Recent advances and perspectives on coated alginate microspheres for modified drug delivery

Background: Alginate microspheres represent a useful tool for modified drug delivery. Their preparation is quite easy and is usually based on the gelling properties of the polysaccharide in the presence of divalent ions; nevertheless, microparticles prepared only with calcium alginate show several problems, mainly related to the mechanical stability and to the release that, in most cases, is too fast. To overcome such inconveniences, polymer-coated alginate microspheres and/or appropriately interpenetrating polymer network (semi-IPNs and IPNs) structures formed with alginate and other macromolecules were developed. Objective: This article reports a synthetic overview on the most recent searches carried out on coated alginate microspheres. Methods: After a section focused on the microsphere preparation, this article is divided into several main topics related to the specific polymer that was used as a coating material to provide a rationale in reporting literature data. In the last section, the advantages and disadvantages of the various approaches are discussed and the authors' opinion on perspectives for further studies and novel applications of coated alginate microspheres are reported. Conclusion: Ca2+-alginate microparticles could experience a new era if scientists will increase their efforts in developing microparticles with smart properties.