Surface Of Titania Nanotubes Research Articles

Combined Infection Control and Enhanced Osteogenic Differentiation Capacity on Additive Manufactured Ti‐6Al‐4V are Mediated via Titania Nanotube Delivery of Novel Biofilm Inhibitors

AbstractAdditive manufacturing (AM) of titanium alloys offers the capacity to fabricate patient‐specific implants with defined porous architecture to enhance bone‐implant fixation. However, clinical challenges associated with orthopedic implants include inconsistent osseointegration and biofilm‐associated peri‐implant infection, leading to implant failure. Here, a strategy is developed to reduce infection and promote osteogenesis simultaneously on AM Ti‐6Al‐4V implants by delivering biofilm inhibitor molecules via titania nanotube surface modification. Electrochemical anodization is performed on polished and as‐manufactured Ti‐6Al‐4V to generate nanotubes, which are utilized for delivery of a novel methylthioadenosine nucleosidase inhibitor (MTANi) that targets MTAN—a key enzyme in bacterial metabolism involved in biofilm formation—thereby offering biofilm inhibition capacity combined with surface nano‐topography for promoting osteogenesis. Clinical isolates of staphylococcus cohnii formed firm biofilms on polished and AM Ti‐6Al‐4V controls whereas modified implants loaded with MTANi inhibit biofilm formation. Anodized AM Ti‐6Al‐4V nanotube substrates enhance alkaline phosphatase production, bone‐specific protein expression (osteocalcin, collagen I) and mineral deposition of human mesenchymal stromal cells (hMSCs), compared to as‐manufactured controls. Importantly, no detrimental effects on hMSC proliferation and osteogenic differentiation are observed for MTANi‐loaded substrates. Application of novel MTANi and electrochemical anodization offers a promising strategy for titanium alloy implant surface modification.

Dynamic Titania Nanotube Surface Achieves UV-Triggered Charge Reversal and Enhances Cell Differentiation.

Stimuli-responsive biomaterials supply a promising solution to adapt to the complex physiological environment for different biomedical applications. In this study, a dynamic UV-triggered pH-responsive biosurface was constructed on titania nanotubes (TNTs) by loading photoacid generators, diphenyliodonium chloride, into the nanotubes, and grafting 2,3-dimethyl maleic anhydride (DMMA)-modified hyperbranched poly(l-lysine) (HBPLL) onto the surface. The local acidity was dramatically enhanced by UV irradiation for only 30 s, leading to the dissociation of DMMA and thereby the transformation of surface chemistry from negatively charged caboxyl groups to positively charged amino groups. The TNTs-HBPLL-DMMA substrate could better promote proliferation and spreading of rat bone mesenchymal stem cells (rBMSCs) after UV irradiation. The osteogenic differentiation of rBMSCs was enhanced because of the charge reversal in combination with the titania-based substrates.

Interaction of blood plasma proteins with superhemophobic titania nanotube surfaces

The need to improve blood biocompatibility of medical devices is urgent. As soon as blood encounters a biomaterial implant, proteins adsorb on its surfaces, often leading to several complications such as thrombosis and failure of the device. Therefore, controlling protein adsorption plays a major role in developing hemocompatible materials. In this study, the interaction of key blood plasma proteins with superhemophobic titania nanotube substrates and the blood clotting responses was investigated. The substrate stability was evaluated and fibrinogen adsorption and thrombin formation from plasma were assessed using ELISA. Whole blood clotting kinetics was also investigated, and Factor XII activation on the substrates was characterized by an in vitro plasma coagulation time assay. The results show that superhemophobic titania nanotubes are stable and considerably decrease surface protein adsorption/Factor XII activation as well as delay the whole blood clotting, and thus can be a promising approach for designing blood contacting medical devices.

TiO2 NANOTUBES-POLYDOPAMINE-SILVER COMPOSITES FOR LONG-TERM ANTIBACTERIAL PROPERTIES: PREPARATION AND CHARACTERIZATION

In this study, antibacterial activity and long-lasting release of silver for clinical applications were achieved by utilizing silver nanoparticles on the Titania nanotubes (TNTs) through in situ polymerization of polydopamine (PDA). TNTs were synthesized with the hydrothermal process from Titania nanoparticles. Then the surface modification of TNTs was accomplished by in situ polymerization of PDA and silver ions were reduced on the PDA surface. The feature of obtained samples was characterized using transmission electron microscope (TEM), field emission scanning electron microscope (FESEM), X-ray diffraction spectroscopy (XRD), Fourier-transform infrared spectroscopy (FTIR) and atomic absorption spectrophotometry (AAS). The results showed that PDA layer formed on the synthesized anatase TNTs surface. This used as reduction agent for silver ions as well as an adhesive layer to tethering the silver nanoparticles on TNTs surface. AAS results indicated that silver ions reduction to silver nanoparticles on the TNTs surface increased from 3.1 wt.% to 9.6 wt.% in presence of PDA. Also, the results of silver release revealed that PDA worked as an adhesive layer by chelating silver nanoparticles on TNTs and slowing silver ions release rate which implying the possible long-term antibacterial activity of PDA coated TNTs. Besides that, TNTs showed 33% antibacterial activity which is half than silver loaded TNTs-PDA samples. This confirms that PDA have extraordinary effect on the antibacterial activity. This work offers a facile process for the preparation of long-lasting silver based antibacterial activity and facilitates their clinical application in the modern biomedical fields.

Synthesis of Titania nanotubes/polyaniline via rotating bed-plasma enhanced chemical vapor deposition for enhanced visible light photodegradation

This study employed rotating bed plasma enhanced chemical vapor deposition technique to coat a thin polymeric film of polyaniline (PANI) onto titania nanotubes (TNT). The effect of plasma power on the growth of thin film polymer on the photocatalyst surface was investigated. Transmission electron microscope micrographs evidenced the formation of thin polymeric layers on TNT surface. Fourier-transform infrared spectra confirmed the presence of functional groups associated with PANI. The band gap of coated photocatalyst reduced from 3.23 eV to 2.54 eV, implying the photosensitivity of TNT-PANI in visible light range, while photoluminescence spectra showed that PANI coated TNT exhibited lower recombination rates. The photocatalytic performance of the resultant TNT-PANI titania were evaluated under both UV and visible light irradiation using reactive black 5 (RB 5) as the model pollutant. Unlike TNT which could only be activated under UV light, TNT-PANI coated using a plasma power of 50 W exhibited superior photoactivity under both ultraviolet (UV) and visible light irradiation. The incorporation of PANI enhanced UV light photodegradation performance, where reaction rate improved to 0.615 ppm min−1and three times higher compared to uncoated TNT. The best sample TNT-PANI 50 W exhibited promising photodegradation efficiency of 56.4% within 240 min of visible light irradiation.

Adhesion and Proliferation of Human Adipose-Derived Stem Cells on Titania Nanotube Surfaces

When a biomaterial is implanted, the body reacts similar to an injury and stem cells are recruited to the implant site. Since, stem cells play an important role in tissue repair in the body, their interaction with biomaterials is critical for long-term success of medical devices. Surfaces with nanostructured features have been shown to alter cellular functionality in vitro and even improve fixation of the implant to the surrounding bone tissues in vivo. In this study, the effect of titania nanotube (NT) size and cell density on the adhesion and proliferation of human adipose-derived stem cells (ASCs) was evaluated. Although many studies have evaluated mesenchymal stem cells response on nanostructured surfaces, very few studies have explored the response of adipose-derived stem cells on titanium nanotube surfaces and none have explored the effect of cell density concurrent with nanotube size on ASC proliferation. Proliferation behavior of ASCs on NT surfaces and titanium control were investigated for a week using three different cell densities. The optimal cell density was 2500 cells/well and the smaller diameter NT exhibited higher ASC proliferation. This study confirms that NT surfaces promote ASC adhesion and proliferation. By more fully understanding the effect of nanostructure size on adhesion and proliferation of stem cells, implants could be specifically designed to achieve the optimal stem cell response from the tissue in which they are implanted. Additionally, the favorable response of ASC to these NT surfaces and determination of optimal cell density suggests a potential use in orthopedic tissue regeneration. When a biomaterial is implanted, the body reacts similar to an injury and stem cells are recruited to the implant site. Since, stem cells play an important role in tissue repair in the body, their interaction with biomaterials is critical for long-term success of medical devices. This study confirms that nanotube surfaces promote stem cell adhesion and proliferation.

Effects of titania nanotube surfaces on osteogenic differentiation of human adipose-derived stem cells

The surface of an implant is important for successful osseointegration and long-term stability as it can aid in cell migration and proliferation, cell differentiation and allow extracellular matrix production. Earlier studies have shown that nanostructuring the surface of titanium can enhance mesenchymal stem cell (MSC) migration, proliferation, and differentiation. Although many studies have evaluated MSC response on nanostructured surfaces, there are only a few studies that have explored the response of adipose-derived stem cells (ADSC) on titania nanotube surfaces. Because ADSC exhibit great potential in regenerative medicine and have already proven effective in developing new treatments, this study aims to further understand how ADSC interact with titania nanotube surfaces. The results of this study indicate that titania nanotube surfaces enhance ADSC proliferation and differentiation that is also dependent on the size of nanotubes. Additionally, the favorable response of ADSC on nanotube surfaces suggests a potential application in orthopedic tissue regeneration.

Stability studies of CdS sensitized TiO2 nanotubes prepared using the SILAR method

Titania nanotubes sensitized with CdS nanoparticles of different sizes and amounts were prepared using the successive ionic layer (SILAR) deposition method. UV/visible spectra indicate a red shift in CdS absorption upon increasing the number of SILAR cycles this is due to an increase in amount and size of CdS particles on the surface of titania nanotube. The stability of CdS particle sensitized on the surface of titania nanotubes were monitored using X-ray photoelectron spectroscopy (XPS). The formation of CdSO4 species on the surface of CdS particles was evident from the XPS analysis. Smaller CdS particles, formed using a lower number of SILAR cycles, are more prone to oxidation than the larger particles formed using a greater number of SILAR cycles. The photocatalytic activity and solar cell efficiency is found to be dependent on the number of SILAR cycles employed.

Rapid heat treatment for anatase conversion of titania nanotube orthopedic surfaces

The amorphous to anatase transformation of anodized nanotubular titania surfaces has been studied by x-ray diffraction and transmission electron microscopy (TEM). A more rapid heat treatment for conversion of amorphous to crystalline anatase favorable for orthopedic implant applications was demonstrated. Nanotube titania surfaces were fabricated by electrochemical anodization of Ti6Al4V in an electrolyte containing 0.2 wt% NH4F, 60% ethylene glycol and 40% deionized water. The resulting surfaces were systematically heat treated in air with isochronal and isothermal experiments to study the temperature and time dependent transformation respectively. Energy dispersive spectroscopy shows that the anatase phase transformation of TiO2 in the as-anodized amorphous nanotube layer can be achieved in as little as 5 min at 350 °C in contrast to reports of higher temperature and much longer time. Crystallinity analysis at different temperatures and times yield transformation rate coefficients and activation energy for crystalline anatase coalescence. TEM confirms the (101) TiO2 presence within the nanotubes. These results confirm that for applications where amorphous titania nanotube surfaces are converted to crystalline anatase, a 5 min production flow-through heating process could be used instead of a 3 h batch process, reducing time, cost, and complexity.

Au Nanoparticles Modified Co/Titania Nanotubes as Electrocatalysts for Borohydride Oxidation

AbstractGold‐cobalt catalysts were deposited on the surface of titania nanotubes (TiO2‐NTs) via galvanic displacement technique. The catalysts were characterized using field emission scanning electron microscopy, energy dispersive X‐ray spectroscopy and inductively coupled plasma optical emission spectroscopy. The electrocatalytic activity of the Au(Co)/TiO2‐NTs catalysts was examined in respect to the oxidation of BH4− ions in an alkaline media by cyclic voltammetry and chronoamperometry. It was found that the Au(Co)/TiO2‐NTs catalysts with Au loadings in the range of 10 up to 59 µgAu cm−2 had a higher activity compared to that of Co/TiO2‐NTs and bare Au. A direct NaBH4‐H2O2 single fuel cell was constructed with the Au(Co)/TiO2‐NTs catalysts as anode and Pt as the cathode. The fuel cell exhibited an open circuit voltage of ca. 1.9 V and peak power densities up to 217 mW cm−2 at 25 °C. The highest specific peak power density of 16.3 kW g−1Au was obtained when employing Au(Co)/TiO2‐NTs with the Au loading of 10 µgAu cm−2 as the anode catalyst.

Drug delivery behavior of titania nanotube arrays coated with chitosan polymer

Titania nanotube (TNT) arrays with the length to diameter ratio of 85:1 were synthetized after anodizing the specimens at the anodizing voltage of 55V for 2h. Ultrasonic cleaning procedure in deionized water caused the formation of micro-cracks, clusters of TNT bundles and distortion of the nanotubes; however, acetone medium decreased the risk of fracture and the formation of clusters. To control the drug delivery rate, chitosan polymer was deposited on the surface of TNTs using dip-coating process. The total release of TNTs with 0, 0.29 and 0.45μm chitosan coating thickness was about 6, 8 and 12days, respectively.

Co-culturing epidermal keratinocytes and dermal fibroblasts on nano-structured titanium surfaces

Long-term success of percutaneous implants depends mostly on the stable connection between the soft tissue and implant surface because bacterial invasion and infection can be prevented by a proper seal between the skin and implant. The percutaneous seal is affected by responses of keratinocytes and/or fibroblasts to the implant. Herein, the in vitro functionality of fibroblasts and keratinocytes on titania nanotubes (TNT) and polished titanium (pTi) surfaces was investigated by different culture methods. Adhesion, proliferation, morphology, and differentiation were evaluated by cell viability assay, fluorescence microscopy, real-time quantitative polymerase chain reaction (RT-PCR), and indirect immunofluorescence. Single cultured fibroblasts on the TNT surface showed increased adhesion, proliferation, and differentiation, while these cellular properties were decreased in single cultured keratinocytes. In non-contact co-culture with keratinocytes, fibroblasts presented better orientation, continuous proliferation, and increased gene expression on TNT. However, decreased adhesion and proliferation were observed for keratinocytes in non-contact co-culture with fibroblasts. Furthermore, keratinocytes presented high abilities to proliferate and differentiate in contact co-culture on fibroblasts adhering on the TNT surface. The gene expression results of contact co-culture model suggested that the nano-structured titanium surface promoted the maturation of fibroblasts and the formation of dermal matrix through secreting collagen I and transforming growth factor-β1 (TGF-β1), and indirectly facilitated the proliferation of keratinocytes and the formation of the basement membrane by stimulating fibroblasts to secrete keratinocyte growth factor (KGF), nidogen, and collagen IVα-1. Meanwhile, keratinocytes secreted TGF-β1 to promote fibroblast differentiation. Moreover, the enhanced proliferation and differentiation of keratinocytes were favorable for skin-implant integration.

Mussel-inspired surface modification of titania nanotubes as a novel drug delivery system

Titania nanotubes (TNTs) have attracted considerable attention for the development of new devices for local drug delivery applications. In this study TNTs were synthesized by hydrothermal method from titania nanoparticles and then the surface of TNTs were functionalized by in situ polymerization of bioinspired polydopamine (PDA). The proposed strategies emphasized on remarkable properties of these materials and their unique combination to design local drug delivery system with advanced performance. The samples were characterized using Transmission Electron Microscope (TEM), Field Emission Scanning Electron Microscope (FESEM), X-ray diffraction pattern (XRD), Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and surface area analysis (BET). The results showed that the specific surface area significantly is increased by creating tubular nanostructure. TGA results indicated Surface functionalization of TNTs with PDA (TNTs-PDA) about 19.3% that led to increase biocompatibility and bioactivity of TNTs as well as improve drug loading and release properties. It is attributed to the effect of NH2 groups which immobilize drug molecules on the TNTs. According to the obtained release profiles for the samples, the release profiles followed from a Hill model. Thus, PDA modified TNTs can be excellent candidate as specific drug delivery systems.

In situ photoreduction of Ag+-ions on the surface of titania nanotubes deposited on cotton and cotton/PET fabrics

This study discusses the possibility of in situ photoreduction of Ag+-ions on the surface of titania nanotubes (TNTs) deposited on the cotton and cotton/PET fabrics in the presence of amino acid alanine and methyl alcohol. TNTs were synthetized by hydrothermal method. The proposed interaction between titania, alanine and Ag+-ions was based on the results obtained by FTIR measurements. In order to enhance the binding efficiency between TNTs and fibers, the fabrics were previously impregnated with polyethyleneimine. The presence of TNT/Ag nanocrystals on the surface of fibers was proved by SEM, AAS, XRD and XPS. Larger amount of silver was detected on the cotton fabric. Fabricated TiO2/Ag nanocrystals provided maximum reduction of bacteria E. coli which was preserved after five washing cycles despite significant release of silver. The perspiration fastness tests indicated that silver release did not depend on pH. The presence of TNT/Ag nanocrystals imparted maximum UV protection to fabrics.

Enhancing Osseointegration of Orthopaedic Implants with Titania Nanotube Surfaces

Category: Basic Sciences/Biologics Introduction/Purpose: Solid biologic fixation at the bone-implant interface provides long-term stability of orthopaedic implants. Historically, coatings and surface treatments on implant surfaces have been used to promote osseointegration of orthopaedic implants. The purpose of this research study is to evaluate two morphologies of titania nanotube (TiNT) surfaces via in vitro experiments as well as an in vivo model of femoral intramedullary fixation, in order to assess the influence of TiNT structure on de novo bone formation and bone-implant stability. Methods: TiNT structures were grown from Ti-6Al-4 V materials via an established electrochemical anodization process. Samples were either sonicated then annealed (Aligned TiNT) or annealed without prior sonication (Trabecular TiNT), to produce different morphologies. As-received titanium alloy was the control. Marrow-derived stem cells were isolated from long bones of Sprague Dawley rats and cultured on samples. Alkaline phosphatase (ALP) and osteocalcin (OC) expression by stem cells were assessed via ELISA. Cells were lysed and subjected to quantitative polymerase chain reaction (qPCR) to assess Col1a1, osteonectin, and IGF- 1 expression. An in vivo study evaluated bone formation at 4- and 12-week endpoints. Eight female Sprague Dawley rats per group per endpoint received bilateral Ti-6Al-4 V K-wires as femoral implants. Left femur received control, while right femur received Aligned/Trabecular TiNT K-wire. Bone formation was assessed via microCT, backscatter electron imaging (BEI), and non- decalcified histologic analyses. Results: Aligned and Trabecular TiNT groups demonstrated higher ALP activity than control at 2 and 3 weeks. The in vivo study demonstrated increased bone volume fractions (BV/TV) and total bone volume (TBV) for TiNT surfaces (microCT). The ratio of both BV/TV and TBV in the distal VOI were nearly equivalent for both TiNT surfaces, indicating similar bone formation between both TiNT surfaces and control. In the midshaft VOI, the ratios between TiNT surfaces and control were 1.5 or greater, indicating increased bone formation. At 12 weeks, the bone-implant contact fraction ratio (BEI) showed Aligned TiNT and Trabecular TiNT were 1.3 and 1.4 times greater than control, respectively. Histologic analysis showed both TiNT surfaces had 1.5 times the bone-implant contact as control. Conclusion: In vitro studies demonstrated improved support for osteogenic functions of cultured marrow-derived stem cells on TiNT surfaces compared to controls. μCT, BEI, and histologic analyses associated with the in vivo study demonstrated increased bone formation in the TiNT femora, at specific timepoints and VOIs.

Effect of three surface modification techniques of pure titanium on bacteria adhesion and ultrasonic cleaning efficacy

To evaluate the bacteria adhesion behavior and ultrasonic cleaning efficacy on pure titanium modified with 3 different techiques. Pure titanium disks with mechanically polished surfaces(MP), titania nanotube surfaces(TNT)and sandblast-large grit and acid-etched surfaces(SLA)were used as substrates. The surface characteristics of the 3 types of specimens were detected. The disks of all groups were co-cultured with Porphyromonas gingivalis(Pg)and microcosm for 1 day and 5 days respectively. The cell viabilities of bacteria attached to the 3 types of surfaces were tested. The remaining bacteria on different surfaces after ultrasonic treatment were observed through live/dead bacteria staining. MP and SLA surfaces demonstrated a micro-scale structure, while TNT surfaces showed a nano-scale structure. The surface roughness of SLA specimen was the highest([1.62 ± 0.13]μm), and that of MP([0.81 ± 0.10]μm)and TNT specimen([0.792 ± 0.080]μm)were relatively lower and showed no statistical difference(P >0.05). At 1 and 5 d, the cell viability and the biomass of Pg attached to MP surfaces were as low as 1 829±210 and 13 811±3 110 and A570 value were 0.80±0.35 and 1.56±0.30 respectively. At 1 d, the cell viability of microcosm adhered on MP and TNT surfaces were lower(63 943±6 990 and 69 860±5 555)than that on the SLA surface, and the biomass of microcosm adhered on MP surfaces demonstrated the lowest value(A570 value 5.84±0.60). At 5 d, both the cell viability and biomass of micorcosm adhered on the three surfaces were of no statistical difference(P<0.05). The remaining bacteria on TNT surfaces were the least in the three groups and distributed sporadically after ultrasonic treatment. The remaining bacteria on all surfaces increased with culture time. Both surface topography and roughness affect early bacteria adhesion. However, this effect can be weakened as the biofilm getting mature. The surface topography can significantly affect the mechanical cleaning efficacy of the biofilm. TNT surface reveals a lower adhesion of microcosm and a higher efficacy of ultrasonic cleaning compared to MP and SLA surfaces.

Gold-Cobalt Deposited on Titania Nanotubes as Anode Catalyst for Direct Borohydride Fuel Cells

In the present work gold-cobalt catalysts deposited on titania nanotubes surface (denoted as AuCo/TiO2-NTs) are studied as possible anode materials for direct borohydride/hydrogen peroxide fuel cells. The fuel cell measurements are performed in the 25 - 55 ºC temperature range on a lab-scale direct alkaline NaBH4-H2O2 single fuel cell. Polarization curves are recorded to evaluate the fuel cell performance using each prepared anode catalyst. It has been determined that the peak power density values are in the range from 87 to 102 mWcm–2 on the Co/TiO2-NTs catalyst and from 163 to 283 mWcm–2 on the AuCo/TiO2-NTs catalysts with Au loadings ranging from 10 to 60 µgAu cm–2.

Gold-Cobalt Deposited on Titania Nanotubes as Anode Catalyst for Direct Borohydride Fuel Cells

In the present work gold-cobalt catalysts deposited on titania nanotubes surface (denoted as Au(Co)/TiO2-NTs) were investigated as anode material in direct borohydride fuel cells (DBFCs). The catalysts were prepared by a simple and cost-effective galvanic displacement technique [1]. At first, the sub-layer of Co was deposited on the titania nanotubes surface via electroless deposition. The gold crystallites were then deposited on the Co/TiO2-NTs electrodes by their immersion into gold(III)-containing solution for different time periods. It has been determined that the Au loadings were in the range from 10 to 60 µg cm–2 in the Au(Co)/TiO2-NTs catalysts. Field emission scanning electron microscopy (FESEM) and energy dispersive X-ray spectroscopy (EDXS) were used to characterize the surface morphology and composition of the samples, respectively. The activity of the Au(Co)/TiO2-NTs catalysts for borohydride oxidation reaction (BOR) was evaluated by cyclic voltammetry and chronoamperometry measurements. The performance of a DBFC operating with 1 M NaBH4 + 4 M NaOH as fuel and 5 M H2O2 + 1.5 M HCl as oxidant, while employing Pt as the cathode catalyst and Au(Co)/TiO2-NTs with different Au loadings as the anode catalyst were investigated. Peak power densities up to 122 mW cm-2 were attained at 25 ºC. It was found that the highest specific peak power density of 9.6 kW g–1 Au was obtained when employing Au(Co)/TiO2-NTs with the Au loading of 10 µg cm–2as the anode catalyst.

In Situ Transformation of Chitosan Films into Microtubular Structures on the Surface of Nanoengineered Titanium Implants.

There is considerable interest in combining bioactive polymers such as chitosan with titanium bone implants to promote bone healing and address therapeutic needs. However, the fate of these biodegradable polymers especially on titanium implants is not fully explored. Here we report in situ formation of chitosan microtube (CMT) structures from chitosan films on the implant surface with titania nanotubes (TNTs) layer, based on phosphate buffer-induced transformation and precipitation process. We have comprehensively analyzed this phenomenon and the factors that influence CMT formation, including substrate topography, immersion solution and its pH, effect of coating thickness, and time of immersion. Significance of reported in situ formation of chitosan microtubes on the TNTs surface is possibly to tailor properties of implants with favorable micro and nano morphology using a self-ordering process after the implant's insertion.

Controlled release behaviour and antibacterial effects of antibiotic-loaded titania nanotubes

Bacterial infections have been identified as the main cause of orthopaedic implant failure. Owing to their high antibiotic delivery efficiency, titania nanotubes loaded with antibiotics constitute one of the most promising strategies for suppressing bacterial infections. However, it is difficult to control the drug-release behaviour of such nanotubes. Although sealing the nanotubes with a polymer solution provides sustained release effects to a certain extent, it inevitably influences their initial antibacterial activity. This study reports on the controlled release of gentamicin sulphate (GS) from titania nanotube surfaces whereby their initial antibacterial activity remains unaffected. Titania nanotubes were fabricated via electrochemical anodization and loaded with GS through physical adsorption. Experimental results showed that this loading method is feasible and efficient. The GS-loaded titania nanotubes were further covered by a thin film comprising a mixture of GS and chitosan (GSCH). The release kinetics confirmed that the drug release could be controlled by this thin film. Moreover, such a film was shown to not only inhibit initial bacterial adherence owing to its strong antibacterial properties but also enhance cell viability. Thus, GS-loaded titania nanotubes coated with GSCH have considerable potential as biomaterials for preventing initial release and peri-implant infection in the field of orthopaedics.