JOURNAL OF MATERIALS SCIENCE: MATERIALS IN MEDICINE 16 (2 0 0 5 ) 253 – 259 Bonelike  R /PLGA hybrid materials for bone regeneration: Preparation route and physicochemical characterisation J. M. OLIVEIRA a, b ,T. MIYAZAKI c ,M. A. LOPES a, b ,C. OHTSUKI c ,J. D. SANTOS a, b, ∗ a INEB—Instituto de Engenharia Biom ´ edica, Laborat ´ orio de Biomateriais, Rua do Campo Alegre, 823, 4150-180 Porto, Portugal E-mail: jdsantos@fe.up.pt b FEUP—Faculdade de Engenharia da Universidade do Porto, DEMM, Rua Dr. Roberto Frias, 4200-465 Porto, Portugal c NAIST—Nara Institute of Science and Technology, 8916-5 Takayama, Ikoma, Nara 630-0192, Japan Bonelike  R /PLGA hybrid materials have been developed using γ -MPS as silane-coupling agent between the inorganic and organic phases for controlled drug delivery applications. Silanization showed to be more effective when cyclohexane was used as a non-polar solvent (nP method) due to a chemical interaction between Bonelike  R and the silane film, while by using a 95/5 (V/V) methanol/water as a polar solvent (P method), a much thinner film was achieved. Functional groups of PLGA, such as the carbonyl group (C O), were identified using Raman and FTIR-ATR analysis and therefore these groups may be used to link therapeutic molecules. These novel hybrid materials prepared by combining silanization and post-hybridisation processes are expected to find use in medical applications of bone regeneration and as drug delivery carrier for therapeutic molecules. C  2005 Springer Science + Business Media, Inc. 1. Introduction Hydroxyapatite (HA), Ca 10 (PO 4 ) 6 (OH) 2 , is an exam- ple of a calcium phosphate ceramic that has been usu- ally applied in bone regeneration surgery, but its use has been limited to low-load applications because of its poor mechanical strength [1]. Apart from that, the hu- man bone mineral is reasonably different from stoichio- metric HA regarding its chemical composition, which contains ions, such as K + , Na + , Mg 2+ , CO 2− 3 and F − as well as beta-tricalcium phosphate (β -TCP) phase, β -Ca 3 (PO 4 ) 2 [2, 3]. Over the past decade, extensive work has been carried out on the development of glass-reinforced hydroxyap- atite (GR-HA) recently registered as Bonelike  R , which has been prepared with the incorporation of a P 2 O 5 - based glass in the HA by means of a liquid phase sin- tering process in order to increase, simultaneously, the mechanical properties of HA and to introduce ions com- monly found in bone tissue [4–10]. Bonelike  R is known to stimulate osteoblast growth and differentiation [11, 12] and showed much faster osseointegration than com- mercially available hydroxyapatite [13]. Recently chemically coupled inorganic-organic hy- brid materials have attracted a great deal of attention as ∗ Author to whom all correspondence should be addressed. new materials of significant importance with potential physicochemical and mechanical properties for bone regeneration and drug delivery systems [14, 15]. Sev- eral authors have proposed the use of biodegradable polymers to modify the calcium phosphate surface due to their good similarity in terms of mechanical proper- ties compared to that of the bone tissue [16, 17]. By choosing polymeric materials with known bio- compatibility and biodegradability, as the poly(D,L- lactide-co-glycolide) (PLGA) [18, 19], it becomes possible to prepare biodegradable calcium phos- phate/polymer hybrids with some potential for bone regeneration applications [20, 21]. By changing the lac- tide/glycolide ratio value, the polymer degradation may be controlled [22] and adjusted to new bone forma- tion rate [23], and the release of proteins and therapeu- tic molecules may also be controlled [24]. However, hybrid materials when exposed to an aqueous physio- logical environment can loose strength rapidly at the inorganic-organic interface if the two phases are not bound together [25]. The mechanical behaviour of hy- brid structures describes the type of interaction between the two phases, and if there is no binding, either phys- ical or chemical, there is a premature failure of the 0957–4530 C  2005 Springer Science + Business Media, Inc. 253