Visible Lamp Research Articles

Membrane potential manipulation with visible flash lamp illumination of targeted microbeads

The electrical membrane potential (Vm) is a key dynamical variable of excitable membranes. Despite the tremendous success of optogenetic methods to modulate Vm with light, there are some shortcomings, such as the need of genetic manipulation and limited time resolution. Direct optical stimulation of gold nanoparticles targeted to cells is an attractive alternative because the absorbed energy heats the membrane and, thus, generates capacitive current sufficient to trigger action potentials [1, Carvalho-de-Souza et al., 2015]. However, focused laser light is required and precise location and binding of the nanoparticles cannot be assessed with a conventional microscope. We therefore examined a complementary method to manipulate Vm in a spatio-temporal fashion by non-focused visible flashlight stimulation (Xenon discharge lamp, 385-485 nm, ∼500 μs) of superparamagnetic microbeads. Flashlight stimulation of single beads targeted to cells resulted in transient inward currents under whole-cell patch-clamp control. The waveform of the current reflected the first time derivative of the local temperature induced by the absorbed light and subsequent heat dissipation. The maximal peak current as well as the temperature excursion scaled with the proximity to the plasma membrane. Transient illumination of light-absorbing beads, targeted to specific cellular sites via protein-protein interaction or direct micromanipulation, may provide means of rapid and spatially confined heating and electrical cell stimulation.

SPR effect of bismuth enhanced visible photoreactivity of Bi2WO6 for NO abatement

Bi2WO6 is a typical visible-light-responsive semiconductor photocatalyst with a layered structure. However, the relatively large bandgap (2.6–2.8 eV) and quick recombination of photo-generated carriers result in its low quantum efficiency. In this paper, Bi-nanospheres-modified flower-like Bi2WO6 was successfully prepared by solvothermal treatment of Bi2WO6 powders in Bi(NO3)3 solution using ethylene glycol as reductant. The photoreactivity of this photocatalyst was evaluated by the oxidation of NO in a continuous-flow reactor under irradiation by a visible LED lamp (λ > 400 nm). It was found that both Bi nanospheres and flower-like Bi2WO6 precursor exhibit very poor photocatalytic activity with NO removal rates of only 7.7% and 8.6%, respectively. The photoreactivity of Bi/Bi2WO6 was found to steadily increase from 12.3% to 53.1% with increase in the amount of Bi nanospheres from 0 to 10 wt%. However, with further increase in the loading amount of Bi nanospheres, the photoreactivity of Bi/Bi2WO6 hybridized photocatalyst begins to decrease, possibly due to the light filtering by the Bi nanospheres. The enhanced visible photoreactivity of Bi/Bi2WO6 towards NO abatement was attributed to surface plasmon resonance driven interfacial charge separation. The excellent stability of Bi/Bi2WO6 hybridized photocatalyst towards NO oxidation demonstrates its potential for applications such as air purification.

Effect of gadolinium doped ZnS nanoparticles: ferro magnetic photocatalyst for efficient dye degradation

In the present work, solution based simple chemical precipitation method has been used to prepare undoped and Gd doped ZnS nanoparticles. The prepared nanoparticles were characterized by standard analytical methods the X-ray diffraction results revealed that the undoped and Gd doped ZnS nanoparticles corresponds to hexagonal wurtizite structure. The FESEM images shows that the formation of agglomerated nanoparticles. The compositional analysis confirmed the presence of Gd in ZnS matrix with reasonable dissolution range. HRTEM results show that undoped and Gd doped ZnS nanoparticles exhibit a uniform size distribution with average grain size lying in the range of 2.4–3.9 nm. The magnetic studies of Gd doped ZnS nanoparticles carried out at room temperature by vibrating sample magnetometer shows that the materials exhibit magnetic hysteresis. The prepared samples shows paramagnetic behavior at room temperature. The degradation of methylene blue dye (MB), methyl orange dye (MO) and effluent collected from industry by the undoped and Gd doped ZnS nanoparticles was studied using 8 W, UV visible lamp light irradiation. The color degradation efficiency for MB is found to be 95%, whereas the color degradation efficiency for MO is 97% and for the effluent collected from a dye industry it was nearly 90%.

Structural, Optical, and Isothermic Studies of CuFe2O4 and Zn‐Doped CuFe2O4 Nanoferrite as a Magnetic Catalyst for Photocatalytic Degradation of Direct Red 264 Under Visible Light Irradiation

Cu and Zn‐doped Cu ferrites were synthesized by sol–gel auto‐combustion method. The samples were characterized by XRD, SEM, EDX, VSM, FT‐IR, and DRS methods. Powder XRD analysis and FT‐IR spectroscopy confirmed the formation of ferrites spinel phase. The crystallite sizes were calculated using Scherrer's equation. The morphologies and sizes of the synthesized nanoparticles have been observed by scanning electron microscopy. The saturation magnetization (MS) is obtained from VSM data. The energy band gaps were calculated from UV–DRS absorption data. Removal of Direct Red 264 was carried out by CuFe2O4 and Zn‐doped CuFe2O4 as catalysts under a visible lamp. The kinetic and isothermic analysis of photocatalytic degradation was studied. © 2019 American Institute of Chemical Engineers Environ Prog, 38:e13109, 2019

Improved Reactor Productivity for the Safe Photo‐Oxidation of Citronellol Under Visible Light LED Irradiation

AbstractA simple continuous flow photochemical reactor was optimized for the safe photo‐oxidation of citronellol into precursors of rose oxide, a flagrance of commercial value. The reactor productivity was increased by a factor of 4 compared to the current literature for a conversion above 99 % and in safe conditions (up to 0.72 mM min−1 mLreactor−1). The reactor was based on a classical design described by Booker‐Milburn et al., i. e. multiple loops of perfluoroalkoxy (PFA) tubing wrapped tightly around a visible LED lamp under slug flow conditions. The influence of the type of visible white LED light (6500 K vs. 3000 K), of photosensitizers (tetraphenylporphyrin vs. methylene blue), of solvent (CH2Cl2 vs. MeOH), concentration of citronellol (0.1 M vs. 2 M) and of mass efficiency of the reactors (PFA tubing of 0.75 mm to 0.25 mm) was paramount to increase the productivity of the reactor.

Magnetic fluorinated mesoporous g-C3N4 for photocatalytic degradation of amoxicillin: Transformation mechanism and toxicity assessment

A novel fluorinated graphitic carbon nitride photocatalyst with magnetic properties was synthesized by a facile hydrothermal method and used for degradation of amoxicillin (AMX) in water. Compared to the bulk g-C3N4, magnetic fluorinated Fe3O4/g-C3N4 (FeGF) with a high specific surface area (243 m2 g−1) and easy separation from aqueous solution by magnet, led to improved photocatalytic activity in terms of AMX removal and mineralization as well as detoxification of the solution. The results showed that in comparison with a 500 W visible lamp, using a UV lamp (10 W) was considerably more effective for AMX removal, its mineralization and detoxification of the solution. Based on the measurement of accurate mass of the transformation products and their main fragments, a degradation pathway for AMX was proposed. The peak intensities of most transformation products (TPs) generated by using modified photocatalyst under UV light (UV/FeGF2) process were significantly lower than those generated by using pristine g-C3N4, suggesting that UV/FeGF2 process produced a higher extent of mineralization and a lower accumulation of transformation by-products. Based on the use of inexpensive precursor and modifier, simple preparation, good photocatalytic activity and low energy consumption, the proposed method can guide the development of low-cost and high-performance photocatalysts.

Surface functionalization of highly luminescent carbon nanodots from Dioscorea hispida with polyethylene glycol and branched polyethyleneimine and their in vitro study

Synthesized carbon dots (C-dots) from Dioscorea hispida (Gadong tuber) starch were modified with passivating agents such as O,O-bis(3-aminopropyl)polyethylene glycol 1500 (PEG1500N) and branched polyethyleneimine (BPEI) to increase the functional efficiency of C-dots to be used in biological investigations. After surface modification, the C-dots decreased in size from 6–25 to 3–20 nm without changing their morphology. The modified C-dots were fluorescent, and the fluorescence peak gradually shifted to a longer excitation wavelength (from 420 to 500). Upon modification, thereby elucidating a competitive quantum yield of 15% (C-dots-PEG1500N) and 12.6% (C-dots-BPEI). The UV-visible spectrum of the C-dots modified with PEG1500N contained an absorption peak at 290 nm, whereas, that of the C-dots modified with BPEI contained peak at 360. Fourier-transform infrared analysis showed a peak at 1700 cm−1 (C-dots-PEG1500N) and 1697 cm−1 (C-dots-BPEI) that corresponds to the amide (HCONH) carbonyl bond, indicating that PEG1500N and BPEI had been successfully passivated on the surface of C-dots. To examine photothermal response, irradiation was carried out for 5 min using three different instruments which is UV-lamp (365 nm), visible lamp and laser (532 nm, 1 W/cm2) where temperature for each sample increased respectively. C-dots demonstrated not losing their luminescent properties upon irradiation to UV-lamp and laser for 30 min. Contrary, the intensity of fluorescence reduced when it exposed to the visible lamp for the same period. In vitro studies of the modified C-dots with zebrafish (Danio rerio) revealed that C-dots-PEG1500N is non-toxic while C-dots-BPEI is highly toxic to the fish embryos. Significantly, this study has successfully demonstrated that Gadong tuber starch can be used as a starch-based modifier for C-dots; which possibly can be utilized as a nanocarrier with thermal sensing properties.

Study on porphyrin/ZnFe2O4@polythiophene nanocomposite as a novel adsorbent and visible light driven photocatalyst for the removal of methylene blue and methyl orange

A new magnetically responsive three-component nanocomposite consisting of ZnFe2O4 (ZnFe), polythiophene (PTh) and porphyrin was successfully prepared by coating of ZnFe2O4 nanoparticles with polythiophene and subsequent sensitizing with tetrakis(4-carboxyphenyl)prophyrin (TCPP). The prepared TCPP/ZnFe2O4@Polythiophene nanocomposite (TCPP/ZnFe@PTh NC) was investigated by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), Energy-dispersive X-ray spectroscopy (EDX), scanning electron microscopy imaging (SEM) and vibrating sample magnetometer (VSM). Diffuse reflectance spectroscopy (DRS) was used to find the photocatalytic ability of this nanocomposite. In addition, photocatalytic–adsorption activities of prepared samples were carried out for removal of methyl orange (MO), methylene blue (MB) and mixture of MB and MO under visible LED lamp light and sunlight irradiation. The results indicated that the synthesized nanocomposite not only shows excellent photocatalytic and adsorption activity for removal of MO and MB, respectively, but also can be separated easily by an external magnet and reused twice more.

Hydrogen production from sulphide wastewater using Ce3+–TiO2 photocatalysis

Cerium (Ce3+) doped TiO2 powder was synthesized by a sol-gel method and characterized by Transmission Electron Microscope (TEM), X-ray Diffraction (XRD), UV–Vis Diffuse Reflectance Spectroscopy (UV-DRS), Fourier Transform Infrared Spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS). The Ce3+ doping strongly reduced the band gap of the TiO2 from 3.2 eV (UV) to 2.7 eV (visible region). The photocatalytic activity of Ce3+ doped TiO2 catalysts was evaluated by hydrogen production from sulphide wastewater under visible light illumination. The photocatalytic production of H2 was studied in a batch recycle tubular photocatalytic reactor. The results show that 0.4% Ce3+–TiO2 suspended in 500 mL of simulated sulphide wastewater irradiated at 150 W visible lamp produced maximum H2 of 6789 μmol h−1. It was noticed that the Ce3+ doped TiO2 performs well than Nano TiO2 and P25 TiO2 photocatalysts.

Hemoglobin-incorporated iron quantum clusters as a novel fluorometric and colorimetric probe for sensing and cellular imaging of Zn(II) and cysteine.

The authors describe a novel water-soluble, stable, biocompatible, and highly fluorescent probe consisting of iron quantum clusters incorporated into human adult hemoglobin (Hb-FeQCs). The Hb-FeQCs were characterized by various spectroscopic techniques. The probe displays strong absorption and yellow fluorescence with a peak centered at 567nm (photo-excited at 460nm). The Hb-FeQCs show excellent photostability over a wide range of pH values (5-12), even in the presence of high electrolyte concentrations. A colorimetric and a fluorometric method were worked out for the quantitation Zn(II) and cysteine in aqueous solution. Zinc ions induce a visible color change from brown to yellow. The sensitivity of Hb-FeQCs towards other metal ions was negligible, with the exception of Co2+ and Cu2+, which caused a modest interference. The Hb-FeQCs were exploited in a sensitive and selective turn-on fluorescence assay for Zn2+. It is also found that cysteine quenches the fluorescence of the Hb-FeQCs/Zn(II) complex. Under the optimized conditions, the probe has a linear response in the 0.04 to 2.2μM Zn(II) concentration range, with a 48nM detection limit. Response to cysteine is linear in the 1-60μM concentration range, with a 0.25μM limit of detection. This fluorescent probe undergoes fluorescent emission intensity enhancement upon binding to zinc ions in living normal human fibroblast cells under visible lamp. The cellular imaging capability and very low cytotoxicity of this soluble iron quantum clusters can be potentially extended as an exciting sub-nanoplatform with promising biomaterial applications. Graphical abstract Schematic of yellow-emitting iron quantum clusters in hemoglobin matrix (Hb-FeQCs) were characterized and successfully applied for sensing zinc(II) and cysteine. The act as an on-off fluorescent probe and can be appliedto image zinc ions in human fibroblast cells under visible light.

Quaternary magnetic BiOCl/g-C3N4/Cu2O/Fe3O4 nano-junction for visible light and solar powered degradation of sulfamethoxazole from aqueous environment

Novel magnetic quaternary BiOCl/g-C3N4/Cu2O/Fe3O4 (BGC-F) nano-heterojunction with excellent photocatalytic activity was prepared by facile co-precipitation method. The visible photodegradation activity of the junction was analyzed for sulfamethoxazole (SME) as target pollutant. BGC-F with a dosage of 0.2 g L−1 exhibits high photocatalytic activity with 99.5% of SME (100 µM) degraded in 60 min under visible (Xe) lamp and 92.1% in 120 min under natural sunlight. The activity of quaternary junction was found to be 7.2, 6.8 and 4.2-fold higher as compared to C3N4/BiOCl/Fe3O4, Cu2O/BiOCl/Fe3O4 and Cu2O/BiOCl/C3N4 junctions respectively. Formation of an effective p-n-p junction (BiOCl-C3N4-Cu2O) leads to shifting of energy bands and rising of an in-built electric field and charge separation. The effect of parameters as pH, catalysts loading amount, NO3− and HCO3− have been studied. The O2− and OH was found to be major reactive species identified by scavenging experiments and the band gap structure analysis The results for mineralization were analyzed in terms of Liquid chromatography-mass spectroscopy (LC-MS), total organic carbon (TOC) removal and chemical oxygen demand (COD). 41.6% of TOC was removed in 3 h experiment under Xe lamp exposure. The drug degradation was also confirmed by testing activity on E. coli and cyto-toxicity on human peripheral blood lymphocytes (PBL). Only 2.1 mm zone of inhibition was observed for E. coli in case of exposure to SME degraded products while for pure SME it was 18.1 mm hinting complete mineralization. In addition 99% cell viability was observed for PBL cells treated with degraded products of SME. Furthermore, BGC-F exhibited good reusability after magnetic separation and regeneration, rendering it a promising multi-functional catalyst with active use of advanced oxidation processes for treating pharmaceutical waste water.

Comparative Study of the Photocatalytic Degradation of the Herbicide 2,4-D Using WO3/TiO2 and Fe2O3/TiO2 as Catalysts

In this study, a comparison of the photocatalytic activity efficiency of the catalysts WO3/TiO2, Fe2O3/TiO2, and TiO2 in the degradation of the herbicide 2,4-D and its main by-product (2,4-dichlorophenol, 2,4-DCP), under natural sunlight, visible, and UV light, was carried out. The catalysts were synthesized by the sol-gel method. All the catalysts showed anatase crystalline phase, and they exhibited similar values of band gap, specific surface area, and crystallite size; however, different photocatalytic activity was observed under the different light sources. Complete degradation of 2,4-D and near to 89% of mineralization using WO3/TiO2 and Fe2O3/TiO2 was achieved after 150 min under solar light, while using TiO2 sol-gel, lower degradation rate was obtained. By using artificial light (UV and visible lamp), the degradation and mineralization rates were lower than those obtained under natural sunlight. The produced 2,4-DCP intermediate was completely degraded after 240 min under sunlight only with the modified catalysts.

Photocatalytic conversion of CO2 into methanol using graphitic carbon nitride under solar, UV laser and broadband radiations

Summary Photocatalytic conversion of carbon dioxide into methanol using highly efficient g-C3N4, in conjunction with three different radiations (solar radiation, broad-band ultraviolet (UV)–visible lamp, and laser beam) is presented. The optical, structural, and morphological properties of the synthesized g-C3N4 were studied using advanced analytical techniques like Fourier transform infrared spectroscopy, UV–visible spectrometer, X-ray diffraction, high-resolution transmission electron microscopy, high-angle annular dark field, and X-ray photoelectron spectroscopy. The relative merits of the three sources of radiation in the presence of g-C3N4 were studied in terms of key figures of merit of the photocatalytic process, namely, methanol production yield and quantum yield. As expected, after 40 min of irradiation, 355-nm laser (40 mJ/pulse, 10 Hz) with g-C3N4 rendered the best methanol production yield (510 μmol g−1 h−1), followed by solar radiation (130 μmol g−1 h−1), and UV broadband lamp. This indicates that the photon flux and the spectral properties of incident light are the key factors for the enhancement of methanol production yield. Although the methanol production yield with 355-nm laser radiation is quite impressive because of the inherent high photon flux and the monochromatic nature of laser, the methanol yield of 130 μmol g−1 h−1 with natural sunlight is quite an important result, as it can be used for the development of large-scale solar fuel generation facilities by harnessing the naturally abundant solar radiation. Copyright © 2017 John Wiley & Sons, Ltd.

Increasing the efficiency of magnetic heterogeneous Fenton catalysts with a simple halogen visible lamp

Abstract The effect of a simple visible halogen lamp was studied in the Fenton-type oxidation of three model aqueous pollutants differing in their structure and electrostatic charge, methylorange (MO), methylene blue (MB) and paranitrophenol (PNP), using maghemite nanoparticles (γ-Fe 2 O 3 NP), or maghemite/silica nanocomposite microspheres (γ-Fe 2 O 3 /SiO 2 MS) as heterogeneous catalysts. These materials, which were fully characterized, differ in size, morphology, porosity and microstructure, although their catalytic activity is related to the same γ-Fe 2 O 3 nanoparticles. Both have a strong magnetic susceptibility, but only the MS catalyst can be easily recovered by magnetic settlement. Whatever the catalyst, the pollutant tested, or the experimental conditions used, much better decolorization rates and mineralization efficiencies were recorded under illumination by visible light in comparison to the same tests in the dark. The large range of experimental conditions tested enabled us to propose a mechanism for photocatalytic activity. Experiments of long-term stability showed that the MS catalyst, although generally less active than the NP catalyst, retained almost all of its activity after five repeated experiments under visible light. The good stability of this catalyst was also confirmed by the low level of iron leaching, making it suitable candidate for an application as photo-Fenton catalyst in industrial wastewater treatment.

Photophoresis in single walled carbon nanotubes

We report optically induced, macro-scale motion of pristine, pure single walled carbon nanotubes (SWNT). Rapid motion is observed in aggregates of SWNTs under UV, visible and NIR illumination. Experiments show optically directed, well-controlled motion of SWNT aggregates. SWNT aggregates show both positive and negative photophoresis in solution i.e. motion away and towards light respectively. Part of the aggregates of pristine SWNT, moving to the top of the vial under UV and visible lamp were separated from the ones at the bottom and characterized using absorption and Raman spectroscopy. Aggregates separated from the top under UV illumination show enrichment in metallic SWNTs whereas ones collected from the top under visible illumination were found enriched in semiconducting SWNTs. This phenomenon of induced motion in selective SWNTs under illumination of specific frequency is also verified using pre-separated (95% pure), metallic and semiconducting SWNTs dispersed in solution. Metallic SWNTs show enhanced photophoresis under an UV lamp, whereas pre-separated semiconductor SWNTs exhibit rapid motion under broadband visible lamp. However, under NIR lamp, no specificity was observed and all particles were seen rapidly moving.

Synthesis and characterization of nanocomposite of polythiophene with Na2[Fe(CN)3(OH)(NO)C6H12N4] H2O: a potent material for EMI shielding applications

Nanocomposite of polythiophene (PTh) with the photoadduct of sodium pentacyanonitrosylferrate(II) dihydrate and hexamine is synthesized by In-situ polymerization technique. Photoadduct was obtained by photoirradiation followed by substitution with hexamine ligand using Osram UV–visible photo lamp which was proved by Elemental analysis, UV–Vis, and FTIR. From elemental analysis, the empirical formula assigned to the synthesized photoadduct was found to be Na2[Fe(CN)3(OH)(NO)C6H12N4] H2O. Synthesized photoadduct was then milled in high energy ball mill to reduce it to nano size, which was confirmed from XRD and TEM. SEM analysis revealed distinct morphological features of photoadduct, PTh and nanocomposite. XRD showed orthorhombic structure of photoadduct which was retained in nanocomposite. Grain size (D) and strain (e) has been evaluated by fitting different models which were nearly well correlated. TEM measurement clearly showed the polymer coating of photoadduct particles which explained the size increase from photoadduct to nanocomposite. TG revealed higher thermal stability of nanocomposite as compared to pure PTh. DSC exhibits increase in the glass transition temperature of nanocomposite which indicated its rigid nature. A cyclic nanoindentation load-depth curve is used to assess mechanical properties. Dielectric measurement shows high value of dielectric constant (e′) and ac-conductivity (σac = 1010 S/m) which can make it useful for EMI shielding applications.

Enhanced photobactericidal activity of ZnO nanorods modified by meso-tetrakis(4-sulfonatophenyl)porphyrin under visible LED lamp irradiation.

In this study, zinc oxide (ZnO) nanorods have been synthesized using a simple template-free precipitation technique and deposited on glass substrate. The meso-tetrakis(4-sulfonatophenyl)porphyrin (TPPS) has been synthesized and then immobilized on the surface of ZnO nanorods to prepare an organic/inorganic composite. The samples were characterized by various techniques such as X-ray diffraction, diffuse reflectance spectra, Fourier transform-infrared spectroscopy and scanning electron microscopy. In addition, the photobactericidal activity of TPPS/ZnO composite, TPPS and ZnO nanorods was tested against the pathogenic bacterium of Escherichia coli under visible LED lamp irradiation. The results indicate that the photobactericidal activity of TPPS-loaded ZnO nanorods was better than TPPS or ZnO nanorods, separately.

The synergistic effect of TiO2 and H5PW10V2O40 in photocatalysis as a function of the irradiation source

This work examined the use of pure TiO2, pure heteropolyacid (HPA) H5PW10V2O40 and TiO2+H5PW10V2O40 catalysts in the photocatalytic decomposition of dimethyl sulfide (DMS) in the gas phase. DMS was irradiated with visible light from an LED (λ>400nm), black light UV-A (λ<400nm) and visible fluorescent lamp ‘daylight’ (variable emission in the UV-A and visible range). DMS decomposition reached almost 100% for the system containing the TiO2+H5PW10V2O40 mixed catalyst with exposure to visible daylight. This system maintained stable catalytic activity up to 500min. These results strongly suggest that a positive synergistic effect occurred between TiO2 and HPA when visible daylight was used.

Is the Photosuturing Agent, Rose Bengal, a Mutagen?

Rose Bengal (RB) is a potential photosuturing agent that may improve standard dermatologic surgical closure techniques. However, RB produces reactive oxygen species with photoactivation and its photomutagenic potential must be considered in clinical application. We investigated cytotoxicity, mutagenicity, and singlet oxygen (SO) production of RB on epithelial Chinese hamster ovary cell line. Cells were exposed to RB concentrations: 0.1%, 0.01%, 0.001%, 0.0001%, 0.00001%; irradiated for 400 s using a high-intensity visible wavelength lamp or maintained in the dark. Cell viability was assessed by XTT assay, mutagenicity by HPRT gene mutation assay, and SO production by Sensor Green reagent. RB > 0.001% was significantly cytotoxic. Viabilities were uninfluenced by ≤0.0001% RB controls, or 30-min incubation. 49% of irradiated cells died after 24-h in 0.0001% RB. At ≥0.001% RB, >90% of cells died. Irradiating 0.00001% - 0.001% RB increased SO; levels dropped significantly between 0.01% - 0.1%. Controls exhibited negligible SO production. HPRT suggested that RB was not mutagenic (0.0001%, 0.00001%); SO induction increased between 0.00001% - 0.001%, with reduced production at higher concentrations. Pilot studies suggested irradiated 0.0001% RB is mutagenic in vitro; current data suggest RB is not photomutagenic. The contribution of RB’s cytotoxicity on observed clinical improvement of scars and mutagenic potential remains unclear, necessitating further study.

Variations on the Benzophenone Skeleton: Novel High Performance Blue Light Sensitive Photoinitiating Systems

Newly developed benzophenone derivatives in combination with an iodonium salt (and optionally N-vinylcarbazole) or amines have been used as photoinitiating systems. Their abilities to initiate cationic photopolymerization of epoxides and/or radical photopolymerization of acrylates under very soft visible halogen lamp, LED and laser diodes irradiations have been investigated. One of them (BPD5) is particularly efficient for the cationic and radical photopolymerization of an epoxide/acrylate blend in a one-step hybrid cure and leads to the formation of an interpenetrated polymer network IPN upon the house hold blue LED bulb exposure (1 min for getting tack free coatings). The performances attained with some derivatives are better than those obtained with camphorquinone, used as reference photoinitiator, highlighting their high initiating abilities. These systems can be useful to overcome the oxygen inhibition for very low light intensity. The photochemical mechanisms are studied by molecular orbital calcula...