Room-Temperature Gas Sensors Under Photoactivation:From Metal Oxides to 2D Materials

Room-temperature gas sensors have aroused great attention in current gas sensor technology because of deemed demand of cheap,low power consumption and portable sensors for rapidly growing Internet of things applications.As an important approach,light illumination has been exploited for room-temperature operation with improving gas sensor's attributes including sensitivity,speed and selectivity.This review provides an overview of the utilization of photoactivated nanomaterials in gas sensing field.First,recent advances in gas sensing of some exciting different nanostructures and hybrids of metal oxide semiconductors under light illumination are highlighted.Later,excellent gas sensing performance of emerging two-dimensional materialsbased sensors under light illumination is discussed in details with proposed gas sensing mechanism.Originated impressive features from the interaction of photons with sensing materials are elucidated in the context of modulating sensing characteristics.Finally,the review concludes with key and constructive insights into current and future perspectives in the light-activated nanomaterials for optoelectronic gas sensor applications.

Efficient synthesis of bottle-brush polymers enabled by selective photoactivation strategy in NIR-induced PET-RAFT polymerization

Bottle-brush polymers possessing densely grafted side chains have special properties that are distinct from linear macromolecules.Herein,an efficient method for preparing bottle-brush polymers based on a selective photoactivation strategy in the photoinduced electron/energy transfer reversible addition-fragmentation chain transfer(PET-RAFT)polymerization was developed.A methacrylate monomer 2-(2-(dodecylthiocarbonothioylthio)propionate)ethyl methacrylate(DTPEMA)containing a 2-(dodecylthiocarbonothioylthio)propionate(DTP)unit with a secondary R group was designed.Utilizing the unique selectivity of metal naphthalocyanine photocatalyst zinc 2,11,20,29-tetra-tert-butyl-2,3-naphthalocyanine(ZnTtBNc)toward trithiocarbonate with tertiary R group,the PET-RAFT polymerization of DTPEMA catalyzed by ZnTtBNc was performed under near infrared(NIR)light(λ_(max)=760 nm)irradiation at room temperature,using 4-cyano-4-[(dodecylsulfanylthiocarbonyl)-sulfanyl]pentanoic acid(CDTPA)with a tertiary R group as a chain transfer agent(CTA).Proton nuclear magnetic resonance(1H NMR)and gel permeation chromatography(GPC)results demonstrated that the DTP units in the side chains were inert during the polymerization.By grafting poly(methyl acrylate)(PMA)from PDTPEMA via thermal-initiated RAFT polymerization,welldefined P(DTPEMA-g-PMA)bottle-brush polymers could be afforded.Furthermore,the film prepared from the bottle-brush polymer exhibited excellent scratch self-healing property due to the interlocking of side chains.

Photoactivated Activities on Spodoptera litura Cell, Singlet Oxygen and Photostability of Photosensitizers

[Objective ]The aim of this study was to improve the photostability of pho-tosensitizers. [Method] 2,5-Diphenylthiophene and 2,5-dithienylethynylthiophene were synthesized by replacing thiophene rings of α-terthienyl （α-T） with benzene rings. Photoactivated activities on Spodoptera litura （SL） cells, singlet oxygen with UV and photostability of photosensitizers were investigated. [Result] The cytotoxicity of pho-tosensitizer 2,5-diphenylthiophene on SL cells was 0.22 and 0.16 μg/ml after treat-ment for 24 and 48 h, respectively, while that of 2,5-dithienylethynylthiophene on SL cells was 0.06 and 0.04 μg/ml. Singlet oxygen of 2,5-diphenylthiophene and 2,5-dithienylethynylthiophene was 1.047 5, 1.529 4 μg/mmol under UV, respectively. Degradation dynamic equations of 2,5-diphenylthiophene and 2,5-dithienylethynylthio-phene in methanol were Ct= 5.227 1e-0.006 1t, Ct= 5.084 2e-0.097 3t and half life was 111.79, 7.12 h. [Conclusion] Photosensitizer 2,5-diphenylthiophene has high singlet oxygen production ability, and high photoactivated cytotoxicity on SL cells under UV. Moreover, 2,5-diphenylthiophene has overcome the deficiency of photoactivated in-secticides, which is not applied directly in field because it degrades quickly in the environment.

Super-resolution microscopy and its applications in neuroscience

Optical microscopy promises researchers to soe most tiny substances directly.However,the resolution of conventional microscopy is resticted by the diffraction limit.This makes it a challenge to observe subcellular processes happened in nanoscale.The development of super-resolution microscopy provides a solution to this challenge.Here,we briefly review several commonly used super-resolution techniques,explicating their basic principles and applications in biological science,especially in neuroscience.In addition,characteristics and limitations of each techrique are compared to provide a guidance for biologists to choose the most suitable tool.

Collagen crosslinking with photoactivated riboflavin in advanced infectious keratitis with corneal melting: Electrophysiological Study

AIM: To assess the effect of photoactivated chromophore for keratitis crosslinking(PACK-CXL) in case of severe keratitis with melting on the electrophysiological function of the retina and the optic nerve.METHODS: The study included 32 eyes of 32 patients with smear positive severe infectious keratitis with corneal melting. The patients were randomly divided into two groups. Group I(control group) included 16 eyes received systemic and topical antimicrobial drugs guarded by culture and sensitivity test. Group II underwent CXL and then continued their antimicrobial treatment. Full field electroretinogram(ERG) and flash visual evoked potential(VEP) were done for each patient in both groups basically and then 1 wk, 1 and 3 mo post-treatment to assess the changes in the electrophysiological function of the retina and optic nerve.RESULTS: Healing of 10 eyes in group I in comparison to 14 eyes in group II was recorded. The mean duration of healing was 36.56±5.21 d in group I vs 20.2±4.4 d in group II(P<0.005). In group II, ERG showed an insignificant reduction of all parameters of ERG and VEP after CXL. The amplitude of scotopic rod response, oscillatory potential amplitude, flicker amplitude and photopic cone response were insignificantly decreased(P=0.4, 0.8, 0.1, and 0.3 respectively). There were insignificant prolongation of latencies of scotopic rod, oscillatory potential, flicker and photopic cone response(P=0.2, 0.7, 0.5 and 0.1). There was slight delay in latency of VEP without a significant reduction in amplitude.CONCLUSION: CXL is an effective technique in treatment of severe infectious keratitis with melting as it halts the melting process with acceptable safety on the retinal and optic nerve function.

PACK-CXL vs.antimicrobial therapy for bacterial,fungal,and mixed infectious keratitis:a prospective randomized phase 3 trial

Background:Infectious keratitis is a major cause of global blindness.We tested whether standalone photoactivated chromophore corneal cross-linking(PACK-CXL)may be an efective frst-line treatment in early to moderate infectious keratitis,compared with standard antimicrobial treatment.Methods:This is a randomized,controlled,multinational phase 3 clinical trial.Participants in fve centers in Egypt,India,Iran,Israel,and China,aged≥18 years,with infectious keratitis of presumed bacterial,fungal,or mixed origin,were randomly assigned(1:1)to PACK-CXL,or antimicrobial therapy.Outcomes measures included healing,defned as time to re-epithelialization of the corneal epithelial defect in the absence of infammatory activity in the anterior chamber and clearance of stromal infltrates.Treatment success was defned as the complete resolution of signs of infection.Results:Between July 21,2016,and March 4,2020,participants were randomly assigned to receive PACK-CXL(n=18)or antimicrobial therapy per American Academy of Ophthalmology(AAO)guidelines(n=21).No participants were lost to follow-up.Four eyes were excluded from the epithelialization time analysis due to treatment failure:two in the antimicrobial therapy group,and two in the PACK-CXL group.Success rates were 88.9%(16/18 patients)in the PACK-CXL group and 90.5%(19/21 patients)in the medication group.There was no signifcant diference in time to complete corneal re-epithelialization(P=0.828)between both treatment groups.Conclusions:PACK-CXL may be an alternative to antimicrobial drugs for frst-line and standalone treatment of early to moderate infectious keratitis of bacterial or fungal origin.

Light-Driven Dinitrogen Activation with Transition Metal Complexes:Mechanisms and Applications

Comprehensive Summary,The Haber-Bosch process,which is used for ammonia(NH3)synthesis,requires vast amounts of energy,accounting for approximately 1%—2%of the world's annual energy consumption.Therefore,researchers in both industry and academia are interested in developing sustainable and environmentally friendly methods for synthesizing nitrogenous compounds at ambient conditions using renewable energy sources such as visible light.While several examples of thermal activation of dinitrogen molecules have been demonstrated using various transition metals and ligand frameworks,the use of light to weaken or split the strong N—N bond has been less explored.This article presents an overview of molecular complexes capable of dinitrogen photocleavage and provides mechanistic insights into the photoactivation process through experimental and theoretical studies.We believe this review will provide readers with an in-depth understanding of the current state-of-the-art and future research perspectives,particularly in the use of visible light for dinitrogen activation and transformation.

Red-Light-Dependent Interaction of phyB with SPA1 Promotes COP1-SPA1 Dissociation and Photomorphogenic Development in Arabidopsis

Arabidopsis phytochromes （phyA-phyE） are photoreceptors dedicated to sensing red/far-red light. Phyto- chromes promote photomorphogenic developments upon light irradiation via a signaling pathway that involves rapid degradation of PIFs （PHYTOCHROME INTERACTING FACTORS） and suppression of COP1 （CONSTITUTIVE PHOTOMORPHOGENIC 1） nuclear accumulation, through physical interactions with PIFs and COP1, respectively. Both phyA and phyB, the two best characterized phytochromes, regulate plant photomorphogenesis predominantly under far-red light and red light, respectively. It has been demonstrated that SPA1 （SUPPRESSOR OF PHYTOCHROME A 1） associates with COP1 to promote COP1 activity and suppress photomorphogenesis. Here, we report that the mechanism underlying phyB- promoted photomorphogenesis in red light involves direct physical and functional interactions between red-light-activated phyB and SPA1. We found that SPA1 acts genetically downstream of PHYB to repress photomorphogenesis in red light. Protein interaction studies in both yeast and Arabidopsis demonstrated that the photoactivated phyB represses the association of SPA1 with COP1, which is mediated, at least in part, through red-light-dependent interaction of phyB with SPA1. Moreover, we show that phyA physically interacts with SPA1 in a Pfr-form-dependent manner, and that SPA1 acts downstream of PHYA to regulate photomorphogenesis in far-red light. This study provides a genetic and biochemical model of how photo- activated phyB represses the activity of COP1-SPA1 complex through direct interaction with SPA1 to promote photomorphogenesis in red light.

New techniques and strategies in drug discovery

Great success has been witnessed in last decades,some new techniques and strategies have been widely used in drug discovery.In this roadmap,several representative techniques and strategies are highlighted to show recent advances in this filed.(A)A DOX protocol has been developed for accurate protein-ligand binding structure prediction,in which first principle method was used to rank the binding poses.Validation against crystal structures have found that DOX prediction achieved an impressive success rate of 99%,indicating significant improvement over molecular docking method.(B)Virtual target profiling is a compound-centric strategy enabling a parallel implementation of interrogating compounds against various targets in a single screen,which has been used in hit/lead identification,drug repositioning,and mechanism-of-action studies.Current and emerging methods for virtual target profiling are briefly summarized herein.(C)Research on targeted autophagy to treat diseases has received encouraging progress.However,due to the complexity of autophagy and disease,experimental and in silico methods should be performed synergistically for the entire process.This part focuses on in silico methods in autophagy research to promote their use in medicinal research.(D)Histone deacetylases(HDACs)play important roles in various biological functions through the deacetylation of lysine residues.Recent studies demonstrated that HDACs,which possess low deacetylase activities,exhibited more efficient defatty-acylase activities.Here,we review the defatty-acylase activity of HDACs and describe examples for the design of isoform selective HDAC inhibitor.(E)The FDA approval of three kinase allosteric inhibitors and some others entering clinical study has spurred considerable interests in this targeted drug discovery area.(F)Recent advances are reviewed in structure-based design of novel antiviral agents to combat drug resistance.(G)Since nitric oxide(NO)exerts anticancer activity depending on its concentration,optimal levels of NO in cancer cells is desirable.In this minireview,we briefly describe recent advances in the research of NO-based anticancer agents by our group and present some opinions on the future development of these agents.(H)The field of photoactivation strategies have been extensively developed for controlling chemical and biological processes with light.This review will summarize and provide insight into recent research advances in the understanding of photoactivatable molecules including photoactivatable caged prodrugs and photoswitchable molecules.

Photosensitivity in Ce/Sm-decorated Keggin polyoxomolybdates:an interesting photoinduced coloration phenomenon of mixed- metal clusters involving energy transfer from rare-earth fluorescence

Ce/Sm ions are covalently grafted to a Keggin polyoxomolybdate cluster[PMo12O40]3-to yield interesting fluorescent-photodarkening molecular systems.Their photoresponce processes are observed to be activated via energy transfer from luminescent fragments to photocoloration components.

Evidence for a specific role of CI^- in keeping the functional organization of Mn complex in PSⅡ

The formation of molecular oxygen from water by PSⅡ is supposed to occur by meansof a linear, four-electron oxidation process involving five so-called S-state intermediates（S0→S4）. The Mn-cluster is considered to be ligated to the PSⅡ reaction centerpolypeptides, but for its functioning, 43 and 47ku chlorophyll proteins, three peripheralproteins of 17, 23 and 33 ku need to be associated with the lumenal surface of thylakoidmembranes. These proteins, together with Ca2+ and Cl-, play a regulatory role in the effi-

Long-term in vivo single-cell lineage tracing of deep structures using three-photon activation

Genetic labeling techniques allow for noninvasive lineage tracing of cells in vivo.Two-photon inducible activators provide spatial resolution for superficial cells,but labeling cells located deep within tissues is precluded by scattering of the far-red illumination required for two-photon photolysis.Three-photon illumination has been shown to overcome the limitations of two-photon microscopy for in vivo imaging of deep structures,but whether it can be used for photoactivation remains to be tested.Here we show,both theoretically and experimentally,that three-photon illumination overcomes scattering problems by combining longer wavelength excitation with high uncaging three-photon cross-section molecules.We prospectively labeled heart muscle cells in zebrafish embryos and found permanent labeling in their progeny in adult animals with negligible tissue damage.This technique allows for a noninvasive genetic manipulation in vivo with spatial,temporal and cell-type specificity,and may have wide applicability in experimental biology.

An Aggregation-Induced Emission Optical Highlighter for the Studies of Endoplasmic Reticulum-Lipid Droplet Content Dynamics

The lipid droplet(LD)is a dynamic organelle responsible for lipid storage and metabolism that plays important roles in maintaining lipid homeostasis.However,limited strategies are available for tracking the LD content exchange.In this contribution,we report a novel fluorescent probe,TPEAmAl,for real-time LD content dynamics tracking.TPE-AmAl is LD-specific,but emits faintly due to its intramolecular motion.Upon photoactivation,it undergoes a photocyclodehydrogenation reaction and shows a large fluorescence increment.Thus,it can be used for highlighting selected LDs with high spatial resolution.By measuring the fluorescence changes in the distal region,the lipid content exchange efficiency can be estimated.In our experiment,LD content exchange rate differences between nascent and mature LDs as well as cells with normal and deficient LD budding machinery are observed.This probe expands the fluorescence-based toolbox for LD content dynamics studies.

Syntheses, Optical Properties and Photoactivated Insecticidal Activities of Cyclic Arylethynylsilanes

Syntheses and optical properties of cyclic arylethynylsilanes containing one or two trialkyne pockets were described. Optical properties such as UV-vis spectra, photoluminescence and quantum yield based on these conjugated structural features were compared with each other. The photoactivated insecticidal activities against the 4th-instar larvae of Aedes albopictus （Skuse） were evaluated.

Light-stimulus Dual-drug Responsive Nanoparticles for Photoactivated Therapy Using Mesoporous Silica Nanospheres

Photoactivated therapy is an exciting new method of cancer treatment. A new light-stimulus dual-drug responsive nanoparticles based on mesoporous silica nanoparticles（MSN） were developed to control cellular anticancer drug release. The prepared Curcumin（Cur）-loaded nanoparticles MSN-Pt-PEG@Cur[PEG=poly（ethylene glycol）] could be activated by photostimulation to generate reactive oxygen species（ROS） from Cur and Pt（II） from Pt（IV）, respectively. Compared with free anti-cancer drugs＇ chemotherapy and single photoactivated therapy, the prepared MSN-Pt-PEG@Cur displayed increased cytotoxicity. Therefore, the strategy of light-stimulus dual-drug responsive nanoparticles is a promising approach to photoactivated therapy.