Surface modified titania nanotubes containing anti-bacterial drugs for controlled delivery nanosystems with high bioactivityElectronic supplementary information (ESI) available. See DOI: 10.1039/c4tb01281j

Surface functionalization of nanomaterials has been realized to be vital to fabricate drug delivery nanosystems that offer high drug loading and sustained release with remarkable in vivo biocompatibility and bioavailability. From these systems, nanomaterials such as titania nanotubes (TNTs) can be functionalized and designed as specific drug delivery nanosystems. Here, two kinds of novel drug delivery nanosystems, i.e. Enro-NH 2 -TNTs and Enro-SH-TNTs, were first prepared by combining the characteristic pH adjusted enrofloxacin (Enro) recrystallized loading process and surface silane coupling agent modified titania nanotubes (NH 2 -TNTs and SH-TNTs). FTIR analysis exhibited that Enro molecules interacted with surface grafted groups, such as -NH 2 or -SH, through an electrostatic effect or a hydrogen effect. The recrystallization and loading of Enro molecules into the two types of modified TNTs was identified using X-ray diffraction patterns (XRD), surface area analysis (BET), and transmission electron microscopy (TEM). In vitro experiments exhibited excellent controlled-release properties and further proved that the Enro drugs had been loaded into TiO 2 nanotubes, which were influenced by grafted molecules. In vitro cell viability, hemolysis assays and cell apoptosis experiments showed that surface modification could increase the biocompatibility and lower the cytotoxicity of TNT nanomaterials to cells. These modified drug delivery nanosystems afforded higher drug bioavailability and longer drug effects on in vivo administration to chickens. Surface modification combined with a pH adjusted process has a large potential for fabricating long-acting drug delivery nanosystems, especially with hydrochloride drugs. Drug delivery nanosystems have been designed as Enro-NH 2 -TNTs and Enro-SH-TNTs with high bioactivity and excellent in vitro and in vivo controlled release.