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We have designed and characterized an injectable, electrostatically bonded, in situ –forming hydrogel system consisting of a cationic polyelectrolyte [(methoxy)polyethylene glycol- b -(poly(ε-caprolactone)- ran -poly(L-lactic acid)] (MP) copolymer derivatized with an amine group (MP-NH 2) and anionic BMP2. To the best of our knowledge, there have been hardly any studies that have investigated electrostatically bonded, in situ –forming hydrogel systems consisting of MP-NH 2 and BMP2, with respect to how they promote in vivo osteogenic differentiation of human turbinate mesenchymal stem cells (hTMSCs). Injectable formulations almost immediately formed an electrostatically loaded hydrogel depot containing BMP2, upon injection into mice. The hydrogel features and stability of BMP2 inside the hydrogel were significantly affected by the electrostatic attraction between BMP2 and MP-NH 2. Additionally, the time BMP2 spent inside the hydrogel depot was prolonged in vivo , as evidenced by in vivo near-infrared fluorescence imaging. Biocompatibility was demonstrated by the fact that hTMSCs survived in vivo , even after 8 weeks and even though relatively few macrophages were in the hydrogel depot. The osteogenic capacity of the electrostatically loaded hydrogel implants containing BMP2 was higher than that of a hydrogel that was simply loaded with BMP2, as evidenced by Alizarin Red S, von Kossa, and hematoxylin and eosin staining as well as osteonectin, osteopontin, osteocalcin, and type 1α collagen mRNA expression. The results confirmed that our injectable, in situ –forming hydrogel system, electrostatically loaded with BMP2, can enhance in vivo osteogenic differentiation of hTMSCs. • An injectable, electrostatically bonded, in situ –forming hydrogel system consisting of a cationic polyelectrolyte copolymer derivatized with an amine group and anionic BMP2 was prepared. • The hydrogel features and stability of BMP2 inside the hydrogel were significantly affected by the electrostatic attraction between BMP2 and cationic polyelectrolyte copolymer. • The electrostatically loaded hydrogel enhanced osteogenic differentiation of human turbinate mesenchymal stem cells better than one with simple loading of BMP2. [ABSTRACT FROM AUTHOR]

Hydrogel is a versatile material that can be manipulated to achieve the desired physicochemical properties, such as stiffness, pore size, and viscoelasticity. Traditionally, these properties have been controlled through parameters such as concentration and pH adjustments. In this study, we focused on exploring the potential of hydrolyzed silk fibroin (HSF) as a molecular weight-modulating agent to control the physicochemical properties of double-composite hydrogels. We developed a synergistic dual-crosslinked hydrogel by combining ionically crosslinked silk fibroin with gellan gum (GG). The hydrolysis of silk fibroin not only enhanced its hydrophilicity but also enabled adjustments in its mechanical properties, including the pore size, initial modulus elasticity, and relaxation time. Moreover, biocompatibility assessments based on cell viability tests confirmed the potential of these hydrogels as biocompatible materials. By highlighting the significance of developing an HSF/GG dual-crosslinked hydrogel, this study contributes to the advancement of novel double-composite hydrogels with remarkable biocompatibility. Overall, our findings demonstrate the capability of controlling the mechanical properties of hydrogels through molecular weight modulation via hydrolysis and highlight the development of a biocompatible HSF/GG dual-crosslinked hydrogel with potential biomedical applications. [ABSTRACT FROM AUTHOR]

The temperature‐dependent phase transition behavior of acetylated polyrotaxanes (PRXs) consisting of acylated α‐cyclodextrins threaded onto a poly(ethylene glycol) chain in an aqueous solution is investigated. Acetyl (Ac), propionyl (Pr), and butyryl (Bu) group‐modified PRXs with different degrees of substitution are synthesized to elucidate the effect of the alkyl chain length of the acyl groups on temperature responsivity. Ac‐PRXs, Pr‐PRXs, and Bu‐PRXs are dissolved in water and exhibit temperature‐dependent transmittance changes accompanied by coacervate formation. However, the temperature responsivity of acylated PRXs is seen in limited degree of substitution range (≈10%). The maximum degree of substitution to show temperature responsivity of acylated PRXs decreases with increasing alkyl chain length of the acyl groups. Transmittance measurements of acylated PRXs in the presence of urea reveal that the alkyl chain length of the acyl groups determines the predominant force involved in the temperature‐induced phase transition. During the temperature‐induced phase transition of Pr‐PRXs and Bu‐PRXs, hydrophobic interactions are predominant; however, hydrogen bond formation may occur in Ac‐PRXs. These fundamental findings related to acylated PRXs will facilitate the application of PRXs as thermoresponsive supramolecular materials. [ABSTRACT FROM AUTHOR]

The cytocompatibility of biological and synthetic materials is an important issue for biomaterials. Gelatin hydrogels are used as biomaterials because of their biodegradability. We have previously reported that the mechanical properties of gelatin hydrogels are improved by cross-linking with polyrotaxanes, a supramolecular compound composed of many cyclic molecules threaded with a linear polymer. In this study, the ability of gelatin hydrogels cross-linked by polyrotaxanes (polyrotaxane–gelatin hydrogels) for cell cultivation was investigated. Because the amount of polyrotaxanes used for gelatin fabrication is very small, the chemical composition was barely altered. The structure and wettability of these hydrogels are also the same as those of conventional hydrogels. Fibroblasts adhered on polyrotaxane–gelatin hydrogels and conventional hydrogels without any reduction or apoptosis of adherent cells. From these results, the polyrotaxane–gelatin hydrogels have the potential to improve the mechanical properties of gelatin without affecting cytocompatibility. Interestingly, when cells were cultured on polyrotaxane–gelatin hydrogels after repeated stress deformation, the cells were spontaneously oriented to the stretching direction. This cellular response was not observed on conventional hydrogels. These results suggest that the use of a polyrotaxane cross-linking agent can not only improve the strength of hydrogels but can also contribute to controlling reorientation of the gelatin. [ABSTRACT FROM AUTHOR]

In this paper, a cartilage acellular-matrix (CAM) is chosen as a biomaterial for an effective antiadhesive barrier to apply between injured tissue and healthy tissues or organs. CAM is cross-linked using glutaraldehyde to create a cross-linked CAM (Cx-CAM) film. Cx-CAM has higher elastic modulus and toughness and more hydrophobic surface properties than CAM before cross-linking. Small intestinal submucosa (SIS), cross-linked SIS (Cx-SIS) as a negative control, and Seprafilm as a positive control are used in an experiment as adhesion barriers. Human umbilical vein endothelial cells (HUVECs) on SIS, Cx-SIS, or in a culture plate get attached and effectively proliferate for 7 days, but Cx-CAM and Seprafilm allow for little or no attachment and proliferation of HUVECs, thus manifesting antiadhesive and antiproliferative effects. In animals with surgical damage to the peritoneal wall and cecum, Cx-CAM and Seprafilm afford little adhesion and negligible inflammation after seven days, as confirmed by hematoxylin and eosin staining and macrophage staining, in contrast to an untreated-injury model, SIS, or Cx-SIS film. Cx-CAM significantly suppresses the formation of blood vessels between the peritoneal wall and cecum, as confirmed by CD31 staining. Overall, the newly designed Cx-CAM film works well as an antiadhesion barrier and has better anti-tissue adhesion efficiency. [ABSTRACT FROM AUTHOR]