Hydrogel-based microparticles

Pereira, D.R., Silva-Correia, J., Caridade, S.G., Oliveira, J.T., Sousa, R.A., Salgado, A.J., Oliveira, J.M., Mano, J.F., Sousa, N., Reis, R.L. Development of geUan gum-based microparticles/hydrogel matrices for application in the intervertebral disc regeneration. Tissue Eng. Part C Methods 17(10), 961-972 (2011)... 

Spherical microparticles are more difficult to manufacture and can be prepared by several methods. One method prepares silica hydrogel beads by emulsification of a silica sol in an immiscible organic liquid [20,21,24,25]. To promote gelling a silica hydrosol, prepared as before, is dispersed into small droplets in a iater immiscible liquid and the temperature, pH, and/or electrolyte concentration adjusted to promote solidification. Over time the liquid droplets become increasingly viscous and solidify as a coherent assembly of particles in bead form. The hydrogel beads are then dehydrated to porous, spherical, silica beads. An alternative approach is based on the agglutination of a silica sol by coacervation [25-27], Urea and formaldehyde are polymerized at low pH in the presence of colloidal silica. Coacervatec liquid... 

D.K. Hwang, D. Dendukuri, and P S. Doyle, Microfluidic-based synthesis of non-spherical magnetic hydrogel microparticles, Lab on a Chip, 8, 1640-1647, (2008). 

Fig. 1 Supramolecular systems described in this chapter. Top-. The extracellular matrix inspires most of the work and consists of fibers to resist tensile stresses such as collagens, fibers to resist compressive stresses such as the glycosaminoglycans, and soluble factors for cell signalling. Bottom Natural systems such as collagen, coiled-coil structures, p-sheet peptides such as peptide amphiphiles and multidomain peptides, hybrid systems such as streptavadin-biotin cross-linked microparticles, and synthetic systems such as the UPy-based hydrogelators...

As for animal cell entrapment in hydrogel microparticles or microcapsules, encapsulation procedure should proceed under physiological conditions within a short time (20-30 min), in order to provide cell viability, and to be as simple as possible because all manipulations are carried out under strictly sterile conditions. Taking into account all these requirements, it should be noted that the list of polymer materials and methods for animal cell encapsulation is rather limited. So-called alginate-based carriers (microparticles, micro- and nanocapsules) assure the favorable polymer systems for animal cell immobilization. 

Yoon YM, Lewis IS, Carstens MR, CampbeU-Thompson M, Wassetfall CH, Atkinson MA, et al. A combination hydrogel microparticle-based vaccine prevents type 1 diabetes in non-obese diabetic mice. Sci Rep 2015 5 13155. 

Ribeiro, M.P., Morgado, P.I., Miguel, S.P., Coutinho, P., Correia, I.J., 2013. Dextran-based hydrogel containing chitosan microparticles loaded with growth factors to be used in wound healing. Mater. Sci. Eng. C 33, 2958-2966. 

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