A pH and near-infrared light dual-responsive drug delivery system based on TiO2 nanotube arrays modified with polydopamine and Fe3+

Abstract

This paper reports a novel drug delivery system based on TiO2 nanotube arrays (TNTs) modified with polydopamine (PDA) and Fe3+, which can load and release alendronate (NaAL), a drug for osteoporosis treatment, in a pH-responsive and near-infrared light-triggered manner. The samples were characterized by electron scanning microscopy(SEM/EDS), Fourier Transform infrared spectroscopy(FTIR), X-ray diffraction(XRD), X-ray Photoelectron Spectroscopy(XPS) and Thermogravimetry(TG). The drug release behavior of the samples was investigated under different pH and light conditions. The results showed that the TNTs-PDA-Fe3+ had improved drug loading capacity compared with the TNTs and TNTs-PDA. The drug release was pH-responsive and near-infrared light-triggered, the drug release from the sample with a pH of 4.6 was much greater than the pH of 11 and 7.4, and the photothermal conversion effificiency of TNTs-PDA-Fe3+-NaAL was 32.9 %. The drug release mechanism was attributed to the coordination bond between Fe3+ and NaAL, and the photothermal effect of the PDA. The cytotoxicity and biocompatibility of the samples were evaluated by MTT assay using mouse embryonic osteoblasts cells. The results indicated that the samples had no obvious cytotoxicity and could promote the cell proliferation and differentiation. The paper concludes that the TNTs-PDA-Fe3+-NaAL system is a potential implantable drug delivery platform for bone-related diseases.