PH Responsive Drug Delivery System Based On TiO₂ Nanotube Arrays

Recent progress in new strategies for controlling drug release from TiO2 nanotube arrays aimed at designing TNTs-based drug delivery implants with optimized performances,including extended drug release and zero-order release kinetics and remotely activated release are described.Furthermore,significant progress in biocompatibility studies on TNTs and their outstanding properties to promote hydroxyapatite and bone cells growths and to differentiate stem cells are highlighted.Examples of ex vivo and in vivo studies of drug-loaded TNTs are shown to.confirm the practical and potential applicability of TNTs-based drug delivery implants for clinical studies.In this paper,arrays of TiO2 nanotubes with controllable diameter and uniform distribution was prepared on the surface of titanium substrate by anodic oxidation method using fluorine-containing glycerol electrolyte and modified on the surface of the titanium nanotube arrays,which could be used as nano-storage sustained-release material for antibacterial drug,the treatment capacity can be obtained by loading the corresponding antibiotics.The drug alendronate,as used herein,is a commonly used anti-bone resorption and osteoporosis drug.Firstly,poly-lysine was modified by hydrothermal method on the prepared TiO2 nanotube arrays.The hydrophilic drug alendronate was loaded with different pH by vacuum drying and hydrothermal method,explore the drug loading and release effect in buffer solution.Because under the acidic condition,the positively charged poly lysine can be combined with alendronate negatively charged,so as to improve the load,prolong release time.At the same time in the tube at the mouth of the polymer coated with polylactic acid coating,can significantly inhibit drug burst release.Secondly,the response of drug delivery system has attracted much attention in recent years,such release system can be affected by the external environment,such as pH,temperature,light,etc.In this paper,a pH-responsive drug delivery system based on the coordination bond of TiO2 nanotube array was constructed and its feasibility was studied.According to the metal coordination,the metal ions and the drug molecules are introduced into the ammnized nanotube arrays in order to form the"amino-metal-drug" coordination system.Due to the different metal coordination ability,the coordination of metal Cu and Fe were carried out in this paper and to study the coordination ability and sustained drug release.The change of the pH value can lead to the cleavage of the coordination bond "amino metal" or "metal drug",so as to release the drug.The results show that the coordination bond can be formed between drug and metal under neutral condition,which increases the drug loading.When the buffer pH=7.4,the coordination bond is firm and not easy to break,and the burst release is reduced at first 12h,and the drug can be released slowly.The morphology,structure and properties were well characterized by SEM,XRD,FTIR,XPS and atomic absorption respectively.