Supported nanoparticles for catalysis and biomedical applications

Introduction In recent years we have prepared a large variety of stable supported metal nanoparticles by using supports such as silica, alumina, titania, magnetite (hereafter generally termed as Oxide Supports, OS) and hydroxyapatite (HA) to be employed as catalytic systems and biomaterials. Material and Methods In this framework, our research group has developed a convenient method for the anchoring, without the addition of any external reducing and/or stabilizing agent, of AuNPs on different OS previously modified with a propynylcarbamate organic functionality. In the HA case, we have instead reported an easy, green and low-cost method to support AgNPs onto multifunctionalized HA-R crystals (R = zoledronate, (9R)-9-hydroxystearate). Results and Discussion It was found that among the investigated systems AuNPs/SiO2 catalyst demonstrated to be the most active in the oxidation of a large variety of primary and secondary alcohols both in batch and in continuous-flow packed bed reactors, yielding very stable performances as a function of time without any detrimental activity degradation and for this reason it has been successively employed as heterogeneous catalysts in hydroamination reactions. With regard to the hydroxyapatite support, loading of AgNPs onto modified HA-R gave rise to multifunctional materials that combine the biological properties of R with a significant long-standing antibacterial activity of silver that hindered the development of bone-associated infections thanks to their significant inhibition of the growth of multi-drug resistant Gram positive and Gram negative bacteria.