Tailoring the surface functionalities of titania nanotube arrays

Vasilev, Krasimir; Poh, Zihan; Kant, Kamal; Chan, Joseph; Michelmore, Andrew; Lošić, Dušan

doi:10.1016/j.biomaterials.2009.09.074

Cited by 194 publications

(128 citation statements)

References 55 publications

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“…To prepare a TNT layer on Ti foil (TNT-Ti), two anodization steps were performed using a specially designed electrochemical cell and computer controlled power supply (Agilent), using previously described procedures [19,27,28]. A specially designed electrode holder permitted only a circular area of diameter 1 cm of Ti metal available for anodization.…”

Section: The Fabrication Of Titania Nanotube (Tnt) Arrays On Timentioning

confidence: 99%

“…Controlling the pore diameters and lengths of TNTs by anodization process is used as a simple method to control drug re-lease characteristics, but this method has considerable limitation for applications where sustained drug release is required [16]. In our previous studies, we showed that the surface modification of pore structures via plasma polymerisation that allows control over pore diameter, has the potential to significantly improve drug delivery performance of porous and nanotubular materials [17][18][19][20]. Even, progress is encouraging; the development of new strategies able to provide sustained and controllable drug release is still required.…”

Section: Introductionmentioning

confidence: 99%

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Controlling Drug Release from Titania Nanotube Arrays Using Polymer Nanocarriers and Biopolymer Coating

Aw¹,

Gulati²,

Lošić³

2011

JBNB

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Titania nanotube arrays (TNT) prepared by self-ordering electrochemical anodization have attracted considerable attention for the development of new devices for local drug delivery applications. Two approaches to extend drug release of water insoluble drugs by integrating TNTs with polymeric micelles and biopolymer coatings are presented in this work. The proposed strategies emphasized on remarkable properties of these materials and their unique combination to design local drug delivery system with advanced performance. The first concept integrates TNTs with drug loaded polymeric micelles (Pluronic F127) as drug nanocarrier, until the second concept includes polymer coating of drug loaded TNT with biodegradable polymer (chitosan). The water insoluble, anti-inflammatory drug, indomethacin was used as a model drug. Both approaches showed a significant improvement of the drug release characteristics, withreduced burst release (from 77% to 39%) and extended overall release from 9 days to more than 28 days. These results suggest the capability of TNT based systems to be applied for local drug delivery deliver over an extended period with predictable kinetics that is particularly important for bone implant therapies.

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Section: The Fabrication Of Titania Nanotube (Tnt) Arrays On Timentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Controlling Drug Release from Titania Nanotube Arrays Using Polymer Nanocarriers and Biopolymer Coating

Aw¹,

Gulati²,

Lošić³

2011

JBNB

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“…Two anodization steps were performed using a specially designed electrochemical cell and computer-controlled power supply (Agilent, Santa Clara, CA), using previously described procedures. 29,30 In the first anodization step, a constant voltage of 100 V was applied for 1 hour in ammonium fluoride/ethylene glycol electrolyte (3% water and 0.3% NH 4 F) at 20°C. The obtained anodic TNT layer was removed (by sonication in methanol), leaving the nanotextured titanium surface for the second anodization.…”

Section: Preparation Of Titania Nanotube Arrays On Ti Wires (Tnt/ti)mentioning

confidence: 99%

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

Gulati

Aw²,

Lošić

2012

IJN

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Abstract: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. Purpose: In this report, a new drug-releasing platform in the form of nanoengineered Ti wires with TNT arrays is proposed as an alternative for local delivery of chemotherapeutics in the brain to bypass the BBB. To prove this concept, drug loading and release characteristics of two drugs important for brain therapy (the neurotransmitter DOPA and the anticancer drug DOXO) were explored. Methods: Titania nanotube arrays on the surface of Ti wires (TNT/Ti) were fabricated using a simple anodization process, followed by separate loading of two drugs (DOPA and DOXO) inside the nanotube structures. The loading and in vitro release characteristics of prepared TNT/ Ti implants were examined using thermogravimetric analysis (TGA) UV-Vis spectroscopy. Results: Scanning electron microscopy studies confirmed that well-ordered, vertically aligned, densely packed nanotube arrays with an average diameter of 170 nm and length 70 µm were formed on the surface of TNT/Ti wires. TGA results showed a total drug loading of 170 µg and 1200 µg inside the TNTs for DOPA and DOXO respectively. Two-phase drug release behavior was observed including a fast release (burst) for the first 6 hours and a prolonged slow release phase for 8 days, both with acceptable dosage and desirable release kinetics. The physical, structural, loading and release characteristics of prepared TNT/Ti implants showed several advantages in comparison with existing and clinically proved brain implants. Conclusion: Our results confirmed that TNT/Ti wires can be successfully employed as a suitable platform to release neurotransmitters such as DOPA and anticancer drugs such as DOXO. Hence, they are a feasible alternative as drug-releasing ...

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“…TNT layers were then prepared by a two-step electrochemical anodization of Ti wires in ammonium fluoride/ethylene glycol electrolyte (3% water and 0.3% ammonium fluoride) at 20°C, using a constant voltage of 100 V for 1 hour, as described previously. [32][33][34] Both pore diameter and length of the TNTs were determined by selecting the appropriate voltage (100 V) and anodization time (1 hour).…”

Section: Preparation Of Tnt-ti Wires As Drug-releasing Implantsmentioning

confidence: 99%

Characterization of drug-release kinetics in trabecular bone from titania nanotube implants

Khalid²,

Gulati³

et al. 2012

IJN

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Purpose: The aim of this study was to investigate the application of the three-dimensional bone bioreactor for studying drug-release kinetics and distribution of drugs in the ex vivo cancellous bone environment, and to demonstrate the application of nanoengineered titanium (Ti) wires generated with titania nanotube (TNT) arrays as drug-releasing implants for local drug delivery Methods: Nanoengineered Ti wires covered with a layer of TNT arrays implanted in bone were used as a drug-releasing implant. Viable bovine trabecular bone was used as the ex vivo bone substrate embedded with the implants and placed in the bone reactor. A hydrophilic fluorescent dye (rhodamine B) was used as the model drug, loaded inside the TNT-Ti implants, to monitor drug release and transport in trabecular bone. The distribution of released model drug in the bone was monitored throughout the bone structure, and concentration profiles at different vertical (0-5 mm) and horizontal (0-10 mm) distances from the implant surface were obtained at a range of release times from 1 hour to 5 days. Results: Scanning electron microscopy confirmed that well-ordered, vertically aligned nanotube arrays were formed on the surface of prepared TNT-Ti wires. Thermogravimetric analysis proved loading of the model drug and fluorescence spectroscopy was used to show drug-release characteristics in-vitro. The drug release from implants inserted into bone ex vivo showed a consistent gradual release of model drug from the TNT-Ti implants, with a characteristic threedimensional distribution into the surrounding bone, over a period of 5 days. The parameters including the flow rate of bone culture medium, differences in trabecular microarchitecture between bone samples, and mechanical loading were found to have the most significant influence on drug distribution in the bone. Conclusion: These results demonstrate the utility of the Zetos™ system for ex vivo drugrelease studies in bone, which can be applied to optimize the delivery of specific therapies and to assist in the design of new drug delivery systems. This method has the potential to provide new knowledge to understand drug distribution in the bone environment and to considerably improve existing technologies for local administration in bone, including solving some critical problems in bone therapy and orthopedic implants.

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Tailoring the surface functionalities of titania nanotube arrays

Cited by 194 publications

References 55 publications

Controlling Drug Release from Titania Nanotube Arrays Using Polymer Nanocarriers and Biopolymer Coating

Controlling Drug Release from Titania Nanotube Arrays Using Polymer Nanocarriers and Biopolymer Coating

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

Characterization of drug-release kinetics in trabecular bone from titania nanotube implants

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