Titania nanotube arrays for local drug delivery: recent advances and perspectives

Abstract

Introduction: Titania nanotube (TNTs) arrays engineered by simple and scalable electrochemical anodization process have been extensively explored as a new nanoengineering approach to address the limitations of systemic drug administration. Due to their outstanding properties and excellent biocompatibility, TNTs arrays have been used to develop new drug-releasing implants (DRI) for emerging therapies based on localized drug delivery (DD). This review highlights the concepts of DRI based on TNTs with a focus on recent progress in their development and future perspectives towards advanced medical therapies.

Areas covered: Recent progress in new strategies for controlling drug release from TNTs arrays aimed at designing TNTs-based DRI 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 DRI for clinical studies. Finally, selected examples of preliminary clinical applications of TNTs for bone therapy and orthopedic implants, cardiovascular stents, dentistry and cancer therapy are presented.

Expert opinion: As current studies have demonstrated, TNTs are a remarkable material that could potentially revolutionize localized DD therapies, especially in areas of orthopedics and localized chemotherapy. However, more extensive ex vivo and in vivo studies should be carried out before TNTs-based DRI could become a feasible technology for real-life clinical applications. This will imply the implementation of different approaches to overcome some technical and commercial challenges.

Keywords:

• drug delivery
• drug release
• drug-releasing implants
• electrochemical anodization
• localized drug delivery
• orthopedic implants
• titania nanotube arrays

Declaration of interest

The authors gratefully acknowledge financially support provided by the Australian Research Council (ARC) for this work (project grants numbers: DP120101680, FT110100711 and DE14010054). The authors are thankful to the School of Chemical Engineering at the University of Adelaide (UoA) for their support in this research. The authors report no conflicts of interest. The authors are solely responsible for the content and writing of this article.

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