Study On The Drug Delivery System Based On Polydopamine Modified Titanium Dioxide Nanotube Arrays

Titanium dioxide nanotubes（TNTs）have been increasingly recognized as implantable biomaterials,owing to good biocompatibility,corrosion resistance,mechanical properties,and TNTs suitable for the adhesion and growth of cells.TNTs as a local release carrier can improve the efficacy,reduce toxic and side effects.Surface functionalization of TNTs is better applied to clinical medicine.In this paper,TNTs are prepared by electrochemical anodic oxidation method.Various modifications of TNTs are designed to achieve controlled and sustained release of drugs.Facing some sudden symptoms,TNTs can be administered on demand as controlled release drug delivery systems for improving drug utilization,reducing drug response and patient suffering.Firstly,the dopamine polymer coating was modified on the surface of TiO₂nanotubes by ultrasonic method,named TNTs-PDA.When dopamine was polymerized,due to the presence of multifunctional groups,it could interact with drug molecules to efficiently enhance drug loading,prevent drug sudden release and improve sustained release performance of the carrier.In this study,the effects of drug concentration and soaking time on drug loading and release were investigated.The cell experiment indicated that samples were beneficial to cell proliferation and enhanced biological activity and biomineralization ability.Secondly,the TNTs-PDA were modified with a certain concentration of CaCl₂/Fe Cl₃·H₂O solution,subsequently,the samples were immersed alendronate sodium solutions by the immersion method.The effects of Ca²⁺/Fe³⁺modification on drug loading,release and biomineralization properties were investigated.Moreover,the optimal drug concentration and soaking time were also explored.The results showed that TNTs-PDA were modified with Ca²⁺/Fe³⁺and make the composite carrier emerged positively charged,which can interact with the negatively charged drug via electrostatic adsorption to improve the loading of alendronate sodium,effectively inhibit the sudden release of drugs.Meanwhile,the different pH values leaded to the difference between Fe³⁺and-NH₂coordination bond in alendronate to achieve pH controlled release of drugs.Finally,in order to better realize the on-demanded drug release according to the lesion of the affected area,combineing the photothermal effect of polydopamine and the temperature-sensitive substance of tetradecanol,we constructed a controlled release drug system with near-infrared light and temperature control.Experimental results showed that the system could better control the drug release through near-infrared light and temperature.It provided a new way for drug release and that was noticeably essential for clinical medication.