Poly-L-lysine-alginate

De, S., Robinson, D. Polymer relationships during preparation of chitosan-alginate and poly(L-lysine)-alginate nanospheres. J. Controlled Release 89, 101-112 (2003)... 

Alginate-poly(L-lysine)-alginate (APA) microcapsules were used to entrap EPO-secreting cells. Implantable and injectable hydrogel-based scaffolds containing the cells have been developed. The implantation of the cell-loaded capsules containing hydrogel-based scaffolds in mice revealed that hematocrit levels were maintained up to 80% for at least 2 months. 

Weber, C.J., Kapp, J.A., Hagler, M.K., Salley, S., Chryssohoos, J.T., and Chaikof, E.L., Long-term survival of poly-L-lysine-alginate microcapsulated xenografts in spontaneous diabetic NOD mice, in Cell encapsulation technology and therapeutics, Kuhtreiber, W.M., Lanza, R.P., and Chick, W.L., Eds., Birkhauser, N-Y-Boston, 1990, pp. 117-137. 

Sawhney, A.S. and Hubbell, J.A., Poly(ethylene oxide)-graft-poly(L-lysine) copolymers to enhance the biocompatibility of poly(L-lysine)-alginate microcapsule membranes. Biomaterials, 13, 863 870, 1992. 

King, A., Strand, BT., Rokstad, AM., Kulseng, B., Andersson, A., Skjak-Braek, G., and Sandler, S., Improvement of the biocompatibiUty of alginate/poly-L-lysine/alginate microcapsules by the use of epimerized alginate as coating, J. Biomed. Mater. Res., 64A (3), 533 539, 2003. 

Consequently, a three-layered structure of microcapsules made of alginic acid-poly-L-lysine-alginic acid is produced. 

Constantinidis, I., S. C. Grant, et al. 2007. Non-invasive evaluation of alginate/poly-L-lysine/alginate microcapsules by magnetic resonance microscopy. Biomaterials 28 2438-2445. 

Another biomedical appHcation of mictocapsules is the encapsulation of Hve mammalian ceUs for transplantation into humans. The purpose of encapsulation is to protect the transplanted ceUs or organisms from rejection by the host. The capsule sheU must prevent entrance of harmful agents into the capsule, aUow free transport of nutrients necessary for ceU functioning into the capsule, and aUow desirable ceUular products to freely escape from the capsule. This type of encapsulation has been carried out with a number of different types of Hve ceUs, but studies with encapsulated pancreatic islets or islets of Langerhans ate most common. The alginate—poly(L-lysine) encapsulation process originally developed in 1981 (54) catalyzed much of the ceU encapsulation work carried out since. A discussion of the obstacles to the appHcation of microencapsulation in islet transplantation reviewed much of the mote recent work done in this area (55). Animal ceU encapsulation has also been researched (56). 

Microcapsules can be used for mammalian cell culture and the controlled release of drugs, vaccines, antibiotics and hormones. To prevent the loss of encapsulated materials, the microcapsules should be coated with another polymer that forms a membrane at the bead surface. The most well-known system is the encapsulation of the alginate beads with poly-L-lysine. 

Polymer grafting can be used to alter chemical and physical properties of a homopolymer. For example, Sawhney and Hubbell [18] grafted polyethyleneoxide to poly L-lysine to enhance biocompatibility of polylysine and improve the polylysine-alginate capsules. Stevenson and Sefton [19] modified alginate by grafting it with hydroxyalkyl methacrylate, again to improve the biocompatibility and to allow for polymerization by means of y-irradiation. Covalently modified (co)-polymers have not been evaluated in this study. 

Microspheres and nanoparticles often consist of biocompatible polymers and belong either to the soluble or the particle type carriers. Besides the aforementioned HPMA polymeric backbone, carriers have also been prepared using dextrans, ficoll, sepharose or poly-L-lysine as the main carrier body. More recently alginate nanoparticles have been described for the targeting of antisense oligonucleotides [28]. As with other polymeric carrier systems, the backbone can be modified with e.g. sugar molecules or antibody fragments to introduce cellular specificity. 

In this case, unilamellar vesicles with a large capture volume were prepared by the reverse phase evaporation technique and alginate was used to microencapsulate the liposome s. The alginate spheres were double coated, first with poly-L-lysine and then with polyvinyl amine (Wheatley and Langer in press). 

Robitaille R, Dusseault J, Henley N, Desbiens K, Labrecque N, Halle J-P. Inflammatory response to peritoneal implantation of alginate-poly-L-lysine microcapsules. Biomaterials 2005, 26, 4119 1127. 

Calcium alginate and poly-L-lysine Gelation Doxorubicin, oligonucleotides [28,89]... 

Alginate-poly(L-lysine) and alginate-chitosan are, by far, the most common polymer-polymer coacer-vation systems, with the former often pregelled, in bead form, with divalent cations such as calcium or barium. As Table 2 indicates, polysaccharides with a rigid structure are generally favored for polysalt formation. 

Pancreas Diabetes Islets of Langerhans Alginate/poly(L-lysine) Encapsulated, restore Active glucose concentration control [30]... 

Halle, J. P Bourassa, S., Leblond, F. A., Chevalier, S., Beudry, M Chapdelaine, A., Cousineau, S Saintonge, J., and Yale, J. F. (1993) Protection of islets of Langerhans from antibodies by microencapsulation with alginate-poly-L-lysine membranes. Transplantation 55(2), 350-354. 

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