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    The relatively weak mechanical properties of hydrogels remain a major drawback for their application as load-bearing tissue scaffolds. Previously, we developed cell-laden double-network (DN) hydrogels that were composed of photocrosslinkable gellan gum (GG) and gelatin. Further research into the materials as tissue scaffolds determined that the strength of the DN hydrogels decreased when they were prepared at cell-compatible conditions, and the encapsulated cells in the DN hydrogels did not function as well as they did in gelatin hydrogels. In this work, we developed microgel-reinforced (MR) hydrogels from the same two polymers, which have better mechanical strength and biological properties in comparison to the DN hydrogels. The MR hydrogels were prepared by incorporating stiff GG microgels into soft and ductile gelatin hydrogels. The MR hydrogels prepared at cell-compatible conditions exhibited higher strength than the DN hydrogels and the gelatin hydrogels, the highest strength being 2.8 times that of the gelatin hydrogels. MC3T3-E1 preosteoblasts encapsulated in MR hydrogels exhibited as high metabolic activity as in gelatin hydrogels, which is significantly higher than that in the DN hydrogels. The measurement of alkaline phosphatase (ALP) activity and the amount of mineralization showed that osteogenic behavior of MC3T3-E1 cells was as much facilitated in the MR hydrogels as in the gelatin hydrogels, while it was not as much facilitated in the DN hydrogels. These results suggest that the MR hydrogels could be a better alternative to the DN hydrogels and have great potential as load-bearing tissue scaffolds.
    Gelatin
    Gellan gum
    Citations (52)
    Research on hydrogels has been geared toward biomedical applications from the beginning due to their relatively high biocompatibility. Initially only the hydrophilic nature and the large swelling properties of hydrogels was explored. Continued research on hydrogels has resulted in the development of new types of hydrogels, such as environment-sensitive hydrogels, thermoplastic hydrogels, hydrogel foams, and sol-gel phase-reversible hydrogels. Application of hydrogels ranges from biomedical devices to solute separation. Examples of hydrogel applications in pharmaceutics, biomaterials, and biotechnology are briefly described.
    Biocompatibility
    Pharmaceutics
    Citations (74)
    Two phase partitioning bioreactors (TPPBs) improve the efficiency of fermentative processes by limiting the exposure of microorganisms to toxic solutes by sequestering them into a non-aqueous phase (NAP). A potential limitation of this technology, when using immiscible organic solvents as the NAP, is the cytoxicity that these materials may exert on the microbes. An improved TPPB configuration is one in which polymeric NAPs are used to replace organic solvents in order to take advantage of their low cost, improved handling qualities, and biocompatibility. A recent study has shown that low molecular weight polymers may confer improved solute uptake relative to high molecular weight polymers (i.e., have higher partition coefficients), but it is unknown whether sufficiently low molecular weight polymers may inhibit cell growth. This study has investigated the biocompatibility of a range of low molecular weight polymers, and compared trends in biocompatibility to the well-established "critical log P" concept. This was achieved by determining the biocompatibility of polypropylene glycol polymers over a molecular weight (MW) range of 425-4,000 to Saccharomyces cerevisiae and Pseudomonas putida, two organisms which have been previously used in TPPB systems. The lower MW polymers were shown to have lower average log P values, and showed more cytotoxicity than polymers of the same structure but with higher molecular weight. Since polymers are generally polydisperse (i.e., polymer samples contain a distribution of MWs), removal of the lower MW fractions via water washing was found to result in improved polymer biocompatibility. These results suggest that the critical log P concept remains useful for describing the toxicity of polymeric substances of different MWs, although it is complicated by the presence of the low MW fractions in the polymers arising from polydispersity.
    Biocompatibility
    Molar mass distribution
    Citations (9)
    The relatively weak mechanical properties of hydrogels remain a major drawback for their application as load-bearing tissue scaffolds. Previously, we developed cell-laden double-network (DN) hydrogels that were composed of photocrosslinkable gellan gum (GG) and gelatin. Further research into the materials as tissue scaffolds determined that the strength of the DN hydrogels decreased when they were prepared at cell-compatible conditions, and the encapsulated cells in the DN hydrogels did not function as well as they did in gelatin hydrogels. In this work, we developed microgel-reinforced (MR) hydrogels from the same two polymers, which have better mechanical strength and biological properties in comparison to the DN hydrogels. The MR hydrogels were prepared by incorporating stiff GG microgels into soft and ductile gelatin hydrogels. The MR hydrogels prepared at cell-compatible conditions exhibited higher strength than the DN hydrogels and the gelatin hydrogels, the highest strength being 2.8 times that of the gelatin hydrogels. MC3T3-E1 preosteoblasts encapsulated in MR hydrogels exhibited as high metabolic activity as in gelatin hydrogels, which is significantly higher than that in the DN hydrogels. The measurement of alkaline phosphatase (ALP) activity and the amount of mineralization showed that osteogenic behavior of MC3T3-E1 cells was as much facilitated in the MR hydrogels as in the gelatin hydrogels, while it was not as much facilitated in the DN hydrogels. These results suggest that the MR hydrogels could be a better alternative to the DN hydrogels and have great potential as load-bearing tissue scaffolds.
    Gelatin
    Gellan gum
    Citations (0)
    Research on hydrogels has been geared toward biomedical applications from the beginning due to their relatively high biocompatibility. Initially only the hydrophilic nature and the large swelling properties of hydrogels was explored. Continued research on hydrogels has resulted in the development of new types of hydrogels, such as environment-sensitive hydrogels, thermoplastic hydrogels, hydrogel foams, and sol-gel phase-reversible hydrogels. Application of hydrogels ranges from biomedical devices to solute separation. Examples of hydrogel applications in pharmaceutics, biomaterials, and biotechnology are briefly described.
    Pharmaceutics
    Biocompatibility
    Citations (196)
    Hydrogels are there-dimensional polymer network in which the voids are filled with water.Hydrogels have been widely used in various fields including biomedical engineering.However,they have very limited applicability due to their poor mechanical strength.Therefore,many efforts have been focused on the enhancement of mechanical properties of hydrogels.This review mainly introduces some novel high strength hydrogels,such as slide-ring hydrogels,double network hydrogels,composite hydrogels and others and analyzes the factors affecting mechanical properties of hydrogels.Biocompatible,degradable,injectable,loading growth factor and high strength hydrogels as major research directions.
    Mechanical strength
    Biocompatible material
    Citations (0)