hydrogel. Moreover, COS-7 cell culture experiment proved that cells could adhere and proliferate well on the chitin/nHAp hydrogels, suggesting good biocompatibility. All these results signified that these bio-materials could be potential candidates as scaffolds for tissue engineering. [Copyright &y& Elsevier]

Abstract: Novel alginate/porous CaCO3 microparticle hybrid hydrogels are facilely fabricated by in-situ release of Ca2+ from CaCO3 microparticles induced by hydrolysis of d-glucono-δ-lactone to reduce pH. The mechanical strength of hybrid hydrogels is easily tunable by the alginate/CaCO3 weight ratio. IBU was adsorbed into the porous CaCO3 microparticles. The embedded porous CaCO3 microparticles endow alginate hydrogels versatile drug loading capability and sustained release, especially for less water-soluble substances. This methodology provides a novel way to create new hybrid hydrogels for biomedical applications. [Copyright &y& Elsevier]

Abstract: Activated carbon (AC) was incorporated into carboxymethylcellulose (CMC) to form CMC/AC hybrid hydrogels with excellent elasticity and flexibility by radiation crosslinking. The effect of AC on the formation, properties and structure of CMC/AC hybrid hydrogels was discussed in terms of gel fraction, gel strength, gel swelling, TGA, FTIR spectra and SEM image. Compared with pure CMC hydrogel, the gel fraction, gel strength and thermal stability were improved obviously after incorporating AC into CMC hydrogels, and similar swelling ability were maintained up to the hybrid of 5%AC. FTIR and TGA spectra of the prepared gels after extracting sol revealed two findings: (1) radiation crosslinking reaction of CMC occurs in side chain of CMC molecules due to the presence of –OH and –CH2 groups; (2) AC enhanced the radiation crosslinking of CMC because AC was binding to CMC through physical adsorption and hydrogen bond as well as other interactions. From SEM images, it was found that AC particles were embedded in the network of CMC gels to form a uniform structure. [Copyright &y& Elsevier]

Bone transplantations are still facing many serious challenges, hydrogel as a new kind of artificial bone substitutes has developed into a promising bone scaffold material. However, it is still a challenge to combine bioactive agents and hydrogel matrix to promote osteoinductivity. Herein, we developed a novel bioactive hydrogel based on arginine-based unsaturated poly (ester amide) (Arg-UPEA) and methacrylated hyaluronic acid (HA-MA) via photo-crosslinking. As the results indicated, we found that the introduction of Arg-UPEA into HA-MA hydrogels could finely modulate their compressive modulus, swelling level and porous structure. Besides, among groups of different feed ratio, groups of 10 % and 15 % of Arg-UPEA content effectively enhanced osteogenic differentiation in osteoblasts when compared with HA-MA hydrogel. Furthermore, better bone regeneration and expression of osteogenesis-related factors in vivo also verified the Arg-UPEA/HA-MA hybrid hydrogels as a promising scaffold material for bone tissue engineering., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

The present work deals with a new type of hybrid polysaccharide-silica hydrogel fabricated by the sol-gel process in which a completely water-soluble precursor of tetrakis-(2-hydroxyethyl) orthosilicates (THEOS) and a biocompatible polysaccharide of carboxymethylated curdlan (CMCD) have been used. The kinetic gelation process, mechanical properties and morphological structures of hybrid silica hydrogels at different concentrations of CMCD and THEOS were investigated by dynamic rheology, compression testing and scanning electron microscopy. CMCD was found to be served as a catalyst and template in the sol-gel process of THEOS in water. The mechanical strength of the resulting silica gels was tunable by the modulation of either the concentration of CMCD or THEOS. Higher content of THEOS and CMCD resulted in stiffer gels. Due to the tunable mechanical property and good biocompatibility, these hybrid hydrogels are promising for the applications as drug release systems in biomedical fields., (Copyright © 2019 Elsevier Ltd. All rights reserved.)