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. 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. 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.

Electrochemical anodization of pure aluminum enables the growth of highly ordered nanoporous anodic alumina (NAA) structures. This has made NAA one of the most popular nanomaterials with applications including molecular separation, catalysis, photonics, optoelectronics, sensing, drug delivery, and template synthesis. Over the past decades, the ability to engineer the structure and surface chemistry of NAA and its optical properties has led to the establishment of distinctive photonic structures that can be explored for developing low-cost, portable, rapid-response and highly sensitive sensing devices in combination with surface plasmon resonance (SPR) and reflective interference spectroscopy (RIfS) techniques. This review article highlights the recent advances on fabrication, surface modification and structural engineering of NAA and its application and performance as a platform for SPR- and RIfS-based sensing and biosensing devices.

This review presents the different types and concepts of drug-releasing implants using new nanomaterials and nanotechnology-based devices.

Here, we report on the development of advanced biopolymer-coated drug-releasing implants based on titanium (Ti) featuring titania nanotubes (TNTs) on its surface. These TNT arrays were fabricated on the Ti surface by electrochemical anodization, followed by the loading and release of a model antibiotic drug, gentamicin. The osteoblastic adhesion and antibacterial properties of these TNT-Ti samples are significantly improved by loading antibacterial payloads inside the nanotubes and modifying their surface with two biopolymer coatings (PLGA and chitosan). The improved osteoblast adhesion and antibacterial properties of these drug-releasing TNT-Ti samples are confirmed by the adhesion and proliferation studies of osteoblasts and model Gram-positive bacteria (Staphylococcus epidermidis). The adhesion of these cells on TNT-Ti samples is monitored by fluorescence and scanning electron microscopies. Results reveal the ability of these biopolymer-coated drug-releasing TNT-Ti substrates to promote osteoblast adhesion and proliferation, while effectively preventing bacterial colonization by impeding their proliferation and biofilm formation. The proposed approach could overcome inherent problems associated with bacterial infections on Ti-based implants, simultaneously enabling the development of orthopedic implants with enhanced and synergistic antibacterial functionalities and bone cell promotion.

The studies of nanomaterial-based drug delivery and nanotoxicity are closely interconnected.