Photochemical & Photobiological Sciences最新文献

New photocatalytic materials based on complex oxides and a widely used and cheap polymer (PMMA) have been prepared. Among complex oxides previously investigated, the following have been used-RbTe_1.5W_0.5O₆, CsTeMoO₆, CsV_0.625Te_1.375O₆, NaVMoO₆, KVMoO₆. For comparison, the binary oxides TiO₂ and WO₃ were used. The form of PMMA matrix was used as sponge and glass. The amount of powder in PMMA was selected based on retaining the polymer properties and getting the photocatalytic activity, which corresponds to 1% powder in sponge and 0.5% in glass. The "photocatalyst/PMMA" composites decompose the methylene blue under visible and UV light as well as possess antibacterial properties. The high electron-hole recombination was found out for composites photocatalysts, which significantly influences only on organic compounds decomposition in solutions. However, there is no direct dependence between effective photodegradation of simple organic molecules and antimicrobial properties. Inactivation of bacteria is determined by many factors such as active generated radicals, adsorption properties of the surface and the photocatalyst form, which can change the main active radicals. The comparison of photocatalytic action on organic solutions and bacteria of initial powders and PMMA composites allow choosing the most effective combination for further application. The most promising antimicrobial properties for composites have been obtained using compounds with β-pyrochlore structure.

Zinc methyl 13²,13²-disubstituted 3-hydroxymethyl-pyropheophorbides-a were prepared as models of bacteriochlorophyll-d, which self-aggregated in the main light-harvesting antenna (chlorosome) of photosynthetic green bacteria. The synthetic zinc 3¹-hydroxy-13¹-oxo-chlorins possessing methyl and methoxycarbonyl groups at the 13²-position could not self-aggregate in an aqueous Triton X-100 solution. However, another model compound bearing an ethane-1,2-diyl group at the 13²-position did self-aggregate under the same conditions to give red-shifted and broadened Qy and Soret absorption bands. The spiro-cyclopropane condensation slightly suppressed the chlorosome-like self-aggregation due to an increase in the steric hindrance around the 13-carbonyl group. The red-shifted and broadened values of these bands by the self-aggregation were dependent on the 13²-substituents. The 13²-substitution substantially controlled the aqueous J-aggregation.

This review aims to provide the readership with an overview of the applications of the time-resolved spectroscopic techniques (often combined with steady-state measurements) in the elucidation of the mechanism of the photochemical behaviour of diaryl- and triarylamines. Such derivatives undergo cyclization to the carbazoles or ionization to the corresponding amine radical cations depending on both the nature of the starting substrates and the reaction conditions. In this context, time-resolved spectroscopy techniques allowed for the detection and the full characterization of all the excited states and the transients involved in these processes. The main characteristics of such species, including lifetime, time-resolved absorption spectra, quantum yield values and rate constants of formation and decay in both homogeneous and micro-heterogeneous environment (e.g. aqueous surfactant solutions) are thus summarized in the presented paper.

The modeling of the bioluminescent system of fireflies is key to understand the binding mode of the oxyluciferin/luciferase complex and its photophysical properties with the aim of developing high-efficiency devices and techniques. In this work, we present the OLUFF force field, which is able to describe the interactions to sample the conformational space of the four possible oxyluciferin emitters in both ground and excited state. This force field has been parameterized to reproduce quantum mechanical (QM) energies and geometrical parameters. Moreover, it has been validated by comparing probability distribution functions, minimized structures, infrared spectra and normal mode analysis obtained from OLUFF-based molecular dynamic (MD) simulations with their QM counterparts. Additionally, ground state simulations have also been performed using the general amber force field (GAFF) and compared with the OLUFF. It has been demonstrated that the OLUFF not only reproduces well the QM properties, but also improves the results from the GAFF.

Basic concepts and theoretical foundations of broken symmetry (BS) and post BS methods for strongly correlated electron systems (SCES) such as electron-transfer (ET) diradical, multi-center polyradicals with spin frustration are described systematically to elucidate structures, bonding and reactivity of the high-valent transition metal oxo bonds in metalloenzymes: photosystem II (PSII) and cytochrome c oxidase (CcO). BS hybrid DFT (HDFT) and DLPNO coupled-cluster (CC) SD(T₀) computations are performed to elucidate electronic and spin states of CaMn₄O_x cluster in the key step for oxygen evolution, namely S₄ [S₃ with Mn(IV) = O + Tyr161-O radical] state of PSII and P_M [Fe(IV) = O + HO-Cu(II) + Tyr161-O radical] step for oxygen reduction in CcO. The cycle of water oxidation catalyzed by the CaMn₄O_x cluster in PSII and the cycle of oxygen reduction catalyzed by the Cu_A-Fe_a-Fe_a3-Cu_B cluster in CcO are examined on the theoretical grounds, elucidating similar concerted and/or stepwise proton transfer coupled electron transfer (PT-ET) processes for the four-electron oxidation in PSII and four-electron reduction in CcO. Interplay between theory and experiments have revealed that three electrons in the metal sites and one electron in tyrosine radical site are characteristic for PT-ET in these biological redox reaction systems, indicating no necessity of harmful Mn(V) = O and Fe(V) = O bonds with strong oxyl-radical character. Implications of the computational results are discussed in relation to design of artificial systems consisted of earth abundant transition metals for water oxidation.

In response to the existing issues of cumbersome and time-consuming detection processes and limited application scope in current pesticide residue detection, this paper designed a novel flexible substrate for surface-enhanced Raman spectroscopy (SERS) by combining flower-like silver nanoparticles prepared by chemical reduction technology with a flexible sponge. The flexible substrate exhibits excellent SERS enhancement effects, with a minimum detection limit of 10^-12 mol/L for the probe molecule rhodamine 6G (R6G) and an average enhancement factor of 6.63 × 10⁵. For the commonly used pesticide thiram, the minimum detection limit is 0.1 mg/L, which is significantly lower than the maximum residue limits set by China and the USA for thiram. Further experiments confirmed the substrate's excellent uniformity and stability, and the use of finite difference time domain (FDTD) software revealed that the model combining flower-like silver nanoparticles with a sponge exhibited higher electromagnetic field intensity compared to the model without the sponge, resulting in abundant "hot spots". Additionally, the sparrow search algorithm (SSA) was used to optimize the backpropagation (BP) neural network for predicting the concentration of thiram pesticide. The experimental results indicated that the SSA-BP algorithm achieved a determination coefficient (R²) of 0.99974 and root mean square error (RMSE) of 300.321, demonstrating good network performance and meeting the requirements of actual detection needs.

The study aimed to assess the impact of combining potassium iodide (KI) with methylene blue (MB) in antimicrobial photodynamic therapy (aPDT) within an oral biofilm formed in situ. A single-phase, 14 days in situ study involved 21 volunteers, who wore a palatal appliance with 8 bovine dentin slabs. These slabs were exposed to a 20% sucrose solution 8 times a day, simulating a high cariogenic challenge. Following the intraoral phase, the biofilms formed on the slabs were randomly assigned to the treatments: C (0.9% NaCl); CHX (0.2% chlorhexidine); KI (75 mM KI); MBKI (0.005% MB + 75 mM KI); L (0.9% NaCl + red laser 660 nm, 18 J, 180 s); LMB (0.005% MB + laser); LKI (75 mM KI + laser); LMBKI (0.005% MB + 75 mM KI + laser). The treated biofilms were collected, diluted, and incubated to assess cell viability (CFU/mL) for total microorganisms, total lactobacilli, total streptococci, and mutans streptococci. Data were subjected to analysis using the Friedman test, followed by the Dunn test (α = 0.05). LMBKI group exhibited a noteworthy decrease in the viability of all microorganisms in comparison to groups C, KI, MBKI, MB, L, LMB, and LKI (p < 0.0001), and demonstrated a comparable reduction to the CHX group (p > 0.99). The combination of KI with MB in aPDT may be advocated as a non-invasive technique for diminishing the viability of polymicrobial oral biofilms, thereby aiding in the management of dental diseases.

Increasing solar ultraviolet radiation (UVR) can raise human exposure to UVR and adversely affect the environment. Precise measurements of ground-level solar UVR and long-term data series are crucial for evaluating time trends in UVR. This study focuses on spectrally resolved data from a UVR measuring station in Dortmund, Germany (51.5° N, 7.5° E, 130 m a.s.l.). After a strict quality assessment, UV data, such as the daily maximum UV Index (UVI_max) and daily erythemal radiant exposure (H_er,day) values, were analyzed concerning monthly and annual distribution, frequency, occurrence of highest values and their influencing factors. An advanced linear trend model with a flexible covariance matrix was utilized and applied to monthly mean values. Missing values were estimated by a validated imputation method. Findings were compared to those from a station in Uccle, Belgium (50.8° N, 4.3° E, 100 m a.s.l.). Parameters possibly influencing trends in both UVR and global radiation, such as ozone and sunshine duration, were additionally evaluated. The 1997-2022 trend results show a statistically significant increase in monthly mean of H_er,day (4.9% p. decade) and UVI_max (3.2% p. decade) in Dortmund and H_er,day (7.5% p. decade) and UVI_max (5.8% p. decade) in Uccle. Total column ozone shows a slight decrease in the summer months. Global radiation increases similarly to the UV data, and sunshine duration in Dortmund increases about twice as much as global radiation, suggesting a strong influence of change in cloud cover. To address health-related consequences effectively, future adaptation and prevention strategies to climate change must consider the observed trends.

This experiment investigated the effects of an ecologically relevant level of dim light at night (dLAN) on behavior, physiology and fat metabolism associated gene expressions in central and peripheral tissues of adult male zebra finches that were hatched and raised in 12:12 h LD cycle (Ev, day = 150 ± 5 lx; Ev, night = 0 lx) at 22 ± 2 °C temperature. Half of the birds (n = 8) were maintained on LD cycle and temperature, as before (control), to the other half of birds the 12 h dark period was dimly illuminated at ~ 5 lx (dim light at night, dLAN; Ev, day = 150 ± 5 lx; Ev, night =  ~ 5 lx) for 6 weeks. The exposure to dLAN altered the 24 h activity and feeding patterns with enhanced activity and feeding at night. Birds under dLAN fattened and gained weight, and had higher night glucose levels. Concurrently, a negative effect of dLAN was found on mRNA expression of ppar-alpha and cd36 genes involved in the fat metabolism in the hypothalamus, intestine, liver and muscle. These results suggest a more global effect of dLAN exposure on obesity and perhaps long-term health risks due to obesity-related complications to diurnal animals including humans inhabiting an urbanized environment.

Control of biological activity with light is a fascinating idea. "Caged" compounds, molecules modified with photolabile protecting group, are one of the instruments for this purpose. Adrenergic receptors are essential regulators of neuronal, endocrine, cardiovascular, vegetative, and metabolic functions. These receptors are largely used as pharmacologic targets. Photolabile "caged" analogs of adrenergic receptor agonists has been reported more than 30 years ago. We report that the photolysis of epinephrine analogs, apart from liberation of the epinephrine, is accompanied by a formation of significant amount of adrenochrome, a compound with neuro- and cardiotoxic effect.