Tunable hydroxyapatite wettability: Effect on adhesion of biological molecules

Surface wettability modifications of biocompatible materials and wettability patterning are attractive methods for directed biological cells immobilization for tissue engineering, drug delivery, gene transfer, etc. Hydroxyapatite is known as an implantable biomimetic material and a substrate for effective adhesion of biological cells of various origins. Here we report the use of a low-energy electron irradiation to achieve tunable wettability of the hydroxyapatite in a wide range of contact angles, from 10 degrees to 100 degrees, with accuracy of +/- 3 degrees. The incident electrons generate electron/hole pairs resulting in significant variation of the surface potential of the hydroxyapatite semiconductor and give rise to pronounced wettability modification. Tailoring the gradually varied wettability state in the hydroxyapatite nanoceramics enabled the differential binding of biological materials with different surface properties, such as bovine serum albumin (BSA) and deoxyribonucleic acid (DNA). (c) 2006 Elsevier Ltd. All rights reserved.