Silver-doped TiO2 Nanoparticles Research Articles

Evaluation of antimicrobial properties of conventional poly methyl methacrylate denture base resin materials containing silver doped titanium dioxide nanoparticles against cariogenic bacteria and candida albicans

The main aim of the study was to find the antimicrobial properties of a poly methyl methacrylate resin (PMMA) which is modified with silver-doped titanium dioxide nanoparticles. This research study was done to prove that the incorporation of silver-doped TiO2 nanoparticles improves the antimicrobial and antifungal properties.The poly methyl methacrylate resin (PMMA) powder was modified using 0 wt%(control) 1wt% and 3wt% silver doped TiO2 nanoparticles Test specimens were prepared of dimensions 5 mm × 5 mm × 2 mm. The antimicrobial properties of the specimens were evaluated by calculating CFU/ml. The obtained values were analyzed by one-way analysis of variance (ANOVA), Kruskal Wallis test, and post-hoc Tukey’s test at a significance level of 5%. The incorporation of silver-doped titanium dioxide nanoparticles into denture base resin improved antimicrobial activity. Compared to 1% and 3% nanoparticle doped, 3% has given better antimicrobial activity calculated using CFU/ml. It is reduced to one-fourth the microbial growth compared to the control group. The addition of silver-doped titanium dioxide nanoparticles to denture base resin is an effective method for antimicrobial and antifungal action.

Decagram-scale synthesis of heterometallic Ag/Ti cluster as sustainable catalyst for selective oxidation of sulfides

Atomically precise heterometallic clusters constitute a new family of model catalysts for understanding the fundamental catalysis process widely occurred in supported nanocatalysts, however, their syntheses and structure/composition modulations are nonetheless daunting challenges. Herein, three novel heterometallic Ag/Ti clusters with different Ag-doping ratios, Ag4Ti14, Ag4Ti6 and Ag4Ti2, have been readily synthesized in decagram-scale quantities through ligand engineering strategy. Thereinto, Ag4Ti2 can be efficiently prepared within 3 h in a quite high yield > 95 %. More remarkably, Ag4Ti2 shows unprecedented catalytic activity (>90 % conversion within 1 min) and selectivity (nearly 100 %) towards oxidation of thioethers with a wide substrate scope even including notorious 2-chloroethyl ethyl sulfide (CEES) at room temperature (turnover frequency = 11,880 h−1), which is mainly attributed to its full-surface-exposure-doping Ag atoms (affinity for binding of substrate) on TiO support and their cooperativity, whereas the other two are not the same case. Moreover, the Ag4Ti2 is highly robust in catalysis process and can be readily recovered and reused at least six cycles without observable loss of activity and selectivity, enabling this cluster hold great promise in industrial applications. This work not only establishes a general method to scale-up synthesis of Ag/Ti clusters but also provides an atom-precise model catalyst to understand the structure–property correlations of real-world conventional nanocatalysts such as silver doped-TiO2 nanoparticles.

Strong Inhibition of Silver-doped TiO2 Nanoparticles Against P. palmivora in Visible Light

Strong Inhibition of Silver-doped TiO2 Nanoparticles Against P. palmivora in Visible Light

Plasmon-enhanced ultrafast and tunable thermo-optic nonlinear optical properties of femtosecond laser ablated TiO2 and Silver-doped TiO2 nanoparticles

We report the results obtained from our extensive femtosecond (fs) nonlinear optical (NLO) studies of titanium dioxide (TiO2) and silver (Ag) doped titanium dioxide (Ag-TiO2) nanoparticles. TiO2 as well as Ag-TiO2 nanoparticles (NPs) were synthesized in deionized water using the techniques of fs laser ablation and simultaneous laser induced chemical reduction through irradiation, respectively. The broadband third-order nonlinear optical (NLO) behaviour of the synthesized NPs was investigated by employing the standard open and closed aperture Z-scan experiments with fs laser pulses delivered from an oscillator (~80 MHz repetition rate at wavelengths of 700 nm, 750 nm, 800 nm, 850 nm) and amplifier pulses (1 kHz repetition rate at wavelengths of 800 nm, 1000 nm, 1100 nm, 1200 nm). The corresponding NLO coefficients [two-photon absorption (2PA) coefficients of ~10-8 cm/W and three-photon absorption (3PA) coefficients of ~10-15 cm3/W2 with MHz excitation] were retrieved from the theoretical fits to the experimental Z-scan data. It was evident from the experimental observations that the Ag-TiO2 NPs demonstrated a significant tendency towards 3PA and also crucially higher nonlinear susceptibility [χ(3)] in comparison with the pure TiO2 NPs. In this extensive investigation, not only a remarkable correlation has been established regarding the incorporation of Ag into TiO2 matrix with thermal-optic influence (MHz interaction) but also the fundamental plasmon-enhanced nonlinear absorption (NLA) in the case of 1 kHz pulse excitation has been decisively recognized. The synthesized nanocomposites were scrupulously probed in the near-IR regime, unveiling the presence of a prominent 3PA (with retrieved coefficients of ~10-23 cm3/W2 using kHz excitation), an essentially rare observation in these kinds of NPs.

Synthesis and development of novel sensitizer from spirulina pigment with silver doped TiO2 nano particles for bio-sensitized solar cells

Pycocyanin pigment of spirulina (blue green algae) was used as photosentizer for the fabrication of Bio sensitized solar cells (BSSC). The pigment was extracted in different solvents such as water, Ethanol and Acetone and pure and “Ag (3 and 5 wt%)” doped TiO2 nanoparticles were prepared by facile sol-gel technique in order to fabricate BSSC. The structural, morphological, optical properties and Electrochemical impedance analysis of the prepared thin films were studied by powder X-ray diffraction, Field Emission Scanning Electron Microscopic (FE-SEM), Transmission Electron Microscopic technique (TEM), UV–Vis spectroscopy and current voltage characteristics respectively. The main observation from this research work is reduction of energy band gap values due to doped “Ag” ion which may allow the delayed recombination rate and enhance the photovoltaic conversion efficiency of around 1.2% when compared to that of pure TiO2 nanoparticles (0.74%) with N719 dye as 6.15. The photocurrent density - photo voltage (J-V) characteristics of fabricated BSSC via Pycocyanine pigments under various solvents adsorbed condition on nanocrystalline pure TiO2 and Ag doped TiO2 film electrodes were carried out. The pigments in association with water solution shows the short-circuit photocurrent density J(sc) of around 3.0 mA/cm2 and the open-circuit photo voltage (Voc) 0.75 V, under an illumination intensity of 40 mW/cm2 respectively. With the above observations, the research work claims that “Ag” doped TiO2 nanoparticles may be a promising candidate for future BSSC applications.

Green synthesis and structural classification of Acacia nilotica mediated-silver doped titanium oxide (Ag/TiO2) spherical nanoparticles: Assessment of its antimicrobial and anticancer activity.

Current exanimation reports, green fabrication of silver doped TiO2 nanoparticles (Ag/TiO2) using aqueous extract of Acacia nilotica as bio-reductant and assess its potential as antimicrobial and anticancer agent. The obtained spherical Ag/TiO2 were characterized by various analytical techniques including FTIR, (XRD), (FE-SEM EDS), and (TEM). Synthesized Ag/TiO2 demonstrated broad spectrum antibacterial and anticandidal activity. The order of antimicrobial activity was found to be E. coli > C. albicans > MRSA > P. aeruginosa. In addition, cytotoxicity and oxidative stress of Ag/TiO2 nanoparticles in (MCF-7) cells was also investigated. Outcomes of MTT assay showed concentration dependent reduction in cell viability. Further, synthesized NPs reduced the level of glutathione, induced ROS generation and lipid peroxidation in the treated cells. Therefore, it is envisaged that these spherical nanoparticles may be exploited in drug delivery, pharmaceutical, and food industry.

Voltammetric detection and determination of mefenamic acid at silver-doped TiO2 nanoparticles modified electrode

Abstract A simple sensitive voltammetric method to detect and to determine a nano level anthranilic acid derivative, mefenamic acid has been developed using different voltammetric techniques in pH 5.0 phosphate buffer solutions with ionic strength 0.2M. An enhancement of oxidation peak current for an analyte on the modified paste was observed followed by characterization with atomic mass spectroscopy analysis. The control of various parameters on the drug oxidation current like accumulation time, amount of modifier, pH, scan rate, and concentration was also evaluated. The analytical applications were studied by square wave voltammetry technique. A suitable electro-oxidation mechanism for mefenamic acid at nanoparticles silver-doped titanium dioxide modified carbon paste electrode was proposed. The oxidation peak currents of mefenamic acid concentration was studied using square wave voltammetry technique in the range 1.0 x 10-8 to 3.0 x 10-6 M with a lower detection limit 1.94 nM compared to earlier reported practice. The modified sensor showed an excellent physiological feature, large surface area, remarkable stability, reproducibility by simple preparation process. The proposed method was successfully employed for the determination of mefenamic acid in pharmaceutical and biological samples with good recovery values.

An enhanced sensing platform for clozapine at 2.0% silver doped TiO2 nanoparticles - A sensitive detection

Metal doped nanoparticles as a modifier have received attention in the development of electrochemical sensors and biosensors. In the current work, we established the electrochemical behaviour and detection of clozapine by utilizing 2.0% silver doped TiO2 nanoparticles modified carbon paste electrode (Ag-TiO2/CPE) at pH 4.2 by employing different voltammetric techniques. Modification enhances the electro-oxidation of clozapine with increased current intensity. The characterization of silver 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 influence of parameters like scan rate, pH, accumulation time, amount of the modifier and concentration on the peak current of the drug were studied. The effect of CLZ concentration variation was studied using square wave voltammetric (SWV) technique and got lowest detection limit compared to reported techniques. The fabricated sensor was employed for the determination of clozapine in pharmaceutical and biological samples

Antibacterial properties of silver doped TiO2 nanoparticles synthesized via sol-gel technique

In this work, antibacterial, micro-structural, and fluorescence properties of silver (Ag) doped TiO2 nanoparticles were studied to analyze the effect of silver for effective improvement in antibacterial properties of TiO2. Antibacterial properties of pure TiO2 and Ag-TiO2 was studied using Escherichia coli, Pseudomonas aeruginosa as Gram Negative and Bacillus subtilis, Staphylococcus aureus as Gram positive bacteria, as a model for Agar disc diffusion assay method. The concept of inhibition zone diameter was applied to observe the antibacterial activity of TiO2 and Ag-TiO2. It was observed that the antibacterial activity of TiO2 improves with doping of Ag. Fluorescence spectra confirm the red shift in band edge emission at excitation wavelength of 360 nm which shows effective fluorescence properties of these nanoparticles. Microstructures of these nanoparticles have studied with the help of transmission electron microscopy (TEM) and atomic force microscopy (AFM).

Ag-TiO2nanoparticles for photocatalytic degradation of lomefloxacin

AbstractThe photocatalytic activity of silver-doped TiO2 (Ag-TiO2) nanoparticles was studied by photocatalytic degradation of lomefloxacin (LMF) using a photoreactor with a mercury lamp (PHILIPS, TUV 8 W T5, Emax = 254 nm). The 1 and 2% silver-doped TiO2 nanoparticles were synthesized by liquid impregnation (LI) method. The resulting nanoparticles were characterized by surface analytical methods such as X-ray diffraction (XRD), scanning electron microscope (SEM), energy dispersive X-ray analysis and transmission electron microscope (TEM). The study shows 2% Ag-TiO2 nanoparticles exhibited better results (95% degradation) in 1 h for the degradation of lomeofloxacin compared to 1% Ag-TiO2 and pure TiO2. XRD analysis indicated that the crystallite size of TiO2 was 17.00 nm, while the crystallite size of 1% Ag-TiO2 and 2% Ag-TiO2 was 13.07 to 14.17 nm. TEM images show the particle size of Ag-TiO2 nanoparticles were in the range 40–45 nm in length and 10–15 nm in breadth. Pseudo-first-order rate constants were...

Application of Ag-doped TiO2nanoparticle prepared by photodeposition method for nitrate photocatalytic removal from aqueous solutions

Nitrate pollution in surface and groundwater resources is considered as an environmental challenge because of the potential risks of nitrate in diseases such as methemoglobinemia, lymphatic disturbances, and blood cancer. On the other hand, nanomaterials have been recently applied for the control of water pollutants. The objective of this research was to investigate the efficiency of silver-doped TiO2 nanoparticles prepared by photodeposition method under UV irradiation for nitrate removal. Ag-doped TiO2 nanomaterials (Ag/Ti = 0.1 at %) were characterized by scanning electron microscope-energy dispersive X ray, transmission electron microscope, X-ray diffraction, and BET and used in doses of 0.1, 0.4, 0.8, and 1.2 g/L. Three nitrate concentrations of 20, 50, and 100 mg/l were considered in the pH range of 5–9. The effect of Ag-doped TiO2 nanoparticles both in dark and with UV irradiation was studied. Nitrite and ammonia, as intermediates of photocatalytic degradation of nitrate, were detected by spectrophotometric method. Also, in the study, the effect of change in Ag percent doped on TiO2 under UV irradiation for nitrate removal was investigated. The effect of calcination temperature was surveyed on Ag-doped TiO2/UV process efficiency in nitrate removal from aqueous solutions. The optimum performance of nitrate removal (95.5%) was obtained with initial concentration of 100 mg/l and in acidic pH. Increase of Nanoparticle concentration up to 0.8 g/L, improved the removal efficiency, but 1.2 g/l of nanoparticles reduced the degradation efficiency. Maximum reduction performances without nanoparticles (with UV irradiation and in dark) were 32 and 23.3%, respectively. Optimal calcination temperature and optimal silver content doped on TiO2 was obtained at 400°C and 1%.

Sol–gel synthesised silver doped TiO2 nanoparticles supported on NaX zeolite for photocatalytic applications

Silver doped TiO2 nanocomposite [1% (w/w)] and undoped nano-TiO2 particles were prepared by sol–gel method from tetraporopyl orthotitanate as the precursor. To improve the photocatalytic efficiency, silver doped TiO2 nanoparticles were immobilised on NaX zeolite and used as photocatalyst. Chemical composition and optical absorption of the photocatalyst were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), infrared and ultraviolet–visible absorption spectroscopy. The XRD patterns show that the supported TiO2 are crystallised in anatase phase, and the intensity of the zeolite peaks decreases with the increase in TiO2 loading. Characterisation of samples by SEM indicates that the outer surface of the zeolite crystals is covered by the titania particles. Infrared spectroscopy revealed that the nanosize titanium oxide particles are linked to the framework through Ti–O–Si bonds. Ultraviolet–visible diffuse reflectance spectrum of metal doped TiO2 nanocomposite shows red shift in the band gap transition. The photocatalytic performances of these composite semiconductors were examined with respect to an azo dye, Orange G. The effects of pH and irradiation time on photodegradation were investigated. According to the UV-vis absorption spectroscopy results, the photodegradation of orange G dye under UV light irradiation in the presence of silver doped TiO2/NaX zeolite catalyst is more efficient than the Ag/TiO2 nanocomposite and also undoped nanotitanium oxide powder.

Photocatalytic degradation of chloramphenicol in an aqueous suspension of silver-doped TiO2 nanoparticles

In this work, silver-doped TiO2 (Ag/TiO2) nanoparticles were synthesized using a photodeposition technique. The prepared Ag/TiO2 nanoparticles were characterized using TEM, SEM, XRD, and EDX techniques. The characterization of Ag/TiO2 nanoparticles using SEM and EDX techniques revealed the dispersion of Ag metal on the surface of TiO2. The photocatalytic activity of Ag/TiO2 and bare TiO2 in the presence of ultraviolet irradiation was investigated in the removal of chloramphenicol (CAP) as an antibiotic. CAP is a broad-spectrum antibiotic exhibiting activity against both Gram-positive and Gram-negative bacteria, as well as other groups of microorganisms. However, it is, in certain susceptible individuals, associated with serious toxic effects in humans including bone marrow depression, particularly severe in the form of fatal aplastic anaemia. The effects of the operational factors, such as doping content of Ag, photocatalyst dosage and calcination temperature were evaluated in the catalytic activity of Ag/TiO2. The results showed that the photocatalytic efficiency of TiO2 nanoparticles for the degradation of CAP, can be significantly improved by deposition an optimum amount of Ag nanoparticles (0.96 wt%) in the calcination temperature 300°C. It was found that 900 mg/L of Ag/TiO2 is the optimum dosage in the removal of CAP with 20 mg/L initial concentration. The highest removal efficiency of CAP (∼100%) at the optimum conditions was observed in 20 min. A mineralization study under optimum conditions showed about 88% reduction in total organic carbon after 120 min of irradiation time.

Enhancement of photocatalytic activity of TiO2 nanoparticles by silver doping: photodeposition versus liquid impregnation methods

Silver doped TiO2 nanoparticles have been prepared by liquid impregnation (LI) and
 photodeposition (PD) methods and characterized by surface analytical methods such as
 scanning electron micrographs (SEM) and X-ray diffraction (XRD). The photocatalytic activity
 of silver doped TiO2 was tested by photocatalytic degradation of C.I. Acid Red 88 (AR88) as a
 model compound from monoazo textile dyes. Results show silver doped TiO2 is more efficient
 than undoped TiO2 at photocatalytic degradation of AR88. The positive effect of silver on the
 photoactivity of TiO2 at degradation of AR88 may be explained by its ability to trap electrons.
 This process reduces the recombination of light generated electron-hole pairs at TiO2 surface.
 Silver content has an optimum value 2% in LI and 0.5% in PD methods for achieving high
 photocatalytic activity. The AR88 decomposition with Ag-photodeposited method was much
 higher than that of deposited with LI method.

Structural and optical characterization of Ag-doped TiO2 nanoparticles prepared by a sol–gel method

Undoped and silver-doped TiO2 nanoparticles (Ti1−xAgxO2, where x = 0.00–0.10) were synthesized by a sol–gel method. The synthesized products were characterized by X-ray diffraction (XRD), particle size analyzer (PSA), scanning electron microscope (SEM), and UV–Visible spectrophotometer. XRD pattern confirmed the tetragonal structure of synthesized samples. Average crystallite size of synthesized nanoparticles was determined from X-ray line broadening using the Debye–Scherrer formula. The crystallite size was varied from 8 to 33 nm as the calcination temperature was increased from 300 to 800 °C. The incorporation of 3 to 5% Ag+ in place of Ti4+ provoked a decrease in the size of nanocrystals as compared to undoped TiO2. The SEM micrographs revealed the agglomerated spherical-like morphology of particles. SEM, PSA, and XRD measurements show that the particles size of the powder is in nanoscale. Optical absorption measurements indicated a red shift in the absorption band edge upon silver doping. Direct allowed band gap of undoped and Ag-doped TiO2 nanoparticles measured by UV–Vis spectrometer were 3.00 and 2.80 eV, respectively, at 500 °C.