Surface Of Titania Nanotubes Research Articles

Mesoporous silica thin film as effective coating for enhancing osteogenesis through selective protein adsorption and blood clotting

The role of blood clots in tissue repair has been identified for a long time; however, its participation in the integration between implants and host tissues has attracted attention only in recent years. In this work, a mesoporous silica thin film (MSTF) with either vertical or parallel orientation was deposited on titania nanotubes surface, resulting in superhydrophilic nanoporous surfaces. A proteomic analysis of blood plasma adsorption revealed that the MSTF coating could significantly increase the abundance of acidic proteins and the adsorption of coagulation factors (XII and XI), with the help of cations (Na+, Ca2+) binding. As a result, both the activation of platelets and the formation of blood clots were significantly enhanced on the MSTF surface with more condensed fibrin networks. The two classical growth factors of platelets-derived growth factors-AB and transformed growth factors-βwere enriched in blood clots from the MSTF surface, which accounted for robust osteogenesis bothin vitroandin vivo. This study demonstrates that MSTF may be a promising coating to enhance osteogenesis by modulating blood clot formation.

Direct In Situ Polymer Modification of Titania Nanomaterial Surfaces via UV‐irradiated Radical Polymerization

AbstractPolymer modification of titania nanomaterials can provide media dispersibility and various functionalities onto the titania surface. Herein, we report the direct in situ polymer modification of the surface of titania nanotubes (TNTs) and titania nanoparticles (TNPs) via ultraviolet (UV)‐irradiated radical polymerization without any pretreatment of titania. The resulting polymer‐modified TNTs and TNPs dispersed well in solvents. The characterization of the products using various techniques including Fourier transform infrared spectroscopy, thermogravimetric analysis, and scanning electron microscopy‐energy dispersive X‐ray spectroscopy confirmed the successful modification of the TNT and TNP surfaces by the polymers produced via UV‐irradiated radical polymerization. The polymers on the titania surface were isolated by dissolving titania using hydrofluoric acid and analyzed by means of size exclusion chromatography and matrix‐assisted laser desorption/ionization‐time of flight‐mass spectrometry. The polymer‐modified TNTs and TNPs maintained their photocatalytic activity in dye degradation under UV irradiation. Moreover, glycopolymer‐modified TNTs were successfully prepared using the UV‐irradiated polymerization system. The glycopolymer retained its lectin biding affinity on the TNT surface.

Lewis acid catalysis of polydopamine electropolymerisation as a tool for shaping its morphology and electrochemical properties

Organic–inorganic semiconductor interfaces are of utmost importance in many photoelectrochemical applications, including water splitting and photodegradation of pollutants. The current work focuses on the fabrication and characterisation of transition metal-loaded polydopamine (PDA) electropolymerised on the surface of titania nanotubes. The structural studies via X-ray photoelectron spectroscopy and electron microscopy confirmed the catalytic effect of d-metal salts on the formation of the PDA layer during electropolymerisation. Cu and Ni loading leads to a significant enhancement of the visible absorption compared to that of the pristine PDA, also confirmed by the density functional theory calculations. Although the boost is greater for the thickest coatings, an excess amount of polymer suppresses the charge transfer and thus photocurrent generation. Synthesis in acidic conditions—optimal for photosensitisation—provides structures with a strong increase in the photocurrent quantum efficiency in the visible range, equal to 20% at 400 nm.Graphical

The M2 Macrophages Derived Migrasomes From the Surface of Titania Nanotubes Array as a New Concept for Enhancing Osteogenesis.

As newly discovered substrate anchored extracellular vesicles, migrasomes (Migs) may bring a new opportunity for manipulating target cells bioactivities. In this study, the M2 macrophages derived Migs are obtained by titania nanotubes surface (NTs). Due to the benefits of nanostructuring, the NTs surface is not only able to induce RAW264.7 for M2 polarization but also to generate more Migs formation, which can be internalized by following seeded mesenchymal stem cells (MSCs). Then, the NTs surface induced Migs are collected by density-gradient centrifugation for MSCs treatment. As indicated by immunofluorescence staining, alkaline phosphatase activity, and alizarin red staining, the osteogenic differentiation capacity of MSCs is significantly enhanced by Migs treatment, in line with the dosage. By RNA-sequence analysis, the enhancement of osteogenic differentiation is correlated with PI3K-AKT pathway activation that may originate from the M2 polarization state of donor cells. Finally, the Migs are coated onto Ti surface for therapeutic application. Both the in vitro and in vivo analysis reveal that the Migs coated Ti implant shows significant enhancement of osteogenesis. In conclusion, this study suggests that the nanosurface may be a favorable platform for Migs production, which may bring a new concept for tissue regeneration.

Influence of electrical polarization on thrombogenicity of titania nanotubes

AbstractThe development of hemocompatible biomaterials with antithrombogenic surface coatings remains a challenge in cardiovascular applications. There is interest in negatively charged surfaces that inhibit thrombus formation through electrostatic repulsion between the biomaterial surface and negatively charged platelets. Hence, the present study investigated the influence of electrical polarization on the thrombogenicity of titania nanotubes (TNT), which are promising candidates for inhibiting thrombogenicity via surface modification. TNTs were formed on commercially pure titanium plate by the electrochemical anodization technique using platinum as a counter electrode at 60 V for 24 h with two kinds of electrolytes (hydrofluoric acid diluted with dimethyl sulfoxide [D‐TNT] or ethylene glycol [E‐TNT]) followed by an annealing at 540°C for 3 h in air. Both TNTs were mixture of anatase and rutile, and the D‐TNT had a diameter of 108.76 ± 2.55 nm and the E‐TNT, 53.833 ± 2.42 nm. The TNTs were electrically polarized at 100 V of DC field and 400°C for 1 h. Water contact angle measurements showed that the non‐polarized (0‐) TNT surface was hydrophilic whereas the positively (P‐) or negatively (N‐) polarized TNT surfaces showed high‐hydrophilicity. Antithrombogenicity was evaluated using the thrombus coverage area ratio (TCAR) after soaking the TNTs in bovine whole blood. The TCARs for 0‐polarized E‐ and D‐TNTs were 5.30 ± 4.34% and 36.3 ± 5.8% and for P‐polarized E‐TNT and D‐TNT were 1.50 ± 0.77% and 2.76 ± 1.07%, whereas no thrombus formation (0 ± 0%) for N‐polarized E‐TNT and very few thrombus formation (0.12 ± 0.22%) for N‐polarized D‐TNT. The electrostatic repulsion between the N‐polarized E‐TNTs and platelets completely inhibits thrombus formation, which cannot be achieved by the nanomorphology and high‐hydrophilicity of other TNTs. Hence, N‐TNTs formed by electrical polarization are potential candidates for cardiovascular devices, such as artificial heart valves with long‐term hemocompatibility.

Osteoimmune-modulating and BMP-2-eluting anodised 3D printed titanium for accelerated bone regeneration.

3D printing of titanium (Ti) metal has potential to transform the field of personalised orthopaedics and dental implants. However, the impacts of controlled surface topographical features of 3D printed Ti implants on their interactions with the cellular microenvironment and incorporation of biological growth factors, which are critical in guiding the integration of implants with bone, are not well studied. In the present study, we explore the role of surface topological features of 3D printed Ti implants using an anodised titania nanotube (TiNT) surface layer in guiding their immune cell interaction and ability to deliver bioactive form of growth factors. TiNT layers with precisely controlled pore diameter (between 21and 130 nm) were anodically grown on 3D printed Ti surfaces to impart a nano-micro rough topology. Immune biomarker profiles at gene and protein levels show that anodised 3D Ti surfaces with smaller pores resulted in classical activation of macrophages (M1-like), while larger pores (i.e., >100 nm) promoted alternate activation of macrophages (M2-like). The in vitro bone mineralisation studies using the conditioned media from the immunomodulatory studies elucidate a clear impact of pore diameter on bone mineralisation. The tubular structure of TiNTs was utilised as a container to incorporate recombinant human bone morphogenetic protein-2 (BMP-2) in the presence of various sugar and polymeric cryoprotectants. Sucrose offered the most sustainable release of preserved BMP-2 from TiNTs. Downstream effects of released BMP-2 on macrophages as well as bone mineralisation were assessed showing bioactivity retention of the released rhBMP-2. Overall, the TiNT surface topography in combination with controlled, sustained, and local release of bioactive growth factors can potentially enhance the osseointegration outcomes of custom 3D printed Ti implants in the clinic.

Dynamical mechanical and impact strength behavior of 3D‐printing testing specimens manufactured by fused filament fabrication of isotactic polypropylene/functionalized titania nanotubes nanocomposites: Influence of β‐crystal promoting

AbstractThermomechanical and impact properties of isotactic polypropylene nanocomposites reinforced with titania nanotubes (TiNTs) at weight distributions of 0.5, 1, and 1.5 wt% were investigated. The goal of this study was to create a novel iPP‐based nanocomposite filament fused filament fabrication (FFF) with improved thermo‐mechanical and impact properties to enable the creation of more customized geometries. First, TiNTs were chemically functionalized with pimelic acid (PA) to promote the β‐crystalline phase using Ca as anchoring. FTIR results revealed the presence of new bands at 1575 and 1413 cm−1, which were attributed to the anchoring of the PA molecule on the TiNT surface. TEM images of the TiNTs confirmed its tubular morphology before and after the functionalization, while the SEM/EDS analysis showed the good dispersion of carbon which can only come from the organic molecule employed in the functionalization. The nano‐reinforcements were incorporated by extrusion generating a filament to produce 3D‐printed specimens. The efficacy of the modified reinforcement as a β‐crystalline phase promoter was evaluated by wide‐angle x‐ray diffraction. The nanocomposite with 1% modified TiNTs showed the highest β‐crystal promotion with a kβ‐index of 89% while the nanocomposites reinforced with unmodified TiNTs reached only 15%. Furthermore, the thermomechanical and impact properties were characterized by dynamic mechanical analysis and Izod. In the first, the storage modulus (E′) was higher than the raw iPP for all nanocomposites, with an increase of about 148% and 107%, while the nanocomposite with a high percentage of β‐crystal showed an increase of 183% in the impact strength properties. A shift of Tg to higher temperatures was attributed to better interfacial interactions polymer/nano‐reinforcement because of the functionalization. The modified nano‐reinforcement was able to generate a 3D‐printed nanocomposite with higher stiffness and impact strength properties than the raw iPP.

Titania nanotubes modified with copper enhance osteogenic differentiation of adipose derived stem cells.

To achieve long term success of orthopedic implants, it is critical to have a successful integration of bone and implant material. To accomplish this, various surface modifications have been investigated in research. Even though titania nanotubes and copper have individually demonstrated successful stem cell adhesion, proliferation and differentiation, these modifications have not yet been investigated together. In this study, we fabricated copper-modified titania nanotubes and evaluated the adhesion, proliferation and osteogenic differentiation of adipose derived stem cells on these surfaces. Implant surfaces also have to interact with blood after insertion in the body. Several studies have shown the importance of blood clots on material surfaces and their influence in differentiation of cells. Hence, blood clotting properties of modified surfaces were also investigated through whole blood clotting, and platelet adhesion and activation. The copper-modified titania nanotube surfaces demonstrated increased differentiation of adipose derived stem cells towards osteogenic lineage as well as enhanced blood clotting properties, thus they can be used as a potential surface for orthopedic implants.

Antifouling Behavior of Copper-Modified Titania Nanotube Surfaces.

Titanium and its alloys are commonly used to fabricate orthopedic implants due to their excellent mechanical properties, corrosion resistance, and biocompatibility. In recent years, orthopedic implant surgeries have considerably increased. This has also resulted in an increase in infection-associated revision surgeries for these implants. To combat this, various approaches are being investigated in the literature. One of the approaches is modifying the surface topography of implants and creating surfaces that are not only antifouling but also encourage osteointegration. Titania nanotube surfaces have demonstrated a moderate decrease in bacterial adhesion while encouraging mesenchymal stem cell adhesion, proliferation, and differentiation, and hence were used in this study. In this work, titania nanotube surfaces were fabricated using a simple anodization technique. These surfaces were further modified with copper using a physical vapor deposition technique, since copper is known to be potent against bacteria once in contact. In this study, scanning electron microscopy was used to evaluate surface topography; energy-dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy were used to evaluate surface chemistry; contact angle goniometry was used to evaluate surface wettability; and X-ray diffraction was used to evaluate surface crystallinity. Antifouling behavior against a gram-positive and a gram-negative bacterium was also investigated. The results indicate that copper-modified titania nanotube surfaces display enhanced antifouling behavior when compared to other surfaces, and this may be a potential way to prevent infection in orthopedic implants.

Synthesis and Characterization of Titania Nanotubes with Au Nanoparticles

TiO2 nanotubes were prepared by hydrothermal synthesis and modified with different amounts of gold nanoparticles by deposition-precipitation with urea. The catalysts were characterized to determine the effect of the presence of Au nanoparticles on the physico-chemical characteristics of the materials and their electron storage capability. Raman spectroscopy revealed the transformation of the trititanate structure into the titania anatase domains upon gold deposition. This transformation was enhanced by an increase in Au loading and the thermal treatment of the materials. The size of Au nanoparticles increased upon the reduction treatment. The presence of Au nanoparticles produced a slight narrowing of the energy bandgap of the titania nanotubular material and had an important effect on its photoluminescence properties, important for some practical applications. Photoluminescence spectroscopy showed that the presence of Au nanoparticles on the surface of titania nanotubes significantly delayed electron-hole recombination and increased the ability of materials for charge separation. Superior performance of Au-containing titania nanotubes was illustrated by the evaluation of their photocatalytic activity. Au-containing titania nanotubes showed enhanced photocatalytic activity in the degradation of methylene blue dye in aqueous solutions upon UV irradiation compared to the pristine nanotubes and the titania Degussa P25.

Functionalization of titania nanotubes surface with platinum(II) complexes

Functionalization of modern materials is one of the possibilities to make them better tailored for human needs. The paper describes a method of covering the titania nanotubes (TNTs) surfaces formed on Ti6Al4V (grade V) titanium alloy with four platinum(II) bimetallic complexes and cisplatin. The first step of the fabricated TNTs modification was their covering with (3-mercaptopropyl)triethoxysilane (MPTES) which plays a role of a bridge between the TNTs and platinum(II) coordination centres. The final application of platinum(II) dimethylformamide (DMF) solutions allowed to form a homogeneous layers of platinum(II) complexes bonded to the TNTs substrate by thiol sulphur atoms of MPTES without visible crystals of physically deposited complexes. The complexes were characterized with XRD, IR, Raman, 1H and 13C NMR spectroscopies, and thermal and elemental analyses. Characterization of titania substrates was done with IR, Raman, SEM, SEM/EDX, XRD, and XPS.

Linking optical and electronic properties to photoresponse of heterojunctions based on titania nanotubes and chromium, molybdenum, and tungsten oxides

The development of photosensitization strategies for titanium dioxide is necessary for the enhancement of its optical and electronic properties towards its application potential in solar photoelectrochemistry. In this work, significant differences in the photosensitizing capability of the 6th group transition metal oxides applied on the surface of titania nanotubes are reported. For the first time, correlations between the experimentally determined Tauc coefficients, sample photoresponse, and ab-initio simulated properties of the heterojunctions are established. Experimental results show undoubtedly that the decoration of TiO2 nanotubes with chromium oxides leads to the enhanced photoresponse, which originates from the interplay of mid-gap states and both direct and indirect nature of the transitions contributing to the optical absorption. The opposite tendency and decrease of photocurrent were found for molybdenum and tungsten oxides which exhibited forbidden nature of dominating transition. Although computations report intraband states in all interfaces, experimentally only chromium oxides contribute to the photocurrent. The uniqueness of this interface lies in the highest density of states in the vicinity of the conduction band and the low energy difference between the direct and indirect transitions of the innate chromium oxide. The obtained results demonstrate that the determination of the Tauc exponent and the nature of optical transition are more reliable experimental predictors of the photoactivity enhancement in the heterojunctions than the value of the band gap.

In Situ Growth of Tunable Gold Nanoparticles by Titania Nanotubes Templated Electrodeposition for Improving Osteogenesis through Modulating Macrophages Polarization.

Driving macrophages M2 polarization has attracted growing attention for improving osteogenesis. Here, the in situ growth of tunable gold nanoparticles (AuNPs) on titania nanotubes (TiNTs) array was realized by electrodeposition, with the guidance of TiNTs. The fabricated Au layer showed excellent biocompatibility with different osteoimmune effects. Briefly, the Au deposition on 5 and 10 V anodized TiNTs surface could induce RAW264.7 cells to M2 polarization, whereas the Au deposition on 20 V anodized TiNTs surface showed M1 polarization, as indicated by various markers determination through immunofluorescence staining, qPCR, Western blot, and ELISA. Furthermore, the osteogenic differentiation of MC3T3-E1 was significantly enhanced by the macrophages conditioned medium from the Au@10VNTs surface. The in vivo tests also confirmed denser and thicker new trabecula bone formation and more M2 macrophages infiltration both on and adjacent to the Au@10VNTs implant surface. In mechanism, the cytokine array analysis of macrophages conditioned medium from the Au@10VNTs surface revealed the upregulation of pro-healing cytokines such as IL-10 and VEGF and downregulation of pro-inflammatory cytokines such as IL-1β and MCSF. In addition, the NF-κB pathway was significantly inhibited. In conclusion, the electrodeposition of a Au layer guided by TiNTs is a promising strategy for reducing postoperative inflammatory reactions and improving osseointegration through modulating macrophages polarization.

Tailoring Additively Manufactured Titanium Implants for Short‐Time Pediatric Implantations with Enhanced Bactericidal Activity

Paediatric titanium (Ti) implants are used for the short-term fixation of fractures, after which they are removed. However, bone overgrowth on the implant surface can complicate their removal. The current Ti implants research focuses on improving their osseointegration and antibacterial properties for long-term use while overlooking the requirements of temporary implants. This paper presents the engineering of additively manufactured Ti implants with antibacterial properties and prevention of bone cell overgrowth. 3D-printed implants were fabricated followed by electrochemical anodization to generate vertically aligned titania nanotubes (TNTs) on the surface with specific diameters (∼100 nm) to reduce cell attachment and proliferation. To achieve enhanced antibacterial performance, TNTs were coated with gallium nitrate as antibacterial agent. The physicochemical characteristics of these implants assessed by the attachment, growth and viability of osteoblastic MG-63 cells showed significantly reduced cell attachment and proliferation, confirming the ability of TNTs surface to avoid cell overgrowth. Gallium coated TNTs showed strong antibacterial activity against S. aureus and P. aeruginosa with reduced bacterial attachment and high rates of bacterial death. Thus a new approach for the engineering of temporary Ti implants with enhanced bactericidal properties with reduced bone cell attachment is demonstrated as a new strategy toward a new generation of short-term implants in paediatrics.

Visible light responsive photocatalytic hydrogen production over composites of anodized TiO2 nanotube array and graphitic carbon nitride measured with a gas circulating reactor

Gas phase photocatalysis over composites of electrochemically anodized titania nanotube (TNT) arrays and graphitic carbon nitride (g-C3N4) nanoparticles were examined with a home-made, gas-circulating reactor system. g-C3N4 nanoparticles were deposited onto anodized TNT surfaces by facile thermal polymerization using melamine and urea as precursors. The existence of g-C3N4 on TNT arrays clearly improved hydrogen production from gas phase photocatalytic decomposition of water/methanol mixture under visible light (VIS) irradiation (370–800 nm). The enhanced production of hydroxyl radicals via water photooxidation for TNT/g-C3N4 composites was also ascertained by photoluminescence measurement using terephthalic acid as a radical trap. These results deriving from synergetic effects of TNT and g-C3N4 can be attributed to the photogenerated hole–electron separation enhanced at TNT/g-C3N4 interface, suggesting that g-C3N4 is a metal-free sensitizer for enabling VIS responsive photocatalysis in anodized TNTs even for gas phase reactions.

Gentamicin-Releasing Titania Nanotube Surfaces Inhibit Bacteria and Support Adipose-Derived Stem Cell Growth in Cocultures.

Infection is the second leading cause of failure of orthopedic implants following incomplete osseointegration. Materials that increase the antimicrobial properties of surfaces while maintaining the ability for bone cells to attach and proliferate could reduce the failure rates of orthopedic implants. In this study, titania nanotubes (Nts) were modified with chitosan/heparin polyelectrolyte multilayers (PEMs) for gentamicin delivery. The antimicrobial activity of the surfaces was tested by coculturing bacteria with mammalian cells. Over 60% of gentamicin remained on the surface after an initial burst release on the first day. Antimicrobial activity of these surfaces was determined by exposure to Gram-positive Staphylococcus aureus (S. aureus) and Gram-negative Escherichia coli (E. coli) for up to 24 h. Gentamicin surfaces had less live E. coli and S. aureus by 6 h and less E. coli by 24 h compared to Nt surfaces. S. aureus and human adipose-derived stem cells (hADSCs) were cocultured on surfaces for up to 7 days to characterize the so-called "race to the surface" between bacteria and mammalian cells, which is hypothesized to ultimately determine the outcome of orthopedic implants. By day 7, there was no significant difference in bacteria between surfaces with gentamicin adsorbed on the surface and surfaces with gentamicin in solution. However, gentamicin delivered in solution is toxic to hADSCs. Alternatively, gentamicin presented from PEMs enhances the antimicrobial properties of the surfaces without inhibiting hADSC attachment and cell growth. Delivering gentamicin from the surfaces is therefore superior to delivering gentamicin in solution and represents a strategy that could improve the antimicrobial activity of orthopedic implants and reduce risk of failure due to infection, without reducing mammalian cell attachment.

Alginate/chitosan modified immunomodulatory titanium implants for promoting osteogenesis in vitro and in vivo

The essentiality of macrophages for biomaterial-mediated osteogenesis has been increasingly recognized. However, it is still unclear what is the specific role and molecular mechanisms of macrophages and material properties in the regulation of osteogenesis. As an interdisciplinary field exploring the cross-talk between immune and skeletal systems, osteoimmunology has shifted the perspective of bone substitute materials from immunosuppressive materials to immunomodulatory materials. To fabricate an immunomodulatory Ti implant, alginate/chitosan multilayer films were fabricated on the surface of titania nanotubes (TNTs) to control the release of an anti-inflammatory cytokine interleukin (IL)-4 according to our previous work. The osteogenic effects and regulation mechanisms of the immunomodulatory Ti implants were investigated in vitro in different BMSCs culture modes. Alginate/chitosan multilayer-coated samples (with or without IL-4 loading) showed better direct osteogenic ability than TNTs by promoting biomineralization and up-regulating osteogenic gene expression (BMP1α, ALP, OPN, OCN) of BMSCs. Notably, material-induced macrophage polarization, M1 and M2, enhanced early and mid-stage osteogenesis of BMSCs via distinct pathways: M1 activated both BMP6/SMADs and Wnt10b/β-catenin pathways; while M2 activated TGF-β/SMADs pathway. Material surface properties dominated in regulating late osteogenesis probably due to the surface chemical composition (alginate, chitosan and Ca2+, etc.). Due to synergistic effects of material-induced inflammatory microenvironment and material surface properties, IL-4-loaded samples exhibited superior osteogenic capability through co-activation of three signaling pathways. The in vivo studies in rat bone defect model revealed that IL-4-loaded immunomodulatory implants successfully achieved macrophage phenotypic transition from pro-inflammatory M1 to anti-inflammatory M2 and subsequently improved new bone formation.

Environmentally friendly approach for the fabrication of polyamide thin film nanocomposite membrane with enhanced antifouling and antibacterial properties

In this work, we employed an environmentally friendly approach based on plasma enhanced chemical vapour deposition (PECVD) to modify titania nanotubes (TNTs), aiming to obtain better dispersion of nanofillers in polyamide (PA) layer of thin film nanocomposite (TFN) reverse osmosis membrane. Owing to the hydrophilic nature of TNTs, dispersing it homogenously in organic solvent during interfacial polymerization process is difficult to achieve. Therefore, the TNTs are mildly modified by PECVD technique in order to ameliorate its stability in organic solvent. Our results showed that depositing thin layer of methyl methacrylate (MMA) on the TNTs surface could enhance its dispersion quality in organic solvent and further improve the properties of PA layer by enhancing membrane water flux by 16% without compromising NaCl rejection. More importantly, the developed TFN membrane showed excellent fouling resistance by recording flux recovery rate of 85.77% compared to 57.94% shown by the control membrane. Its antibacterial property was also obviously better than that of control membrane. Overall, the developed TFN membrane demonstrated good performance stability with respect to NaCl rejection and water permeability and the trace amount of nanofillers detected in the water sample (in the level ofμg/L) did not negatively influence the membrane filtration performance.

Visible light induced photodegradation of bio-polymeric waste using boron-enhanced titania nanotubes

Visible light-activated photocatalytic degradation allows renewable solar energy harvesting for sustainable waste remediation. The incorporation of dopant into the structure of photocatalysts enables photoactivation using visible light. In this work, titania nanotube (TNT) was doped with boric acid of different molarities (0.25, 0.5, 1.0 M) under alkaline hydrothermal condition to produce TNT doped boron (TNT-B) photocatalyst. The formation of microcrystalline structure on the surface of TNT evidenced the attachment of boron nanoparticle on the surface of TNT. The nanotube diameter and surface negativity increased with increasing dopant molarity. The doping did not incur significant changes on the crystallinity of TNT but resulted in an extension of light absorption to visible light range. Pristine TNT and TNT-B were tested for their photocatalytic activity under visible light irradiation for the photodegradation of bio-based polymeric colour pigments, namely lignin and tannic acid (TA). The doping significantly improved photoactivity of TNT under visible light conditions. Optimal doping was achieved with 0.5 M of boric acid, where TNT-B degraded 96.47% of lignin and 96.91% of TA within 240 min of irradiation. Radical scavenging experiments also revealed that both OH− and •O2− radicals were the major reactive species responsible for the degradation.

Antibacterial and Osteogenic Activity of Titania Nanotubes Modified with Electrospray-Deposited Tetracycline Nanoparticles.

The nanotubular surface of titanium implants is known to have superior osteogenic activity but is also vulnerable to failure because of induced bacterial attachment and consequent secondary infection. Here, the problem was attempted to be solved by depositing nanosized tetracycline (TC)-loaded particles in poly(lactic-co-glycolic acid) on titania nanotubes (TNTs) using the electrospray deposition method. The antibacterial effect of the newly formed TNT surface was considered using the common pathogen Staphylococcus aureus. Maintenance of the biocompatibility and osteogenic characteristics of TNTs has been tested through cytotoxicity tests and osteogenic gene expression/extra-cellular matrix mineralization, respectively. The results showed that TNTs were successfully formed by anodization, and the characterization of TC deposited on the TNTs was controlled by varying the spraying parameters such as particle size and coating time. The TC nanoparticle-coated TNTs showed antibacterial activity against Staphylococcus aureus and biocompatibility with MC3T3-E1 pre-osteoblasts, while the osteogenic activity of the TNT structure was preserved, as demonstrated by osteocalcin and osteopontin gene expression, as well as Alizarin red staining. Hence, this study concluded that the electrosprayed TC coating of TNTs is a simple and effective method for the formation of bactericidal implants that can maintain osteogenic activity.