Polymeric Microspheres and Nanospheres

Perhaps the most common particle type used for bioapplications is the polymeric microsphere or nanosphere, which consists basically of a spherical, nonporous, hard particle made up of long, entwined linear or crosslinked polymers. Creation of these particles typically involves an emulsion polymerization process that uses vinyl monomers, sometimes in the presence of 

Polymeric particles traditionally have been called latex beads or spheres, probably from the classic definition of an emulsion of rubber or plastic globules in water . However, due to 

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This volume in the series deals in a timely and comprehensive manner with the crucial topic of biodegradable polymers of natural synthetic or semi-synthetic origin. All the key classes of absorbable polymers used in the fabrication of microspheres and nanospheres, membranes, reservoirs and other components ofinjected or implanted delivery systems are covered. A better understanding of the chemical and physical factors affecting biodegradability will allow more precise prediction of the lifetime of systems in vivo and the more informed choice of polymeric vehicle. 

Polymeric carriers are biodegradable or water-soluble polymer matrices, typically in the form of colloidal-sized particles (microspheres or nanospheres), rods, or films. The active agent is entrapped within but not chemically bonded to the matrix. The drug is released in a sustained fashion as the polymer is dissolved or degraded, eroded, and finally resorbed [24,30,58-62]. 

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