Evaluation of the Characteristics of the Adsorption of Fibrinogen onto Hydroxyapatite

Abstract

Three chemical substances namely Hydroxyapatite, HAP (Sigma), HAP (locally prepared) and calcium hydrogen phosphate dehydrate (CHP), were investigated for the adsorption of fibrinogen onto them. Of the three, the Sigma sample of HAP adsorbed the highest amount of fibrinogen. Increase in the concentration of fibrinogen up to 0.8mg/cm3 resulted in increased adsorption onto HAP. The adsorption followed the Langmuir model (which is typically monolayer adsorption). For the Sigma sample of HAP, there was increase in the amount of fibrinogen adsorbed with time but it remained constant after 120 minutes. Desorption after this time is attributable to conformational changes in the molecule. Treatment of HAP with calcium and magnesium ions increased the amount of fibrinogen adsorbed onto it as against treatment with potassium ion (a monovalent ion). Electrostatic attraction on the surface of the treated HAP and hydrogen are responsible for the adsorption. The results are useful in fabricating bone and teeth implants that are compatible with body fluid and blood.

Keywords: Hydroxyapatite, Fibrinogen, Biocompatibilty, Implants