Adsorption and Sustained Release of Insulin from Zinc Hydroxyapatite Microparticle with Poly (Lactic Acid) Coating
Insulin delivery carriers using low crystalline porous zinc hydroxyapatite (ZnHAp) microparticles with different crystal sizes and novel formulation method of poly (lactic acid) (PLA) have been developed to achieve the sustained-release of insulin. The adsorption isotherm curves of insulin dissolved into acetic acid of pH4.5 onto ZnHAp nanocrystals show non-Langmuir type due to the dissolution of the ZnHAp microparticles; the adsorption amounts were increased with the increase of crystalline sizes. The PLA formulation, coating the outer layer of microparticles, showed the apparent reduction of initial burst for insulin. The amounts of initial release of insulin decreased with the increase of crystalline sizes of ZnHAp, which could be attributed to the different meso-porous structure depending on its crystal sizes.
Marcelo Prado and Cecília Zavaglia
T. Tonegawa et al., "Adsorption and Sustained Release of Insulin from Zinc Hydroxyapatite Microparticle with Poly (Lactic Acid) Coating", Key Engineering Materials, Vols. 396-398, pp. 507-510, 2009