Doped Titanium Dioxide Nanoparticles Research Articles

Enhanced durability of Pt electrocatalyst with tantalum doped titania as catalyst support

The performance and durability of PEMFCs highly depend on the catalyst support material. Traditionally, carbon is being used as support but its susceptibility to corrosion makes it less favorable for fuel cell applications. The weak interaction between PtC leads to the non-uniform distribution of platinum nanoparticles over the surface of support and poor durability, which in turn lowers the overall performance of PEMFCs. In order to introduce a robust support, which is more stable and durable as compared to the carbon, tantalum doped titania nanoparticles are synthesized via modified sol-gel method and investigated as a catalyst support for Pt electrocatalysts. The optimum calcination temperature for doped titania preparation is found to be 800 °C. The support is characterized through X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), inductively coupled plasma optical emission spectroscopy (ICPOES) and transmission electron microscopy (TEM). Electrochemical performance shows that tantalum doped titania has much improved electrical conductivity than that of pure titania. Furthermore, Pt/TaTiO2 exhibits higher ECSA retention and comparable ORR activity as compared to the Pt/C, indicating the desired durability.

Investigations on Ho-TiO2 nanoparticles synthesized by precipitation method for optical applications

The holmium doped titania nanoparticles are synthesized by precipitation method using titanium tetrachloride as a raw material. XRD for phase structure, DRS-UV absorption spectrum, FTIR presence of functional group, HRSEM with EDX morphological structure and presence of the elements in the synthesis material are assessed and the results evaluated. The study investigates the photocatalytic activity degradation of methylene blue dye under the visible light irradiation at different calcination temperatures enhancing the photocatalytic activity relatively with rise in temperature to 700°C parallelly records the inverse proportionality of photocatalytic activity with electron hole recombination through Photoluminescence spectra.

Surface plasmon resonance effect of Cu nanoparticles in a dye sensitized solar cell

Pure and copper doped titanium dioxide nanoparticles (TiO2 NPs) for Dye Sensitized Solar Cell (DSSC) photo anodes with different doping amounts of copper (Cu) 0.1, 0.3 and 0.5mole% are synthesized using modified sol-gel route. Addition of Cu in TiO2 matrix can enhance absorption towards visible spectrum and can reduce the charge carrier recombination due to Localized Surface Plasmon Resonance (LSPR). The samples are characterized by X-Ray Diffraction (XRD), Scanning Electron Microscope (SEM), UV–vis spectroscopy (UV-VIS), X-ray Photoelectron Spectroscopy (XPS), Electro Chemical Impedance Spectroscopy (EIS). The crystallite size is measured by XRD and surface morphology of the samples is analyzed using SEM. UV–vis measurement shows that the influence of Cu in TiO2 lattice altered its optical properties and extended absorption in the visible region. The resistances between different junctions of the cell are measured by EIS. The J-V measurement of the cell prepared using pure and Cu-doped TiO2 NPs is carried out by solar simulator. The optimized Cu doped DSSC with 0.3mole% Cu in TiO2 shows the best power conversion efficiency of 8.65% which is approximately 26% greater than the efficiency of undoped DSSC (6.41%).

Medium-term in situ experiment by using organic biocides and titanium dioxide for the mitigation of microbial colonization on stone surfaces

Organic biocides are commonly used to reduce the biocolonization on stone surfaces. However, it should be possible to prolong a new re-colonization by the use of a combined application of organic and inorganic active compounds. TiO2, thanks to its high chemical stability, non-toxicity, high photo-reactivity and low cost, make it a potential effective molecule for long-term biocide activity against several biofoulers. In this research, a multi analytical approach, including microscopy, cultural and molecular analyses, has been applied to monitoring the treated surfaces of the southeast wall of Villa dei Papiri in Ercolano. In this study case, organic conventional biocide has been used, followed by the application of newly formulated products based on pure and doped titanium dioxide nanoparticles. As control, one part of the wall was treated only with organic biocides before applying only the binder.Biological sampling was carried out during eight months, before and after the treatments with biocide, and after the treatments with undoped and doped TiO2. The comparative analysis of results showed that microorganisms were drastically reduced after the biocide treatments, while the treatment with bare and doped TiO2 reduced a potential new recolonization. However, the effectiveness of the treatments was dependent on distance from the ground since high humidity reduced the efficiency of the treatments.

Biomimetic nitrogen doped titania nanoparticles as a colorimetric platform for hydrogen peroxide detection

Nanoparticles proved a viable alternative to the already used sensing and diagnostics methods due to their low cost, good stability, easy availability and easy synthesis. In the present approach, nitrogen doped titania nanoparticles are prepared through freeze drying method, and subsequently stabilized through ionic liquid. These nanoparticles were characterized through various techniques such as X-ray diffraction (XRD), Fourier transformation infrared spectroscopy (FTIR), Scanning electron microscopy (SEM), BET pore size and surface area analyzer, X-ray photoelectron spectroscopy (XPS) and UV–Visible diffuse reflectance spectroscopy (UV–Vis. DRS). The synthesized nitrogen doped titania nanoparticles were proved to be a novel peroxidase mimetic with great potential to catalyze oxidation of 3,3′,5,5′-tetramethylbenzidine (TMB) in the presence of hydrogen peroxide (H2O2) to form a blue color product. As a proof of concept, this new enzyme mimic was used as a robust nanoprobe for the detection of hydrogen peroxide with improved analytical characteristics. A linear response for hydrogen peroxide detection was obtained in the range of 10–300μmol/L, with a detection limit of 2.5μmol/L. Taking into account the valuable intrinsic peroxidase activity, the present work may find widespread applications in the field of sensors and biosensors for diverse applications.

Photocatalysis effect of a novel green synthesis gadolinium doped titanium dioxide nanoparticles on their biological activities

Abstract We report the synthesis of gadolinium doped titanium dioxide (GdT) nanoparticles (NPs) via hydrothermal method using a novel bioreductant Piper betel leaf. The physiochemical properties of green synthesized GdT NPs were characterized using various techniques. The results reveal that GdT NPs have attached with the biomolecules which were supporting evidence for the reduction and capping agents. GdT NPs have crystalline in nature and their estimated grain size is of about 5.45 nm by the Scherer’s formula. GdT NPs consist of well-dispersed agglomerates of grains with a narrow size distribution of about 4 nm to 7 nm and are having spherical in nature. GdT NPs are thermally stable. In addition, GdT NPs were subjected to antimicrobial and antioxidant assays. Herein, we observed that the GdT NPs show higher antibacterial activities against Staphylococcus aureus as compared with Escherichia coli and the minimum inhibitory concentration (MIC) value was found to be 25 μg mL−1 under UV irradiation condition for both the cases. Furthermore, antioxidant activities of GdT NPs were evaluated in vitro, using the 1, 1- diphenyl-2-picrylhydrazyl (DPPH) radical cation decolorization test. Results suggest that GdT NPs give promising antioxidant activity as compared to standard ascorbic acid and Piper betel leaf. This novel and efficient strategy will show the route for avoiding the use of toxic solvents and a promising green route to restrict for drug discovery from natural products. Thus, the present findings may shine in the field of green pharmaceuticals industries.

Degradation of gaseous formaldehyde via visible light photocatalysis using multi-element doped titania nanoparticles

This study developed a modified titanium dioxide photocatalyst doped with multi-element synthesized via sol-gel process to productize a novel photocatalyst. The study includes degradation of gaseous formaldehyde under visible light using the synthesized novel titanium dioxide photocatalyst. Varying molar ratios from 0 to 2 percent (%mole in titanium dioxide) of ammonium fluoride, silver nitrate and sodium tungstate as dopant precursors for nitrogen, fluorine, silver and tungsten were used. Photodegradation of gaseous formaldehyde was examined on glass tubular reactors illuminated with blue light emitting diodes (LEDs) using immobilized photocatalyst. The photocatalytic yield is analyzed based on the photocatalyst surface chemical properties via X-ray Photoelectron Spectroscopy (XPS), Fourier Transform Infrared (FTIR) Spectrophotometry, Brunauer-Emmett-Teller (BET) and X-ray Diffraction (XRD) characterization results. The applied modifications enhanced the visible light capability of the catalyst in comparison to the undoped catalyst and commercially available Degussa P-25, such that it photocatalytically degrades 88.1% of formaldehyde in 120 min. Synthesized titanium dioxide photocatalyst exhibits a unique spin orbital at 532.07 eV and 533.27 eV that came from the hybridization of unoccupied Ti d(t2g) levels.

Efficacy of radiosensitizing doped titania nanoparticles under hypoxia and preparation of an embolic microparticle.

The aim of this study was to develop a manufacturing protocol for large-scale production of doped titania radiosensitizing nanoparticles (NPs) to establish their activity under hypoxia and to produce a multimodal radiosensitizing embolic particle for cancer treatment. We have previously shown that radiosensitizing NPs can be synthesized from titania doped with rare earth elements, especially gadolinium. To translate this technology to the clinic, a crucial step is to find a suitable, scalable, high-throughput method. Herein, we have described the use of flame spray pyrolysis (FSP) to generate NPs from titanium and gadolinium precursors to produce titania NPs doped with 5 at% gadolinium. The NPs were fully characterized, and their capacity to act as radiosensitizers was confirmed by clonogenic assays. The integrity of the NPs in vitro was also ascertained due to the potentially adverse effects of free gadolinium in the body. The activity of the NPs was then studied under hypoxia since this is often a barrier to effective radiotherapy. In vitro radiosensitization experiments were performed with both the hypoxia mimetics deferoxamine and cobalt chloride and also under true hypoxia (oxygen concentration of 0.2%). It was shown that the radiosensitizing NPs were able to cause a significant increase in cell death even after irradiation under hypoxic conditions such as those found in tumors. Subsequently, the synthesized NPs were used to modify polystyrene embolization microparticles. The NPs were sintered to the surface of the microparticles by heating at 230°C for 15 minutes. This resulted in a good coverage of the surface and to generate embolization particles that were shown to be radiosensitizing. Such multimodal particles could therefore result in occlusion of the tumor blood vessels in conjunction with localized reactive oxygen species generation, even under hypoxic conditions such as those found in the center of tumors.

Dye - Sensitized Solar Cell Photoanode Based on Silver – Doped Titanium Dioxide Nanoparticles

Silver - doped titanium dioxide (Ag-TiO2) nanoparticles were prepared from TiO2 (P25, Degussa) and silver nitrate (AgNO3) by gamma Co-60 irradiation method with various initial concentration of AgNO3 (0.1 – 0.75%, w/w). The formed silver nanoparticles and optical band gap of Ag-TiO2 films were investigated by XRD, XRF, TEM and UV-Vis spectrocopy. The silver nanoparticles with grain size about 17 – 20 nm are woven on TiO2 nanoparticles and decrease the optical bandgap of TiO2 film. Ag-TiO2 nanoparticles were used to fabricate photoanode in N719-dye-sensitized solar cells (DSCs). Under full sunlight illumination (1000 W/m2, 1.5 AM) the DSC assembled with Ag-TiO2 (0.75% AgNO3) photoanode has shown a 25% increase in energy conversion efficiency compared with the DSC using undoped TiO2 photoanode. The improvement of energy conversion efficiency was attributed to enhanced photocurent of the cell. The effect of silver dopant content on DSC performance was also studied by electrochemical impedance spectrocopy. The impedance arc at intermediate frequency region in Nyquist plots are reduced with the concentration of AgNO3 precursor, demonstrating that charge transfer at TiO2/dye interface was improved in the presence of silver dopant. The Ag- TiO2 nanoparticles synthesized by gamma Co-60 irradiation method have shown themselves as promising photoanode materials for DSCs. This work may inspire new ideas for constructing high-performance photoanodes for large scale DSCs

Sol–Gel Synthesis of Manganese Doped Titanium Oxide Nanoparticles for Electrochemical Sensing of Hydroquinone.

Here we report development of a hydroquinone (HQ) electrochemical sensor using nanosized manganese doped titanium oxide as a composite material. The nanomaterial was synthesized with sol gel method using calculated amount of Mn and Ti atoms resulting into a composite metal oxide. Morphological observations indicated a uniform particle size and shape distribution with almost spherical shape and size of about 20–30 nm. While structural analysis indicated formation of mixed phase of TiO₂ and MnO forming MnTiO₃. The synthesized nanomaterial was used as a matrix for fabrication of hydroquinone electrochemical sensor and tested over a wide range from 2 mM to 10 mM. The developed electrochemical sensor exhibited sensitivity of 2.96 μA mM⁻¹ (23.55 μA mM⁻¹ cm⁻²) with a detection limit of 7.5 μM, which is rarely reported for such composite nanomaterial.

An electrochemical sensor for clozapine at ruthenium doped TiO2 nanoparticles modified electrode

A new modified sensor based on carbon paste electrode (CPE) was developed using ruthenium doped titanium dioxide nanoparticles (Ru-TiO2). In this work, we demonstrated the analytical behavior and applications of CPE modified with Ru-TiO2 (Ru-TiO2/CPE) for the determination of Clozapine by employing different voltammetric techniques. The characterization of synthesized ruthenium doped titanium dioxide nanoparticles was accomplished by utilizing X-ray diffraction (XRD), scanning electron microscope (SEM), Energy-dispersive X-ray spectroscopy (EDX) and transmission electron microscope (TEM). The morphology of the sensing surface was analyzed by atomic force microscope (AFM). Modification of working electrode increases the electro-oxidation of clozapine with increased current intensity. The influence of parameters like scan rate, pH, accumulation time, amount of the modifier and concentration on the peak current of the drug were studied. A probable electro-oxidation mechanism was proposed based on the obtained experimental results. The effect of CLZ concentration variation was studied using square wave voltammetric (SWV) technique in the range of 9.0×10−7M to 4.0×10−5M with the detection limit of 0.43nM. The prepared Ru-TiO2 modified sensor was employed for the determination of clozapine in pharmaceutical formulations and human urine.

Bismuth doping effect on crystal structure and photodegradation activity of Bi–TiO2 nanoparticles

The bismuth precursor is adopted as dopant to synthesize bismuth doped titanium dioxide nanoparticles (Bi–TiO2 NPs) with sol–gel method following by the thermal annealing treatment. We systematically developed a series of Bi–TiO2 NPs at several calcination temperatures and discovered the corresponding crystal structure by varying the bismuth doping concentration. At a certain 650 °C calcination temperature, the crystal structure of bismuth titanate (Bi2Ti2O7) is formed when the bismuth doping concentration is as high as 10.0 mol %. The photocatalytic activity of Bi–TiO2 NPs is increased by varying the doping concentration at the particular calcination temperature. By the definition X-ray diffraction (XRD) structural identification, a phase diagram of Bi–TiO2 NPs in doping concentration versus calcination temperature is provided. It can be useful for further study in the crystal structure engineering and the development of photocatalyst.

Solvent-free synthesis of polyhydroquinoline derivatives employing mesoporous vanadium ion doped titania nanoparticles as a robust heterogeneous catalyst via the Hantzsch reaction

Mesoporous vanadium ion doped titania nanoparticles were used as reusable catalyst for the synthesis of PHQ derivativesviaHantzsch reaction at 80 °C under greener conditions. The catalyst could easily be recycled and reused without decrease in catalytic activity.

Silver doped titanium dioxide nanoparticles as antimicrobial additives to dental polymers

ObjectiveThe objectives of this in vitro study were to produce a filled resin containing Ag–TiO2 filler particles and to test its antibacterial properties. MethodsAg–TiO2 particles were manufactured using the ball milling method and incorporated into an epoxy resin using a high speed centrifugal mixer. Using UV/vis spectrophotometry investigations were performed to assess how the photocatalytic properties of the Ag–TiO2 particles are affected when encased in resin. Adopting the bacteria colony counting technique, the antibacterial properties of Ag–TiO2 particles and Ag–TiO2 containing resins were assessed using Streptococcus mutans under varying lighting conditions. ResultsAg doping of TiO2 results in a band gap shift towards the visible spectrum enabling Ag–TiO2 to exhibit photocatalytic properties when exposed to visible light. Small quantities of Ag–TiO2 were able to produce a bactericidal effect when in contact with S. mutans under visible light conditions. When incorporated into the bulk of an epoxy resin, the photocatalytic properties of the Ag–TiO2 particles were significantly reduced. However, a potent bactericidal effect was still achieved against S. mutans. SignificanceAg–TiO2 filled resin shows promising antimicrobial properties, which could potentially be used clinically.

In vitro cytotoxicity effect and antibacterial performance of human lung epithelial cells A549 activity of Zinc oxide doped TiO2 nanocrystals: Investigation of bio-medical application by chemical method

We report the synthesis of high quality ZnO doped TiO2 nanocrystals by chemical method at room temperature (RT), it can cause serious oxidative stress and DNA damage to human lung epithelial cells (A549) lines. Our aim in this study, to reduce the cytotoxicity effect of ZnO doped TiO2 nanocrystals are widely in biological fields. Several studies have been performed to understand the influence of ZnO doped titanium dioxide (TiO2-NPs) on cell function; however the effects of nanoparticle against to exposure on the cell membrane have been duly addressed fascinatingly so far. However, In this interaction, which may alter cell metabolism and integrity, it is one of the importance to understand the modifications of the cell membrane, mechanisms of pulmonary A549 cell lines nanoparticles were uptake and the molecular pathway during the initial cell responses are still unclear and much more investigative efforts are need to properly characterize the ZnO doped titanium dioxide nanoparticles were reported successfully. In particular of the epithelial cells, upon particles are exposed human pulmonary epithelial cells (A549) to various concentrations of composition, structure and morphology of the nanocrystals were analyzed by X-ray diffraction (XRD) and high resolution transmission electron microscopy (HRTEM). XRD assessed the crystal structure of the nanocrystals which identified peaks associated with (002), (100) and (101) planes of hexagonal wurtzite-type ZnO with lattice constants of a=b=3.249Å and c=5.219Å. The IR results showed high purity of products and indicated that the nanocrystals are made up of TiO and ZnO bonds. The Photoluminescence (PL) spectra are dominated by a strong narrow band edge emission tunable in the blue region of the visible spectra indicating a narrow size distribution of ZnO/TiO2 nanocrystals which exhibits antibacterial activity over a broad range of bacterial species and in particular against Stre. Mut where it out competes four other commonly used E.coli, Pse. Aug, Stre. Mut and Salm. sps, well as testing four different appropriate concentration from the results showed a significant gain in viable cell numbers of all four bacteria species, with 5mM and 10mM being the most effective and 2mM being the worst, where it provided an effective improvement from the growth mechanism has been also proposed to the current interest of these nanocrystals will discussed in detail.

Preparation of silica doped titania nanoparticles with thermal stability and photocatalytic properties and their application for leather surface functionalization

Doped nanoparticles based on titanium dioxide are of interest for their multifunctional properties and enlarged photocatalytic activity in visible domain. Silica doped titanium dioxide nanoparticles were prepared by hydrothermal method and their structural characteristics and photocatalytic activity were determined, in order to be used for leather coating as alternative to halogen based flame retardants and dry cleaning solvents. A range of concentrations from 2% to 20% silica doped titanium dioxide nanoparticles (% denotes the theoretical weight percent of Si) was synthesized and characterized by ICP-OES, FT-IR, UV-vis spectroscopy, XRD, HRTEM and DLS. Titanium dioxide network penetration was supported by Si-O-Ti and OH identification in FT-IR spectra mainly on surface of 10% and 20% silica doped titanium dioxide nanoparticles. The increase of Si-O-Ti bonds with Si dopant concentration acts as efficient barriers against sinterization and growth of TiO2 particles and explains the low particle size identified in HRTEM analyses as compared to undoped TiO2NPs. UV-vis diffuse reflectance spectra of doped titanium dioxide nanoparticles showed the shifting of absorption band to visible domain for 10% silica doped titanium dioxide nanoparticles. The crystallite sizes were calculated from XRD spectra, ranging between 16.2 and 18.1nm. HRTEM measurement of hydrothermally synthesized titanium dioxide nanoparticles showed anatase crystallites in the range of 8.8–27nm, while in the 20% silica doped titanium dioxide nanoparticle sample smaller crystallite with sizes between 2.7nm and 3.5nm was identified due to the constraints of the SiO2-based amorphous matrix. Nano sizes of 64nm and 72nm were found in water dispersions of 10% and 20% silica doped titanium dioxide nanoparticles and the Zeta potentials were of −53.6mV and −52.9mV, which indicate very good stabilities. The leather surface treated with composites of film forming polymers and 10% silica doped titanium dioxide nanoparticles displayed photocatalytic properties against methylene blue dye under UV and visible light exposure, attributed to reactive species generation with effect on surface hydrophilicity increase. The activation energies for decomposition of leathers treated with 10% and 20% silica doped titanium dioxide nanoparticles were 2.083×104J/mol and 2.36×104J/mol respectively, as compared to 6.576×103J/mol for untreated leathers, showing increased thermal stability according to DSC measurements. The hydrothermal route for silica doped nanoparticle preparation proved advantages in enhancing photocatalytic properties in the visible domain and thermal resistance, with prospect for multifunctional applications.

The impact of silver and titanium dioxide nanoparticles on the in-vessel composting of municipal solid waste

The study evaluated the impact of commercial silver doped titanium dioxide nanoparticles (Ag-TiO2NPs) and silver nanoparticles (AgNPs) on the in-vessel composting of municipal solid waste (MSW), using fluorescence excitation-emission matrix (EEM) spectroscopy as a tool to evaluate the microbial degradation of MSW and subsequent soil application of compost. The fate of NPs present in mature compost used as a top-layer soil conditioner was investigated using a column approach at laboratory scale. The results suggested that the presence of either Ag-TiO2NPs or AgNPs did not inhibit the microbial degradation process within the range of metal concentrations used (5/225, 10/450, 20/900, 50/2250mg Ag/Ti per kg of organic matter for Ag-TiO2NP and 5, 10, 20, 50mg Ag per kg of organic matter for AgNPs). Higher concentrations of Ag-TiO2NP and AgNPs resulted in a higher inorganic carbon removal, and lower formation of humins. Formation of humins was higher for non-contaminated MSW and compost. EEM peaks shifted towards the humic substances (HS) region during in-vessel composting, indicating that microbial degradation occurred and that NPs did not have any effect on humification and therefore on compost stability. The leaching results suggested that only a low percentage of the total NPs (in weight) in compost, up to ca. 5% for Ag and up to ca. 15% for Ti, leached out from the columns, which was assumed the amount that potentially could leach to the environment. These results suggested that NPs will mainly accumulate in soils’ top layers following application of compost contaminated with NP.

A life cycle assessment of the use of compost from contaminated biodegradable municipal solid waste with silver and titanium dioxide nanoparticles

The environmental impact of compost application to soil due to the presence of silver nanoparticles (AgNPs) and silver doped titanium dioxide nanoparticles (Ag-TiO2NPs) in municipal solid waste (MSW) streams was investigated by conducting a comparative life cycle assessment (LCA) study using data collected from literature, databases and laboratory tests. Different NP-contaminated composts used for this study were characterized by the initial silver concentration present in the waste (5 and 10 mg Ag per kg of organic matter for AgNP-contaminated MSW and 5/225 and 10/450 mg Ag/Ti per kg of organic matter for Ag-TiO2NP-contaminated MSW). The comparison of NP-contaminated composts resulted in different LCA scores implying that they exhibited different environmental impacts. A totally different LCA outcome resulted when using Hierarchist (H) perspective as compared to the use of Egalitarian (E) perspective. While the performance of compost was calculated to be environmental friendly, when looking at the overall score resulted using E perspective, it is recommended that a detailed analysis of the LCA results shall be made as the effects of Ag in terrestrial ecotoxicity and human toxicity were significant. The LCA study indicated that the effects of nanoparticle-contaminated compost to human health and ecosystems endpoint categories increased due to the presence of nanoparticles (NPs). The risks were associated with terrestrial ecotoxicity and human toxicity midpoint categories and were mainly attributed to the accumulation of Ag in soils.

Direct quantification of rare earth doped titania nanoparticles in individual human cells

There are many possible biomedical applications for titania nanoparticles (NPs) doped with rare earth elements (REEs), from dose enhancement and diagnostic imaging in radiotherapy, to biosensing. However, there are concerns that the NPs could disintegrate in the body thus releasing toxic REE ions to undesired locations. As a first step, we investigate how accurately the Ti/REE ratio from the NPs can be measured inside human cells. A quantitative analysis of whole, unsectioned, individual human cells was performed using proton microprobe elemental microscopy. This method is unique in being able to quantitatively analyse all the elements in an unsectioned individual cell with micron resolution, while also scanning large fields of view. We compared the Ti/REE signal inside cells to NPs that were outside the cells, non-specifically absorbed onto the polypropylene substrate. We show that the REE signal in individual cells co-localises with the titanium signal, indicating that the NPs have remained intact. Within the uncertainty of the measurement, there is no difference between the Ti/REE ratio inside and outside the cells. Interestingly, we also show that there is considerable variation in the uptake of the NPs from cell-to-cell, by a factor of more than 10. We conclude that the NPs enter the cells and remain intact. The large heterogeneity in NP concentrations from cell-to-cell should be considered if they are to be used therapeutically.

Biosynthesis of titanium dioxide nanoparticles using Bacillus amyloliquefaciens culture and enhancement of its photocatalytic activity for the degradation of a sulfonated textile dye Reactive Red 31

The present study aims at exploiting Bacillus amyloliquefaciens for the biosynthesis of titanium dioxide nanoparticles and also investigates role of bacterial enzymes in the biosynthesis of titanium dioxide nanoparticles. Bacterial synthesized as well as metal doped titanium dioxide nanoparticles were characterized by X-ray diffractometer (XRD), Fourier transform infrared spectroscopy (FTIR), Transmission electron microscopy (TEM), Energy dispersive X-ray spectroscopy (EDAX). Amylase activity (43.37IU) in culture supernatant evinced a potential involvement of extracellular enzyme in TiO2 nanoparticle biosynthesis. Crystallite size of bio-synthesized nanoparticles was found to be in the range of 15.23–87.6nm. FTIR spectroscopy and native-PAGE (Polyacrylamide Gel Electrophoresis) clearly indicated involvement of alpha amylase in biosynthesis of TiO2 nanoparticles and in their stabilization. TEM micrographs of the synthesized titanium dioxide nanoparticles revealed the formation of spherical nanoparticles with a size range of 22.11–97.28nm. Photocatalytic degradation of Reactive Red 31 (RR31) dye was carried out using bio-synthesized TiO2 nanoparticles under UV radiation. Photocatalytic activity of synthesized nanoparticles was enhanced by Ag, La, Zn and Pt doping. Platinum doped TiO2 showed highest potential (90.98%) in RR31 degradation as compared to undoped (75.83%).