Surface functionalization of bioactive glasses with the enzyme alkaline phosphatase (ALP) was studied in order to combine the inorganic properties of bioactive glass (bioactivity) with the biological properties of the biomolecule (mineralization). Two different bioactive glasses (SCNA and CEL2), with different degree of bioactivity, were used as substrates for the functionalization. ALP was grafted either by direct bonding or via an organic coupling agent. The cellular response to surface-modified bioactive glass was investigated using human osteosarcoma cells (MG63, osteoblast-like). Biocompatibility of all modified surfaces was verified. Of note, the more reactive glass (CEL2), modified with ALP, showed improved mineralization ability. (C) 2014 Elsevier B.V. All rights reserved.