-
Amyloid : the International Journal of... Mar 2017Thioflavin T (ThT) has been widely used to investigate amyloid formation since 1989. While concerns have recently been raised about its use as a probe specific for... (Review)
Review
Thioflavin T (ThT) has been widely used to investigate amyloid formation since 1989. While concerns have recently been raised about its use as a probe specific for amyloid, ThT still continues to be a very valuable tool for studying kinetic aspects of fibrillation and associated inhibition mechanisms. This review aims to provide a conceptual instruction manual, covering appropriate considerations and pitfalls related to the use of ThT. We start by giving a brief introduction to amyloid formation with focus on the morphology of different aggregate species, followed by a discussion of the quality of protein needed to obtain reliable fibrillation data. After an overview of the photochemical basis for ThT's amyloid binding properties and artifacts that may arise from this, we describe how to plan and analyze ThT assays. We conclude with recommendations for complementary techniques to address shortcomings in the ThT assay.
Topics: Amyloid; Animals; Benzothiazoles; Humans; Photochemistry; Thiazoles
PubMed: 28393556
DOI: 10.1080/13506129.2017.1304905 -
Functional Plant Biology : FPB Jul 2021Solar-induced chlorophyll (chl) fluorescence (SIF) has been shown to be positively correlated with vegetation photosynthesis, suggesting that it is a useful signal for...
Solar-induced chlorophyll (chl) fluorescence (SIF) has been shown to be positively correlated with vegetation photosynthesis, suggesting that it is a useful signal for understanding of environmental responses and spatial heterogeneity of photosynthetic activity at various scales from leaf to the globe. Photosynthesis is often inhibited in stressful environments (photoinhibition), but how photoinhibition influences the relationship between photosynthesis and chl fluorescence remains unclear. Here, I studied light energy allocation among photosynthesis, chl fluorescence and heat dissipation in photoinhibited leaves and tested whether photosynthesis in photoinhibited leaves can be evaluated from chl fluorescence and reflectance spectra in remote sensing. Chl fluorescence and reflection spectra were examined with the pulse amplified modulation (PAM) system and spectroradiometer, respectively. Photoinhibited leaves had lower photosynthetic rates and quantum yields of photochemistry (ΦP) and higher chl fluorescence yields. Consequently, photosynthesis was negatively correlated with chl fluorescence, which contrasts the positive relationships between photosynthesis and SIF observed in past remote sensing studies. This suggests that vegetation photosynthesis evaluated solely from chl fluorescence may be overestimated if the vegetation is dominated by severely photoinhibited leaves. When a model of energy allocation was applied, ΦP estimated from chl fluorescence and photochemical reflectance index (PRI) significantly correlated with the observed ΦP, suggesting that the model is useful to evaluate photosynthetic activities of photoinhibited leaves by remote sensing.
Topics: Chlorophyll; Fluorescence; Photochemistry; Photosynthesis; Plant Leaves
PubMed: 33832552
DOI: 10.1071/FP20365 -
Nano Letters Sep 2022Plasmonic nanostructures have attracted increasing interest in the fields of photochemistry and photocatalysis for their ability to enhance reactivity and tune reaction...
Plasmonic nanostructures have attracted increasing interest in the fields of photochemistry and photocatalysis for their ability to enhance reactivity and tune reaction selectivity, a benefit of their strong interactions with light and their multiple energy decay mechanisms. Here we introduce the use of earth-abundant plasmonic aluminum nanoparticles as a promising renewable detoxifier of the sulfur mustard simulant 2-chloroethylethylsulfide through gas phase photodecomposition. Analysis of the decomposition products indicates that C-S bond breaking is facilitated under illumination, while C-Cl breaking and HCl elimination are favored under thermocatalytic (dark) conditions. This difference in reaction pathways illuminates the potential of plasmonic nanoparticles to tailor reaction selectivity toward less hazardous products in the detoxification of chemical warfare agents. Moreover, the photocatalytic activity of the Al nanoparticles can be regenerated almost completely after the reaction concludes through a simple surface treatment.
Topics: Aluminum; Chemical Warfare Agents; Mustard Gas; Nanoparticles; Photochemistry
PubMed: 36073653
DOI: 10.1021/acs.nanolett.2c03188 -
Photochemical & Photobiological... Aug 2022Plants play a central role in the photochemistry of chemicals in the environment. They represent a major atmospheric source of volatile organic compounds (VOCs) but also... (Review)
Review
Plants play a central role in the photochemistry of chemicals in the environment. They represent a major atmospheric source of volatile organic compounds (VOCs) but also an important environmental surface for the deposition and photochemical reactions of pesticides, gaseous and particulate pollutants. In this review, we point out the role of plant leaves in these processes, as a support affecting the reactions physically and chemically and as a partner through the release of natural constituents (water, secondary metabolites). We discuss the influence of the chosen support (leaves, needle surfaces or fruit cuticles, extracted cuticular waxes and model surfaces) and other factors (additives, pesticides mixture, and secondary metabolites) on the photochemical degradation kinetics and mechanisms. We also show how plants can be a source of photochemically reactive species which can act as photosensitizers promoting the photodegradation of pesticides or the formation and aging of secondary organic aerosols (SOA) and secondary organic materials (SOM). Understanding the fate of chemicals on plants is a research area located at the interface between photochemistry, analytical chemistry, atmospheric chemistry, microbiology and vegetal physiology. Pluridisciplinary approaches are needed to deeply understand these complex phenomena in a comprehensive way. To overcome this challenge, we summarize future research directions which have been clearly overlooked until now.
Topics: Aerosols; Interdisciplinary Research; Pesticides; Photochemistry; Plants
PubMed: 35532879
DOI: 10.1007/s43630-022-00228-w -
Journal of Nanobiotechnology Sep 2023Calcium (Ca) is essential for mitochondrial homeostasis and function coordination, particularly in cancer cells that metabolize frequently to sustain their growth....
Calcium (Ca) is essential for mitochondrial homeostasis and function coordination, particularly in cancer cells that metabolize frequently to sustain their growth. Photochemistry mediated calcium overload has attracted lots of attention as an effective way to achieve tumor suppression. Herein, we developed a photonanomedicine to synergistically induce calcium overload via cell-surface photochemistry and thus tumor suppression. Specifically, the photosensitizer, protoporphyrin IX (PpIX) was loaded onto upconversion nanoparticles (UCNP), which was subsequently modified by a polymer bearing photo-crosslinking cinnamate (CA) groups. The resulting nanoparticle was further functionalized by anti-CD20 aptamers (Apt), to give photonanomedicine. The interaction between CD20 receptors and anti-CD20 aptamers allowed photonanomedicine to accurately attach onto the Raji cell surface after an intravenous injection. Following the local application of a 980 nm NIR laser, the photonanomedicine was able to capture the NIR light and convert it into ultraviolet (UV) light. On one hand, the converted UV light led the crosslinking of cinnamate groups in photonanomedicine, further stimulating the clustering of CD20 receptors and causing Ca influx. On the other hand, the UV light could simultaneously excited PpIX to generate reactive oxygen species (ROS) in situ to break down the integrity of cell membrane and lead to an influx of Ca. The synergistic Ca overload mediated by photonanomedicine exhibited an enhanced and superior anti-tumor efficacy. We believe this photonanomedicine expands the toolbox to manipulate intracellular Ca concentration and holds a great potential as an anti-tumor therapy.
Topics: Calcium; Photochemistry; Cell Membrane; Light; Cinnamates; Oligonucleotides
PubMed: 37726778
DOI: 10.1186/s12951-023-02090-z -
Chemical Reviews Jan 2022Recent progress in the development of photocatalytic reactions promoted by visible light is leading to a renaissance in the use of photochemistry in the construction of... (Review)
Review
Recent progress in the development of photocatalytic reactions promoted by visible light is leading to a renaissance in the use of photochemistry in the construction of structurally elaborate organic molecules. Because of the rich functionality found in natural products, studies in natural product total synthesis provide useful insights into functional group compatibility of these new photocatalytic methods as well as their impact on synthetic strategy. In this review, we examine total syntheses published through the end of 2020 that employ a visible-light photoredox catalytic step. To assist someone interested in employing the photocatalytic steps discussed, the review is organized largely by the nature of the bond formed in the photocatalytic step.
Topics: Biological Products; Catalysis; Light; Oxidation-Reduction; Photochemistry
PubMed: 34232019
DOI: 10.1021/acs.chemrev.1c00247 -
Environmental Science and Pollution... Apr 2019Heavy metals are discharged into aquatic environment and causes serious problems to the environment, human's health, and other organisms. The industrial effluents... (Review)
Review
Heavy metals are discharged into aquatic environment and causes serious problems to the environment, human's health, and other organisms. The industrial effluents contain high concentration of heavy metals that should be treated by different technologies. Numerous technologies have been widely used for the remediation of heavy metals such as chemical precipitation, ion exchange, membrane filtration, adsorption, coagulation-flocculation, floatation, electrochemical treatment, bioremediation, and photocatalysis. Among these technologies, photocatalysis has gained much attention due to chemical, physical, and electrical properties of heterogeneous semiconductor nano-photocatalysis. Bismuth vanadate is an n-type semiconductor photocatalyst having 2.4 eV band gap that was widely used from several decades having three monoclinic, tetragonal, and tetragonal zircon structures, but it also have some limitation that can be overcome by modification with metals or non-metals to gain high removal efficiency of heavy metals. This modification can tune its photocatalytic properties like band gap, absorption capacity, and surface area resulting in high photocatalytic performance towards heavy metals detoxification.
Topics: Bismuth; Metals, Heavy; Nanotechnology; Photochemistry; Vanadates; Water Pollutants, Chemical
PubMed: 30835072
DOI: 10.1007/s11356-019-04547-x -
Bioconjugate Chemistry Oct 2021Phase transition is a promising aspect of DNA as biopolymers. Anionic DNA oligonucleotides easily form complexes with cationic polypeptides such as polylysine, and...
Phase transition is a promising aspect of DNA as biopolymers. Anionic DNA oligonucleotides easily form complexes with cationic polypeptides such as polylysine, and duplex formation significantly influences their complexation and resulting microcompartments. In this study, phase transition of microcompartments containing DNA and polylysine was systematically induced by modulating duplex formation of arylazopyrazole-conjugated oligonucleotides with light. We demonstrated that UV irradiation destabilized DNA duplex and generated isotropic coacervates, while duplex stabilization by visible light irradiation caused the formation of liquid crystalline coacervates. This photocontrol of phase transition was highly repeatable, and similar changes were observed even after ten cycles of light irradiation. Our approach would provide a robust control layer to the development of tailor-made microcompartments.
Topics: DNA; Oligonucleotides; Photochemistry
PubMed: 34498851
DOI: 10.1021/acs.bioconjchem.1c00302 -
Medecine Sciences : M/S Mar 2015Numerous achievements in biology have resulted from the evolution of biophotonics, a general term describing the use of light in the study of living systems. Over the... (Review)
Review
Numerous achievements in biology have resulted from the evolution of biophotonics, a general term describing the use of light in the study of living systems. Over the last fifteen years, biophotonics has progressively blended with molecular genetics to give rise to optogenetics, a set of techniques enabling the functional study of genetically-defined cellular populations, compartments or processes with optical methods. In neuroscience, optogenetics allows real-time monitoring and control of the activity of specific neuronal populations in a wide range of animal models. This technical breakthrough provides a new level of sophistication in experimental approaches in the field of fundamental neuroscience, significantly enhancing our ability to understand the complexity of neuronal circuits.
Topics: Animals; Fluorescent Dyes; Gene Transfer Techniques; Humans; Neurons; Neurosciences; Opsins; Optogenetics; Photochemistry
PubMed: 25855283
DOI: 10.1051/medsci/20153103015 -
Angewandte Chemie (International Ed. in... Feb 2023Light passes through biological tissue, and so it is used for imaging biological processes in situ. Such observation is part of the very essence of science, but... (Review)
Review
Light passes through biological tissue, and so it is used for imaging biological processes in situ. Such observation is part of the very essence of science, but mechanistic understanding requires intervention. For more than 50 years a "second function" for light has emerged; namely, that of photochemical control. Caged compounds are biologically inert signaling molecules that are activated by light. These optical probes enable external instruction of biological processes by stimulation of an individual element in complex signaling cascades in its native environment. Cause and effect are linked directly in spatial, temporal, and frequency domains in a quantitative manner by their use. I provide a guide to the basic properties required to make effective caged compounds for the biological sciences.
Topics: Photochemistry; Signal Transduction; Biology
PubMed: 36646644
DOI: 10.1002/anie.202206083