Light-induced Activity Research Articles

Mesoporous Nano-Sized BiFeVOx.y Phases for Removal of Organic Dyes from Wastewaters by Visible Light Photocatalytic Degradation.

With an increasing demand for industrial dyes in our daily lives, water conditions have become worse. Recently, the removal of such environmentally hazardous pollutants from wastewaters through photocatalytic degradation has been drawing increased attention. Three mesoporous nanophases of BiFeVOx.y as (Bi2FeIIIV1−yO5.5−y) visible light photocatalysts were synthesized in this study using ethylene glycol-citrate sol-gel synthesis combined with microwave- assisted calcination. X-ray diffraction (XRD), differential thermal analysis (DTA), FTIR spectroscopy, X-ray photoelectron spectroscopy (XPS), scanning electron microscopy coupled with energy dispersive X-ray spectrometry (SEM-EDS), nitrogen adsorption-desorption isotherms, and UV-Vis diffuse reflectance spectrophotometry (UV-Vis/DRS) were used to characterize the BiFeVOx.y photocatalysts. The visible light-induced photocatalytic activities of the BiFeVOx.y phases were evaluated by the degradation of methylene blue (MB) dye in aqueous solution at pH ~10.0. The results of this study show that the combination of doping strategy with the utilization of advanced synthesis methods plays an important role in improving the structure and surface properties of BiFeVOx.y phases, and thereby enhancing their adsorption and photocatalytic efficiencies. The synthesized mesoporous tetragonal γ-BiFeVOx.y nanophase has been proven to be a potential visible-light photocatalyst for the degradation of organic dyes.

Construction of BODIPY functional ZIF-8 with improved visible light-induced antibacterial activity

Developing novel bactericide and therapeutic strategy to inhibit bacterial –resistance has become the attractive research area. Light-activated nano-antibacterial agents have become the current research hotspot due to their multimodal antibacterial effect. However, the poor response to visible light and wide energy gap greatly reduce nano-material photo-induced antibacterial activity. Herein, a novel visible light-induced nano-antibacterial composite (BODIPY-ZIF-8) are constructed by introducing boron dipyrromethene (BODIPY) into the framework of ZIF-8. BODIPY-ZIF-8 are found to be the microporous hollow spheres with specific surface area of 612.30 m2/g and exhibit extraordinary photo-induced antibacterial activity against E. coli and S. aureus in comparison to the reported ZIF-8 based antibacterial agents. The successful introduction of BODIPY decreases the band gap energy and increases the light absorption, simultaneously BODIPY acts as a structure-directing agent of controlling the morphology of BODIPY-ZIF-8. The study of antibacterial mechanism indicates that BODIPY-ZIF-8 show synergistic antibacterial effect due to the reactive oxygen species (ROS) production under LED irradiation. The work not only provides a facile method for the preparation of antibacterial composite but develops a valuable strategy to the visible light-induced antibacterial agent.

Effect of Purple Corn Anthocyanin on Antioxidant Activity, Volatile Compound and Sensory Property in Milk During Storage and Light Prevention.

The aim of this study was to observe the effect of purple corn anthocyanin on the light-induced antioxidant activity, free radicals, volatile compounds, color parameters, and sensory properties of milk during storage. There were four groups: (1) negative control, no addition of anthocyanins + exposure to fluorescent light (NC); (2) positive control 1, no addition of anthocyanins + protected from fluorescent light (PC1); (3) positive control 2, the addition of 0.3% (w/v) anthocyanins + exposure to fluorescent light (PC2); and (4) the addition of 0.3% anthocyanins + protected from fluorescent light (AC). The results indicated that the concentration of antioxidant activity parameters in the NC group decreased during the entire storage period, whereas antioxidant activity parameters were unchanged except for the glutathione peroxidase (GSH-Px) in the AC group. Moreover, the NC group showed lower levels of 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging activity and higher levels of superoxide anion and hydrogen peroxide than the other groups after 1 d of storage period. The extent of malondialdehyde accumulation and lipid peroxidation in the control groups were greater than that of the AC group. Twenty-two volatile compounds were determined in milk, which consisted of eight alcohols, three ketones, five aldehydes, two esters, and four hydrocarbons by headspace gas chromatography mass spectrometer analysis. Specifically, individual aldehydes, esters and hydrocarbons in the AC group remained at relatively stable values during storage relative to the other three groups. Stronger positive correlations were detected between several antioxidant activities (superoxide dismutase, GSH-Px) and DPPH scavenging activity as well as total ketones in milk. Adding of anthocyanin did not impact on the color values of L*, a* and b* in light-protected milk during the entire storage period. Some sensory evaluation parameters (flat, garlic/onion/weedy, oxidized-light, oxidized-metal, rancid) in AC group were significantly higher than that of the control group at the end of the period. In conclusion, the current study revealed that the addition of purple corn anthocyanin pigment to light-protected milk had the potential to prevent lipid oxidation, enhance antioxidant activity, maintain volatile compounds and increase the sensory scores.

Hypothesis-Driven, Structure-Based Design in Photopharmacology: The Case of eDHFR Inhibitors.

Photopharmacology uses light to regulate the biological activity of drugs. This precise control is obtained through the incorporation of molecular photoswitches into bioactive molecules. A major challenge for photopharmacology is the rational design of photoswitchable drugs that show light-induced activation. Computer-aided drug design is an attractive approach toward more effective, targeted design. Herein, we critically evaluated different structure-based approaches for photopharmacology with Escherichia coli dihydrofolate reductase (eDHFR) as a case study. Through the iterative examination of our hypotheses, we progressively tuned the design of azobenzene-based, photoswitchable eDHFR inhibitors in five design–make–switch–test–analyze cycles. Targeting a hydrophobic subpocket of the enzyme and a specific salt bridge only with the thermally metastable cis-isomer emerged as the most promising design strategy. We identified three inhibitors that could be activated upon irradiation and reached potencies in the low-nanomolar range. Above all, this systematic study provided valuable insights for future endeavors toward rational photopharmacology.

Visible light-induced photocatalytic chlorine activation enhanced the 0.5% neutral-NaClO/TiO2-x system as an efficient and safe root canal irrigant

A root canal irrigant system with efficiency and safety was constructed using TiO 2-x nanoparticles, 0.5% Neutral-NaClO, and visible light irradiation, generating extensive ROS and RCS rapidly via photocatalysis chlorine activation process. The process enhanced the antibacterial and tissue-dissolution abilities of low concentrations of NaClO in endodontic therapy. • A novel 0.5%Neu-NaClO/TiO 2-x root canal irrigant system was proposed. • The photocatalysis chlorine activation boosted the production of ROS and RCS. • The system exhibited strong antibacterial and tissue-dissolving abilities. • The system showed acceptable application safety in vivo. Root canal irrigation is an essential step for ensuring successful root canal therapy (RCT). Among available irrigants, sodium hypochlorite (NaClO) (0.5%-5.25%) is the most used irrigant solution because of its comprehensive ability to kill bacteria and dissolve organic tissues. Hence, high concentration of NaClO may have negative effects that would lead to devastating complications, and low concentration of NaOCl is safe but shows decreased efficacy. Therefore, a safe and efficient novel catalysis-enhanced root canal irrigant system consisting of 0.5% neutral-NaClO (pH = 7.5), TiO 2-x nanoparticles (5 mg mL −1 ), and visible light irradiation (LED, 10 W, 405–800 nm) was proposed. The effect of the photocatalytic chlorine activation rapidly increased the generation of reactive oxygen species (ROS, •OH) and reactive chlorine species (RCS, •Cl and •ClO) in the system. Consequently, the system exhibited greatly enhanced degradation ability toward methylene blue and typical biological macromolecules, implying its good antibacterial and tissue dissolution activities. Additionally, the antibacterial rates against Enterococcus faecalis in both planktonic and biofilm forms were > 99% after treatment with the proposed system for 5 min, which was comparable to that of the 3% alkaline NaClO. Meanwhile, the system showed desirable pulp tissue-dissolving efficacy, successfully solving the dilemma caused by neutralization. L929 cell experiments as well as rats subcutaneous injection experiments demonstrated the biocompatibility and safety of the system. This work describes a safe and effective endodontic irrigant and proposes a promising strategy for developing NaClO-based disinfectants for wider application.

Perturbation of amygdala/somatostatin-nucleus of the solitary tract projections reduces sensitivity to quinine in a brief-access test

Neural processing in the nucleus of the solitary tract (NST) is critical for concentration-dependent intake of normally preferred and avoided taste stimuli (e.g. affective responding); and is influenced by descending input from numerous forebrain regions. In one region, the central nucleus of the amygdala (CeA), a subpopulation of neurons that project to the NST express the neuropeptide somatostatin (Sst). The present study investigated whether this CeA/Sst-to-NST pathway contributes to concentration-dependent intake of sucrose and quinine hydrochloride (QHCl) solutions using brief-access lick trials (5 s). In both female and male mice, we used virus-based optogenetic tools and laser light illumination to manipulate the activity of CeA/Sst neurons that project to the NST. During light-induced inhibition of CeA/Sst-to-NST neurons, mice licked significantly more to our three highest concentrations of QHCl compared to control mice, while sucrose intake was unaffected. Interestingly, light-induced activation of this descending pathway did not influence licking of either sucrose or QHCl. These findings suggest that the CeA/Sst-to-NST pathway must be active for normal affective responding to an exemplary aversive taste stimulus.

Proton-controlled Action of an Imidazole as Electron Relay in a Photoredox Triad.

Electron relays play a crucial role for efficient light-induced activation by a photo-redox moiety of catalysts for multi-electronic transformations. Their insertion between the two units reduces detrimental energy transfer quenching while establishing at the same time unidirectional electron flow. This rectifying function allows charge accumulation necessary for catalysis. Mapping these events in photophysical studies is an important step towards the development of efficient molecular photocatalysts. Three modular complexes comprised of a Ru-chromophore, an imidazole electron relay function, and a terpyridine unit as coordination site for a metal ion were synthesized and the light-induced electron transfer events studied by laser flash photolysis. In all cases, formation of an imidazole radical by internal electron transfer to the oxidized chromophore was observed. The effect of added base evidenced that the reaction sequence depends strongly on the possibility for deprotonation of the imidazole function in a proton-coupled electron transfer process. In the complex with MnII present as a proxy for a catalytic site, a strongly accelerated decay of the imidazole radical together with a decreased rate of back electron transfer from the external electron acceptor to the oxidized complex was observed. This transient formation of an imidazolyl radical is clear evidence for the function of the imidazole group as an electron relay. The implication of the imidazole proton and the external base for the kinetics and energetics of the electron trafficking is discussed.

Optothermal grid activation of microflow with magnetic nanoparticle thermophoresis for microfluidics.

We report focused light-induced activation of intense magnetic microconvection mediated by suspended magnetic nanoparticles in microscale two-dimensional optothermal grids. Fully anisotropic control of microflow and mass transport fluxes is achieved by engaging the magnetic field along one or the other preferred directions. The effect is based on the recently described thermal diffusion-magnetomechanical coupling in synthetic magnetic nanofluids. We expect that the new phenomenon can be applied as an efficient all-optical mixing strategy in integrated microfluidic devices. This article is part of the theme issue 'Transport phenomena in complex systems (part 2)'.

Noninvasive near-infrared light triggers the remote activation of thermo-responsive TRPV1 channels in neurons based on biodegradable/photothermal polymer micelles.

In this study, we developed a novel biodegradable/photothermal polymer micelle-based remote-activation method for a temperature-sensitive ion channel, namely transient receptor potential cation channel subfamily V member 1 (TRPV1). Biodegradable/photothermal polymer micelles containing indocyanine green (ICG-micelles) were prepared using a simple one-pod mixing method. The obtained ICG-micelles showed biocompatibility and biodegradability. Furthermore, under tissue-penetrable near-infrared (NIR) laser irradiation, the ICG-micelles exhibited excellent photothermal effects and NIR emission. Moreover, NIR light-induced remote activation of neurons was successfully performed. ICG-micelles loaded with anti-TRPV1 antibodies effectively bound TRPV1 on cell membranes, and accelerated Ca2+ ion influx into neuronal cells was induced under NIR irradiation. Based on these findings, it is anticipated that the ICG-micelles can serve as a novel noninvasive remote-activation tool for neuronal cells.

Feature-Based Molecular Networking-An Exciting Tool to Spot Species of the Genus Cortinarius with Hidden Photosensitizers.

Fungi have developed a wide array of defense strategies to overcome mechanical injuries and pathogen infections. Recently, photoactivity has been discovered by showing that pigments isolated from Cortinarius uliginosus produce singlet oxygen under irradiation. To test if this phenomenon is limited to dermocyboid Cortinarii, six colourful Cortinarius species belonging to different classical subgenera (i.e., Dermocybe, Leprocybe, Myxacium, Phlegmacium, and Telamonia) were investigated. Fungal extracts were explored by the combination of in vitro photobiological methods, UHPLC coupled to high-resolution tandem mass spectrometry (UHPLC-HRMS2), feature-based molecular networking (FBMN), and metabolite dereplication techniques. The fungi C. rubrophyllus (Dermocybe) and C. xanthophyllus (Phlegmacium) exhibited promising photobiological activity in a low concentration range (1–7 µg/mL). Using UHPLC-HRMS2-based metabolomic tools, the underlying photoactive principle was investigated. Several monomeric and dimeric anthraquinones were annotated as compounds responsible for the photoactivity. Furthermore, the results showed that light-induced activity is not restricted to a single subgenus, but rather is a trait of Cortinarius species of different phylogenetic lineages and is linked to the presence of fungal anthraquinones. This study highlights the genus Cortinarius as a promising source for novel photopharmaceuticals. Additionally, we showed that putative dereplication of natural photosensitizers can be done by FBMN.

Understanding the Photochemical Properties of Polythiophene Polyelectrolyte Soft Aggregates with Sodium Dodecyl Sulfate for Antimicrobial Activity.

The threat of antibiotic-resistant bacteria is an ever-increasing problem in public health. In this report, we examine the photochemical properties with a proof-of-principle biocidal assay for a novel series of regio-regular imidazolium derivative poly-(3-hexylthiophene)/sodium dodecyl sulfate (P3HT-Im/SDS) materials from ultrafast sub-ps dynamics to μs generation of reactive oxygen species (ROS) and 30 min biocidal reactivity with Escherichia coli (E. coli). This broad series encompassing pure P3HT-Im to cationic, neutral, and anionic P3HT-Im/SDS materials are all interrogated by a variety of techniques to characterize the physical material structure, electronic structure, and antimicrobial activity. Our results show that SDS complexation with P3HT-Im results in aggregate materials with reduced ROS generation and light-induced anti-microbial activity. However, our characterization reveals that the presence of non-aggregated or lightly SDS-covered polymer segments is still capable of ROS generation. Full encapsulation of the P3HT-Im polymer completely deactivates the light killing pathway. High SDS concentrations, near and above critical micelle concentration, further deactivate all anti-microbial activity (light and dark) even though the P3HT-Im regains its electronic properties to generate ROS.

Enhanced photocatalytic degradation of bisphenol A over N,S-doped carbon quantum dot-modified MIL-101(Fe) heterostructure composites under visible light irradiation by persulfate

A novel nitrogen- and sulfur-doped carbon quantum dot-modified MIL-101(Fe) (N,S:CQD/MIL-101(Fe)) heterojunction for visible light-induced activation of persulfate (PS) for bisphenol A (BPA) degradation was studied. The photocatalytic performance of BPA degradation was remarkably promoted by the composite material under the simultaneous action of PS and visible light irradiation. BPA photodegradation (100%) was achieved over 60 min with 0.4 g/L of the N,S:CQD/MIL-101(Fe) composite and 3 mM PS at natural pH. The degradation kinetics rate constants (k) approached 3.6 times higher than that of MIL-101(Fe). The enhanced performance in BPA degradation can be ascribed to the interfacial transference of photoinduced electrons from N,S:CQD to MIL-101(Fe), leading to the valid separation of electron-hole pairs and greatly accelerating PS activation to generate highly reactive SO4•−. Both holes (h+), sulfate radicals (SO4•−), superoxide radicals (•O2−), and hydroxyl radicals (•OH) contributed to BPA degradation according to radical quenching experiments. N,S:CQD/MIL-101(Fe) also exhibited great reusability and excellent catalytic performance after four consecutive cycles of use. This work provides valid organic contaminant degradation under the dual action of visible light and PS with a novel perspective on the fabrication of heterojunction photocatalysts ground on Fe-based MOFs.

TAMI-69. NF1 MUTATION DRIVES NEURONAL ACTIVITY-DEPENDENT OPTIC GLIOMA INITIATION

Abstract Neurons have recently emerged as essential cellular constituents of the tumor microenvironment, where their activity increases the growth of a diverse number of solid tumors. While the role of neurons in tumor progression has been previously demonstrated, the importance of neuronal activity to tumor initiation is less clear, particularly in the setting of cancer predisposition syndromes. In the Neurofibromatosis-1 (NF1) cancer predisposition syndrome, in which tumors arise in close association with nerves, 15% of individuals develop low-grade neoplasms of the optic pathway (optic pathway gliomas [OPGs]), during early childhood, raising the intriguing possibility that postnatal light-induced optic nerve activity drives tumor initiation. Here, we employ an authenticated murine model of Nf1-OPG to demonstrate that stimulation of optic nerve activity increases optic glioma growth, while decreasing visual experience via light deprivation prevents tumor formation and maintenance. We show that Nf1-OPG initiation depends on visual experience during a developmental period susceptible to tumorigenesis. Germline Nf1 mutation in retinal neurons results in aberrantly high optic nerve neuroligin-3 (Nlgn3) shedding in response to retinal neuronal activity. Moreover, genetic Nlgn3 loss or pharmacological inhibition of Nlgn3 shedding blocks murine Nf1 optic gliomagenesis and progression. Collectively, these studies establish an obligate role for neuronal activity in the development of certain brain tumors, elucidate a therapeutic strategy to reduce OPG incidence or mitigate tumor progression, and underscore the role of Nf1 mutation-mediated dysregulation of neuronal signaling pathways in the NF1 cancer predisposition syndrome.

Treatment of Light-Induced Degradation for Solar Cells in a p-PERC Solar Module via Induction Heating

In the photovoltaic industry, there is great interest in increasing the power output of solar cells to achieve grid parity and to promote the widespread use of solar cells. However, despite many developments, a phenomenon called light-induced degradation causes the efficiency of solar cells to deteriorate over time. This study proposes a treatment that can be applied to cells within solar modules. It uses a half-bridge resonance circuit to induce a magnetic field and selectively heat Al electrodes in the solar cells. The electrical state of a solar module was measured in real time as it was being heated, and the results were combined with a kinetics simulation using a cyclic reaction. As the temperature of the solar module increased, the time taken to reach the saturation point and the recovery time decreased. Moreover, the value of the saturation point increased. The light-induced degradation activation energy was similar to results in the existing literature, suggesting that the kinetic model was valid and applicable even when 72 cells were connected in series. This demonstrates that an entire solar module can be treated when the cells are connected in series, and in future multiple modules, could be connected in series during treatment.

Reflective mirror-based line-scan adaptive optics OCT for imaging retinal structure and function.

Line-scan OCT incorporated with adaptive optics (AO) offers high resolution, speed, and sensitivity for imaging retinal structure and function in vivo. Here, we introduce its implementation with reflective mirror-based afocal telescopes, optimized for imaging light-induced retinal activity (optoretinography) and weak retinal reflections at the cellular scale. A non-planar optical design was followed based on previous recommendations with key differences specific to a line-scan geometry. The three beam paths fundamental to an OCT system -illumination/sample, detection, and reference- were modeled in Zemax optical design software to yield theoretically diffraction-limited performance over a 2.2 deg. field-of-view and 1.5 D vergence range at the eye's pupil. The performance for imaging retinal structure was exemplified by cellular-scale visualization of retinal ganglion cells, macrophages, foveal cones, and rods in human observers. The performance for functional imaging was exemplified by resolving the light-evoked optical changes in foveal cone photoreceptors where the spatial resolution was sufficient for cone spectral classification at an eccentricity 0.3 deg. from the foveal center. This enabled the first in vivo demonstration of reduced S-cone (short-wavelength cone) density in the human foveola, thus far observed only in ex vivo histological preparations. Together, the feasibility for high resolution imaging of retinal structure and function demonstrated here holds significant potential for basic science and translational applications.

Graphitic Carbon Nitride as a New Sustainable Photocatalyst for Textile Functionalization.

As a promising organic semiconducting material, polymeric graphitic carbon nitride (g-C3N4) has attracted much attention due to its excellent optical and photoelectrochemical properties, thermal stability, chemical inertness, nontoxicity, abundance, and low cost. Its advantageous visible light-induced photocatalytic activity has already been beneficially used in the fields of environmental remediation, biological applications, healthcare, energy conversion and storage, and fuel production. Despite the recognized potential of g-C3N4, there is still a knowledge gap in the application of g-C3N4 in the field of textiles, with no published reviews on the g-C3N4-functionalization of textile materials. Therefore, this review article aims to provide a critical overview of recent advances in the surface and bulk modification of textile fibres by g-C3N4 and its composites to tailor photocatalytic self-cleaning, antibacterial, and flame retardant properties as well as to create a textile catalytic platform for water disinfection, the removal of various organic pollutants from water, and selective organic transformations. This paper highlights the possibilities of producing g-C3N4-functionalized textile substrates and suggests some future prospects for this research area.

Optogenetic Manipulation of Olfactory Responses in Transgenic Zebrafish: A Neurobiological and Behavioral Study.

Olfaction is an important neural system for survival and fundamental behaviors such as predator avoidance, food finding, memory formation, reproduction, and social communication. However, the neural circuits and pathways associated with the olfactory system in various behaviors are not fully understood. Recent advances in optogenetics, high-resolution in vivo imaging, and reconstructions of neuronal circuits have created new opportunities to understand such neural circuits. Here, we generated a transgenic zebrafish to manipulate olfactory signal optically, expressing the Channelrhodopsin (ChR2) under the control of the olfactory specific promoter, omp. We observed light-induced neuronal activity of olfactory system in the transgenic fish by examining c-fos expression, and a calcium indicator suggesting that blue light stimulation caused activation of olfactory neurons in a non-invasive manner. To examine whether the photo-activation of olfactory sensory neurons affect behavior of zebrafish larvae, we devised a behavioral choice paradigm and tested how zebrafish larvae choose between two conflicting sensory cues, an aversive odor or the naturally preferred phototaxis. We found that when the conflicting cues (the preferred light and aversive odor) were presented together simultaneously, zebrafish larvae swam away from the aversive odor. However, the transgenic fish with photo-activation were insensitive to the aversive odor and exhibited olfactory desensitization upon optical stimulation of ChR2. These results show that an aversive olfactory stimulus can override phototaxis, and that olfaction is important in decision making in zebrafish. This new transgenic model will be useful for the analysis of olfaction related behaviors and for the dissection of underlying neural circuits.

Light-induced activities of novel naphtho[1,8-ef]isoindole-7,8,10(9H)-trione and oxoisoaporphine derivatives towards mosquito larvae

Infected mosquitoes are significant vectors of dengue, yellow fever, chikungunya, zika and other pathogens. In the view of increasing resistance in mosquito larvae control, photoactivated insecticides is a promising approach by utilizing highly toxic singlet oxygen produced by photosensitizer through irradiation. However, the choice of photosensitizer for mosquito control is limited. Here, we report a novel series of naphtho[1,8-ef]isoindole-7,8,10(9H)-trione and oxoisoaporphines derivatives as excellent type II photosensitizers. Meanwhile, the light-dependent activities against permethrin-susceptible and permethrin-resistant strain of Aedes aegypti mosquito larvae of these compounds were evaluated. Among them, compound 7b was proved to be potential photodynamic insecticide due to its excellent phototoxicity, the LC50 value was 0.19 μg mL−1 under visible light irradiation. The irradiation-generated enhancement in the activity was more than 520-fold. This compound could be the potential candidate in the search for new photoactivated insecticide leads. Importantly, 7b has good fluorescence quantum yield (ϕF = 0.70), it can be used as a fluorescence indicator in mosquito larvae to observe uptake and morphology change.

Visible Light-Induced Antibacterial Activity of Pigments Extracted from Dregs of Green and Black Teas.

Chlorophyll and its derivatives are potential natural sensitizers frequently applied in antimicrobial photodynamic therapy. Chlorophyll derivatives are formed naturally during tea processing, but they do not contribute to the color of tea infusions and thus are presumably left in the tea dregs. The present study aimed to investigate (i) the chlorophyll remnants in the pigments recovered from dregs of green and black teas and (ii) the antibacterial activity of pigments extracted from the tea dregs upon illumination using a light-emitting diode (LED) as the light source. Pigment analysis using high-performance liquid chromatography (HPLC) revealed the presence of main degradation products of chlorophylls, such as pheophytin and its epimers, pyropheophytin, and pheophorbides. In vitro assays demonstrated significant reductions in the number of viable bacteria in the presence of the pigments after 30 min of incubation with LED light irradiation. The descending order of bacterial susceptibility was Listeria monocytogenes > Staphylococcus aureus > Escherichia coli > Salmonella typhi. At an equivalent irradiation intensity, the blue and red LEDs could stimulate a comparable inactivation effect through photodynamic reactions. These findings demonstrated the valorization potential of tea dregs as a source of chlorophyll derivatives with visible light-induced antibacterial activity.

Optogenetic modulation of cardiac action potential properties may prevent arrhythmogenesis in short and long QT syndromes.

Abnormal action potential (AP) properties, as occurs in long or short QT syndromes (LQTS and SQTS, respectively), can cause life-threatening arrhythmias. Optogenetics strategies, utilizing light-sensitive proteins, have emerged as experimental platforms for cardiac pacing, resynchronization, and defibrillation. We tested the hypothesis that similar optogenetic tools can modulate the cardiomyocyte’s AP properties, as a potentially novel antiarrhythmic strategy. Healthy control and LQTS/SQTS patient–specific human induced pluripotent stem cell–derived cardiomyocytes (hiPSC-CMs) were transduced to express the light-sensitive cationic channel channelrhodopsin-2 (ChR2) or the anionic-selective opsin, ACR2. Detailed patch-clamp, confocal-microscopy, and optical mapping studies evaluated the ability of spatiotemporally defined optogenetic protocols to modulate AP properties and prevent arrhythmogenesis in the hiPSC-CMs cell/tissue models. Depending on illumination timing, light-induced ChR2 activation induced robust prolongation or mild shortening of AP duration (APD), while ACR2 activation allowed effective APD shortening. Fine-tuning these approaches allowed for the normalization of pathological AP properties and suppression of arrhythmogenicity in the LQTS/SQTS hiPSC-CM cellular models. We next established a SQTS–hiPSC-CMs–based tissue model of reentrant-arrhythmias using optogenetic cross-field stimulation. An APD-modulating optogenetic protocol was then designed to dynamically prolong APD of the propagating wavefront, completely preventing arrhythmogenesis in this model. This work highlights the potential of optogenetics in studying repolarization abnormalities and in developing novel antiarrhythmic therapies.