Nanoengineered drug-releasing Ti wires as an alternative for local delivery of chemotherapeutics in the brain

The blood–brain barrier (BBB) blocks the passage of active molecules from the blood which makes drug delivery to the brain a challenging problem. Oral drug delivery using chemically modified drugs to enhance their transport properties or remove the blocking of drug transport across the BBB is explored as a common approach to address these problems, but with limited success. Local delivery of drugs directly to the brain interstitium using implants such as polymeric wafers, gels, and catheters has been recognized as a promising alternative particularly for the treatment of brain cancer (glioma) and neurodegenerative disorders. The aim of this study was to introduce a new solution by engineering a drug-releasing implant for local drug delivery in the brain, based on titanium (Ti) wires with titania nanotube (TNT) arrays on their surfaces. Drug loading and drug release characteristics of this system were explored using two drugs commonly used in oral brain therapy: dopamine (DOPA), a neurotransmitter agent; and doxorubicin (DOXO), an anticancer drug. Results showed that TNT/Ti wires could provide a considerable amount of drugs (>170 μg to 1000 μg) with desirable release kinetics and controllable release time (1 to several weeks) and proved their feasibility for use as drug-releasing implants for local drug delivery in the brain

Drug-eluting Ti wires with titania nanotube arrays for bone fixation and reduced bone infection

Current bone fixation technology which uses stainless steel wires known as Kirschner wires for fracture fixing often causes infection and reduced skeletal load resulting in implant failure. Creating new wires with drug-eluting properties to locally deliver drugs is an appealing approach to address some of these problems. This study presents the use of titanium [Ti] wires with titania nanotube [TNT] arrays formed with a drug delivery capability to design alternative bone fixation tools for orthopaedic applications. A titania layer with an array of nanotube structures was synthesised on the surface of a Ti wire by electrochemical anodisation and loaded with antibiotic (gentamicin) used as a model of bone anti-bacterial drug. Successful fabrication of TNT structures with pore diameters of approximately 170 nm and length of 70 μm is demonstrated for the first time in the form of wires. The drug release characteristics of TNT-Ti wires were evaluated, showing a two-phase release, with a burst release (37%) and a slow release with zero-order kinetics over 11 days. These results confirmed our system's ability to be applied as a drug-eluting tool for orthopaedic applications. The established biocompatibility of TNT structures, closer modulus of elasticity to natural bones and possible inclusion of desired drugs, proteins or growth factors make this system a promising alternative to replace conventional bone implants to prevent bone infection and to be used for targeted treatment of bone cancer, osteomyelitis and other orthopaedic diseases

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

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

Progress in the Synthesis of Catalyst Supports: Synergistic Effects of Nanocomposites for Attaining Long-Term Stable Activity in CH₄–CO₂ Dry Reforming

To attain sustained activity and stability in CH₄–CO₂ dry reforming (CCDR), two nanocomposite materials comprising silicon carbide or alumina and ceria–zirconia were introduced to support cobalt–nickel (CoNi) catalysts. Following the sequential impregnation-ultrasonication–deposition precipitation procedure, catalysts were systematically characterized and their performances were tested at 1.2 bar and 750 °C, where undiluted CH₄–CO₂ (ratio = 1:1) streams simulating biogas and the real industrial conditions were fed into a continuous flow reactor. For CCDR reactions conducted at a weight hourly space velocity (WHSV) of 12 L/(g_cat h), good activity and stability were shown for both catalysts. Carbon content as low as 0.3 wt % and high conversions (70%–78% and 78%–88% for CH₄ and CO₂, respectively) were recorded over 23 h and 550 h tests. Interestingly, by increasing the WHSV value to an order of magnitude higher, i.e., at 120 L/(g_cat h) with all other conditions held constant, a 6 h short-term test showed remarkably high conversions near equilibrium values, implying that the reactions still occurred within the thermodynamic regime, despite a reduced 10-fold mass of catalyst bed. This infers that not all active sites available on the catalyst surface were fully exploited. Compared to previous catalyst performances, the progress made in this work is ascribed to the synergistic effects from selected support materials that contributed remarkable redox properties, high surface area, mechanical and thermal stability to the catalysts