Effect of chitosan content on protein adsorption capacity of Mg(II) ion-containing apatite/chitosan composite particles

In this study, Mg2+-containing hydroxyapatite (MgHAp) and chitosan (CS) composite particles (MgHAp/CS) with different CS contents were synthesized, and the relationship between CS content and adsorption of negatively charged protein (bovine serum albumin), was investigated. The CS content in the particles ranged from 18–42 wt %. Specific surface area results indicated that higher CS content could lead to CS aggregation on and between MgHAp particles. The saturation adsorption of bovine serum albumin on the MgHAp/CS particles ranged from 1.48 to 3.64 mg/m2. The particles with 42 wt % CS content exhibited the highest saturation adsorption amount among the particles. Additionally, protein adsorption tended to increase with higher CS content, probably because more positively charged CS (–NH3+) on the particle surface facilitates electrostatic interactions with negatively charged proteins. This suggests that positively charged CS in the particles can regulate the amount of protein adsorbed.