In situ construction of a titanate–silver nanoparticle–titanate sandwich nanostructure on a metallic titanium surface for bacteriostatic and biocompatible implants

Abstract

A synthetic approach has been developed to in situ construct a new hierarchical nanostructure as an ideal biocompatible and bacteriostatic implant. A highly porous nano-network made of sodium titanate is first formed on the titanium surface by hydrothermal treatment. Silver ions are then inserted between the layered titanate lattices to form silver titanate via ion-exchange with sodium ions. Finally, silver ions are reduced by glucose, leading to the in situ growth of Ag nanoparticles that are sandwiched between layer-structured hydrogen titanate. The amount and the size of the Ag nanoparticles in the titanate–Ag nanoparticles–titanate sandwich can be adjusted by the concentrations of both the AgNO₃ and the glucose solutions. The test results show that the silver ions are completely leached from silver titanate after 7 days of immersion in an aqueous solution. In contrast, the Ag ions continue to be released from the titanate–Ag nanoparticle–titanate sandwich nanostructure after 15 days. This steady and prolonged release characteristic is helpful to the long-standing antibacterial process for prevention of severe infection after surgery. A series of antimicrobial and biocompatible tests have shown that the sandwich nanostructure with a low level of silver loading exhibits a bacteriostatic rate as high as 99.99% while retaining low toxicity against cells. The titanate–Ag nanoparticle–titanate sandwich nanostructure, which is fabricated with a low-cost surface modification method, is a promising implantable material that will find applications in artificial bones, joints and dental implants.