Over the years there have been substantial development

Over the years there have been substantial development in the field of biotechnology related to delivery of bioactive molecules using  carriers.The need for the development of carrier molecules is to prevent the degradation of these bioactive compounds from the external environment. A variety of bioactive compounds , including synthetic drug, protein, and cells have been encapsulated in biocompatible microcarriers in the form of  particles or capsules for a wide range applications1.The application of the carriers used  for the purpose of delivering bioactive compounds is diversified into various fields of biotechnology  which includes fundamental studies of biological systems, drug delivery, tissue engineering, and immunoisolation of cells.1 Depending on the field of application microcarriers are designed to achieve the set target.The significance of delivery of bioactive molecules such as protein , enzymes , peptides , adjuvants is dependent on the efficiency of microcarrier in various aspects . for example ,drug delivery vehicles should satisfy the specific conditions of a target site in the body; the size of a vehicle is critical to the ability to pass through a narrow channel in an organ, and the vehicle shape is important for determining the interactions among vehicles and cells1. Microcarrier is a term used for spherical particles with diameters in the  range typically from 1 ?m to 1000 ?m used for the delivery of  compounds .Polymeric microcarriers are formed by a polymer matrix in which a smaller amount of  active compound can be immobilized2. On the basis of the distribution of the active compound, microcarriers can be distinguished into two categories: microspheres and microcapsules . Microspheres  comprises of  homogeneous mixture of active compound and raw material, whereas microcapsules are defined to  be microparticles that present a core where the active compound is immobilized. The core  may or may not be  removed  by a different material . The core may be solid, liquid or even gas. Depending upon the core structure microcapsule can be divided into two categories:solid microspheres, where the core of the microcapsule is kept intact and hollow microspheres where the core of the microcapsule is removed.3