Generation Of Reactive Intermediates Research Articles

New insights into aqueous Hg(II) photoreduction from paddy field system to natural water: Gear effect of straw returning and soil tillage

Soil dissolved organic matter (SDOM) has a strong complex with divalent mercury (Hg(II)) and can affect the fate of aqueous Hg(II) photoreduction. However, little is known about the influence of straw returning and soil tillage on the composition of SDOM in paddy soil and Hg(II) photoreduction in paddy water. Here, we demonstrate that the combined drivers of long-term straw returning and tillage can result in higher degrees of aromatization, and the enrichment of oxygen-containing functional groups in surface SDOM. Hg(II) photoreduction under low Hg/DOC conditions is mainly constrained by the composition of SDOM, whereas solar radiation emerged as a dominant controlling factor associated with high ratio of Hg/DOC. By increasing the release of SDOM and mobility of Hg(II), reducing the stability of Hg(II)-SDOM complexes, and potentially enhancing generation of reactive intermediates, gear effect of straw returning and soil tillage significantly enhanced Hg(II) photoreduction in the presence of surface SDOM from 0-40cm (maximum photoreduction percentage can reach 44.76 ± 2.24%). Previous inventories of Hg(0) emissions from paddy field system may have overlooked or underestimated this critical process. Future modeling work should be carried out to evaluate the role of straw returning and soil tillage on global Hg cycle.

Generation and Application of Sulfur Ylides in Light‐Mediated Transformations

Sulfur ylides are essential reagents in various organic reactions like epoxidation and cyclopropanation. While traditionally employed in ionic chemistry, recent advancements in visible‐light‐driven photocatalysis reveal their potential as sources of radicals or free carbenes. The photochemical or photocatalytic generation of reactive intermediates using sulfur ylides expands the utility of these reagents in modern organic synthesis, offering sustainable solutions to emerging challenges. Despite early demonstrations in the 1960s, the past years have witnessed a surge in photochemical methods utilizing sulfur ylides as precursors. The use of redox‐active photocatalysts has facilitated numerous radical reactions. This review consolidates key findings in sulfur ylide chemistry, particularly focusing on photo‐mediated reactions, to stimulate further research interest in this dynamic field.

Dissolved Black Carbon Facilitates the Photodegradation of Microplastics via Molecular Weight-Dependent Generation of Reactive Intermediates.

Photodegradation of microplastics (MPs) induced by sunlight plays a crucial role in determining their transport, fate, and impacts in aquatic environments. Dissolved black carbon (DBC), originating from pyrolyzed carbon, can potentially mediate the photodegradation of MPs owing to its potent photosensitization capacity. This study examined the impact of pyrolyzed wood derived DBC (5 mg C/L) on the photodegradation of polystyrene (PS) MPs in aquatic solutions under UV radiation. It revealed that the photodegradation of PS MPs primarily occurred at the benzene ring rather than the aliphatic segments due to the fast attack of hydroxyl radical (•OH) and singlet oxygen (1O2) on the benzene ring. The photosensitivity of DBC accelerated the degradation of PS MPs, primarily attributed to the increased production of •OH, 1O2, and triplet-excited state DBC (3DBC*). Notably, DBC-mediated photodegradation was related to its molecular weight (MW) and chemical properties. Low MW DBC (<3 kDa) containing more carbonyl groups generated more •OH and 1O2, accelerating the photodegradation of MPs. Nevertheless, higher aromatic phenols in high MW DBC (>30 kDa) scavenged •OH and generated more O2•-, inhibiting the photodegradation of MPs. Overall, this study offered valuable insights into UV-induced photodegradation of MPs and highlighted potential impacts of DBC on the transformation of MPs.

Chemical nature of metabolic activation of natural products in traditional Chinese medicines possibly associated with toxicities

Ensuring the safety of traditional Chinese medicines (TCM) has perennially presented a universal challenge in the healthcare realm. Meticulous investigations into the toxicological intricacies of natural products are of paramount significance, particularly regarding the metabolic transformation of these substances and the subsequent generation of reactive intermediates. This biochemical process underlies the genesis of diverse toxic manifestations, including hepatotoxicity, nephrotoxicity, pulmonary toxicity, and genotoxicity. Compounds sorted within TCM, including pyrrolizidine alkaloids, anthraquinones, furanoterpenoids, alkenylbenzenes, bisbenzylisoquinoline alkaloids, flavonoids, and methylenedioxyphenyl derivatives, evince a spectrum of deleterious mechanisms upon metabolic activation. This review provides a comprehensive delineation of the pathways through which these compounds induce toxicity via metabolic activation. This review emphasizes the chemical mechanisms involved in the metabolic activation of natural products that may trigger a toxic cascade, rather than a superficial phenomenon. Furthermore, this study enriches the extant literature by delving into advancements in elucidating the mechanisms of toxicity engendered by metabolic activation. In conclusion, this review highlights the importance of scrutinizing the mechanisms of toxicity and provides insights into the judicious and safe use of TCM.

Enhanced photocatalytic CO2 reduction to methanol by modulating valence states of copper in CuSrTiO3

Manipulating the oxidation states of transition metals is an ideal solution to achieve selective generation of different products and copper is widely used in CO2 photocatalytic reduction to methanol. However, the understanding on the effects of valence states of copper species in SrTiO3 on its structure and the selectivity of the corresponding product in CO2 photocatalysis are currently still limited. Here, copper-doped SrTiO3 nanofibers with different controllable ratios of Cu+/Cu2+ and Cu+/Cu0 were prepared by the combination of the electrospinning with the in-situ reduction method. The proportion of copper with different valence states (Cu+/Cu2+ and Cu+/Cu0) was changed by rationally adjusting the time of hydrogen reduction. The presence of monovalent copper facilitated the generation of reactive intermediates, thereby enhancing its photocatalytic activity. The copper-doped SrTiO3 nanofibers obtained after 3 h of hydrogen reduction (STCu0.08-H-3 h) had the highest proportion of Cu+/Cu2+ and Cu+/Cu0 with the highest methanol yield (6.96 μmol·g−1·h−1). Methanol generation rate and Cu+/Cu2+ ratio of STCu0.08-H-xh (x = 1, 2, 3, 4,5) with different hydrogen reduction time were proven to be linearly positively correlated. Furthermore, theoretical investigation and in-situ CO2 infrared spectrum deeply understood the difference of CO2 adsorption behavior and CO2 activation over Cu2+ and Cu+ of STCu0.08-H-3 h photocatalyst and the reaction intermediates involved in the photocatalytic CO2 reduction to methanol.

The Application of Porous Organic Polymers as Metal Free Photocatalysts in Organic Synthesis.

Concerns about increasing greenhouse gas emissions and their effect on our environment highlight the urgent need for new sustainable technologies. Visible light photocatalysis allows the clean and selective generation of reactive intermediates under mild conditions. The more widespread adoption of the current generation of photocatalysts, particularly those using precious metals, is hampered by drawbacks such as their cost, toxicity, difficult separation, and limited recyclability. This is driving the search for alternatives, such as porous organic polymers (POPs). This new class of materials is made entirely from organic building blocks, can possess high surface area and stability, and has a controllable composition and functionality. This review focuses on the application of POPs as photocatalysts in organic synthesis. For each reaction type, a representative material is discussed, with special attention to the mechanism of the reaction. Additionally, an overview is given, comparing POPs with other classes of photocatalysts, and critical conclusions and future perspectives are provided on this important field.

Ion Trap LC/MS reveals the generation of reactive intermediates in acalabrutinib metabolism: phase I metabolic profiling and bioactivation pathways elucidation.

Acalabrutinib (CALQUENCE; ACB) is a Bruton tyrosine kinase inhibitor (BTKI) used to treat mantle cell lymphoma, small lymphocytic lymphoma (SLL), and chronic lymphocytic leukemia (CLL). On 21 November 2019, ACB was approved by the U.S. FDA for the use as a single therapy for the treatment of CLL/SLL. In silico studies were first done to propose vulnerable sites of metabolism and reactivity pathways by StarDrop software and Xenosite online software; respectively. ACB metabolites and stable adducts were characterized in vitro from rat liver microsomes (RLMs) using Ion Trap LC/MS. Generation of reactive intermediates (RIs) in the in vitro metabolism of ACB was investigated using glutathione, potassium cyanide, and methoxylamine as trapping nucleophiles for the RIs including iminopyridinone, iminium, and aldehyde, respectively, to form stable adducts that can be identified and characterized by Ion Trap LC/MS. Five phase I metabolites, seven 6-iminopyridin-3(6H)-one and five aldehyde RIs of ACB were identified. Based on literature reviews, the generation of RIs of ACB, and the subsequent drug-induced organ toxicity (DIOT) reactions may provide an explanation of ACB ADRs. Additional drug discovery investigations can be performed to facilitate the creation of novel medications with improved safety characteristics.

Mechanochemical generation of aryne.

Mechanical force is unique in promoting unusual reaction pathways and especially for the generation of reactive intermediates sometimes inaccessible to other forms of activation. The mechanochemical generation of reactive species could find application in synthetic and materials chemistry alike. However, the nature of these reactive intermediates has been mostly limited to radicals or carbenes. Here, we present a new mechanophore that generates a reactive aryne intermediate upon dissociation of a benzocyclobutene (BCB) core via a force-promoted retro [2 + 2] cycloaddition.

Sustainable and selective transfer hydrogenation using waste shrimp shell‐based tetrazene‐Ru (II) para‐cymene catalyst with ethanol as a hydrogen source

Sustainable chemical research emphasizes chitosan‐based catalysts and the need to explore the direct utilization of waste shrimp shells, whereas the use of ethanol as a hydrogen source in transfer hydrogenation is less explored due to its unfavorable redox potential, higher energy barriers, generation of reactive intermediates, and catalyst poising via metal carbonyl species or decarbonylation. Herein, we disclosed an efficient synthetic approach, conducted at ambient temperature, for surface functionalization of waste shrimp shells with 3‐(3,5‐dimethyl‐1H‐pyrazol‐1‐yl)‐1,2,4,5‐tetrazine (DMPZ‐Tz) via nucleophilic substitution using 3,6‐bis(3,5‐dimethyl‐1H‐pyrazol‐1‐yl)‐1,2,4,5‐tetrazine (BDMPZ‐Tz). This method results in a color change and a 75% increase in surface nitrogen content, eliminating the need for multiple syntheses and harsh reaction conditions. We utilized the strong coordination property between DMPZ‐Tz and [Ru(p‐cym)Cl2]2/RuCl3.3H2O to develop ruthenium‐embedded transfer hydrogenation catalysts supported on shrimp shells. These catalysts were employed for the selective transfer hydrogenation of unsaturated carbonyl/aldehydes to saturated carbonyl/alcohols, utilizing ethanol as the hydrogen source and potassium carbonate as the base. The performance, selectivity, and reusability of the catalyst were thoroughly assessed through spectroscopic studies, in‐situ monitoring of the reaction progress, initial rate kinetics, and control experiments. The obtained results strongly indicated that the anchoring of DMPZ‐Tz played a crucial role in achieving superior performance compared with catalysts synthesized without it or utilizing its homogeneous counterparts. The catalyst exhibits efficient reactivity, selectivity, and broad substrate scope.

Protein-Protein Interaction in Multicomponent Reaction Enables Chemoselective, Site-Selective, and Modular Labeling of Native Proteins.

A protein's pool of functionalities presents a formidable challenge for its single-site modification. Here, we report a method to harness protein-protein interaction (PPI) to drive selective modification. It involves the chemoselective reversible generation of reactive intermediates and utilizes PPI-specificity to drive the subsequent site-selective irreversible step. The disintegrate (DIN) theory-driven multicomponent aza-Morita-Baylis-Hillman (aza-MBH) reaction offers homogeneous and modular single-site protein modification capable of late-stage mono- and dual-probe installation.

Photoredox catalysis harvesting multiple photon or electrochemical energies.

Photoredox catalysis (PRC) is a cutting-edge frontier for single electron-transfer (SET) reactions, enabling the generation of reactive intermediates for both oxidative and reductive processes via photon activation of a catalyst. Although this represents a significant step towards chemoselective and, more generally, sustainable chemistry, its efficacy is limited by the energy of visible light photons. Nowadays, excellent alternative conditions are available to overcome these limitations, harvesting two different but correlated concepts: the use of multi-photon processes such as consecutive photoinduced electron transfer (conPET) and the combination of photo- and electrochemistry in synthetic photoelectrochemistry (PEC). Herein, we review the most recent contributions to these fields in both oxidative and reductive activations of organic functional groups. New opportunities for organic chemists are captured, such as selective reactions employing super-oxidants and super-reductants to engage unactivated chemical feedstocks, and scalability up to gram scales in continuous flow. This review provides comparisons between the two techniques (multi-photon photoredox catalysis and PEC) to help the reader to fully understand their similarities, differences and potential applications and to therefore choose which method is the most appropriate for a given reaction, scale and purpose of a project.

Exposure to PAHs during Firefighting Activities: A Review on Skin Levels, In Vitro/In Vivo Bioavailability, and Health Risks.

Occupational exposure as a firefighter is a complex activity that continuously exposes subjects to several health hazards including fire emissions during firefighting. Firefighters are exposed to polycyclic aromatic hydrocarbons (PAHs), known as toxic, mutagenic, and carcinogenic compounds, by inhalation, dermal contact, and ingestion. In this work, a literature overview of firefighters’ dermal exposure to PAHs after firefighting and data retrieved from skin in vitro/in vivo studies related to their dermal absorption, bioavailability, and associated toxicological and carcinogenic effects are reviewed. The evidence demonstrates the contamination of firefighters’ skin with PAHs, mainly on the neck (2.23–62.50 ng/cm2), wrists (0.37–8.30 ng/cm2), face (2.50–4.82 ng/cm2), and hands (1.59–4.69 ng/cm2). Concentrations of possible/probable carcinogens (0.82–33.69 ng/cm2), including benzopyrene isomers, were found on firefighters’ skin. PAHs penetrate the skin tissues, even at low concentrations, by absorption and/or diffusion, and are locally metabolized and distributed by the blood route to other tissues/organs. Lighter PAHs presented increased dermal permeabilities and absorption rates than heavier compounds. Topical PAHs activate the aryl hydrocarbon receptor and promote the enzymatic generation of reactive intermediates that may cause protein and/or DNA adducts. Future research should include in vitro/in vivo assays to perform a more realistic health risk assessment and to explore the contribution of dermal exposure to PAHs total internal dose.

UV-induced highly efficient removal of As(III) through synergistic photo-oxidation in the presence of Fe(II).

In polluted waters, arsenic (As) poses substantial risks to the environment and human health. Inorganic As mainly exists as As(V) and As(III), and As(III) usually shows higher mobility and toxicity and is more difficult to be removed by coagulation. The oxidation of coexisting Fe(II) can accelerate As(III) oxidation and removal by promoting the generation of reactive intermediates and Fe(III) coagulant in the presence of dissolved oxygen. However, the removal efficiency of As from acidic wastewaters is far from satisfactory due to the low Fe(II) oxidation rate by dissolved oxygen. Herein, UV irradiation was applied to stimulate the synergistic oxidation of Fe(II)/As(III), and the effects of coexisting Fe(II) concentration and pH were also evaluated. The synergistic oxidation of Fe(II)/As(III) significantly enhanced the removal of As from acidic waters. Under UV irradiation, Fe(II) significantly promoted the generation of reactive oxygen species (ROS), thereby facilitating As(III) oxidation. In addition, the formation of ferric arsenate and amorphous ferric (hydr)oxides contributed much to As removal. In the As(III)-containing solution with 200μmol L-1 Fe(II) at initial pH 4.0, the total arsenic (As(T)) concentration decreased from 67.0 to 1.3 and 0.5μmol L-1, respectively, at 25 and 120min under UV irradiation. The As(T) removal rate increased with increasing Fe(II) concentration, and first increased and then decreased with increasing initial pH from 2.0 to 6.0. This study clarifies the mechanism for the synergistic photo-oxidation of Fe(II)/As(III) under UV irradiation, and proposes a new strategy for highly efficient As(III) removal from acidic industrial and mining wastewaters.

Bisulfite activated permanganate for oxidative water decontamination

Recently, bisulfite-activated permanganate (MnO4−; Mn(VII)) process has attracted considerable attention as a novel class of advanced oxidation technology for destruction of organic contaminants in water. However, disputes over the underlying activation mechanism as well as reactive species generated in the Mn(VII)/bisulfite system remain for a long period due to the fairly complex chemistry involved in this system. This article aims to present a critical review on scientific development of the Mn(VII)/bisulfite system, with particular focus on the generation and contribution of various reactive intermediates. Both reactive manganese species (RMnS) (i.e., soluble Mn(III), Mn(V), and Mn(VI)) and radical species (primarily SO4•−) are identified as the oxidizing components responsible for enhanced degradation of organic contaminants by the Mn(VII)/bisulfite system. Bisulfite plays a dual role of being an activating agent for reactive intermediates generation and acting as a complexing agent to stabilize RMnS. Solution chemistry (e.g., the [Mn(VII)]/[bisulfite] molar ratio, solution pH, the type of contaminants, ligands, and water matrix components) greatly impacts the generation and consumption of RMnS and radicals, thus influencing the degradation kinetics and pathways of organics. Particularly, dissolved oxygen (DO) is a vital factor for driving the oxidation of organics since the absence of DO can block the generation of SO4•− and meantime causes the consumption of RMnS by excess SO3•− as a strong reductant. Interestingly, ferrate (FeO42−, Fe(VI)) and hexavalent chromium (CrO42−/HCrO4−, Cr(VI)) that are high-valent metal oxyanions analogous to Mn(VII) can be activated by bisulfite via a similar pathway (i.e. both high-valent metal-oxo intermediates and reactive radicals are involved). Furthermore, key knowledge gaps are identified and future research needs are proposed to address the potential challenges encountered in practical application of the Mn(VII)/bisulfite oxidation technology.

Systematic understanding of char-volatile evolution and interaction mechanism during sewage sludge pyrolysis through in-situ tracking solid-state reaction and products fate

The complexity of sludge components and the heterogeneity of pyrolysis products make it challenging to trace char-volatile evolutions and interaction mechanisms during pyrolysis. Herein, we systematically dissected the solid-state reactions and volatile dynamic variations via in-situ infrared/mass spectral probes coupled signal amplification techniques. The identification of hidden reactions was further enhanced by comparing the discrepancies in the pyrolysis of three systems: raw sludge, sludge-extracted organics, and pseudo-components of organics. A three-stage sludge pyrolysis of bond cleavage (α = 0.2–0.5), intermediates diffusion (α = 0.5–0.7), and interface interaction (α = 0.7–0.8) was proposed through solid-state reaction tracing, and the pyrolysis reaction was found to be dominated by the first two stages. The generation of reactive intermediates accelerated the collision frequency between reactants, which increased the order of solid-state reactions and raised the energy barrier from 148 to 180–261–297 kJ/mol. The temperature-response sequence of the major pyrolysis volatiles was H2O/CO2/furans/alcohols (<250 °C), amine-N/acids/ketones/esters (250–350 °C), heterocyclic-N/phenols/C2–3 (300–400 °C), CH4/aromatics/nitrile-N (350–450 °C), and CO/HCN (>450 °C). The temperature-dependent evolution of these volatiles was consistent with the variations of chars in terms of pyrolysis behaviors, reaction models, and surface characteristics. The comprehensive understanding of the staged pyrolysis pathways and the char-volatile interaction mechanisms may provide critical information for pyrolysis procedure design and product targeted regulation.

Convergent paired electrochemical synthesis of symmetric dispiro and spiropyrimidine derivatives based on reduction of para-nitrophenol

• Electrochemical study of para -nitrophenol. • Electrochemical synthesis of dispiro and spiropyrimidine derivatives. • Evaluation of antibacterial susceptibility of synthesized compounds. • Detailed mechanistic study of synthesized compounds. • Optimization of effective parameters on the yield of synthesized compounds. A green electrochemical method was developed for the synthesis of new types of spiro and dispiro pyrimidine derivatives. The electrochemical generation of reactive intermediates from para -nitrophenol ( PNP ) and their reactions with barbituric acids ( BA1-BA3 ) is a key step in the formation of target products ( P 1- P 3 ). Our data show that the reactivity of the nucleophile (barbituric acids) plays an important role in the type of product. Accordingly, when barbituric acid ( BA1 ) or thiobarbituric acid ( BA2 ) is used as a nucleophile, dispiro product ( P 1 or P 2 ) is formed in a convergent paired electrochemical reaction. However, when 1,3-dimethylbarbituric acid ( BA3 ) is used as a nucleophile, due to its higher reactivity than BA1 , the final product is an spiro compound that results from the reaction of BA3 with cathodically generated para -nitrosophenol. The highly symmetric dispiro and spiro compounds ( P 1- P 3 ) have been successfully synthesized in a water/ethanol mixture at the carbon electrode in an undivided cell using the constant current electrolysis method. Also, the antibacterial tests indicated that the products P 1- P 3 showed good antibacterial performance against gram-positive bacteria ( Bacillus cereus and Staphylococcus aureus ). In this work, we synthesized a number of new spiro and dispiro pyrimidine compounds ( P 1- P 3 ) using a convergent paired electrochemical method, by electrolysis of PNP in the presence of barbituric acids ( BA1-BA3 ), under mild and green conditions for the first time.

UV‐vis spectroscopy of gas‐phase ions

Photodissociation action spectroscopy has made a great progress in expanding investigations of gas-phase ion structures. This review deals with aspects of gas-phase ion electronic excitations that result in wavelength-dependent dissociation and light emission via fluorescence, chiefly covering the ultraviolet and visible regions of the spectrum. The principles are briefly outlined and a few examples of instrumentation are presented. The main thrust of the review is to collect and selectively present applications of UV-vis action spectroscopy to studies of stable gas-phase ion structures and combinations of spectroscopy with ion mobility, collision-induced dissociation, and ion-ion reactions leading to the generation of reactive intermediates and electronic energy transfer.

(Organic and Biological Electrochemistry Division Manuel M. Baizer Award) Concepts for Electrifying Organic Synthesis

The direct use of electrochemistry for the generation of reactive intermediates can have major advantages towards conventional synthetic strategies.[1] Less or no reagent waste is generated and new reaction pathways are accessible.[2] In order to exploit the electricity driven conversions for synthetic purposes and to install unique selectivity two modern approaches will be outlined: Solvent-controlled selective dehydrogenative cross-coupling reactions: A key for this is the use of boron-doped diamond anodes and fluorinated alcohols within the electrolyte.[3] This methodology opened new pathways for innovative and scalable arylation reactions.[4] New electrode systems for the anodic and cathodic conversion to value-added organic compounds. These systems are capable to go beyond common limits in electro-organic synthesis. The working horse to identify suitable electrolytic conditions is the electrosynthetic screening approach. This strategy gives also rise to fast optimization and subsequent scale-up.[5]

Absorption, metabolism and excretion of pictilisib, a potent Pan-Class I phosphatidylinositol-3-Kinase (PI3K) inhibitor, in rats, dogs, and humans

1. The absorption, metabolism and excretion of pictilisib, a selective small molecule inhibitor of class 1 A phosphoinositide 3-kinase (PI3K), was characterized following a single oral administration of [14C]pictilisib in rats, dogs and humans at the target doses of 30 mg/kg, 5 mg/kg and 60 mg, respectively. 2. Pictilisib was rapidly absorbed with Tmax less than 2 h across species. In systemic circulation, pictilisib represented the predominant total radioactivity greater than 86.6% in all species. 3. Total pictilisib and related radioactivity was recovered from urine and faeces in rats, dogs, and human at 98%, 80% and 95%, respectively, with less than 2% excreted in urine and the rest excreted into faeces. 4. In rat and dog, more than 40% of drug-related radioactivity was excreted into the bile suggesting biliary excretion was the major route of excretion. Unchanged pictilisib was a minor component in rat and dog bile. The major metabolite in bile was O-glucuronide of oxidation on indazole moiety (M20, 21% of the dose) in rats and an oxidative piperazinyl ring-opened metabolite M7 (10.8% of the dose) in dogs. 5. Oxidative glutathione (GSH) conjugates (M18, M19) were novel metabolites detected in rat bile, suggesting the potential generation of reactive intermediates from pictilisib. The structure of M18 was further confirmed by NMR to be a N-hydroxylated and GSH conjugated metabolite on the moiety of the indazole ring.

In Situ Stable Generation of Reactive Intermediates by Open Microfluidic Probe for Subcellular Free Radical Attack and Membrane Labeling.

Subcellular stimulation by free radicals is crucial for deeper insight of cell behaviors. However, it remains a tough challenge due to the high spatial precision requirement and short life of radicals. Herein, we report a versatile open microfluidic probe for stable generation of free radical and subcellular stimulation. By optimizing parameters, the chemical reaction can be confined in a microregion with a diameter of several μm, and the real-time produced reactive radicals can attack the desired subcellular region of a single cell. In order to reveal the attacked region, fluorescent cyanine 3 labeled tyramide free radicals are synthesized, and the target microregion on a single cell is successfully stained by the covalent linking reaction between radicals and membrane proteins, which proves the feasibility of our method. We believe this method will open new avenues for short-lived reactive intermediates stimulation at the single-cell/sub-cell level and selective membrane labeling.