Journal of Photochemistry and Photobiology最新文献

Introduction

Temporomandibular disorders (TMD) are considered the most common complaint associaetd with orofacial pain. A treatment approach for TMD is photobiomodulation auriculotherapy, however, a method that which still requires studies mainly with pulsed frequency.

Objective

To evaluate the feasibility of conducting a randomized clinical trial using pulsed frequency photobiomodulation auriculotherapy and determine the relevant sample size.

Methods

The study was a controlled randomized pilot study. Twenty one volunteers with TMD were randomized into experimental and placebo groups. The evaluation periods were pre-intervention and again after four weeks. The instruments used for the assessment were axis I (mandibular movement measurements [MMM]) and axis II (Graded Chronic Pain Scale [GCPS], Jaw Functional Limitation Scale [JFLS-8], The Patient Health Questionnaire [PHQ-4], and Generalized Anxiety Disorder [GAD-7]) from Diagnostic Criteria for Temporomandibular Disorders (DC/TMD). Mann–Whitney and Wilcoxon tests were used for comparison of groups. The intervention protocol was performed once a week for foour weeks.

Results

The GCPS question about “pain at this exact moment” indicated lower values for the treated group compared to the placebo group (U = 15.50; p = 0.005) after the intervention. The calculation of the total sample was 22 volunteers. The JFLS-8 variable showed no difference between the groups and the sample calculation ranged from 39 to 281 volunteers. The MMM showed no difference between the groups, and the calculation of the necessary sample ranged from 27 to 2.317. The variable PHQ-4 (U = 21.00; p = 0.02) and GAD-7 (U = 20.00; p = 0.02) showed differences between groups with type I error. The required sample was 22 volunteers for PHQ-4 and 25 for GAD-7.

Conclusion

We conclude that this study is feasible and that the required sample should be 11 volunteers for each group in the GCPS subitem “pain intensity at this exact moment”. We were able to find results for this GCPS subitem. However, for other variables we need 25 volunteers for GAD7 and 22 volunteers for PHQ-4. Other variables, such as JFLS-8 and MMM, made it impossible to conduct these scales for future studies.

Skin cells present many endogenous photosensitizers (ePS) that interact with light, generating oxidizing species, causing molecular damage in proteins, lipids, and nucleic acids, and consequently triggering cellular and organelle malfunction. Several cell lines with terminal differentiation are susceptible to accumulating non-digestible pigments, such as lipofuscin or melanin-lipofuscin. Besides being hallmarks of aging, both pigments can work as photosensitizers, increasing and expanding the toxicity of sunlight to the range of visible light (VL, 400–700 nm). In here we review the literature to describe the mechanisms by which the photosensitized oxidation reactions induced by VL cause DNA damage. We aim to provide the mechanistic background needed to improve the current strategies of photoprotection.

The photophysical properties and photocatalysis of tris(pentafluorophenyl)borane [B(C₆F₅)₃], known as a strong Lewis acid, were revealed. The excited-state B(C₆F₅)₃ exerts single-electron oxidation capability with an oxidation potential (E_red* = 2.02 V vs SCE) close to those of electronically unbiased toluene derivatives (E_ox = 2.01 to 2.29 V). This property was experimentally proven by the direct observation of the radical cation of the toluene dimer by the transient absorption spectroscopy of a mixture of B(C₆F₅)₃ and toluene. In cooperation with a suitable Brønsted base catalyst, B(C₆F₅)₃ catalytically generated benzylic radicals from toluene derivatives under photoirradiation for subsequent carbon-carbon bond-forming reactions.

A lot of effort has been given to the development of nontoxic ternary semiconductor nanoparticles that could act as photocatalyst NIR-I (750–850 nm) or NIR-II (1000–1400 nm) optical windows. This is due to their good stability, high optical absorption coefficient, and desirable band gap that absorbs well within the solar spectrum. CuInS₂ is one of the ternary sulphide semiconductors, which has been considered to be a highly promising photocatalyst. The properties are attributed to its high optical absorption coefficient. In this study, copper indium sulphide (CuInS₂) nanoparticles were synthesized by a microwave irradiation route using copper(II) bis (N-methyl-N-ethanol dithiocarbamate) and In(III) tris (N-methyl-N-ethanol dithiocarbamate) as a precursor complexes. The copper(II) complex was varied in two different ratios (3:1 and 2:1) to determine the best synthesis regime. Then, the effect of the varying ratios on the crystalline structure, morphology, and optical properties of the CuInS₂ was studied by using X-ray diffraction (XRD), scanning and transmission electron microscopy (SEM and TEM), and absorption spectroscopy. The microscopic analyses revealed that the CuInS₂ nanoparticles have similar spherical grain-like shapes whose sizes range between 10.3–50.1 nm. The increase in the concentration of copper(II) complex also altered the band gap energy, given 2.87 and 1.61 eV for CuInS₂(3:1) and CuInS₂(2:1) respectively. The photocatalytic activities of the nanoparticles were determined for the degradation of Tetracycline (TC) under visible light irradiation. The effects of process parameters such as photocatalyst dosage and initial concentration of TC were investigated to establish the optimal performance of the CuInS₂ nanoparticles. The experimental data showed a higher TC degradation percentage for CuInS₂(2:1) (95 %) compared to CuInS₂(3:1) (90 %), indicating its high potential as a photocatalyst for the degradation of TC in aqueous solution.

Recent publications have confirmed the ability of visible light from sunlight (in the absence of Ultraviolet A or B) to cause free radical formation in human skin, increases in metalloproteinases, induced pigmentation and even erythema from exposures within reasonable exposure periods (e.g. less than 8 h). This raises questions regarding the role of visible light on the formation of skin cancers and even the need for protection against visible light in general. Conducting such studies is a challenge, considering the doses of visible light required for observation of reactions, the difficulty in conducting animal studies with appropriate models in the current regulatory environment, and the lack of funding for basic photobiological research. A review of research from an earlier era in photobiology studies gives us some clues and suggests that there may in fact be detectable influences of visible radiation (for example on skin cancer induction) that warrant new approaches to photoprotection in this era.

Electron donor and acceptor undergo association in solution to form a weak molecular complex, namely a charge transfer complex. The formation of the complex is apparent by its new low-energy absorption band. Upon photoexcitation of this charge transfer band, an intracomplex electron transfer is facilitated to form a contact ion radical pair. The theoretical basis for the complex formation and the subsequent photoinduced electron transfer process has been well established already half a century ago. Nevertheless, the charge transfer complex photochemistry is now in a renaissance, due to its synthetic utility of its radical ion pair. By intentionally sidestepped unproductive back electron transfer process, a desired product is effectively obtained with or without external reagent and/or catalyst. In addition, the photoexcitation of the complex does not require any additional photocatalyst and often conceivable with the visible light. Accordingly, various donor/acceptor pairs and synthetic applications have been emerged as novel photoreaction systems in the last two decades. Some have also addressed the stereoselective transformations. This mini review highlights the recent progress of the asymmetric photoreaction, in particular in synthetic applications, based on the photoexcitation of the charge transfer complex, in comparison with photoredox catalysis.

Fluorescence quenching of an excited guest encapsulated within a cationic host by a cationic molecule was examined on an anionic inorganic surface. Repulsion between the host and the quencher was overcome by adsorbing both an anionic surface. Dimethyl stilbene (DMS), octa amine (OAm₂¹⁶⁺), viologen derivatives (VD²⁺) and saponite are used as guest, cationic capsule, cationic electron acceptor and anionic inorganic surface, respectively. The fluorescence behavior of DMS within OAm₂¹⁶⁺ (denoted as DMS@OAm₂¹⁶⁺) was observed by steady-state and time-resolved fluorescence measurements. As a result of electron transfer the fluorescence of DMS@OAm₂¹⁶⁺ was quenched by VD²⁺ under the presence of saponite, while no quenching was observed in the absence of saponite. Those results indicate that the dynamic electron transfer between DMS@OAm₂¹⁶⁺ and VD²⁺ which are electrostatically repulsive, can be observed in the (DMS@OAm₂¹⁶⁺)-VD²⁺-saponite triad supramolecular system where the two cationic systems are brought closer by the anionic clay sheet.

Presently we report a second example of a biochemical reaction sensitized remotely by excitons (electronic excited states) efficiently transferred along intermediate filaments (IFs) over macroscopic distances. IFs are excellent conductors of energy in the form of excitons, with the efficiency of ca. 0.53 reported in vitro. Excitons were generated by visible light and propagated along Müller cell (MC) intermediate filaments, about 100 μm long. These experiments used a capillary matrix filled by MC IFs extracted from porcine retina. Excitons induced efficient isomerization of 11-cis- to all-trans-retinal, with the reaction quantum yield φ_cis/trans = 0.347 obtained for 11-cis-retinal concentration of 1.0 × 10⁻³ M (0.284 g/L) using 546 nm light at 6.87 mW/cm² power density. Exciton quantum yield φ_exc at 546 nm was also measured in function of radiation power density, with nonlinearity indicative of biphotonic processes. This is the first case of biphotonic processes occurring at such low light intensities with steady-state illumination. The present results support quantum mechanism of high-contrast vision of vertebrate eyes.

Open-shell species are attracting significant attention owing to their unique physicochemical properties and highly reactive characteristics. Over the past decade, photoredox catalysis (PRC) has emerged as a powerful strategy for radical reactions. Recently, photocatalysis involving the excitation of open-shell catalytic species generated from in situ photo- or electrochemical electron transfer has also attracted significant attention in synthetic organic chemistry. These systems can achieve redox potentials that are difficult to achieve in the ground state of the photocatalyst or by simple excitation of the photocatalyst. In this review article, we discuss recent advancements in highly reducing organic photocatalyst (OPC) systems involving the photoexcitation of electron-primed catalytic species, which can be engaged in photochemically (conPET: consecutive photoinduced electron transfer) or electrochemically (e-PRC: electrochemically mediated photoredox catalysis). We believe that expanding the redox windows of catalysts to activate inert substrates from the viewpoint of redox potential will improve rational reaction design, and the use of sophisticated OPC systems will be promising for achieving elusive molecular transformations.

Visible light (VL) has been shown to promote genotoxicity through free radical generation and structural protein degradation. These stressful events promote cellular vulnerability, which manifests clinically as erythema, hyperpigmentation, and photoaging. Having established biologic impacts of VL, development of photoprotection strategies against this part of the solar spectra are warranted. This invited review presents advances in the VL literature and discusses available and potential means of VL photoprotection.