Shear‐reversibly Crosslinked Alginate Hydrogels for Tissue Engineering

Abstract

Injectable delivery vehicles in tissue engineering are often required for successful tissue formation in a minimally invasive manner. Shear-reversibly crosslinked hydrogels, which can recover gel structures from shear-induced breakdown, can be useful as an injectable, because gels can flow as a liquid when injected but re-gel once placed in the body. In this study, injectable and shear-reversible alginate hydrogels were prepared by combination crosslinking using cell-crosslinking and ionic crosslinking techniques. The addition of a small quantity of calcium ions decreased the number of cells that were required to form cell-crosslinked hydrogels without changing the shear reversibility of the system. The physical properties and gelation behavior of the gels were dependent on the concentration of both the cells and the calcium ions. We found that gels crosslinked by combination crosslinking methods were effective to engineer cartilage tissues in vivo. Using both ionic and cell-crosslinking methods to control the gelation behavior may allow the design of novel injectable systems that can be used to deliver cells and other therapeutics for minimally invasive therapy, including tissue engineering.

Drug release behavior of a pH/temperature sensitive calcium alginate/poly(N-acryloylglycine) bead with core-shelled structure

“…It is necessary to mention that the release rate of indomethacin in this work is lower than that reported by Park et al [13] and Choi et al [16] at 25°C. In the investigation of Park and Choi, drug was loaded into the beads by the sorption method, and most of the drug existed in the surface layer of the beads.…”

“…For example, the amount of indomethacin released from the bead reached 46.4 and 12.1% within 330 minutes when the temperature was fixed at 37 and 24°C, respectively. For the core-shelled bead, the effective crosslinking density of PAG in the core constructed via H-bonding was decreased by increasing the temperature, which accelerated the drug release [13]. Accordingly, the transition of sol to gel of PAG or the cross-linking density formed by H-bonding in the core plays a key role in regulating the release of the entrapped drug molecules from the beads.…”

“…The unique properties of a smart hydrogel imply that it can be used as a promising material in the biomedical and industrial applications. Some significant applications of hydrogels have been widely investigated including dialysis membranes [11], enzyme immobilization [12], tissue engineering [13], and drug controlled release systems [14][15][16][17] and so on. Among the smart materials, pH-and temperature-sensitive hydrogels have been paid more attentions because the two physiological factors are very important for the human body [18][19][20][21].…”

Lactobacillus casei loaded Soy Protein-Alginate Microparticles prepared by Spray-Drying

“…Additionally, the cross--linking segments of alginate by soy protein isolate can change the conformation of alginate and increase the local charge density, thus promoting adsorption of soy protein isolate and probiotic cells. The same was observed when a well-known adhesive ligand arginine-glycine-aspartic acid (RGD) was conjugated to the alginate backbone (31). When fibroblast cells were added to the RGD-modified alginate solution without the use of calcium, a larger number of cells were mobilised due to the more available bonds between the cells and cell-interactive polymers.…”

Hybrid Hydrogels with Extremely High Stiffness and Toughness

“…Hydrogels are used as scaffolds in tissue engineering, 1 carriers for drug delivery, 2 valves in microfluidics, 3 and superabsorbent polymers in disposable diapers. 4 Many other applications require hydrogels of exceptional mechanical properties.…”