Evaluation of UV-C Decontamination of Clinical Tissue Sections for Spatially Resolved Analysis by Mass Spectrometry Imaging (MSI).

Clinical tissue specimens are often unscreened, and preparation of tissue sections for analysis by mass spectrometry imaging (MSI) can cause aerosolization of particles potentially carrying an infectious load. We here present a decontamination approach based on ultraviolet-C (UV-C) light to inactivate clinically relevant pathogens such as herpesviridae, papovaviridae human immunodeficiency virus, or SARS-CoV-2, which may be present in human tissue samples while preserving the biodistributions of analytes within the tissue. High doses of UV-C required for high-level disinfection were found to cause oxidation and photodegradation of endogenous species. Lower UV-C doses maintaining inactivation of clinically relevant pathogens to a level of increased operator safety were found to be less destructive to the tissue metabolome and xenobiotics. These doses caused less alterations of the tissue metabolome and allowed elucidation of the biodistribution of the endogenous metabolites. Additionally, we were able to determine the spatially integrated abundances of the ATR inhibitor ceralasertib from decontaminated human biopsies using desorption electrospray ionization-MSI (DESI-MSI).

Two-photon uncaging of bioactive thiols in live cells at wavelengths above 800 nm.

Photoactivatable protecting groups (PPGs) are useful for a broad range of applications ranging from biology to materials science. In chemical biology, induction of biological processes via photoactivation is a powerful strategy for achieving spatiotemporal control. The importance of cysteine, glutathione, and other bioactive thiols in regulating protein structure/activity and cell redox homeostasis makes modulation of thiol activity particularly useful. One major objective for enhancing the utility of photoactivatable protecting groups (PPGs) in living systems is creating PPGs with longer wavelength absorption maxima and efficient two-photon (TP) absorption. Toward these objectives, we developed a carboxyl- and dimethylamine-functionalized nitrodibenzofuran PPG scaffold (cDMA-NDBF) for thiol photoactivation, which has a bathochromic shift in the one-photon absorption maximum from λmax = 315 nm with the unfunctionalized NDBF scaffold to λmax = 445 nm. While cDMA-NDBF-protected thiols are stable in the presence of UV irradiation, they undergo efficient broad-spectrum TP photolysis at wavelengths as long as 900 nm. To demonstrate the wavelength orthogonality of cDMA-NDBF and NDBF photolysis in a biological setting, caged farnesyltransferase enzyme inhibitors (FTI) were prepared and selectively photoactivated in live cells using 850-900 nm TP light for cDMA-NDBF-FTI and 300 nm UV light for NDBF-FTI. These experiments represent the first demonstration of thiol photoactivation at wavelengths above 800 nm. Consequently, cDMA-NDBF-caged thiols should have broad applicability in a wide range of experiments in chemical biology and materials science.

Wearable Bracelet Monitoring the Solar Ultraviolet Radiation for Skin Health Based on Hybrid IPN Hydrogels.

The risk of extensive exposure of the human epidermis to solar ultraviolet radiation is significantly increased nowadays. It not only induces skin aging and solar erythema but also increases the possibility of skin cancer. Therefore, a simply prepared, highly sensitive, and optically readable device for monitoring the solar ultraviolet radiation is highly desired for the skin health management. Because of the photoinitiated polymerization triggered by graphene-carbon nitride (g-C3N4) under ultraviolet radiation, g-C3N4 is homogeneously distributed in the hybrid hydrogels containing N-isopropylacrymide (NIPAM), poly(ethylene glycol) methyl ether methacrylate (OEGMA300), and sodium alginate (SA). By further immersing the hybrid hydrogels into calcium chloride solution, hybrid alginate-Ca2+/P(NIPAM-co-OEGMA300)/g-C3N4 interpenetrating polymeric network (IPN) hydrogels are obtained. Due to the homogeneous distribution of g-C3N4 and the existence of thermoresponsive polymers, the hybrid IPN hydrogels present good adsorption capability and high degradation efficiency for methylene blue (MB) especially at high temperature under ultraviolet radiation. Based on this unique property, the bracelet monitoring skin health is prepared by simply immersing the hybrid IPN hydrogels into the MB solution and then wrapping it with PET foil. Because the immersion time for the top, middle, and bottom parts of the hybrid IPN hydrogels is gradually increased, their colors vary from light to dark blue. A longer time is required for the discoloration of the darker part under solar ultraviolet radiation. Thus, the bracelet can be used to conveniently monitor the dose of solar ultraviolet radiation by simply checking the discoloration in the bracelet under sunshine. Due to the facile preparation and low cost of the bracelet, it is a promising candidate for wearable devices for skin health management.

The Influence of UV Radiation on the Degradation of Pharmaceutical Formulations Containing Quercetin.

The aim of this study was to assess the photostability of quercetin in the presence of anionic and nonionic polymeric gels with varied compositions of an added component-glycerol. The samples were irradiated continuously at constant temperature. The stability of quercetin in solution and incorporated into the gels was evaluated by an UV-Vis spectrophotometer. FTIR spectroscopy (Fourier-transform infrared spectroscopy) was used to detect the changes in the structure of quercetin depending on the polymer used in the gel, and on the exposure time. Photostabilization is an important aspect of quality assurance in photosensitive compounds. The decomposition rate of quercetin in the ionic preparation of polyacrylic acid (PAA) with glycerol was 1.952·10-3 min-1, whereas the absence of glycerol resulted in a decay rate of 5.032·10-4 min-1. The formulation containing non-ionic methylcellulose resulted in a decomposition rate of quercetin in the range of 1.679·10-3 min-1. The decay rate of quercetin under light influence depended on the composition of the gel. It was found that the cross-linked PAA stabilized quercetin and the addition of glycerol accelerated the photodegradation.

Near UV and Visible Light Induce Iron-Dependent Photodegradation Reactions in Pharmaceutical Buffers: Mechanistic and Product Studies.

Near UV (λ = 320-400 nm) and visible light (λ = 400-800 nm) can lead to the oxidation of pharmaceutical proteins, which can affect efficiency and promote immunogenicity. However, no concise mechanism has been established for the photo-oxidation of pharmaceutical proteins under near UV and visible light. Here, we show that carboxylic acid buffer-Fe3+ complexes can function as photosensitizers, causing peptide degradation via the formation of various radicals and oxidants. Three pharmaceutical relevant carboxylic acid buffers (citrate, acetate, and succinate) were tested under near UV and visible light. Oxidation reactions were monitored for model peptides containing readily oxidizable amino acids, such as methionine- or leucine-enkephalin and proctolin peptide. Oxidation products were evaluated by RP-HPLC coupled to UV or fluorescent detection and RP-HPLC-MS/MS. Specifically for citrate buffer, the light-induced formation of H2O2, •OH, •CO2-, and formaldehyde was demonstrated. The peptides displayed oxidation of Met, hydroxylation of Tyr and Phe, as well as the formation of novel products from Tyr. Experiments with 18O2 resulted in the incorporation of 18O into various reaction products, consistent with a metal-catalyzed activation of O2 into reactive oxygen species. The addition of EDTA and DTPA did not prevent the oxidation of the peptides and, in some cases, enhanced the oxidation. Our results demonstrate that pharmaceutical buffer-Fe3+ complexes, exposed to UV and visible light, can promote various pathways of oxidation reactions in pharmaceutical formulations.

Cleavage of Disulfide Bonds in Cystine by UV-B Illumination Mediated by Tryptophan or Tyrosine as Photosensitizers.

Photolytic cleavage of disulfide bonds in proteins by UV light will influence their structure and functionality. The present study aimed to investigate the efficiency of disulfide cleavage by UV-B light in a system without a protein backbone consisting of combinations of cystine (a disulfide) and tryptophan (Trp) or tyrosine (Tyr) under anaerobic and aerobic conditions and to identify oxidation products formed by UV-B light. Cystine was reduced to cysteine (Cys) almost with a 1:1 stoichiometry by photoexcited Trp for anaerobic equimolar aqueous solutions (each 200 µM; pH 7.0), while photoexcited Tyr provided lower concentrations of Cys. The calculation of apparent quantum yields allowed for a comparison between the efficiency of reactions and showed that formation of Cys from disulfide cleavage of cystine was more efficient by photoexcited Trp than by photoexcited Tyr and of cystine alone and that Trp was more sensitive to photodegradation than Tyr and cystine under both aerobic and anaerobic conditions. Increasing the ratio between cystine and Trp to a 1:2 ratio did not increase the efficiency of free thiol formation but caused a more efficient photodegradation of Trp. The free thiol formed from disulfide cleavage of cystine was further oxidized to other unidentified compounds. Trp oxidation products (3-hydroxykynurenine (3-OH-Kyn) and tryptamine) were only identified in minor concentrations following light exposure of cystine and Trp in 1:1 and 1:2 ratios under both aerobic and anaerobic conditions, indicating further photodegradation to unidentified compounds. 3,4-Dihydroxyphenylalanine (DOPA) was formed from the oxidation of Tyr in the illuminated samples of cystine and Tyr in a 1:1 ratio under both aerobic and anaerobic conditions.

Drug loaded essential oil microemulsions enhance photostability and evaluation of in vitro efficacy.

Loss of stability of pharmaceutical APIs (Active Pharmaceutical Ingredient) due to photolytic activity has been a major concern in the pharmaceutical industry as it leads to loss of activity of API and excipients, the formation of toxic by-products, change in color and flavor. Itraconazole (ITZ) bulk drug was exposed to UVC (254 nm) irradiation in an environmental chamber (37 °C, 75 %RH) and its photoprotection by cinnamon, clove, eugenol, and oregano based microemulsion was analyzed. No significant change in the spectra was observed at various time points, confirming the photo-protective activity of microemulsions, unlike the bulk drug. FTIR spectra illustrate the fundamental peaks of the functional groups of ITZ and ITZ loaded MEs. The overlaid spectra showed that there was a minor change in peaks of UV exposed ITZ bulk drug but the ITZ loaded microemulsions were able to protect all the major functional groups. The in vitro anti-microbial assay against C. albicans demonstrated no significant change in the activity of ITZ loaded microemulsion between untreated, 7th day and 15th day while the activity of bulk drug was reduced drastically in the UVC exposed sample. It was concluded that microemulsions can be used as an effective photo-protective drug delivery vehicle for light-sensitive compounds.

Green synthesis of iron oxide nanorods using Withania coagulans extract improved photocatalytic degradation and antimicrobial activity.

Present work compares the green synthesis of iron oxide nanorodes (NRs) using Withania coagulans and reduction precipitation based chemical method. UV/Vis confirmed the sharp peak of Iron oxide NRs synthesized by biologically and chemically on 294 and 278 nm respectively. XRD and SEM showed highly crystalline nature of NRs with average size 16 ± 2 nm using Withania extract and less crystalline with amorphous Nanostructure of 18 ± 2 nm by chemical method. FTIR analysis revealed the involvement of active bioreducing and stabilizing biomolecules in Withania coagulans extract for synthesis of NRs. Moreover, EDX analysis indicates 34.91% of Iron oxide formation in biological synthesis whereas 25.8% of iron oxide synthesis in chemical method. The degradation of safranin dye in the presence of Withania coagulans based NRs showed 30% more effectively than chemically synthesized Nanorods which were verified by the gradual decrease in the peak intensity at 553 nm and 550 nm respectively under solar irradiation. Furthermore, Withania coagulans based NRs showed effective Antibacterial activity against S.aureus and P. aeuroginosa as compared to NRs by chemical method. Finally, we conclude that green synthesized NRs are more effective and functionally more efficient than chemically prepared NRs. Therefore, our work will help the researchers to boost the synthesis of nanoparticles via biological at commercial level.

Mechanism for Inhibition of Folic Acid Photodecomposition by Various Antioxidants.

Folic acid, a synthetic form of folate, is a water-soluble vitamin that is essential during periods of rapid cell division and growth. However, it decomposes upon ultraviolet irradiation to form inactive photoproducts. In this study, the protective effect and mechanisms of antioxidants, including cinnamic acids, flavonoids, catechol and its derivatives, stilbenes, p-benzoquinone and its derivatives, isoprenoids, curcumin, oleic acid, and linoleic acid, against folic acid photodecomposition were investigated by using fluorescence and absorbance spectroscopy, high-performance liquid chromatography, and antioxidant assay. It was found that antioxidants could inhibit or delay the folic acid decomposition in varying degrees, among which caffeic acid was the most effective. The increase in its remarkable antioxidant efficiency and absorbance in the UVA region during irradiation contributed to its effective protection. This finding could be useful for the protection of photolabile components in food and other uses.

Photochemical and photocatalytic degradation of 1-propanol using UV/H2 O2 : Identification of malonate as byproduct.

1-propanol is a primary alcohol extensively used in the pharmaceutical, chemical, and food industries. It has been also found as a contaminant in the atmosphere and is considered a model compound to mimic the behavior and fate of aliphatic alcohols exposed to environmental conditions. In order to understand that role of relevant variables, this paper presents results obtained with a simple experimental set-up to investigate the reactivity of 1-propanol under mild oxidizing conditions. Coupling this system with CE-C4 D allowed the quantification of the carboxylic acids formed. For the described experiments, aqueous solutions of 1-propanol were placed inside a photoreactor and oxidized upon the addition of TiO2 and/or H2 O2 . According to the described results, the addition of H2 O2 (0.1% w/w) was the most significant variable, roughly tripled the amount of carboxylic acids generated and led to the conversion of up to 70% of the initially available 1-propanol (1 mmol/L). More importantly, the reaction yielded the formation (within 10 min) of propionate (50 µmol/L), acetate (400 µmol/L), formate (50 µmol/L), and malonate (200 µmol/L). The latter is critically important because it represents the first example of the photochemical oxidation of both terminal carbons of the C3 -chain of 1-propanol under mild conditions, and opens new avenues for the production of this important chemical building block.

Linkages between stratospheric ozone, UV radiation and climate change and their implications for terrestrial ecosystems.

Exposure of plants and animals to ultraviolet-B radiation (UV-B; 280-315 nm) is modified by stratospheric ozone dynamics and climate change. Even though stabilisation and projected recovery of stratospheric ozone is expected to curtail future increases in UV-B radiation at the Earth's surface, on-going changes in climate are increasingly exposing plants and animals to novel combinations of UV-B radiation and other climate change factors (e.g., ultraviolet-A and visible radiation, water availability, temperature and elevated carbon dioxide). Climate change is also shifting vegetation cover, geographic ranges of species, and seasonal timing of development, which further modifies exposure to UV-B radiation. Since our last assessment, there has been increased understanding of the underlying mechanisms by which plants perceive UV-B radiation, eliciting changes in growth, development and tolerances of abiotic and biotic factors. However, major questions remain on how UV-B radiation is interacting with other climate change factors to modify the production and quality of crops, as well as important ecosystem processes such as plant and animal competition, pest-pathogen interactions, and the decomposition of dead plant matter (litter). In addition, stratospheric ozone depletion is directly contributing to climate change in the southern hemisphere, such that terrestrial ecosystems in this region are being exposed to altered patterns of precipitation, temperature and fire regimes as well as UV-B radiation. These ozone-driven changes in climate have been implicated in both increases and reductions in the growth, survival and reproduction of plants and animals in Antarctica, South America and New Zealand. In this assessment, we summarise advances in our knowledge of these and other linkages and effects, and identify uncertainties and knowledge gaps that limit our ability to fully evaluate the ecological consequences of these environmental changes on terrestrial ecosystems.

The effect of light wavelength on in vitro bilirubin photodegradation and photoisomer production.

BACKGROUND: The action spectrum for bilirubin photodegradation has been intensively studied. However, questions still remain regarding which light wavelength most efficiently photodegrades bilirubin. In this study, we determined the in vitro effects of different irradiation wavelength ranges on bilirubin photodegradation. METHODS: In our in vitro method, normalized absolute irradiance levels of 4.2 × 1015 photons/cm2/s from light-emitting diodes (ranging from 390-530 nm) and 10-nm band-pass filters were used to irradiate bilirubin solutions (25 mg/dL in 4% human serum albumin). Bilirubin and its major photoisomer concentrations were determined; the half-life time of bilirubin (t1/2) was calculated for each wavelength range, and the spectral characteristics for bilirubin photodegradation products were obtained for key wavelengths. RESULTS: The in vitro photodegradation of bilirubin at 37 °C decreased linearly as the wavelength was increased from 390 to 500 nm with t1/2 decreasing from 63 to 17 min, respectively. At 460 ± 10 nm, a significantly lower rate of photodegradation and thus higher t1/2 (31 min) than that at 500 nm (17 min) was demonstrated. CONCLUSION: In our system, the optimum bilirubin photodegradation and lumirubin production rates occurred between 490 and 500 nm. Spectra shapes were remarkably similar, suggesting that lumirubin production was the major process of bilirubin photodegradation.

Photolytic Labeling To Quantify Peptide-Water Interactions in Lyophilized Solids.

Interactions of a lyophilized peptide with water and excipients in a solid matrix were explored using photolytic labeling. A model peptide "KLQ" (Ac-QELHKLQ-NHCH3) was covalently labeled with NHS-diazirine (succinimidyl 4,4'-azipentanoate), and the labeled peptide (KLQ-SDA) was formulated and exposed to UV light in both solution and lyophilized solids. Solid samples contained the following excipients at a 1:400 molar ratio: sucrose, trehalose, mannitol, histidine, or arginine. Prior to UV exposure, the lyophilized solids were exposed to various relative humidity (RH) environments (8, 13, 33, 45, and 78%), and the resulting solid moisture content (Karl Fischer titration) and glass transition temperature ( Tg; differential scanning calorimetry, DSC) were measured. To initiate photolytic labeling, solution and solid samples were exposed to UV light at 365 nm for 30 min. Photolytic-labeling products were quantified using reversed-phase high-performance liquid chromatography (rp-HPLC) and mass spectrometry (MS). In lyophilized solids, studies excluding oxygen and using H218O confirmed that the source of oxygen in KLQ adducts with a mass increase of 18 amu are attributable to reaction with water, while those with a mass increase of 16 amu are not attributable to reaction with either water or molecular oxygen. In solids containing sucrose or trehalose, peptide-excipient adducts decreased with increasing solid moisture content, while peptide-water adducts increased only at lower RH exposure and then plateaued, in partial agreement with the water replacement hypothesis.

From micro to macro-contaminants: The impact of low-energy titanium dioxide photocatalysis followed by filtration on the mitigation of drinking water organics.

This study evaluated strategies targeting macro- and micro-organic contaminant mitigation using low-energy titanium dioxide photocatalysis. Energy inputs of 1, 2, and 5 kWh m-3 resulted in incomplete oxidation of macro-organic natural organic matter, signified by greater reductions of UV254 and specific ultraviolet UV absorbance (SUVA) in comparison to dissolved organic carbon (DOC). The rate of UV254 removal was 3 orders of magnitude greater than the rate of DOC degradation. Incomplete oxidation improved operation of downstream filtration processes. Photocatalysis at 2 kWh m-3 increased the bed life of downstream granular activated carbon (GAC) filtration by 340% relative to direct filtration pretreatment. Likewise, photocatalysis operated ahead of microfiltration decreased fouling, resulting in longer filter run times. Using 2 kWh m-3 photocatalysis increased filter run time by 36 times in comparison to direct filtration. Furthermore, levels of DOC and UV254 in the membrane permeate improved (with no change in removal across the membrane) using low-energy photocatalysis pretreatments. While high-energy UV inputs provided high levels of removal of the estrogenic micro-organics estrone (E1), 17ß-estradiol (E2), estriol (E3), and 17α-ethynlestradiol (EE2), low-energy photocatalysis did not enhance removal of estrogens beyond levels achieved by photolysis alone. In the cases of E1 and E3, the addition of TiO2 as a photocatalyst reduced degradation rates of estrogens compared to UV photolysis. Overall, process electrical energy per order magnitude reductions (EEOs) greatly improved using photocatalysis, versus photolysis, for the macro-organics DOC, UV254, and SUVA; however, energy required for removal of estrogens was similar between photolysis and photocatalysis.

Comparative study of the toxicity between three non-steroidal anti-inflammatory drugs and their UV/Na2S2O8 degradation products on Cyprinus carpio.

The efficiency of advanced oxidation processes (AOPs) for disposing of non-steroidal anti-inflammatory drugs (NSAIDs) has been widely studied, but the environmental fates and effects of the NSAIDs and their degradation products (DPs) are poorly understood. In this study, the efficiency of ultraviolet light/Na2S2O8 (UV/PS) in degrading three NSAIDs-diclofenac, naproxen, and ibuprofen-and the toxicity of their DPs on Cyprinus carpio (C. carpio) was investigated. Results showed that the three NSAIDs can be completely removed (removal rate > 99.9%) by UV/PS, while the mineralization rate of the NSAIDs was only 28%. When C. carpio were exposed to 0.1 µM NSAIDs, 10 µM persulfate (PS), and 0.1 µM DPs of the NSAIDs for 96 h, respectively, the toxicity effects are as the NSAID DPs > PS > NSAIDs. Research results into the time-dependent effect of NSAID DPs on C. carpio demonstrated that obvious toxicity effects were observed in the first 48 hours, and the toxicity effects strengthened over time. NSAID DPs may have more severe toxicity effects than NSAIDs on C. carpio; therefore, the operating conditions of UV/PS must be optimized to eliminate the ecotoxicity of DPs.

Cadmium selenide quantum dot-zinc oxide composite: Synthesis, characterization, dye removal ability with UV irradiation, and antibacterial activity as a safe and high-performance photocatalyst.

In this paper, cadmium selenide quantum dot (CdSe QD)-zinc oxide (ZnO) nanocomposite (CdSe QD-ZnO) was synthesized and characterized and its photocatalytic dye degradation ability was investigated. The XRD, FTIR, UV-Vis, AFM and SEM were used to characterize the synthesized nanomaterials. The correlation coefficient of pseudo-first-order kinetic reaction is 0.98. The rate constants from 20 to 30 mg/L of pollutant concentrations was reduced by the order of 0.9. The temporal change in dye concentration reduces as the photocatalyst dosage increase up to optimum value of 0.04 g/L, then beyond that value the increase in the dosage becomes detrimental. Antibacterial activity of the synthesized nanocomposite as a safe photocatalyst was studied in details. Antibacterial activity of as prepared samples was also examined against Escherichia coli (E. coli). For in vitro study, Human umbilical vein endothelial cells (HUVEC) was utilized for the modeling of toxicity of each as prepared samples as representative of human normal cell line. In vivo study was conducted using leeches (Hirudo orientalis). In the presence of ethanol as hydroxyl radical (OH) scavenger, the removal efficiency significantly depresses compared to the di methyl sulfoxide as electron scavengers suggesting OH possesses a major role in photocatalytic dye (Basic Red 18: BR18) decolorization. By coupling with CdSe QD, the zone of inhibition was greatly increased suggesting the size dependent inactivation of E. coli. The results presented that the composite had no significant effect on the proliferation of HUVEC normal cells. In addition, the treatment of cells with ZnO and the composite does not impact on the cell morphology.

Biogenic synthesis of gold nanoparticles and their application in photocatalytic degradation of toxic dyes.

Plants and their extracts play an important role in the green synthesis of nanoparticles mainly because of their environmental benignity. Based on plant extracts number of metal nanoparticles have been synthesized. In our study, we report a green technique for the synthesis of gold nanoparticles using the aqueous extracts of Alpinia nigra leaves and their photocatalytic activities. The antioxidant, antibacterial and antifungal potential of the synthesized nanoparticles were also evaluated. The aqueous extract of the plant is rich in flavonoids with Total Flavonoid Content of 491mgRE/g extract. The presence of flavonoids was further confirmed through analytical High Performance Liquid Chromatography (HPLC) analysis. The A. nigra mediated syntheses of gold nanoparticles (ANL-AuNPs) were characterized by UV-Vis spectrophotometer, Fourier Transform Infrared (FTIR) Spectroscopy, X-ray Diffraction (XRD) and Transmission Electron Microscopy (TEM). The crystalline nature of the ANL-AuNPs was confirmed by the powder XRD analysis. The TEM micrographs showed that the ANL-AuNPs was predominantly spherical in shape and the average particle size was 21.52 nm. The polyphenolics and other functional groups present in the aqueous extract that acted as reducing and capping agent in the synthesis of the Au-NPs were identified via FTIR spectral analysis. These green synthesized nanoparticles exhibited antioxidant activity with IC50 value of 52.16 µg/ml and showed inhibition in the growth of both gram-positive and gram-negative bacteria. The pathogenic fungus, Candida albicans was also susceptible to these nanoparticles. The ANL-AuNPs in the presence of sunlight catalyzed the degradation of the anthropogenic pollutant dyes, Methyl Orange and Rhodamine B with percent degradation of 83.25% and 87.64% respectively. The photodegradation process followed pseudo first order kinetic model. These results confirm that Alpinia nigra is a potential bioresource for the synthesis of Au-NPs with versatile applications.

Biosynthesis of iron nanoparticles using Trigonella foenum-graecum seed extract for photocatalytic methyl orange dye degradation and antibacterial applications.

Trigonella foenum-graecum is the source of various biological and chemical constituents with a wide area of applications, especially in the treatment/prevention of diabetes and other chronic diseases such as cancer. Multiple biological and organic moieties in the aqueous or the organic phase of Trigonella foenum-graecum carry soft reduction properties to reduce the metal cations to nanoparticles. In this investigation, the Trigonella foenum-graecum was found in the seed extract for the first time in an aqueous medium. We successfully synthesized zero-valent iron nanoparticles (Fe0) (ZV-Fe NPs) and stabilized these nanoparticles in an aqueous medium. The stabilization mechanism of Fe NPs by Trigonella foenum-graecum in an aqueous extract was investigated. Further, Fe NPs were characterized by UV-visible spectrometry, X-ray diffraction (XRD), thermogravimetric analysis - derivative thermo-gravimetric (TGA/DTG), magnetization, Fourier transform infrared (FTIR) spectroscopy and transmission electron microscopy (TEM) images. The size of the nanoparticles, calculated using the Debye-Scherer equation and TEM, was found to be approximately 11 nm with the highest particle distribution number. Fe NPs are very effective for methyl orange dye degradation under UV light following pseudo first-order kinetics, and the rate constant kapp was found to be 0.025 min-1. Furthermore, Fe NPs were applied to check the antibacterial activities with microorganisms such as gram-negative E. coli and gram-positive S. aureus. The Minimum Inhibitory Concentration (MIC) of Fe NPs for E. coli and S. aureus was calculated as 32 µg/mL and 64 µg/mL, respectively.

In vitro photodynamic activity of lipid vesicles with zinc phthalocyanine derivative against Enterococcus faecalis.

Zinc(II) phthalocyanine bearing eight non-peripheral 2-propoxy substituents was subjected to physicochemical study and, after incorporation in lipid vesicles, assessed as a potential photosensitizer for antibacterial photodynamic therapy. The phthalocyanine derivative obtained in the macrocyclization reaction was characterized by MS and NMR techniques. Moreover, its chemical purity was confirmed by HPLC analysis. X-ray structural analysis revealed that overcrowding of the phthalocyanine derivative leads to a strong out-of-plane distortion of the π-system of the macrocycle core. In the UV-Vis absorption spectra of zinc(II) phthalocyanine two characteristic bands were found: the Soret (300-450 nm) and the Q band (600-800 nm). Photophysical properties of mono- and diprotonated forms of phthalocyanine derivative were studied with time-resolved fluorescence spectroscopy. Its tri- and tetraprotonated forms could not be obtained, because compound decomposes in higher acid concentrations. The presented zinc(II) phthalocyanine showed values of singlet oxygen generation ΦΔ = 0.18 and 0.16, the quantum yield of the photodecomposition ΦP = 3.06∙10-4 and 1.23∙10-5 and the quantum yield of fluorescence ΦFL = 0.005 and 0.004, designated in DMF and DMSO, respectively. For biological studies, phthalocyanine has been incorporated into modified liposome vesicles containing ethanol. In vitro bacteria photoinactivation study revealed no activity against Escherichia coli and 5.7 log reduction of the Enterococcus faecalis growth.

Fast sonochemically-assisted synthesis of pure and doped zinc sulfide quantum dots and their applicability in organic dye removal from aqueous media.

In this research, a sono-assisted chemical precipitation method was developed for a quick and efficient water-based synthesis of zinc sulfide (ZnS) quantum dots (QDs), in room temperature. ZnS QDs as pure and doped with some transition metal ions (such as Cu2+, Mn2+, Ag+) were prepared in the presence of l-cysteine, as capping agent. In comparison with the previous conventional methods, applying the ultrasonic irradiation provides a significant decrease in the reaction time. In comparison with previous reported conventional chemical QD synthesis methods, the required time for a complete synthesis in the presence of ultrasonic irradiations was significantly reduced to a period as short as 15 min, in a temperature of 40 °C. The sono-synthesized QDs were characterized with various techniques such as colorimetry, UV-Vis absorption spectroscopy, X-ray diffraction (XRD) and transmission electron microscopy (TEM). A broad absorption band between 270 and 290 nm was observed for colloidal ZnS QDs with the optical band gap larger than 3.68 eV. From the XRD and TEM results, the average particle size below 5 nm was estimated for the prepared QDs. After characterization, the samples were employed as nanophotocatalysts during a UV-derivate photocatalytic process for the degradation of Victoria blue R (VBR), as a pollutant dye. To obtain the optimal operating conditions, the influence of the affecting parameters such as the initial pH of the dye solution, irradiation time, initial dye concentration, type, electrolyte salt concentration and dosage of the nanophotocatalyst samples on the degradation efficiency (DE % was comprehensively studied, all in batch mode. Taking the optimum conditions into account, the maximum removal of VBR dye (>95%) can be obtained by spectrophotometric measurements at alkaline pH of 10.5, in the presence of low amounts of QDs (3 mg) and after 30 min of being exposed to UV irradiations. The results demonstrate that despite the removal of VBR, the QDs prepared by sonochemically method can be reused for at least six more times; without a significant decrease in their photocatalytic properties.