Light Irradiation Research Articles

An Aged Tree with a New Bloom: A Simple Spatiotemporal Programming Strategy Enables Carbon Dot Photosensitizers to Regulate Cell Pyroptosis for Enhanced Tumor Photodynamic-Immunotherapy.

Pyroptosis induced by photodynamic therapy (PDT) is a promising field in both PDT and immunotherapy for tumors. However, effectively inducing tumor cell pyroptosis while triggering a strong immune response using current photosensitizers remains challenging. Herein, the developed positively charged carbon dots (PCDs) nanoPSs were utilized to modulate tumor cell pyroptosis for the first time through a simple spatiotemporal programming strategy. Briefly, PCDs enabled precisely time-dependent targeting of the cell membrane or lysosome. Upon light irradiation, in vitro studies revealed that lysosome-targeted PDT primarily induced apoptosis, while membrane-targeted PDT triggered pyroptosis, resulting in enhanced PDT efficacy and robust activation of the immune response. Conclusively, in vivo studies demonstrated that PCDs could serve as a novel pyroptosis nanotuner for enhanced photodynamic-immunotherapy, thereby simultaneously eliminating primary tumors and inhibiting distant tumor growth and metastases. This spatiotemporal programming strategy unprecedentedly offers a rejuvenation of aged PSs and expands the biomedical use of CDs in immunotherapy.

A Photo‐Switchable Peptide Fibril Esterase

AbstractRecent attempts to mimic enzyme catalysis using simple, short peptides have been successful in enhancing various reactions, but the on‐demand, temporal or spatial regulation of such processes by external triggers remains a great challenge. Light irradiation is an ideal trigger for regulating molecular functionality, since it can be precisely manipulated in time and space, and because most reaction mediums do not react to light. We herein report the selection of a photo‐switchable amphiphilic peptide catalyst from a small library of isomeric peptides, each containing an azobenzene‐based light responsive group and a catalytic histidine residue. In its native fibrillar form, the selected peptide is efficiently and enantio‐selectively active for ester hydrolysis, but after irradiation by UV light inducing trans‐to‐cis azobenzene isomerization, the fibrils disassemble to amorphous aggregates that are much less catalytically active. Significantly, this esterase‐like activity can be manipulated multiple times, as the fibrillar peptide assembly is reversibly reduced and restored upon alternate irradiation by UV and visible light, respectively. We propose that this research may shine light on the origin of complex functions in early chemical evolution. Furthermore, it paves the way to regulate additional functions for peptide nanotechnology, such as replication, charge transfer, and delivery.

Photocatalytic degradation of methylene blue dye by ZnO nanoparticle thin films, using Sol-gel technique and UV laser irradiation.

The focus of the current work is the study of the effect of the photo-catalytic activity of ZnO nanoparticles. The photocatalytic destruction of methylene blue dye, a common water contaminant, was used to assess the photocatalytic efficiency of the ZnO nanoparticles from its aqueous solution by using ZnO nanoparticles thin film under UV light and laser irradiation. Sol-gel methods prepared ZnO nanoparticle thin films. X-ray diffraction and a field-emitted scanning electron microscope were utilized to examine the structure of the produced ZnO nanoparticles. An extended characterization by laser-based fluorescence and UV-visible spectroscopic techniques. The effects of operational parameters such as photo-catalyst load and contact time on photocatalytic degradation of methylene blue were investigated. The recent study's findings showed that irradiation with a UV laser increases with power density 25 µW/cm2, the photo-catalytic rate. The UV spectra show decay for the band at 664nm decreased and the concentration of M.B. in monomer form decayed to 26% of the original concentration in 24 h, while the band at 612 which is related to the dimer M.B. molecules was not affected. The laser irradiation did the same for monomer M.B. molecules in only 3 h, while the dimer decreased to 28% of its original concentration. The reaction mechanism has been discussed by molecular modelling. Quantum mechanical calculations at B3LYP/6-311g(d,p) level indicated that methylene blue changed from dimers to monomers in the existence of ZnO. The current results present a method for degrading M.B. not only in wastewater but also in the industrial waste scale.

Core–Shell–Satellite Au@CeO2–Pd Plasmonical Photocatalysts for Suzuki–Miyaura Coupling Reaction

ABSTRACTIntegration of localized surface plasmon resonance (LSPR) metallic nanocrystals into photocatalysis is an intriguing approach for light‐driven organic transformations. However, uncertain direction of hot carriers is a grand challenge, which fails to take full advantage of the LSPR excitation. In this work, core–shell gold@ceria nanosphere–supported segregated palladium species (Au@CeO2–Pd) have developed to steer the light absorption capability and charge carrier migration. Under simulated solar light irradiation, the core–shell–satellite Au@CeO2–Pd exhibited efficient light harvesting and colossal activity in the Suzuki coupling reaction. The plasmon‐induced hot electrons overpassed the Schottky barrier at the Au@CeO2 interfaces and migrated from Au core to CeO2 shell accordingly. Subsequently, the photogenerated electrons and hot electrons migrated from Au@CeO2 core–shells to Pd, which acted as an electron acceptor. Detailed photocatalytic mechanism studies revealed that both photoexcited electrons and holes were the main active species involved in the photocatalytic Suzuki coupling reaction process. In particular, the diphenyl yield over Au@CeO2–Pd catalyst was ~1.7 times higher than that of core–shell–satellite Au@SiO2–Pd, where a 19‐nm‐thick SiO2 shell was introduced to prevent the migration of hot electrons. This distinctly certified that the hot electrons transfer in the core–shell–satellite Au@CeO2–Pd under illumination played an important role to drive Suzuki reaction. Overall, this design of core–shell–satellite Au@CeO2–Pd plasmonic photocatalyst has the potential in the field of photo‐driven organic transformations.

Pyrene‐4,5,9,10‐Tetraone‐Based Porous Aromatic Frameworks for Photocatalytic Production of Hydrogen Peroxide

AbstractThree pyrene‐4,5,9,10‐tetraone‐based porous aromatic frameworks (PT‐PAFs) are synthesized and their photocatalytic properties for H2O2 production are studied. It is found that the combination of pyrene‐4,5,9,10‐tetraone with anthraquinone affords an efficient PT‐PAF photocatalyst (PAF‐371) for H2O2 production, which achieves production rates of 3791 µmol g−1 h−1 (with sacrificial reagent) and 923 µmol g−1 h−1 (without sacrificial reagent) from water and oxygen under visible light irradiation. This work demonstrates that pyrene‐4,5,9,10‐tetraone molecule could be introduced into PAF materials to construct efficient organic semiconductor photocatalysts for H2O2 production.

Anthracene-Based Endoperoxides as Self-Sensitized Singlet Oxygen Carriers for Hypoxic-Tumor Photodynamic Therapy.

Singlet oxygen is a crucial reactive oxygen species (ROS) in photodynamic therapy (PDT). However, the hypoxic tumor microenvironment limits the production of cytotoxic singlet oxygen through the light irradiation of PDT photosensitizers (PSs). This restriction poses a major challenge in improving the effectiveness of PDT. To overcome this challenge, researchers have explored the development of singlet oxygen carriers that can capture and release singlet oxygen in physiological conditions. Among these developments, anthracene-based endoperoxides, initially discovered almost 100 years ago, have shown the ability to generate singlet oxygen controllably under thermal or photo stimuli. Recent advancements have led to the development of a new class of self-sensitized anthracene-endoperoxides, with potential applications in enhancing PDT effects for hypoxic tumors. This review discusses the current research progress in utilizing self-sensitized anthracene-endoperoxides as singlet oxygen carriers for improved PDT. It covers anthracene-conjugated small organic molecules, metal-organic complexes, polymeric structures, and other self-sensitized nano-structures. The molecular structural designs, mechanisms, and characteristics of these systems will be discussed. This review aims to provide valuable insights for developing high-performance singlet oxygen carriers for hypoxic-tumor PDT.

Formation of 3-Alkynylidenephthalides by Gold(I)-Catalyzed Alkynylative Cyclization of o-Alkynylbenzoic Acids under Visible Light Irradiation.

Herein, we report a Csp2-Csp cross-coupling process involving the merger of gold catalysis and visible light photocatalysis leading to the alkynylative cyclization of o-alkynyl benzoic acids. The corresponding and previously undescribed alkynylidenephthalide products were obtained as mixtures of E:Z isomers. The key C-C bond formation is based on the photoactivation of the oxidative addition of an alkynyliodide to a vinylgold(I) intermediate resulting from an initial 5-exo-dig cyclization pathway, as supported by mechanistic studies including DFT calculations.

Unraveling the Synergy of Au and Polar MgO(111) Surface in Photothermal Catalytic Oxidative Coupling of Methane

AbstractDirect and selective catalytic oxidative coupling of methane (OCM) into high‐carbon products is a great challenge in C1 chemistry. Herein, the successful fabrication of a series of Au clusters loaded on different MgO facets of (111), (110), and (100) is reported. This work demonstrates the Au‐loaded MgO(111) (denoted as Au/MgO(111)) shows the highest C2H6 yield of 12733.4 µmol g−1 h−1 and selectivity of 90.4%, which is 2.46 times higher than that of Au/MgO(110) (5171.4 µmol g−1 h−1) and 25.14 times higher than that of Au/MgO(100) (506.4 µmol g−1 h−1). Moreover, the high activity of Au/MgO(111) can be well maintained over 100 h. Detailed in situ experiments and theoretical calculation reveal such great performance can be attributed to 1) the strong electronic affinity of the surface oxygen species on polar MgO(111) and CH4with the lowest adsorption energy of −0.82 eV; 2) the Au/MgO(111) shows the lowest ΔERDS of 0.53 eV in the rate‐deterime step of OCM that comes in activating the second CH4 molecule; 3) the Au can act as a hole acceptor under light irradiation and adsorb *CH3 with a strong d‐σ hybridization, resulting in an increased C2H6 selectivity.

A Portable Zn2+ Fluorescence Sensor for Information Storage and Bio-Imaging in Living Cells.

A fluorescence probe (Probe-ITR) was designed and synthesized for the rapid detection of Zn2+ based on the excited state intramolecular proton transfer (ESIPT) mechanism. The specific recognition ability of Probe-ITR to Zn2+ was tested using UV-VIS and fluorescence emission spectroscopy. The results demonstrated a rapid response within 40s upon addition of an appropriate amount of Zn2+ into the mixed solution of the target probe molecules (DMSO/PBS = 5/5). Under 365nm ultraviolet light irradiation, the colorless solution changed to yellow-green fluorescence with a 150-folds increase in intensity. Furthermore, the detection limit for specific recognition of Zn2+ by the probe molecule is only 17.3 nmol/L, indicating high sensitivity. The practical application potential of the probe molecules was enhanced by employing on information storage and conducting cell imaging experiments.

Synthesis of Bicyclo[3.2.0]heptanes by Organophotoredox Catalytic Diastereoselective Anion Radical [2+2] Photocycloadditions of Arylenones under Batch and Flow Conditions

AbstractIn this study, the anion radical [2+2] photocycloaddition of aryl‐enones was investigated under batch and flow conditions. The reaction was promoted by LiBr as a Lewis acid and catalyzed by Eosin Y under visible light irradiation. Symmetrical enones and asymmetrical unsaturated ketoesters were effectively cyclized to yield substituted bicyclo[3.2.0]heptanes in high yield and diastereoselectivity. Through the exploration of different experimental setups and reaction conditions, a precise control over the diastereoselectivity of the process was achieved, favoring the formation of either cis or trans substituted bicyclo[3.2.0]heptanes. In‐flow experiments allowed to further improve the efficiency of the methodology, leading to higher productivity and space time yields. Furthermore, DFT investigations were conducted in order to elucidate the reaction mechanism.

Flavin-Catalyzed, Photochemical Conversion of Dehydroalanine into 4,5-Dihydroxynorvaline.

The chemical synthesis of unnatural amino acids (UAA) is a key strategy for preparing designed peptides, including pharmaceutically active compounds. Alterations of existing amino acid residues such as dehydroalanine (Dha) are particularly important since selected positions can be addressed without the necessity of a complete de novo synthesis. The intriguing UAA 4,5-dihydroxynorvaline (Dnv) is found in a variety of naturally occurring peptides and biologically active compounds. However, no method is currently available to modify an existing peptide with this residue. We report the use of flavin catalysts and visible light irradiation for this challenge, which serves as a versatile strategy for converting Dha into Dnv. Our study shows that excited flavins are competent hydrogen atom abstraction catalysts for ethers and acetals, which allows masked 1,2-dihydroxyethylene functionalization from 2,2-dimethyl-1,3-dioxolane. The masked diol was successfully coupled to Dha residues, and a series of Dnv-containing products is reported. A mild and orthogonal protocol for deprotection of the acetal group was also identified, allowing free Dnv-modified peptides to be obtained. This method provides a straightforward strategy for Dnv functionalization, which is envisioned to be crucial for accessing natural products and synthetic analogues with pharmaceutical activity.

Application of Hydroxyaromatic Aldehydes in Ultra-Efficient and Metal-Free Photocatalytic E→Z Isomerization of Olefin.

The strategy of photocatalyzed E→Z isomerization of olefins to access thermodynamically less stable Z-alkenes has recently received considerable attention. Here, we have discovered a sensitizer of hydroxyaromatic aldehyde that can rapidly achieve olefin E→Z isomerization under blue light irradiation. Notably, 2-hydroxybenzene-1,3,5-tricarbaldehyde, when assisted by blue light, can achieve efficient and selective conversion within just 5 minutes (Z/E=92 : 8). The reaction can be successfully scaled up to gram scale, and exhibits remarkable reactivity toward various derivatives of ethyl cinnamate (27 examples) and other olefins. Furthermore, the former can be directly cyclized by a hydroxyl derivative to produce 4-substituted coumarin. The prominent preponderance of this method includes being metal-free, efficient, convenient, no by-products and achieving high selectivity. Correlation of sensitizer triplet energy (ET) and preliminary mechanistic experiments indicate that the accomplishment of this reaction is based on the selective excitation mechanism.

Photoinduced On and Off Polymeric Room Temperature Phosphorescence Based On Polycyclic Aromatic Hydrocarbon Isomers.

As family members of polycyclic aromatic hydrocarbons, compound anthracene (Ant) and phenanthrene (Phe) as isomers are widely used in organic optical materials and electronic materials. But their photochemical and physical properties are very different. In this work, the room temperature phosphorescence (RTP) properties of PVA-B-Ant and PVA-B-Phe are discussed carefully which are prepared by B-O click reaction through polyvinyl alcohol (PVA) with 9-anthraceneboronic acid (B-Ant) and 9-phenanthrenylboronic acid (B-Phe), respectively. PVA-B-Phe 1 % film exhibits excellent fluorescence (FL) emission at 374 nm and RTP emission at 523 nm with green afterglow and around 1.9 s phosphorescence lifetime. However, PVA-B-Ant 1 % film only shows strong blue FL emission at 414 nm, and the emission intensity decreases seriously with the extension of irradiation time. Experimental and theoretical calculations results suggest that the photodimer of Ant which is formed in PVA matrix under the UV light irradiation would be competitive with the process of RTP emission. This work demonstrates that the RTP properties of organic molecules might be probably affected by the photostability of the organic phosphor under UV irradiation.

Rational Design, Synthesis, and Evaluation of Rofecoxib-Based Photosensitizers for the NIR Imaging and Photo-Oxidization of Aβ Aggregates.

The photo-oxidation of amyloid-β (Aβ) protein catalyzed by Aβ-targeting photosensitizers shows high potential in treating Alzheimer's disease (AD). Herein, we report the first example of photosensitizers based on the rofecoxib scaffold, in which rational introduction of the electron-absorbing pyridinium/quinolinium moiety to the skeleton of rofecoxib could not only extend the absorption and emission wavelengths but also increase the efficiency of singlet oxygen (1O2) production. The emission wavelengths of R-S-MP, R-S-MC, and R-S-MQ are red-shifted to 860 nm, which might benefit the NIR imaging of Aβ aggregates with low photoscattering and autofluorescence. In addition, R-S-MP can identify Aβ plaques in brain sections of AD mice and detect abnormal viscosity environments, facilitating the pathological study of Alzheimer's disease. Most importantly, upon complexation with Aβ plaques, R-S-MP and R-S-MC could produce high singlet oxygen (1O2) under light irradiation, which can achieve the specific photo-oxidation of Aβ protein. Our optimized photosensitizers could change the conformation of β-rich Aβ protein and enhance its clearance through the lysosomal pathway, leading to the reduction of the Aβ-mediated neurotoxicity. All these excellent characteristics of our dual-functional photosensitizers for simultaneous imaging and photo-oxidation of Aβ aggregates suggest their promising prospects in pathological research in AD.

Photothermal optical coherence microscopy for studying lipid architecture in human carotid arteries

Photothermal optical coherence microscopy (PT-OCM) combines the high-resolution, label-free morphological imaging of OCM with the ability to discriminate tissue composition through phase-sensitive photothermal imaging. In this study, we perform 2D imaging of human carotid endarterectomies to spectrally determine lipid distribution, with verification via histologically stained samples. The structural information from OCM is combined with the spectral information gained from measuring the resulting sample surface displacement from thermoelastic expansion, following light irradiation. PT-OCM is thus demonstrated as a potential tool in the investigation of atherosclerotic plaque lipids, contributing towards the understanding of plaque instability.

Coordination-Induced Magnetism Strategy for Highly Selective and Efficient Uranium Separation.

Highly efficient separation of dispersed uranium is important for the sustainable development of nuclear industry, and adsorption is the most recognized approach. However, there are many coexisting interfering metal ions that compete with uranyl ion for the chelating ligands in the adsorbents and lead to low separation selectivity and efficiency. Herein, a coordination-induced magnetism strategy is presented for the separation of uranium based on the conversion of diamagnetic cyanoferrocene (Fc-CN) nanocrystals to uranium-containing magnetic recoverable ferromagnetic aggregates. Different from previous adsorption strategies, this strategy combines the mechanisms of photocatalytic uranium enrichment and chemical uranium adsorption. Under light irradiation, electron of Fe(II) in Fc-CN is excited and transfers to uranyl ion via the cyano group to form tight coordination bond between N atom in cyano group and uranium. This phenomenon is unique for uranyl ion, and thus, a high uranium removal rate of 97.98% is achieved in simulated nuclear wastewater with the presence of tremendous interfering ions, proving its highly selective and efficient uranium separation performance. The ability to form highly stable magnetic aggregates via photoinduced interaction between Fc-CN and uranium enriches the understanding on the chemical properties of Fc-CN and uranium.

Enhanced photocatalytic degradation of organic pollutants by randomly oriented 2D SnS2 nanostructures

Abstract In this study, we present a bottom-up solvothermal technique using tin tetrachloride pentahydrate (SnCl4.5H2O) and thioacetamide as precursors to synthesize SnS2 nanostructures. Different solvents including isopropyl alcohol, ethanol (EN), and ethylene glycol were used in the reaction to enhance the photodegradation efficiency of organic pollutants, Methylene Blue (MB), and Tetracycline (TC) in an aqueous medium under simulated solar light irradiation. The SnS2 nanostructures synthesized with these solvents were characterized using various structural, morphological, and optical techniques, including x-ray diffraction, RAMAN, field emission scanning electron microscope, x-ray photoelectron spectroscopy, UV–Vis, and Brunauer–Emmett–Teller analysis. The choice of solvent was found to significantly affect the structural, morphological, and optical properties of the SnS2 nanostructures. Notably, the sample synthesized with EN as the solvent displayed a unique morphology, enhanced light-harvesting ability, efficient charge carrier separation, and a larger specific surface area, all of which contributed to its superior photocatalytic activity. This sample achieved 99.9% degradation of MB and 95% degradation of TC within 20 and 40 min, respectively. The kinetic analysis revealed maximum rate constant (k) values of 0.15242 min−1 for MB and 0.060 95 min−1 for TC, as determined by the pseudo-first-order kinetic model. We also discuss the plausible mechanism involving visible light-induced electron–hole pairs that generate reactive species, leading to the mineralization of dyes into H2O, CO2, and other gaseous products. The synthesized SnS2 nanostructures demonstrate significant potential for enhanced photocatalytic activity in organic pollutant degradation, underscoring their promise in addressing water pollution challenges.

Dication Disulfuranes as Photoactivatable Sources of Radical Organocatalysts.

The recent development of photoredox and energy transfer catalysis has led to a significant expansion of visible light-driven chemical transformations. These methods have demonstrated exceptional efficiency in converting a wide range of substrates into radical intermediates and generating open-shell catalytic species. However, the simplification of catalytic systems and the direct generation of highly reactive radical organocatalysts through direct visible light irradiation from stable precatalysts remains largely an unrealized goal. This challenge is mainly due to the limited availability of precatalysts that are responsive to visible light. Herein, we introduce a new class of bench-stable dicationic disulfuranes, which release highly reactive thiyl radicals upon blue light excitation. Spectroscopic and computational studies reveal that this reactivity arises from a combination of structural features and intermolecular interactions. This family of molecules has been employed to catalyze radical cascades previously incompatible with photoredox conditions, enabling the efficient formation of 1,2-dioxolanes and 1,3-hydroxyketones in excellent yields and short reaction times.

Plasmonic Nanocomposite for Visible Light‐Modulated Bimorph‐Actuator

AbstractSoft actuators have great potential applications in sophisticated movement and sensitive devices due to their flexible nature, good interaction, and precise control. However, existing carbon‐based optical actuators are limited in their response under visible light irradiation. The limited visible light absorbance of the carbon nanostructure brought the metallic nanoparticle into the soft actuators that can absorb visible light. This study introduces a new type of plasmonic photothermal‐bimorph actuator, using graphene oxide (GO), reduced graphene oxide (rGO), and silver nanorods (Ag NRs) to overcome the limitations of traditional optical actuators. The bimorph film is actuated by visible and near‐infrared light stimuli with various power densities showing reversible deformation behavior. The actuator shows significant bending associated with a ≈50° change in bending angle under visible light irradiation with a response time of ≈5 ± 1 sec. Furthermore, a smart photo‐controlled non‐contact switch is fabricated based on photo‐thermal conversion properties, demonstrating perfect integration of plasmonic bimorph actuators. The density functional theory based molecular dynamics calculations provide an additional understanding of the bending of actuators under external stimulus. Using illustrative demonstrations of actuators, these results hint at a method for generating multipurpose visible light‐based soft robots, supporting a new approach to developing an optical locking system.

AIE-derived fluorescent silsesquioxane-based hybrid aerogel for light-enhanced gold recovery

In this work, two aggregation-induced emission (AIE)-active organic fluorescent monomers (TPV, TPC) were synthesized by Knoevenagel reaction of 2,2′-([1,1′-biphenyl]-4,4′-diyl)diacetonitrile with benzaldehyde and 4-bromobenzaldehyde, respectively. Subsequently, two fluorescent hybrid porous polymers with semiconductor performance (PCS-TPV, PCS-TPC) were prepared successfully by connecting octavinyl silsesquioxane (OVS) with TPV and TPC through Friedel-Crafts reaction and Heck coupling, respectively. Among them, PCS-TPV with a hyper-crosslinked structure offered a specific surface area of up to 1165 m2 g−1; PCS-TPC was the first AIE-derived fluorescent hybrid silsesquioxane-based semiconductor polymer with 3-D conjugated structure. Compared with PCS-TPV, PCS-TPC exhibited stronger visible light absorption, higher fluorescent performance and quantum yield due to its high AIE-active unit content. Besides, PCS-TPC exhibited a remarkable gold recovery capacity (Qm = 2728 mg g−1) when exposed to visible light irradiation. Adsorption mechanism revealed that the photoelectrons produced by PCS-TPC under visible light irradiation reduced all adsorbed Au(III) to Au(I) and Au(0). Furthermore, a hybrid aerogel was prepared through physical blending of PCS-TPC with chitosan, overcoming the limitation that insoluble powder was difficult to process and recycle. This work provided a very efficient, sustainable, and industrially feasible way for gold recovery in e-waste.