Journal of Photochemistry and Photobiology最新文献

Purpose

Early detection and diagnosis of cancer is critical for achieving positive therapeutic outcomes. Biomarkers that can provide clinicians with clues to the outcome of a given therapeutic course are highly desired. Oxygen is a small molecule that is nearly universally present in biological tissues and plays a critical role in the effectiveness of radiotherapies by reacting with DNA radicals and subsequently impairing cellular repair of double strand breaks.

Techniques for measuring oxygen in biological tissues often use blood oxygen saturation to approximate the oxygen partial pressure in surrounding tissues despite the complex, nonlinear, and dynamic relationship between these two separate oxygen populations.

Methods and materials

We combined a directly oxygen-sensitive, tumor-targeted, chemical contrast nanoelement with the photoacoustic lifetime-based (PALT) oxygen imaging technique to obtain image maps of oxygen in breast cancer tumors in vivo. The oxygen levels of patient-derived xenografts in a mouse model were characterized before and after a course of radiotherapy.

Results

We show that, independent of tumor size, radiotherapy induced an increase in the overall oxygenation levels of the tumor. Further, this increase in the oxygenation of the tumor significantly correlated with a positive response to radiotherapy, as demonstrated by a reduction in tumor volume over the twenty-day monitoring period following therapy and histological staining.

Conclusion

Our PALT imaging presented here is simple, fast, and non-invasive. Facilized by the PALT approach, imaging of tumor reoxygenation may be utilized as a simple, early indicator for evaluating cancer response to radiotherapy. Further characterization of the reoxygenation degree, temporal onset, and possible theragnostic implications are warranted.

Organic dyes are a major source of environmental pollution from different industries. To remove these recalcitrant, a novel ternary g-C₃N₄/ZnO/Ag₂CrO₄ and its polyaniline-supported (PANI) composites were synthesized using an “in situ” oxidative polymerization approach. XRD, SEM, UV–Vis DRS, and PL techniques were utilized to characterize the as-prepared composites. The photocatalytic efficiency was evaluated using a model organic pollutant, methylene blue (MB), and samples of the effluent of the textile industry. The as-synthesized ternary g-C₃N₄/ZnO/Ag₂CrO₄ (ZT3= 87.87 %) composite showed better photocatalytic performance than the single (5 %) and binaries (15–25 %) counterparts for MB degradation. The influence of various experimental settings on the photodegradation of MB dye was examined and these were an initial dye amount of 10 ppm, photocatalyst load of 0.15 g/L, and pH 10. Under optimized conditions, PANI-supported g-C₃N₄/ZnO/Ag₂CrO₄ composite (PAST) demonstrated substantial degradation efficiency (97.5 %). The reusability study of the spent catalyst revealed a reduced efficiency from 97.5 to 78.5 % photodegradation of MB after four successive cycles, demonstrating the photocatalyst's stability and efficiency. According to the study on the effect of scavengers, h⁺ plays a significant part in the discoloration of MB. The PAST photocatalyst outperformed the MB discoloration (97.5 %) and adequate degradation for real textile effluent samples (77.7 %) collected from Hawassa textile industries. The photodegradation efficiency result of this study demonstrated that PANI-supported g-C₃N₄/ZnO/Ag₂CrO₄ might serve as an advantageous photocatalyst for the efficient removal of MB and other dyes under visible light irradiation at the optimum conditions. The total estimated cost analysis of synthesis and photocatalytic degradation using Polyaniline-supported g-C₃N₄/ZnO/Ag₂CrO₄ composite found that it was quite affordable, costing around $5 per 1,000 L of wastewater treatment.

A rather simple model was developed, which predicted a hyperbolic relation between the photocatalytic reaction rate and solution conductivity. Experimental validation was performed using methyl orange as a model pollutant and titanium dioxide as a photocatalyst. The experiments, conducted with three different salts confirm the hyperbolic correlation between the photocatalytic degradation rate and solution conductivity. The results have evinced this correlation, albeit the model ignores crucial factors, such as the role of one of the two types of charges generated during light absorption and the chemical decomposition pathway. In addition, the experimentally derived hyperbolic function displays a positive shift along the ordinate.

The review focuses on photoinduced electron transfer (PET) reactions between small molecules and various kinds of chemical and biological systems using a weak external magnetic field (MF). Laser flash photolysis is a competent tool to characterize the intermediates which are formed due to PET. A weak MF, very close to the hyperfine interaction of the system, has the potential to inhibit or enhance reaction channels for singlet and triplet states, which eventually effects the product distribution. At first, well-documented examples of PET involving small molecules like derivatives of phenazines, carbazoles and acridines with classical electron donors in varying homogeneous and heterogeneous media have been discussed and the influence of a weak MF on the dynamics of PET is highlighted. Secondly, utilization of magnetic field effect (MFE) to probe PET in protein pockets has been described. Thirdly, an extensive discussion on PET involving nucleobases, nucleosides, nucleotides and nucleic acids and subsequent MFE on such reactions has been reported. Next, MFE has been exploited to study PET involving nanomaterials. Finally, some very recent studies of MFE have been discussed. Thus, this review is an attempt to unravel various aspects of PET in a large number of systems of varying dimensions by means of several facets of MFE like B_1/2 parameter, its capability to authenticate the initial spin state and distance dependence property.

Solar powered conversion / reduction of carbon dioxide into value added chemicals has been identified as one of the foremost challenges for materials science in the 21st century. Despite extensive research, product yield remained low and one of the primary factors has been the issue of competing adsorption of CO₂ and water vapour on the catalyst surface. In this work we employ reduced graphene oxide wrapped TiO₂ nanotubes (TiO₂ - rGO) as a heterojunction photocatalyst and demonstrate that UV irradiation induces hydrophilicity on the TiO₂ surface and, hydrophobicity on the rGO surface. The resulting photocatalyst shows 25 % higher yield of methane over that of untreated photocatalyst. Hence, UV irradiation induced tailoring of the hydrophilicity yields selective adsorption sites for the CO₂ and water vapour leading to a significant enhancement of the methane yield through photocatalytic reduction process.

The structure and quality of eggshells (ES) vary around a mean value depending on different items, and these variations are important in their many industrial and technological applications as will be mentioned (vide infra). Five commercial egg brands of different laying hens are examined and their quality indices, morphological microstructure, elemental composition, and light absorbance at 200–700 nm UV/Vis spectra were compared. The ES layers include a limiting membrane, inner and outer shell membranes, a mammillary layer, a palisade layer, a surface vertical crystal layer, and a bilayer cuticle. The elemental composition of each layer reflects the proteinous or calcified nature of the layers, and various elements, C, O, N, Ca, Fe, Mg, Mn, Pb, Sr, Sc, Hf, Co, and La, were found. The weight difference between egg brands was significant, as well as the difference in ES percentage between white and colored eggs. ES weight possessed a positive relationship with the thickness of the calcified layer. So, the ES is heavier and the egg is larger and heavier when the calcified layer is thicker. The calculated average ES index was 7.99% ± 0.16 SE. In all ES samples, the absorbance in UV wavelength spectra (300–350 nm) was slightly higher than in Vis spectra (400 - 700 nm) and their difference was significant. The difference in absorbance of various treatments was significant and mean absorbance was the highest in the after-furnace (ash) samples and was the lowest for acid-treated ones. It seems that turning the ES into ash can improve the absorbance capability, especially in white ESs.

Exposure to ultraviolet (UV) radiation from the sun has both harms and benefits for human health. The best-known benefit of sun exposure is the generation of vitamin D within the skin and the best-known harm is malignant skin cancer. Australia and New Zealand have very high ambient UV radiation, resulting in high rates of skin cancer incidence and mortality, yet there is an appreciable prevalence of vitamin D deficiency (defined as blood 25-hydroxyvitamin D (25(OH)D) < 50 nmol/L) in both populations. The purpose of this study was to create a microsimulation model to replicate population 25(OH)D concentrations of people living in Australia and New Zealand, thus enabling the effect of different population-wide interventions to be estimated. We used large population datasets containing data on sun behaviours and socio-demographic variables, and environmental data on UV radiation, ozone, and solar zenith angle. Latitude, weather and time of day were accounted for. We simulated the conversion of daily UV radiation to a standard vitamin D dose (SDD) (100 J/m² vitamin D-weighted UV) and monthly accumulation of SDD to 25(OH)D concentration. The model was calibrated to match the seasonal prevalence of vitamin D deficiency. This report describes the Sun Exposure (SUNEX) microsimulation model, its development, data inputs and calibration against population prevalence of vitamin D deficiency.

The main flavonoid pigment in the petals of Kigelia Africana and the calyx of Hibiscus sabdariffa is anthocyanin, responsible for the vibrant red, maroon, and purple hues in flowers. This pigment can modulate incident light on flowers, prompting its selection for detailed investigation. TiO₂ nanostructures were synthesized using a one-step hydrothermal method, revealing the formation of nanorods and a single-phase rutile structure through FESEM and XRD analyses, respectively. The study aimed to assess the impact of various solvents on the extraction of natural dyes, which were subsequently sensitized on TiO₂ photoanodes for DSSC applications. Four solvents-water, water with HCl, ethanol, and citric acid were employed to extract natural dyes from Kigelia Africana's petals and Hibiscus sabdariffa's calyx. Notably, dyes extracted with citric acid demonstrated promising results. The conversion efficiency of DSSCs fabricated with Kigelia Africana dye and Hibiscus sabdariffa dye, extracted using citric acid as the solvent, was found to be 0.87 % and 0.92 %, respectively. The implications of these findings are discussed.

Various integrated technologies have been investigated for the remediation of heavily polluted industrial dye effluent. Also, more than 70 % of these dyes are known to be solely azo dyes used in the textile industry with 5–30 % presence in the effluent as loose dye molecules which are recalcitrant to treatment. These challenges led to the investigation of energy-efficient processes (solar) and the fabrication of high-performance nano-photocatalysts for proficient photocatalysis of dye effluent while mediating the process with Fenton reagents. The study fabricated nanopolymeric catalyst composites (P-AKT) via novel in situ coupling and impregnation of the polyaniline (PANI) with surface-activated TiO₂ NPs. This fabrication is aimed at developing a high-performance catalyst with rapid and proficient photocatalytic activities to photons from sunlight irradiation. The photocatalytic process was mediated using a novel Fenton reagent to enhance the generation of radical species for dye degradation. Various instrumental characterization methods were used to study the structural, molecular, elemental, functional and optoelectronic properties of the fabricated nanocomposite photocatalysts. The result reveals functional groups aiding dye-catalyst bonding and morphological interaction reveal a surface-activated tetragonal crystalline mixture of anatase and rutile from TiO₂⁻Nps embedded in the macromolecular chain of PANI. It also reveals the optimal conditions of 20 mg dosage, 10 mg/L initial concentration with substantial effectiveness at pH of 5 and 7. However, the most efficient photocatalyst recorded was P-AKT-2 % and P-AKT-3 % having 95 % and 94 % efficiencies at 90 min of solar irradiation. The photocatalyst equally demonstrated its capacity for effluent treatability up to 4 cycles of use.

Near-infrared photoimmunotherapy (NIR-PIT) is a recently described method for cancer treatment that utilizes an antibody-conjugated phthalocyanine photosensitizer and NIR light. In NIR-PIT, light of 690 nm wavelength is used to activate a photosensitizer, IR700, while longer-wavelength light penetrates deeper into tissues. Thus, more effective NIR-PIT would be achieved by using photosensitizers that are activated by longer-wavelength light. The absorption wavelength would be red-shifted by destabilizing the highest occupied molecular orbital (HOMO) energy level by introducing electron donating groups at the α positions of a phthalocyanine ring. In this study, we developed a red-shifted photosensitizer for NIR-PIT, KA800, whose absorption wavelength was red-shifted by the introduction of ethoxy groups to IR700. As intended, the absorption maximum of KA800 was red-shifted compared to IR700 by 84 nm. Although phototoxicity of the antibody-KA800 (Ab-KA800) conjugate was observed in cultured cancer cells, no therapeutic effect was observed in mice. This is because the cytotoxicity of Ab-KA800 was mainly due to singlet oxygen, which can be quenched by abundant antioxidants in vivo. KA800 had low reactivity with respect to axial ligand cleavage required for inducing cell death via aggregate formation, a unique cytotoxic mechanism in NIR-PIT. The axial ligand cleavage proceeds via the anion radical formation of the photosensitizer, and KA800 was found to be less likely to receive an electron than IR700. This may be due to the destabilization of the HOMO energy level of KA800. Therefore, our findings suggest that stabilizing the lowest unoccupied molecular orbital (LUMO) energy level would be better than destabilizing the HOMO energy level for developing a red-shifted photosensitizer for NIR-PIT.