UV-visible Wavelength Research Articles

A Visible‐Light‐Driven Photocatalyst of NASICON Li2Ni2(MoO4)3 Nanoparticles

A visible‐light‐driven photocatalyst based on the well‐known cathode material of NASICON‐type Li2Ni2(MoO4)3 was prepared by a modified Pechini method. The sample was characterized by X‐ray diffraction, scanning electron microscope, transmission electron microscopy, and UV‐vis absorption spectrum. The average size of Li2Ni2(MoO4)3 particle is below 50 nm. NASICON nanoparticles Li2Ni2(MoO4)3 has an efficient absorption in the UV‐visible light wavelength region with a direct allowed electronic transition of 2.07 eV. The photocatalytic properties of Li2Ni2(MoO4)3 were evaluated by the photodegradation of methylene blue (MB). Li2Ni2(MoO4)3 has an efficient photocatalytic activity and could be a potential photocatalyst driven by visible‐light. The photocatalytic activity was discussed on the optical absorption and special hexagonal tunnel structure connected by optical active centers of MoO4 and NiO6 and its good conductivity.

高密度プラズマアシスト蒸着により作製したSiO<sub>2</sub>およびNb<sub>2</sub>O<sub>5</sub>薄膜の光学的・機械的特性

As a main optical thin-film material, SiO2 has a low refractive index in the UV-visible wavelength region. It is used widely for optical coatings with superior environmental resistance. In contrast, Nb2O5 is a high refractive index material. To improve their mechanical properties, SiO2 and Nb2O5 single-layer thin films were prepared using high-density plasma assisted vapor deposition. Plasma conditions were varied by changing the coil current related to energy intensity, and the oxygen gas flow rate related to ionization. Analyses of SiO2 and Nb2O5 thin films using XRD revealed amorphous composition irrespective of the assist. However, cross-sectional SEM images showed that thin film densification differed according to the assist. Furthermore, XPS showed differences in SiO2 thin films from the bonding state according to the assist. The Nb2O5 thin films exhibited slight differences according to the assist. Surface roughness measurements and abrasion resistance tests were done for thin films deposited under various plasma conditions. The plasma-assisted deposited SiO2 films were much more durable than non-assist films. The refractive indexes of the films were measured using optical transmission spectra and ellipsometry. Results show correlation between the durability and the refractive indexes. The film packing density was related to the durability. No difference was found in the durability for Nb2O5 between plasma-assisted deposited films and non-assisted deposited ones. However, a difference was found in the refractive index between the films of two types. The film hardness was measured using nanoindentation. The Nb2O5 films were harder than the SiO2 films. The Nb2O5 film stiffness was also three times greater than that of SiO2 films. However, the damage to plasma-assisted SiO2 films was less than that to plasma-assisted Nb2O5 films. This high stiffness is expected to cause plastic deformation. Future investigations must examine the relations among film packing density, durability, hardness, and stiffness.

Nanoparticle Characterization of Traditional Homeopathically- Manufactured Gelsemium sempervirens Medicines and Placebo Controls

Multiple studies have observed nanostructures in traditionally-manufactured homeopathic medicines. Homeopathy is a 200-year-old system of complementary and alternative medicine used worldwide. The nature of homeopathic medicines has historically stimulated much debate. The present placebo-controlled study extended previous work to characterize nanoparticles (NPs) in homeopathically-prepared Gelsemium sempervirens (GELS), a natural botanical source with previously-documented anxiolytic, analgesic, and anticancer properties. An ethanolic GELS herbal extract was serially diluted and succussed (agitated) in a 95% ethanol-water diluent solvent in glass vials, following Homeopathic Pharmacopoeia of the U.S. guidelines. GELS (VERUM, at homeopathic potencies of 6C, 30C, 200C, each n=3 vials), succussed controls (SUCC-CONT, at homeopathic potencies of 6C, 30C, 200C, each n=3), and one set of unsuccussed solvent control vials also used natural cork (Quercus suber) stoppers (UNSUCC-cork, n=3). A final set of unsuccussed solvent controls used silicone stoppers (UNSUCCsilicone, n=3). Analytical methods included nanoparticle tracking analysis (NTA), zeta potentials, and UV-Visible spectroscopy. NTA revealed >4 x 108 nanoparticles per milliliter in all VERUM, SUCC-CONT, and UNSUCC-cork vials, significantly more than the UNSUCC-silicone controls. Particle sizes were polydisperse, significantly larger in the VERUM 30C at 129.8 nanometers versus SUCC-CONT at 6C, 30C, 200C and the UNSUCC-cork controls. Zeta potentials consistent with greater particle stability were significantly most negative in the VERUM GELS 200C (-47.75 mV). Within the UV-vis wavelength range 300-400 nm, the SUCC-CONT 30C exhibited significantly higher, whereas UNSUCC-silicone stopper controls had significantly lower, mean absorbance than all other samples. Taken together, the data suggest that traditional homeopathic methods involving succussions release not only the previously-shown silica from glassware walls, but also Quercus suber materials from natural cork stoppers to stabilize NPs in solution. With verum source material Gelsemium, additional NP size growth and surface stabilization can occur. Further study of homeopathic manufacturing materials and methods and their biological correlates is indicated.

Porphyrin nanorods-polymer composites for solar radiation harvesting applications

The interest in exploring porphyrin-based nanostructures for artificial solar radiation harvesting stems from their structural similarity to chlorophylls. In nature, the precise organization and orientation of the chlorophylls result in efficient absorption of light energy. Inspired by these naturally occurring architectures relevant optical studies including the dynamics of intermolecular and intra-molecular processes of the porphyrin nanorods were investigated. The design of artificial light harvesting systems requires several key factors, such as absorption in the UV-visible and near-infrared wavelengths, energy transfer ability and the selection of light absorbing pigments. Another key factor is the organizational structure through which the components will interact. We attempted to accomplish this by incorporating porphyrin nanorods into polymer matrices and this will also aid in achieving an arrangement where they can be directly used as devices. The nanorods were embedded in a polymeric matrix, using latex technology and electrospinning which gave the possibility of investigating the orientation of nanorods in the polymer. Spectroscopic and microscopic studies were conducted to investigate the optical and morphological properties of the porphyrin nanorods-polymer composites for applications in artificial solar radiation harvesting systems.

Synthesis of anisotropic nanostructures of silver for its possible applications in glucose and temperature sensing

Syntheses of anisotropic nanostructures of silver have been demonstrated by using a simple chemical synthesis route and the roles of temperature and reaction time in the anisotropic growth of the material have been reported. The role of multiple twinned particles in the anisotropic shape evolution and branching growth of synthesized silver nanostructures is demonstrated. The optical absorption and photoluminescence (PL) properties of the non-functionalized silver nanostructures have been studied in the UV–visible wavelength region and there exist two surface plasmon resonance (SPR) peaks, one called transverse surface plasmon resonance (TSPR) peak situated at smaller wavelength at ∼410–415 nm, and another called longitudinal surface plasmon resonance (LSPR) peak appearing at longer wavelength at ∼595–615 nm in the visible region. Intense PL emission spectra centered at ∼410 nm have been observed from the synthesized products obtained at lower temperature, whereas the PL spectra of higher temperature materials are divided into two broad peaks staying >100 nm apart at both sides of 410 nm. It has been demonstrated that the synthesized non-functionalized silver nanostructure can further be utilized for sensing of glucose and temperature. Tyndall effect experiment with the synthesized silver nanostructures dispersed in methanol has been performed and demonstrated the stability of the nanostructures.

Antibacterial activity of silver and zinc nanoparticles against Vibrio cholerae and enterotoxic Escherichia coli

Vibrio cholerae and enterotoxic Escherichia coli (ETEC) remain two dominant bacterial causes of severe secretory diarrhea and still a significant cause of death, especially in developing countries. In order to investigate new effective and inexpensive therapeutic approaches, we analyzed nanoparticles synthesized by a green approach using corresponding salt (silver or zinc nitrate) with aqueous extract of Caltropis procera fruit or leaves. We characterized the quantity and quality of nanoparticles by UV–visible wavelength scans and nanoparticle tracking analysis. Nanoparticles could be synthesized in reproducible yields of approximately 108particles/ml with mode particles sizes of approx. 90–100nm. Antibacterial activity against two pathogens was assessed by minimal inhibitory concentration assays and survival curves. Both pathogens exhibited similar resistance profiles with minimal inhibitory concentrations ranging between 5×105 and 107particles/ml. Interestingly, zinc nanoparticles showed a slightly higher efficacy, but sublethal concentrations caused adverse effects and resulted in increased biofilm formation of V. cholerae. Using the expression levels of the outer membrane porin OmpT as an indicator for cAMP levels, our results suggest that zinc nanoparticles inhibit adenylyl cyclase activity. This consequently deceases the levels of this second messenger, which is a known inhibitor of biofilm formation. Finally, we demonstrated that a single oral administration of silver nanoparticles to infant mice colonized with V. cholerae or ETEC significantly reduces the colonization rates of the pathogens by 75- or 100-fold, respectively.

Ascorbic acid surface modified TiO₂-thin layers as a fully integrated analysis system for visual simultaneous detection of organophosphorus pesticides.

TiO₂ photocatalysis and colorimetric detection are coupled with thin layer chromatography (TLC) for the first time to develop a fully integrated analysis system. Titania@polystyrene hybrid microspheres were surface modified with ascorbic acid, denoted AA-TiO₂@PS, and used as the stationary phase for TLC. Because the affinity between AA-TiO₂@PS and organophosphorus pesticides (OPs) was different for different species of OPs (including chlopyrifos, malathion, parathion, parathion-methyl, and methamidophos), OPs could be separated simultaneously by the mobile phase in 12.0 min with different Rf values. After surface modification, the UV-vis wavelength response range of AA-TiO₂@PS was expanded to 650 nm. Under visible-light irradiation, all of the OPs could be photodegraded to PO₄(3-) in 25.0 min. Based on the chromogenic reaction between PO₄(3-) and chromogenic agents (ammonium molybdate and ascorbic acid), OPs were quantified from color intensity images using a scanner in conjunction with image processing software. So, AA-TiO₂@PS was respectively used as the stationary phase of TLC for efficient separation of OPs, as a photocatalyst for species transformation of phosphorus, and as a colorimetric probe for on-field simultaneous visual detection of OPs in natural water. Linear calibration curves for each OP ranged from 19.3 nmol P L(-1) to 2.30 μmol P L(-1). This integrated analysis system was simple, inexpensive, easy to operate, and sensitive.

Synthesis and properties of novel soluble and high T g poly(ether imide)s from diamine containing 4,5-diazafluorene and trifluoromethyl units

The synthesis and properties of soluble, high T-g and transparent aromatic polyimides containing 4,5-diazafluorene and trifluoromethyl units in the polymer backbone on the basis of a novel diamine monomer, 9,9-di[4-(4-amino-2-trifluoromethyl phenoxy)phenylene]-4,5-diazafluorene, are described. Incorporation of 4,5-diazafluorene and trifluoromethyl groups into rigid polyimides improves their solubility and transparency without decreasing their physical properties. All of the thermal imidization polyimides are soluble at room temperature in aprotic and protic polar solvents such as N,N-dimethylacetamide, N,N-dimethylformamide, dimethylsulfoxide, pyridine and m-cresol and can be solution cast into transparent, flexible and tough films. These films have a UV-visible absorption cutoff wavelength at 386-407nm and light transparencies of 73%-84% at a wavelength of 550nm. In addition, the polymers exhibit high thermal stability with a glass transition temperature (T-g) of 305 to 362 degrees C and 5% weight loss at temperatures ranging from 525 to 543 degrees C in nitrogen and from 521 to 538 degrees C in air. The polyimide films possess tensile strengths in the range 79-113MPa, a tensile modulus of 1.75-2.10GPa and elongations at break of 7%-16%. (c) 2014 Society of Chemical Industry

Structural, electronic and optical properties of 7-atom Ag-Cu nanoclusters from density functional theory

The structures and electronic properties of 7-atom silver and copper bimetallic clusters are systematically investigated by density functional theory (DFT) in the theoretical frame of the generalised gradient approximation (GGA) exchange-correlation functional. Optical absorption, Raman spectra, as well as vibrational spectra are calculated by DFT/GGA and semi-core pseudopotentials. The lowest-energy stable motifs are primarily related to the quantity of Cu-Cu bonds and Ag-Cu bonds. The Ag5Cu2 2-I with D 5h symmetry cluster is the lowest energy cluster in the family of the 7-atom Ag-Cu nanoclusters, but has the lowest electronic stability. The Ag5Cu2 2-I, Ag4Cu3 3-I and Ag3Cu4 4-I clusters with mixed motifs indicate that silver and copper may be miscible on the nanoscale but not in bulk. Overall, with increasing Cu atoms, for the lowest energy nanoclusters, blue-shift of the maximum absorption peaks presents in the UV-Vis wavelength range, the intensities of the maximum peak of the Raman spectra weaken, the Cu atom(s) introduced make the vibrational spectra complex, and the intensities of the vibrational spectra strengthen. The calculated vibrational and Raman spectroscopy of 7-atom Ag-Cu clusters may be helpful in determining the size and structure of the experimental cluster.

Optical and structural properties of polycrystalline CVD diamond films grown on fused silica optical fibres pre-treated by high-power sonication seeding

In this paper, the growth of polycrystalline chemical vapour deposition (CVD) diamond thin films on fused silica optical fibres has been investigated. The research results show that the effective substrate seeding process can lower defect nucleation, and it simultaneously increases surface encapsulation. However, the growth process on glass requires high seeding density. The effects of suspension type and ultrasonic power were the specific objects of investigation. In order to increase the diamond density, glass substrates were seeded using a high-power sonication process. The highest applied power of sonotrode reached 72 W during the performed experiments. The two, most common diamond seeding suspensions were used, i.e. detonation nanodiamond dispersed in (a) dimethyl sulfoxide and (b) deionised water. The CVD diamond nucleation and growth processes were performed using microwave plasma assisted chemical vapour deposition system. Next, the seeding efficiency was determined and compared using the numerical analysis of scanning electron microscopy images. The molecular composition of nucleated diamond was examined with micro-Raman spectroscopy. The sp3/sp2 band ratio was calculated using Raman spectra deconvolution method. Thickness, roughness, and optical properties of the nanodiamond films in UV–vis wavelength range were investigated by means of spectroscopic ellipsometry. It has been demonstrated that the high-power sonication process can improve the seeding efficiency on glass substrates. However, it can also cause significant erosion defects at the fibre surface. We believe that the proposed growth method can be effectively applied to manufacture the novel optical fibre sensors. Due to high chemical and mechanical resistance of CVD diamond films, deposition of such films on the sensors is highly desirable. This method enables omitting the deposition of an additional adhesion interlayer at the glass–nanocrystalline interface, and thus potentially increases transmittance of the optical system.

Recycling of Silicon Sludge and its Optical Properties

We have developed a mass production process of Si quantum dots using photo-induced chemical etching method with oxidation and etching agents and have investigated its optical properties. Average size of the fabricated Si quantum dots was estimated to be 2 nm. Absorption peaks of the fabricated quantum dots were observed in the short wavelength regions, e.g., 200 - 350 nm. On the other hand, in the case of raw sludge, absorption was not observed in the UV-visible wavelength regions due to the narrow energy band gap (e.g., 1.12 eV). The calculated energy band gap of fabricated Si quantum dots was calculated to be 3.5 eV by the modified Kubelka- Munk function. Blue emission peaks around 475 nm wavelengths were observed due to the quantum confinement effect. When the emission peak was fixed, two excitation peaks were observed in 340 nm and 380 nm, respectively, which seemed to be due to the energy band gap widening and/or surface coating with an ultrathin layer. Keywords: Chemical etching, Photoluminescence, Recycling, Silicon sludge.

Aqueous synthesis and characterization of CdS quantum dots capped with some amino acids and investigations of their photocatalytic activities

The current study examines the influence of some amino acids such as alanine, histidine, and serine as stabilizers in the synthesis of CdS quantum dots. The CdS quantum dots (QDs) exhibited strong absorption and photoluminescence properties upon UV–vis wavelength in the region from 200nm to 800nm. Structural and spectroscopic properties of the synthesized CdS QDs were characterized by absorption and fluorescence spectroscopy, X-ray diffraction, field emission scanning electron microscopy, and Fourier transform infrared (FT-IR) spectroscopy. Influence of some parameters on fluorescence intensity of CdS QDs including the precursor ratio, type of modifier, temperature, and initial pH of the reaction was thoroughly studied. Results indicated that the pH and the type of modifier that used played crucial roles in determining luminescence properties of the synthesized CdS nanoparticles. Generally, the luminescence intensity can be enhanced significantly when the CdS QDs are illuminated by room light or sunlight. Also, results specified that the synthesized CdS QDs were capable of effectively degrading organic dyes such as alizarin under visible light irradiation and exhibiting good recycling stability during photocatalytic experiments.

Highly Responsive Ultrathin GaS Nanosheet Photodetectors on Rigid and Flexible Substrates

The first GaS nanosheet-based photodetectors are demonstrated on both mechanically rigid and flexible substrates. Highly crystalline, exfoliated GaS nanosheets are promising for optoelectronics due to strong absorption in the UV-visible wavelength region. Photocurrent measurements of GaS nanosheet photodetectors made on SiO2/Si substrates and flexible polyethylene terephthalate (PET) substrates exhibit a photoresponsivity at 254 nm up to 4.2 AW(-1) and 19.2 AW(-1), respectively, which exceeds that of graphene, MoS2, or other 2D material-based devices. Additionally, the linear dynamic range of the devices on SiO2/Si and PET substrates are 97.7 dB and 78.73 dB, respectively. Both surpass that of currently exploited InGaAs photodetectors (66 dB). Theoretical modeling of the electronic structures indicates that the reduction of the effective mass at the valence band maximum (VBM) with decreasing sheet thickness enhances the carrier mobility of the GaS nanosheets, contributing to the high photocurrents. Double-peak VBMs are theoretically predicted for ultrathin GaS nanosheets (thickness less than five monolayers), which is found to promote photon absorption. These theoretical and experimental results show that GaS nanosheets are promising materials for high-performance photodetectors on both conventional silicon and flexible substrates.

Artificial Intelligence in Numerical Modeling of Silver Nanoparticles Prepared in Montmorillonite Interlayer Space

Artificial neural network (ANN) models have the capacity to eliminate the need for expensive experimental investigation in various areas of manufacturing processes, including the casting methods. An understanding of the interrelationships between input variables is essential for interpreting the sensitivity data and optimizing the design parameters. Silver nanoparticles (Ag‐NPs) have attracted considerable attention for chemical, physical, and medical applications due to their exceptional properties. The nanocrystal silver was synthesized into an interlamellar space of montmorillonite by using the chemical reduction technique. The method has an advantage of size control which is essential in nanometals synthesis. Silver nanoparticles with nanosize and devoid of aggregation are favorable for several properties. In this investigation, the accuracy of artificial neural network training algorithm was applied in studying the effects of different parameters on the particles, including the AgNO3 concentration, reaction temperature, UV‐visible wavelength, and montmorillonite (MMT) d‐spacing on the prediction of size of silver nanoparticles. Analysis of the variance showed that the AgNO3 concentration and temperature were the most significant factors affecting the size of silver nanoparticles. Using the best performing artificial neural network, the optimum conditions predicted were a concentration of AgNO3 of 1.0 (M), MMT d‐spacing of 1.27 nm, reaction temperature of 27°C, and wavelength of 397.50 nm.

Ultraviolet-Visible and Fluorescence Spectroscopy Techniques Are Important Diagnostic Tools during the Progression of Atherosclerosis: Diet Zinc Supplementation Retarded or Delayed Atherosclerosis

Background. In this study, we examined whether UV-visible and fluorescence spectroscopy techniques detect the progression of atherosclerosis in serum of rabbits fed on high-cholesterol diet (HCD) and HCD supplemented with zinc (HCD + Zn) compared with the control. Methods. The control rabbits group was fed on 100 g/day of normal diet. The HCD group was fed on Purina Certified Rabbit Chow supplemented with 1.0% cholesterol plus 1.0% olive oil (100 g/day) for the same period. The HCD + Zn group was fed on normal Purina Certified Rabbit Chow plus 1.0% cholesterol and 1.0% olive oil supplemented with 470 ppm Zn for the same feeding period. UV-visible and fluorescence spectroscopy and biochemistry in Rabbit's blood serum and blood hematology were measured in Rabbit's blood. Results. We found that the fluorescent peak of HCD shifted toward UV-visible wavelength compared with the control using fluorescent excitation of serum at 192 nm. In addition, they showed that supplementation of zinc (350 ppm) restored the fluorescent peak closely to the control. By using UV-visible spectroscopy approach, we found that the peak absorbance of HCD (about 280 nm) was higher than that of control and that zinc supplementation seemed to decrease the absorbance. Conclusions. This study demonstrates that ultraviolet-visible and fluorescence spectroscopy techniques can be applied as noninvasive techniques on a sample blood serum for diagnosing or detecting the progression of atherosclerosis. The Zn supplementation to rabbits fed on HCD delays or retards the progression of atherosclerosis. Inducing anemia in rabbits fed on HCD delays the progression of atherosclerosis.

Self assembled TiO2 with 5-sulfosalicylic acid for improvement its surface properties and photodegradation activity of dye

A new photocatalyst, 5-sulfosalicylic acid grafted TiO2 (5-SA-TiO2) was synthesized by a chemical adsorption-based self assembly technique, and its surface properties were characterized by means of XRD, BET, IR, and UV–vis spectra. After self assembly, a stable, yellow complex was formed quickly on TiO2 surface and then its UV–vis wavelength response range was expanded from 375 nm to 600 nm. The band gap of 5-SA-TiO2 was 2.95 ev, less than that of TiO2 (3.10 ev). The crystalline structure of TiO2 could be adjusted by self assembly, i.e., anatase was transformed into brookite and the proportion between brookite and anatase was increased. After self assembly, the adsorption ratio of acid violet 43 (AV 43) was enhanced from 13.56% to 52.36%, because the crystallite size of both anatase and brookite was smaller, the surface areas were larger, and the affinity of between AV 43 and the catalyst was enhanced for the interactions between phenyl groups. The visible light degradation ratio of TiO2 was increased by self assembly from 36.60% to 97.01% and 82.65% removal of total organic carbon was achieved.

Supramolecular Chirality Measurement of an Optically Anomalous Single Crystal

Abstract The compound 1,8-dihydroxyanthraquinone (DHA) forms chiral crystals composed of several distinct homogeneous regions giving triclinic symmetry in an apparently tetragonal unit cell. True chirality measurement of an optically anomalous DHA crystal was achieved for the first time using a universal chiroptical spectrophotometer in the UV–vis wavelength range.

ZnO-coated carbon nanotubes: an enhanced and red-shifted emission band at UV-VIS wavelength

Porous arrays of ZnO-coated carbon nanotubes exhibit multi-excitations and the intensity of light emission at UV wavelengths is significantly enhanced. Carbon diffusion into the oxide is also observed and resultant effects include red-shift and an additional emission centre at 387 nm.

The period effects of intraperitoneal administration of different gold nanoparticle sizes on heart tissue of rats using fluorescence measurements: In vivo

Despite many benefits of nanotechnology, some studies indicate that certain nanoparticle (NPs) may cause adverse effects because of their small size and unique properties. The aim of the present study was to elucidate the period effects of intraperitonealy administration of different gold nanoparticle sizes on rat heart tissue in vivo using fluorescence spectroscopy. The experimental rats were divided into control and six groups (G1A, G1B, G2A, G2B, G3A and G3B; G1: 20 nm; G2: 10 nm; G3: 50 nm; A: infusion of GNPs for 3 days; B: infusion of GNPs for 7 days). To investigate the period effects of gold nanoparticles (GNPs) 10, 20 and 50 nm on the heart tissue of rats, 50 µl dose of GNPs (of concentration 0.1% Au) were intraperitonealy injected into rats for periods of 3 and 7 days to identify the toxicity and tissue distribution of GNPs in vivo using fluorescence measurements. The high electron densities of GNPs as well as the homogeneity of the particles shape and size make them highly conspicuous under the transmission electron microscope (TEM). The peak fluorescence intensity increased for G1B compared with G1A, increased for G2B compared with G2A and sharply decreased for G3A and G3B compared with the control. The peaks of G1A, G1B, G2A, G2B, G3A and G3B shifted towards the UV-Visible wavelength compared with the control. The peak fluorescence intensity for G1A was higher than G2A, G3A and G3B while G2A was higher than G3A. The peak fluorescence intensity for G2B was higher than G1B and G3B while G1B was higher than G3B. GNPs of sizes 10 and 20 nm have spherical shape while GNPs of size 50 nm have hexagonal shape. Fluorescence intensity of GNPs was size, shape and infusion period dependent. The decrease in peak fluorescence intensity induced in large 50 nm GNPs may be attributed to occurrence of quenching, decrease number and surface area of GNPs in addition to high clearance of GNPs via urine and bile. Moreover, decreasing size may lead to an exponential increase in surface area relative to volume, thus making the GNPs surface more reactive on itself (aggregation) and to its surrounding environment (biological components). Size, shape, surface area, number and clearance of GNPs play a key role in toxicity, and alterations of accumulation of GNPs in the heart tissue which may be mediated by dynamic protein binding and exchange. A better understanding of these mechanisms will improve drug delivery. Key words: Gold nanoparticles, sizes, administration period, heart tissue, fluorescence spectroscopy.

Silver and gold modified plasmonic TiO 2 hybrid films for photocatalytic decomposition of ethanol under visible light

Plasmonic noble metal nanoparticles (NPs) (silver and gold) are able to sensitise photocatalysts in visible light by modifying the TiO 2 surface with 0.5 wt% loading. These plasmonic catalysts were supported by optically transparent zirconium dioxide and layer silicate. The hybrid catalyst films (with ∼10 μm thickness) were prepared by sputtering the aquatic suspension of the catalyst/support suspension on glass slides and irradiated the films by visible light ( λ ≥ 435 nm). The photocatalytic efficiency was studied on decomposition of ethanol vapour, and the residual concentration of ethanol was monitored. The intermediates during illumination were analysed by GC–MS. Modifications with silver and gold lead to a change in the optical properties due to the plasmonic light absorption on TiO 2. The supporting binding materials are almost transparent in UV–vis wavelength range, thus Ag- and Au-modified TiO 2 can be excited by the incoming light without much loss of the photon energy. Furthermore, the layered silicate promoted the photocatalytic process by its high adsorption capacity. Due to these two phenomena, a synergistic effect was found on the photocatalytic activity of the nanocomposite hybrid films.