Absence Of Visible Light Irradiation Research Articles

Synthesis of platinum decorated copper oxide doped layer graphite carbon nitrite: An efficient photocatalyst for disintegration of bacteria and decomposition of dye

Platinum decorated copper oxide doped layer graphite carbon nitrite (Pt/CuO@g-C 3 N 4 ) was synthesized by green hydrothermal method. Amylopectin was employed as a source of reduction and stabilization. Aforementioned nanomaterial is made up of a layer graphite carbon nitrite nanosheet with CuO nanofibers and Pt embedded in a cluster of nanofibers. Methylene blue (MB) degradation, free radical stabilization, and photo inactivation of bacteria were all targets for the synthesized photocatalyst. For instance, the developed composites exhibited the remarkable photocatalytic activity to degrade 90% MB in about 20 minutes, under visible light irradiation. Moreover, the synthesized nanomaterials were also tested against bacteria Staphylococcus aureus and Escherichia coli (S. aureus & E. coli ) both in the presence and absence of visible light irradiation. The light-treated platinum adorned copper oxide doped layer graphite carbon nitrite has inhibitory diameter 13 and 18 mm for E. coli and S. aureus respectively though in dark was 7 and 10 mm respectively. The effects of various factors on the photoinhibition potency of the said nanomaterial were also investigated. Furthermore, the nanomaterial exhibits a high resistance to 2,2-diphenyl-1-picrylhydrazyl (DPPH) stabilization. • Preparation of Platinum decorated Copper Oxide doped Layer Graphite Carbon Nitrite by simple, non-toxic way • Antibacterial activity examination • Examination of MB degradation • DPPH scavenging activity examination

Synthesis and characterization of Photochromic inkless coating based on WO3-Titania nanocomposite under sun light and solar simulation condition

A highly efficient and surfactant free hydrothermal method is adopted to synthesis tungsten trioxide (WO3) modified Titania (TiO2) composite for direct visible light photochromic applications. The physico chemical characterization of anatase phase formation confirmed by X-Ray diffraction (XRD) and Raman Spectroscopy. The different weight percent amount of tungsten trioxide incorporated into TiO2 nanocomposite have been studied for coloration and bleaching property under in the presence and absence of visible light irradiation. The as prepared composite form of WO3-Titania shows efficient and stable cycle performance up to 15 cycles at various time intervals. The Transmission electron microscopy (TEM), Scanning electron microscopy (SEM) reveals the largely consisting of square and small circular like particles formation and each square and spherical shapes. The photochromic response of the materials increases in the order of WO3/TiO2(0.5:1)> WO3/TiO2 (1:1)> >WO3/TiO2-2(1:2) and in the case of WO3/TiO2-3(1:3) and WO3/TiO2-(1:4) are consumed little more time for coloration and bleaching process. The cycle stability and color transformation have also been studied for efficient WO3/TiO2 (WT-2) sample under direct sun light and in controlled solar simulator reaction condition.

Visible light-induced apoptosis activatable nanoparticles of photosensitizer-DEVD-anticancer drug conjugate for targeted cancer therapy

The therapeutic efficacy of photodynamic therapy (PDT) in cancer treatment is attributed to the conversion of tumor oxygen into reactive singlet oxygen (1O2) using photosensitizers. However, poor tissue penetration and rapid oxygen depletion have limited the effectiveness of PDT. Therefore, we have developed visible light-induced apoptosis activatable nanoparticles of the photosensitizer (Ce6)-caspase 3 cleavable peptide (Asp-Glu-Val-Asp, DEVD)-anticancer drug monomethyl auristatin E (MMAE) conjugate, resulting in Ce6-DEVD-MMAE nanoparticles. The average size of self-assembled Ce6-DEVD-MMAE nanoparticles was 90.8 ± 18.9 nm. Compared with conventional PDT based on high-energy irradiation, the new therapy uses lower-energy irradiation to induce apoptosis of cancer cells, and activation of caspase 3 to successfully cleave the anticancer drug MMAE from the Ce6-DEVD-MMAE nanoparticles, resulting in strong cytotoxic effects in cancer cells. Notably, the one-time activation of MMAE in the Ce6-DEVD-MMAE nanoparticles further amplified the cytotoxic effect resulting in additional cell death in the absence of visible light irradiation. Furthermore, Ce6-DEVD-MMAE nanoparticles passively accumulated in the targeted tumor tissues via enhanced permeation and retention (EPR) effect in mice with squamous cell carcinoma (SCC7). The high levels of toxicity were retained after exposure to lower-energy irradiation. However, Ce6-DEVD-MMAE nanoparticles did not show any toxicity in the absence of exposure to visible light irradiation, in contrast to the toxicity of free MMAE (1–10 nM). Thus, the light-induced therapeutic strategy based on apoptotic activation of Ce6-DEVD-MMAE nanoparticles can be used to treat solid tumors inaccessible to conventional PDT.

Influence of TiO₂ Nanoparticles on Liquid Crystalline, Structural and Electrochemical Properties of (8Z)-N-(4-((Z)-(4-pentylphenylimino)methyl)benzylidene)-4-pentylbenzenamine.

Organic–inorganic hybrids based on liquid crystalline symmetrical imine (8Z)-N-(4-((Z)-(4-pentylphenylimino)methyl)benzylidene)-4-pentylbenzenamine (AZJ1) with two aliphatic chains and TiO2 nanomaterials were obtained and investigated taking into account thr crystallographic form of titanium dioxide i.e., anatase versus rutile. The type of TiO2 influences the mesomorphic properties of imine AZJ1, as observed by differential scanning calorimetry (DSC) and polarizing optical microscopy (POM) techniques. Fourier-Transform Infrared Spectroscopy (FT-IR) was used to investigate the interactions of oxygen vacancies located on the TiO2 surface with the studied AZJ1 imine together with studying the influence of temperature. Both imine:TiO2 anatase versus rutile hybrids possessed the highest occupied molecular orbital (HOMO) levels of about −5.39 eV (AZJ1:anatase) and −5.33 eV (AZJ1:rutile) and the lowest unoccupied molecular orbital (LUMO) levels of about −2.24 eV. The presence of TiO2 in each hybrid did not strongly affect the redox properties of imine AZJ1. Organic devices with the configuration of ITO/TiO2/AZJ1 (or AZJ1:TiO2 anatase versus rutile)/Au were fabricated and investigated in the presence and absence of visible light irradiation with a light intensity of 93 mW/cm2. Finally, to analyze defects in the constructed organic devices we used thermal imaging and atomic force microscopy (AFM). The addition of TiO2 in both crystallographic forms has a positive influence on layer-forming properties that manifests itself as a very homogenous heat distribution for the whole sample.

Structural and electrochemical studies of TiO2 complexes with (4,4'-((1E,1'E)-(2,5-bis(octyloxy)-1,4-phenylene)bis(ethene-2,1-diyl))bis-(E)-N-(2,5-bis(octyloxy)benzylidene)) imine derivative bases towards organic devices.

Three (4,4'-((1E,1'E)-(2,5-bis(octyloxy)-1,4-phenylene)bis(ethene-2,1-diyl))bis-(E)-N-(2,5-bis(octyloxy)benzylidene)) imine derivatives were synthesized via a condensation reaction with p-toluenesulfonic acid as a catalyst. The effects of the end groups and vinylene (-HC[double bond, length as m-dash]CH-) moieties on the structural, thermal, optical, electrochemical and photovoltaic properties of imines were investigated to check the influence of TiO2 on the imine properties. The thermal behavior of imines and their complexes with TiO2 was widely investigated using FT-IR, XRD, DSC and POM methods in order to determine the order type in the imine structure. All imines present the highest occupied molecular orbital (HOMO) levels of about -5.39 eV (SAI1 and SAI2) and -5.27 eV (SAI3) and the lowest unoccupied molecular orbital (LUMO) levels at about -3.17 eV. The difference of the end groups in the imines in each case did not affect redox properties. Generally, both oxidation and reduction are easier after TiO2 addition and it also changes the HOMO-LUMO levels of imines. Moreover, changes in the characteristic bands for imines in the region 1500-1700 cm-1 observed as a drastic decrease of intensity or even disappearance of bands in the imine : TiO2 mixture suggest the formation of a complex (C[double bond, length as m-dash]N)-TiO2. Organic devices with the configuration of ITO/TiO2/SAIx (or SAIx : TiO2)/Au were fabricated and investigated in the presence and absence of visible light irradiation with an intensity of 93 mW cm-2. In all imines and complexes with TiO2, the generation of the photocurrent indicates their use as photodiodes and the best result was observed for SAI3 : TiO2 complexes.

Mn3+ ion in perovskite lattice: a potential Fenton’s reagent exhibiting remarkably enhanced degradation of cationic and anionic dyes

Lanthanum ferrite is reported to possess catalytic properties. However, catalytic activity of Mn-doped lanthanum ferrites has not been reported so far. The work reports, for the first time, the synthesis of LaMn x Fe1−x O3 (x = 0.0, 0.1, 0.2, 0.3, 0.4 and 0.5) and investigates their catalytic activity in the presence and absence of visible light irradiation. The synthesized ferrites possessed phase purity and had same symmetry as pure LaFeO3. The unit cell volume of ferrite compositions decreased with increasing manganese content. The average crystallite size was ~60 nm. The d.c. resistivity of ferrites decreased with increasing temperature, confirming semiconductor behaviour of ferrite compositions. Further, these were utilized to study the decomposition reaction of hydrogen peroxide solution. It was observed that the ferrites catalysed the decomposition of hydrogen peroxide. The rate of hydrogen peroxide decomposition increased with increasing manganese substitution. Based upon this observation, the ferrites were employed as heterogeneous catalysts in the H2O2-assisted degradation of anionic dyes (Remazol Turquoise Blue, Remazol Brilliant Yellow) and cationic dyes (Methylene Blue, Safranine-O) in absence as well as in the presence of visible light irradiation. The hydrogen peroxide decomposition using different types of ferrites as heterogeneous catalysis was studied. The catalytic activity was found to be strongly dependent on the particle size and the cation distribution of the ferrite sample.

Cationic Half-Sandwich Iron(II) and Iron(III) Complexes with N-Heterocyclic Carbene Ligands

The cationic piano-stool iron complexes containing the N-heterocyclic carbene ligand tethered to a tetramethylcyclopentadienyl ring [(Cp*-NHC)Fe(CO)(L)][X] (L = NCMe, DMSO; X = BF4, OTf) have been prepared and analyzed by spectroscopic, electrochemical, and crystallographic methods. Oxidation reactions of the cationic complex [(Cp*-NHC)Fe(CO)(NCMe)][BF4] (2) with silver tetrafluoroborate and tert-butyl hydroperoxide in acetonitrile yield the dicationic iron(III) complexes [(Cp*-NHC)Fe(NCMe)2][BF4]2 and [(Cp*-NHC)Fe(H2O)][BF4]2, respectively. When the reaction of 2 with AgBF4 is performed in dichloromethane, the cationic complex [(Cp*-NHC)FeCl][BF4] is obtained. These new iron(III) complexes have been characterized by Mössbauer spectroscopy and in one case by X-ray diffraction studies. DFT calculations were used to rationalize experimental results. The cationic complex [(Cp*-NHC)Fe(CO)(NCMe)][OTf] is catalytically active toward the reduction of benzaldehyde and acetophenone using phenylsilane under neat conditions and in the absence of visible light irradiation.

Nitric oxide photorelease from a trinuclear ruthenium nitrosyl complex and its in vitro cytotoxicity against melanoma cells

In vitro cytotoxicity study of the [Ru3O(CH3COO)6(4-pic)2(NO)]PF6 triruthenium nitrosyl cluster (compound 1, 4-pic=4-methylpyridine) against B16F10 melanoma cell line was evaluated in the presence and absence of visible light irradiation. The nitrosyl cluster 1 showed a significant tumoricidal activity when irradiated at λ=532nm, reducing cell viability up to 90% at a concentration of 62.5μM. However, cell death of 60% is also observed in the dark which can be assigned to the NO release mediated by a redox reaction of the cluster in cell medium. This possibility was confirmed by amperometric detection of NO after the addition of ascorbic acid to compound 1 in phosphate buffer. A control experiment was performed with the solvated cluster [Ru3O(CH3COO)6(4-pic)2(CH3OH)]PF6 (compound 2) and no significant lowering of cell viability was observed. These results suggest that the nitrosyl cluster acts as a pro-drug, delivering NO, which is the actual active species.

Photo-enhanced activity of Pt and Pt–Ru catalysts towards the electro-oxidation of methanol

Electrocatalyst materials, consisting of Pt or Pt–Ru supported on carbon with and without TiO2, are evaluated for their activity towards the methanol oxidation reaction (MOR) in 1.0 M H2SO4 at 25 °C in the presence and absence of visible light irradiation. Electrochemical studies showed that enhanced MOR activity is achieved upon irradiation with visible light for each catalyst, in both the presence and absence of TiO2. Irradiation leads to no improvement in activity towards the formic acid oxidation reaction (FAOR) indicating that irradiation aids in the removal of adsorbed intermediate species, such as CO, during MOR. While the presence of a TiO2 support does lead to an increase in activity upon irradiation, about 50% of the improvements arise solely from the irradiation of the metal-containing electrocatalysts themselves.

Photocytotoxic activity of a nitrosyl phthalocyanine ruthenium complex — A system capable of producing nitric oxide and singlet oxygen

The synthesis, structural aspects, pharmacological assays, and in vitro photoinduced cytotoxic properties of [Ru(NO)(ONO)(pc)] (pc = phthalocyanine) are described. Its biological effect on the B16F10 cell line was studied in the presence and absence of visible light irradiation. At comparable irradiation levels, [Ru(NO)(ONO)(pc)] was more effective than [Ru(pc)] at inhibiting cell growth, suggesting that occurrence of nitric oxide release following singlet oxygen production upon light irradiation may be an important mechanism by which the nitrosyl ruthenium complex exhibits enhanced biological activity in cells. Following visible light activation, the [Ru(NO)(ONO)(pc)] complex displayed increased potency in B16F10 cells upon modifications to the photoinduced dose; indeed, enhanced potency was detected when the nitrosyl ruthenium complex was encapsulated in a drug delivery system. The liposome containing the [Ru(NO)(ONO)(pc)] complex was over 25% more active than the corresponding ruthenium complex in phosphate buffer solution. The activity of the complex was directly proportional to the ruthenium amount present inside the cell, as determined by inductively coupled plasma mass spectroscopy. Flow cytometry analysis revealed that the photocytotoxic activity was mainly due to apoptosis. Furthermore, the vasorelaxation induced by [Ru(NO)(ONO)(pc)], proposed as NO carrier, was studied in rat isolated aorta. The observed vasodilation was concentration-dependent. Taken together, the present findings demonstrate that the [Ru(NO)(ONO)(pc)] complex induces vascular relaxation and could be a potent anti-tumor agent. Nitric oxide release following singlet oxygen production upon visible light irradiation on a nitrosyl ruthenium complex produces two radicals and may elicit phototoxic responses that may find useful applications in photodynamic therapy.

Protective effects of antioxidants on micronuclei induced by irradiated 9‐fluorenone/N,N‐dimethyl‐p‐toluidine in CHO cells

9-Fluorenone (9F), the aromatic photosensitizer, is widely used as an initiator in visible-light (VL) cured resin systems. There is growing concern that 9F may produce genetic damage by inducing mutation. In this study, 9F in the presence or absence of reducing agent N,N-dimethyl-p-toluidine (DMT) with or without VL irradiation was analyzed for the induction of chromosomal aberrations indicated by micronuclei (MN) induced in CHO cells. Our data demonstrated that a dose-related increase in the frequency of MN and prolonged cell cycles in 9F with or without DMT in the presence or absence of VL irradiation (p < 0.05). The rank orders with respect to genotoxicity and cytotoxicity were found to be as follows: 9F/DMT +VL > 9F/DMT = 9F + VL > 9F. To determine whether oxidative stress could modulate MN induced by 9F/DMT with or without VL irradiation in CHO cells, cells were pretreated with N-acetyl-L-cysteine (NAC), ascorbic acid, and alpha-tocopherol. The pretreatment with antioxidants could diminish not only the prolonged cell cycle but also the decreased frequency of MN which is induced by 9F with or without DMT in the presence or absence of VL irradiation in CHO cells (p < 0.05). Our findings provide the evidences for the induction of MN by 9F in the presence or absence of DMT with or without VL irradiation in CHO cells, indicating clastogenic activity of 9F/DMT in vitro. These antioxidants act as the antagonists against the genotoxicity and cytotoxicity of 9F/DMT. Thus, leaching photoinitiator and reducing agent might be contributing the sources of oxidative stress.

The genetic activity of aminoacridines: effect of dose and time in the presence and absence of visible light irradiation : Fahrig, R., Zentrallaboratorium für Mutagenitätsprüfung der Deutschen Forschungsgemeinshaft, Freiburg i.Br. (W. Germany)

The genetic activity of aminoacridines: effect of dose and time in the presence and absence of visible light irradiation : Fahrig, R., Zentrallaboratorium für Mutagenitätsprüfung der Deutschen Forschungsgemeinshaft, Freiburg i.Br. (W. Germany)