A novel strategy for fabrication of fluorescent hydroxyapatite based polymer composites through the combination of surface ligand exchange and self-catalyzed ATRP.

A novel and facile strategy that combination of surface ligand exchange and photo-initiated atom transfer radical polymerization (ATRP) has been developed for the preparation of fluorescent hydroxyapatite (HAp) based polymer composites, which were utilized for biological imaging applications. In particular, the photo-initiated ATRP not only inherited advantages of traditional ATRP but also overcome its deficiencies such as high energy consumption, transition metal contamination and long reaction time. In this method, a hydrophilic and biocompatible PEGMA was introduced to enhance the hydrophilic and biocompatibility of HAp nanocomposites. Simultaneously, the HAp-poly(PEGMA-co-AcFl) composites are endowed with bright green fluorescence by grafting with AcFl on the surface via copolymerization. The physicochemical properties of HAp-poly(PEGMA-co-AcFl) composites were characterized by a series of methods in detail. Results confirmed that HAp-poly(PEGMA-co-AcFl) composites possess controlled size and morphology, high water dispersibility and strong fluorescence. The cell viability and cell uptake behavior demonstrated that HAp-poly(PEGMA-co-AcFl) composites present low toxicity and can be potentially used for biological imaging. Taken together, we have developed a facile and efficient method for the fabrication of fluorescent HAp composites with desirable physicochemical and biological properties.