Specific examples of suitable polymers include polysaccharides such as dextran or cellulose; chitin; chitosan; proteins; aliphatic polyesters; poly(lactide); poly(glycolide); poly(??-caprolactone); poly(hydroxybutyrate); poly(anhydrides); aliphatic polycarbonates; poly(ortho esters); poly(amino acids); poly(ethylene oxide); polyphosphazenes, and combinations thereof.