Chlorhexidine Adsorption in Hydroxyapatite and Alginate Microspheres by Extrusion in Zinc and Calcium Chloride

In this work, the adsorption of a low-concentration solution of chlorhexidine (CHX), an antimicrobial drug, in hydroxyapatite (HA) and alginate microspheres was studied. The microspheres were formed by extrusion of a 1:10 mixture of alginate and HA in two different divalent solutions: CaCl2 and ZnCl2. UV-Vis spectroscopy showed that the microspheres adsorbed approximately half of the chlorhexidine in solution, which was initially at 0.2%. XRD patterns obtained prior adsorption confirmed the presence of HA as the only crystalline phase. Scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy (EDX) analysis were performed before and after CHX adsorption. The spheres produced in CaCl2 solution did not show significant change after adsorption. However, samples obtained in ZnCl2 solution showed a different microstructure, with the presence of crystals with a high Zn concentration. X-Ray Fluorescence (XRF) confirmed the presence of ZnO in the samples after CHX absorption.