Types Of Reactive Oxygen Species Research Articles

The Switching of the Type of a ROS Signal from Mitochondria: The Role of Respiratory Substrates and Permeability Transition

Flashes of superoxide anion (O2−) in mitochondria are generated spontaneously or during the opening of the permeability transition pore (mPTP) and a sudden change in the metabolic state of a cell. Under certain conditions, O2− can leave the mitochondrial matrix and perform signaling functions beyond mitochondria. In this work, we studied the kinetics of the release of O2− and H2O2 from isolated mitochondria upon mPTP opening and the modulation of the metabolic state of mitochondria by the substrates of respiration and oxidative phosphorylation. It was found that mPTP opening leads to suppression of H2O2 emission and activation of the O2− burst. When the induction of mPTP was blocked by its antagonists (cyclosporine A, ruthenium red, EGTA), the level of substrates of respiration and oxidative phosphorylation and the selective inhibitors of complexes I and V determined the type of reactive oxygen species (ROS) emitted by mitochondria. It was concluded that upon complete and partial reduction and complete oxidation of redox centers of the respiratory chain, mitochondria emit H2O2, O2−, and nothing, respectively. The results indicate that the mPTP- and substrate-dependent switching of the type of ROS leaving mitochondria may be the basis for O2−- and H2O2-selective redox signaling in a cell.

Weak magnetic field for enhanced degradation of sulfamethoxazole by the CoFe2O4/PAA system: Insights into performance and mechanism

In this work, a novel approach coupling a heterogeneous weak magnetic field (WMF) with the CoFe2O4/peroxyacetic acid (PAA) system was employed to enhance the degradation of sulfamethoxazole (SMX). Under the optimized conditions of 50 mT WMF, 0.1 g/L CoFe2O4, 0.2 mM PAA, and initial pH 6.0, a complete degradation of 10 μM SMX was achieved in 25 min, exhibiting a high synergistic coefficient of 1.61. This result indicates a significant synergistic effect among WMF, CoFe2O4, and PAA in effectively degrading SMX. The introduction of WMF did not alter the pH application range of the CoFe2O4/PAA system. Furthermore, the degradation efficiency of SMX by the CoFe2O4/PAA/WMF system was significantly reduced in the presence of humic acid (HA) and bicarbonate ions (HCO3−), while chloride ions (Cl−) exhibited a minor inhibitory effect. Quenching experiments and electron paramagnetic resonance (EPR) analysis reveal that WMF did not alter the types of reactive oxygen species (ROS) generated in the CoFe2O4/PAA system. The degradation of SMX in the CoFe2O4/PAA/WMF system involved both radical (CH3C(O)O∙ and CH3C(O)OO∙) and non-radical (1O2) oxidation pathways, driven by the redox cycling between ≡Co2+/≡Co3+ and PAA, as well as the rapid adsorption and transformation of oxygen (O2) at oxygen vacancies (OV), respectively. The presence of WMF enhanced the utilization of PAA by CoFe2O4 by improving the convection and mass transport in the solution, facilitating the formation of superoxide anion (O2∙−) and supplemented lattice oxygen (O2−) through the directional migration of paramagnetic O2 towards the CoFe2O4 surface, thus significantly promoting ROS formation. Additionally, the degradation pathways of SMX in the CoFe2O4/PAA/WMF system were proposed based on density functional theory (DFT) calculations and the detected transformation products (TPs). The toxicity of SMX was effectively reduced, as verified by predictions from the Ecological Structure-Activity Relationship Model (ECOSAR) procedure. The excellent catalytic performance, reusability, and effective degradation of various organic pollutants demonstrated by the CoFe2O4/PAA/WMF system suggest its potential as a promising strategy for water treatment.

Effects of photodynamic therapy using bisdemethoxycurcumin combined with melatonin or acetyl-melatonin on C. Albicans

The current study aims to explore the efficacy of antifungal photodynamic therapy (PDT) on C. albicans biofilms by combining photosensitizers, bisdemethoxycurcumin (BDMC), and melatonin (MLT) or acetyl-melatonin (AcO-MLT). Additionally, the relationship between different types of reactive oxygen species and PDT’s antifungal efficacy was investigated. BDMC, MLT and AcO-MLT were applied, alone and in combination, to 48-hour C. albicans biofilm cultures (n = 6/group). Blue and red LED light (250 mW/cm2 with 37.5 J/cm2 for single or 75 J/cm2 for dual photosensitizer groups) were used to irradiate BDMC groups and MLT/AcO-MLT groups, respectively. For combination groups, blue LEDs and subsequently red LEDs were used. Drop plate assays were performed at 0, 1 and 6 h post-treatment. Colony forming units (CFUs) were then counted after 48 h. Hydroxyl radicals and singlet oxygen were measured using fluorescence spectroscopy and electron spin resonance (ESR) spectroscopy. Additionally, cell cytotoxicity was tested on human oral keratinocytes. Significant CFU reductions were observed with combinations 20 µM BDMC + 20 µM AcO-MLT and 60 µM BDMC + 20 µM MLT at 0 and 1 h post-treatment, respectively. Singlet oxygen production increased with the addition of MLT/AcO-MLT and had moderate-substantial correlations with inhibition at all times. Hydroxyl radical production was not significantly different from the control. Additionally, BDMC exhibited subtle cytotoxicity on human oral keratinocytes. PDT using BDMC + MLT or AcO-MLT, with blue and red LED light, effectively inhibits C. albicans biofilm through singlet oxygen generation. Melatonin acts as a photosensitizer in PDT to inhibit fungal infection.

Glucose and pH dual-responsive hydrogels with antibacterial, reactive oxygen species scavenging, and angiogenesis properties for promoting the healing of infected diabetic foot ulcers

The healing process of diabetic foot ulcers is challenging due to the presence of a complex and severe inflammatory microenvironment, characterized by hyperglycemia, low pH, susceptibility to infection, vascular dysfunction, and over-expression of reactive oxygen species (ROS), which can potentially lead to amputation or even mortality. Herein, a glucose and pH dual-responsive hydrogel was designed and prepared by crosslinking phenylboronic acid-grafted quaternary chitosan (QF, 4 wt%) with dopamine-grafted oxidized hyaluronic acid (OD, 5 wt%) through phenylboronation, schiff-base reaction, and other techniques. The multifunctional QO/@PV@AB7 hydrogel was prepared by incorporating pravastatin-loaded chitosan nanoparticles (CSNPs@PV, 2 mg/mL) and antimicrobial peptide AMP-AB7 loaded silica nanoparticles (SiO2NPs@AB7, 0.5 mg/mL). The results demonstrate that the QO/@PV@AB7 hydrogel exhibits good responsiveness to acidic conditions and high glucose levels, while effectively scavenging various types of ROS. Moreover, it exerted protective effects against oxidative stress on cells, enhanced HUVECs viability, and promoted angiogenesis. Notably, the QO/@PV@AB7 hydrogel displayed potent antibacterial activity against methicillin-resistant Staphylococcus aureus (MRSA) and Escherichia coli. Additionally, in an MRSA-infected rat model of diabetic foot wounds, administration of the QO/@PV@AB7 hydrogel led to increased secretion of pro-angiogenic factors such as vascular endothelial nitric oxide synthase (eNOS), vascular endothelial-generating factor (VEGF), and endothelial cell adhesion molecule (CD31). Furthermore, the hydrogel significantly reduced the levels of inflammatory factors such as interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α), while simultaneously increasing the levels of anti-inflammatory cytokines such as interleukin-10 (IL-10). The findings suggest that multifunctional hydrogels incorporating PV@CSNPs and SiO2NPs@AB7 demonstrate promising potential as a therapeutic approach for the treatment of diabetic foot. Statement of SignificanceHere, a glucose and pH dual-responsive QO/@PV@AB7 hydrogel with antimicrobial and angiogenesis-promoting properties was developed for the treatment of infected wounds in diabetic feet. Our findings demonstrate that the proposed hydrogel exhibits good responsiveness, effectively scavenges various types of reactive oxygen species (DPPH, O2-, -OH, and ABTS+), provides protection against oxidative stress, enhances HUVECs cell viability, and promotes angiogenesis. Notably, it also demonstrates potent antibacterial activity against methicillin-resistant Staphylococcus aureus (MRSA) and Escherichia coli. Additionally, in vivo experiments demonstrated that the hydrogel exhibited accelerated wound healing in MRSA-infected diabetic foot ulcers, with a reduction of four days compared to the control group.

A Novel Cerium Oxide/Gold/Carbon Nanocomposite-Based Electrochemical Sensor for Detecting Hydroxyl Radicals

Hydroxyl radicals (•OH), a type of reactive oxygen species (ROS), play a crucial role in maintaining the normal physiological processes of human cells. Nevertheless, an excessive accumulation of these radicals may perturb cellular mechanisms, so triggering the onset of severe diseases, including cancer, neurological disorders, and heart disease. The detection of •OH is thus of utmost importance in the early diagnosis of these disorders. The combination of an electrochemical methodology with a recognition system is considered as a promising approach for the detection of •OH. This is primarily due to its capacity to provide fast and direct readings without the need for any preliminary sample preparation. This study presents the development of a new electrochemical sensor for the detection of •OH. The sensor was developed by modifying a screen-printed carbon electrode (SPCE) with a nanocomposite consisting of cerium oxide nanoclusters (CeOx), gold nanoparticles (AuNPs), and a highly conductive carbon. The synthesis of AuNPs supported by carbon was carried out using a deposition-precipitation process. Subsequently, the meticulous deposition of CeOx nanoclusters onto the AuNPs was achieved by the use of surface organometallic chemistry (SOMC). Energy dispersive X-ray spectroscopy (EDS) and transmission electron microscopy (TEM) were applied to assess the distribution of AuNPs on the carbon substrate and their subsequent embellishment with CeOx nanoclusters. The actual loadings of Ce and Au present in the nanocomposite were measured using inductively coupled plasma optical emission spectroscopy (ICP-OES). Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were employed to analyze the electrochemical responses resulting from the interaction of the CeOx-Au/Carbon nanocomposite with •OH. The CV results demonstrated that the proposed sensor exhibited the capability to effectively identify the presence of •OH in the Fenton reaction, with a notably low limit of detection of 58 µM. The sensor demonstrated a linear correlation between the current response and the concentration of •OH, within the range of 0.05 to 5 mM. Compared to a sensor modified with CeOx/Carbon, the CeOx-Au/Carbon-modified sensor exhibited enhanced electrochemical performance, as demonstrated by an increased current response and a reduced peak potential difference when detecting •OH radicals. Furthermore, the EIS studies showed that the sensor could distinguish •OH from other comparable ROS, such as hydrogen peroxide (H2O2).

Degradation of Anthraquinone dye wastewater by sodium percarbonate with CoO heterogeneous activation

AbstractBACKGROUNDAnthraquinone dyes have an anthraquinone structure as their nucleus, with one or more substituents forming different organic dyes. Anthraquinone dyes have a complex structure that allows them to exist stably in water environment, but also makes them more toxic than azo dyes. This results in varying degrees of harm to both humans and the environment as a result of residual dyes in the water or on the material’ surface. Sodium percarbonate (SPC) is a highly promising oxidant due to its green end product. Therefore, in this study, the catalytic performance and kinetic study of cobalt oxide (CoO) on SPC under different conditions were systematically investigated using RB19 as the target pollutant. The Box–Behnken Design (BBD) model was used to model the degradation of RB19 by CoO/SPC system, which gives the basis for practical application. The types of reactive oxygen species that effectively degrade RB19 and the potential degradation mechanism of the CoO/SPC system were revealed. At the same time, the CoO/SPC system was evaluated in terms of its practicality.RESULTSIn this work, the activation of SPC using CoO towards reactive blue 19 (RB19) degradation was explored. Experimental results showed that nearly 93.8% of RB19 could be removed within 30 min using 1 mmol L−1 SPC and 30 mg L−1 CoO. The three‐factor interaction effects of SPC concentration, CoO dosage and initial pH were investigated. The BBD model was set up to obtain the optimum working conditions of 1.039 mmol L−1 SPC, 33.35 mg L−1 CoO and the initial pH of 7.82, which gave a degradation rate of 95.372%. Additionally, it was confirmed that the solubility of Co2+ is consistently <150 μg L−1, meeting the emission standard (1 ppm). The presence of Cl−, NO3–, and HA had a similar profile, with a slight promoting effect in small amounts and an inhibitory effect when introduced in excess. The introduction of SO42– had a negligible effect on RB19 degradation, whereas the presence of HCO3− produced a slight inhibitory effect. Furthermore, the presence of PO43– showed a strong inhibitory effect. The CoO/SPC system is suitable for other organic dyes (32.7%–100%) and antibiotics (97.1–100%). Electron paramagnetic resonance (EPR) analysis and quenching experiments confirmed the presence and relative contribution of free radicals in the CoO/SPC system as CO3•‐ (88.12%) >O2•‐ (51.11%) >1O2 (37.21%) >•OH (5.27%) > SPC (3.33%) >CoO (0.09%). It has been confirmed that CoO activates SPC through electron transfer.CONCLUSIONThe present study describes a less time‐consuming, and more efficient method of treating anthraquinone dye wastewater that requires less oxidizer and catalyst, making it more economical. This proposes a straightforward, cost‐effective and efficient technique using SPC triggered by transition metal oxides. © 2024 Society of Chemical Industry (SCI).

Prolonged resident nanoparticles effectively treat acute lung injury via the selective upregulation of intracellular hydrogen peroxide

Selective modulation of the types of reactive oxygen species (ROS) for the treatment of acute lung injury (ALI) has not been tackled, whereas the usually applied hydrophobic nanoparticles (NPs) are easily excreted and metabolized. Herein, a zwitterionic-segment containing polyurethane was synthesized to formulate into Pazopanib (Pazo)-loaded NPs (PUSB@Pazo NPs), which had the ability to selectively enhance the expression of H2O2 but suppress other types of ROS, and achieved long retention in lung and thereby improved treatment efficacy. The zwitterionic group of PUSB effectively decreased the clearance rate of PUSB@Pazo NPs in vivo, and prolonged their resident time in lung post inhalation up to 48 h. The increase of local H2O2 concentration decreased the permeability of lung epithelial cells, accompanied by the significantly reduced tissue edema and inflammatory cell recruitment. The system also reduced the expression of various inflammatory factors, revealing its effective and promising treatment for ALI.

Strategic implementation of upflow microbubble airlift photocatalytic process to control heavy metal resistant-MDR bacteria and the associated genes in wastewater

The emergence of multidrug resistance (MDR) and heavy metal resistance (HMR) in bacterial pathogens and genes through mobile genetic elements (MGEs) from wastewater effluents needs to be eradicated using green technology. HMR is critical to controlling antimicrobial resistance but has been neglected in most photocatalytic disinfection (PCD) studies. Advanced photocatalysis in antimicrobial studies requires a strategic approach to enhance the disinfection efficiency. This study applied an optimized upflow airlift photocatalytic reactor (UAPR) with microbubble air and blue light to remove the antimicrobial resistance (HMR–MDR bacteria (HMR–MDRB), HMR genes (HMRGs), antibiotic resistant genes (ARGs) and MGEs) and inhibit pathogenicity in a mixed culture of high-strength HMR–MDRB isolated from wastewater. Stable dissolved oxygen (DO) supplementation and blue light significantly affected the HMRGs and MGE reduction, resulting in enhanced disinfection activity (30 %) and reaction time (60 min) required for the complete inactivation of HMR-MDRB mixed culture. The process effectively reduced the blaNDM-1 (3.37 log), pbrT (2.18 log), intl1 (2.16 log), and tn916/1545 (4.07 log), with a PCD rate constant (kg) of 0.0515 min−1, 0.0359 min−1, 0.0292 min−1, and 0.0662 min−1, respectively. Process mechanism studies showed that the stable supplementation of DO was a critical factor in controlling the type of reactive oxygen species (ROS), resulting in type II ROS, 1O2, as the critical free radical contributing to the reduction of ARGs and integron, whereas h+ was the ROS for pbrT and transposon.

A continuous-wave spectroscopic singlet oxygen sensor for photodynamic therapy dosimetry: Preclinical studies in a murine model of actinic keratosis

SignificanceSinglet oxygen (1O2), a type of reactive oxygen species, destroys cancer cells during photodynamic therapy (PDT). Inter-patient variations in tissue oxygen levels, dose of photosensitizer (PS), and fluence of light can affect 1O2 generation and result in suboptimal treatment efficacy in the clinic. ApproachHere, we describe a high throughput spectrometer system based on computational spectroscopy for real-time measurement of PS levels and 1O2 luminescence during PDT. The dosimeter provides a direct real-time measurement of 1O2 production in continuous-wave mode. Data were obtained from in-vitro protoporphyrin IX (PpIX) phantoms, and from in-vivo studies in mice with actinic keratosis (AK, an early form of squamous cell carcinoma) using the dosimeter. ResultsData indicated a correlation between 1O2 levels and treatment outcome (lesion shrinkage/clearance). ConclusionsThis study provides additional evidence for a correlation between 1O2 generation and AK treatment response, suggesting that 1O2 dosimetry could have utility in the dermatology clinic.

Bioactive Compounds for Combating Oxidative Stress in Dermatology.

There are extensive studies that confirm the harmful and strong influence of oxidative stress on the skin. The body's response to oxidative stress can vary depending on the type of reactive oxygen species (ROS) or reactive nitrogen species (RNS) and their metabolites, the duration of exposure to oxidative stress and the antioxidant capacity at each tissue level. Numerous skin diseases and pathologies are associated with the excessive production and accumulation of free radicals. title altered Both categories have advantages and disadvantages in terms of skin structures, tolerability, therapeutic performance, ease of application or formulation and economic efficiency. The effect of long-term treatment with antioxidants is evaluated through studies investigating their protective effect and the improvement of some phenomena caused by oxidative stress. This article summarizes the available information on the presence of compounds used in dermatology to combat oxidative stress in the skin. It aims to provide an overview of all the considerations for choosing an antioxidant agent, the topics for further research and the answers sought in order to optimize therapeutic performance.

Reduced porous 2D Co3O4 enhanced peroxymonosulfate activation to form multi-reactive oxygen species: The key role of oxygen vacancies

The introduction of oxygen vacancies (Ov) into Co-based metal oxides has been considered a promising strategy for activating peroxymonosulfate (PMS) to effectively degrade refractory organic contaminants. However, the types of reactive oxygen species (ROS) generated in Ov-catalyst/PMS systems exhibited variability. Therefore, the effect of the interaction between Ov and PMS on ROS generation required further research. Herein, the Ov-tuned 2D porous Co3O4 catalysts were easily constructed by simply controlling the NaBH4 concentration. The as-prepared 2D Co3O4-1.6 had the highest Ov content (2.88 × 1014 spins/g, δ = 0.726), and its catalytic activity for benzotriazole (BTA) degradation (k = 0.032 min−1) was three times higher than that of pristine 2D Co3O4 (k = 0.011 min−1). A series of characterizations and DFT calculations demonstrated that the major active site was Co(II), with Ov serving as an localized electron-rich co-site. These dual sites synergistically improved the adsorption capacity for PMS, enabling rapidly electrons transfer to PMS while promoting the dissociation of O-O bond in PMS to form multiple ROS. Compared to the pristine 2D Co3O4/PMS system, which was dominated only by SO4−, the key ROS in the 2D Co3O4-1.6/PMS system were found to be 1O2 (3.56 µM) and SO4− (2.53 µM), while both O2– (0.72 µM) and OH (0.65 µM) were involved in the activation reaction, the contributions of these four ROS were as follows: 1O2 (36.8%) > SO4− (25.4%) >O2– (9.5%) >OH (6.3%). Finally, three possible degradation pathways of BTA were proposed, and the toxicity of BTA degradation decreased with time, which was consistent with the toxicity prediction results of eleven intermediates. This study provides new insights into the key role of Ov in the heterogeneous catalytic system of PMS-based advanced oxidation processes.

PH-Activated Ce-Doped Molybdenum Oxide Nanoclusters for Tumor Microenvironment Responsive Photothermal and Chemodynamic Therapy.

Molybdenum-based nanomaterials have shown promise for anticancer treatment due to their strong photothermal and redox-activated capabilities. Herein, we have fabricated cerium-doped MoOx (Ce-MoOv) with tunable Mo/Ce molar ratios by a one-pot method and investigated their effect on chemodynamic therapy (CDT) and photothermal therapy (PTT). It is found that Ce-MoOv can self-assemble into nanoclusters in acidic conditions and the increasing Ce amount will generate oxygen vacancy defects and induce the valence change of Mo6+/Mo5+ and Ce4+/Ce3+, which leads to strong near-infrared absorption with high photothermal conversion efficiency of 71.31 and 49.86% for 808 and 1064 nm. Other than photothermal conversion, the materials demonstrate pH-/glutathione (GSH)-activated photoacoustic (PA) imaging capability in vitro. In addition, Ce-MoOv acts as a CDT reagent capable of converting endogenous H2O2 to two types of reactive oxygen species (•OH, 1O2) while depleting GSH. Ce-MoOv demonstrates an excellent therapeutic effect against HCT116 cells and effectively reduces the intracellular GSH level and significantly increases the number of reactive radicals under 1064 nm laser irradiation as compared with the no-laser group in vitro. This work provides a new paradigm using lanthanide-doped polymetallic oxides for pH-/GSH-responsive photothermal/chemodynamic therapy with PA imaging ability.

Biomimetic Epigallocatechin Gallate-Cerium Assemblies for the Treatment of Rheumatoid Arthritis.

Rheumatoid arthritis (RA) is an autoimmune and inflammatory disease that is so far incurable with long-term health risks. The high doses and frequent administration for the available RA drug always lead to adverse side effects. Aiming at the obstacles to achieving effective RA treatment, we prepared macrophage cell membrane-camouflaged nanoparticles (M-EC), which were assembled from epigallocatechin gallate (EGCG) and cerium(IV) ions. Due to its geometrical similarity to the active metal sites of a natural antioxidant enzyme, the EC possessed a high scavenge efficiency to various types of reactive oxygen species (ROS) and reactive nitrogen species (RNS). The macrophage cell membrane assisted M-EC in escaping from the immune system, being uptaken by inflammatory cells, and specifically binding IL-1β. After tail vein injection to the collagen-induced arthritis (CIA) mouse model, the M-EC accumulated at inflamed joints and effectively repaired the bone erosion and cartilage damage of rheumatoid arthritis by relieving synovial inflammation and cartilage erosion. It is expected that the M-EC can not only pave a new way for designing metal-phenolic networks with better biological activity but also provide a more biocompatible therapeutic strategy for effective treatment of RA.

Combined bisdemethoxycurcumin and potassium iodide-mediated antimicrobial photodynamic therapy

Antimicrobial photodynamic therapy is emerging as a promising way to treat infections with minimal side effects. Typically, a single photosensitizer used in photodynamic therapy is capable of generating only one type of reactive oxygen species, which may have inadequate capability to eradicate certain types of microbes, especially Candida species. Thus, the use of combined photosensitizers is examined as a means of achieving superior antimicrobial results. We postulate that bisdemethoxycurcumin, a type I reactive oxygen species generator, combined with potassium iodide, an antimicrobial iodide molecule, might exhibit superior antimicrobial effects compared to a single photosensitizer-mediated photodynamic therapy. The effects of bisdemethoxycurcumin + potassium iodide + dental blue light on Candida albicans reduction were examined. Candida biofilms were treated with 20, 40 or 80 μM bisdemethoxycurcumin, 100 mM potassium iodide or a combination of these species for 20 min before irradiation with a dental blue light (90 J/cm2). The negative and positive controls were phosphate buffer saline and nystatin at 1 : 100,000 units/ml, respectively. Candidal numbers were quantified at 0, 1, 6 and 24 h. Hydroxyl radicals were spectrophotometrically measured using 2-[6-(4′amino phynoxyl-3H-xanthen-3-on-9-yl)] benzoic acid or APF probe-mediated fluorescence intensity (Varioskan) at 490/515 nm (excitation/emission). Candidal counts and hydroxyl radical comparisons were performed using the Kruskal-Wallis test and one-way ANOVA, respectively. Correlations between candidal numbers and hydroxyl radical levels were done with a Pearson correlation test. Forty μM bisdemethoxycurcumin+100 mM KI could provide a 3.5 log10 CFU/ml reduction after 6 h. Bisdemethoxycurcumin alone generated OH levels that were strongly correlated with candidal reduction. In conclusion, 40 μM bisdemethoxycurcumin+100 mM KI could reduce C. albicans biofilm.

Polysiloxane-based hyperbranched fluorescent probe for dynamic visualization of HClO in lysosomes and vivo.

As a type of reactive oxygen species, hypochlorous acid (HClO) is associated with inducing oxidative stress in lysosomes. Once its concentration is abnormal, it may lead to lysosomal rupture and subsequent apoptosis. Meanwhile, this may provide new inspiration for cancer treatment. Therefore, it is crucial to visualize HClO in lysosomes at the biological level. So far, numerous fluorescent probes have emerged to identify HClO. However, fluorescent probes that combine low biotoxicity with lysosome-targetable properties are scarce. In this paper, hyperbranched polysiloxanes were modified by embedding perylenetetracarboxylic anhydride red fluorescent cores with naphthalimide derivative green fluorophores to synthesize novel fluorescent probe (PMEA-1). PMEA-1 was a lysosome-targetable fluorescent probe with unique dual emission, high biosafety, and good response speed. PMEA-1 exhibited excellent sensitivity and responsiveness to HClO in PBS solution and could dynamically visualize HClO fluctuations in cells and zebrafish. Simultaneously, PMEA-1 also had monitoring ability for HClO produced in the process of cellular ferroptosis. In addition, the bioimaging results indicated that PMEA-1 was capable of accumulating within the lysosomes. We anticipate that PMEA-1 will broaden the application of silicon-based fluorescent probes in the field of fluorescence imaging.

Photosensitizers with multiple degradation modes for efficient and postoperatively safe photodynamic therapy

Photodynamic therapy (PDT) is emerging as a powerful tool for cancer treatment due to its unique advantages in terms of noninvasive and spatiotemporal selectivity. However, the residue of photosensitizers (PSs), which usually lead to thorny post-treatment side effects after photodynamic therapy (PDT), is one of bottlenecks for clinical translation. Herein, PSs with multiple degradation modes are developed to solve this issue. Upon 660 nm laser excitation, PSs can produce different types of reactive oxygen species (ROS), in which 1O2 and O2·- could kill the cancer cells, while ·OH could oxide the PSs themselves for photodegradation. After PDT, the residual few number of PSs could be further oxidized by endogenous ROS for biodegradation, and the degradation products could be further excreted by urine. This process therefore solves the slow-metabolism issue of traditional PSs. Among them, SQSe demonstrates the highest killing efficiency with best degradation ability, as confirmed by both in vitro and in vivo results. The postoperative safety of SQSe is further verified by assessment on in vivo artificially induced post-operative side effects.

Laser-induced tuning of carbon nanosensitizers to maximize nitrogen doping and reactive oxygen species production in the visible range

Carbon nanodots (CNDs) have emerged as novel fluorescent nanosensitizers able to expand the photocatalytic response of conventional semiconductors beyond the ultraviolet spectral window. Key aspects of CNDs related with their high photostability, resistance to photobleaching and optical properties (including downconversion and upconversion luminescence) are often associated with the capacity to dope the carbogenic network with light heteroatoms, especially nitrogen. In this work, we present the use of laser pyrolysis as a versatile and convenient synthesis technique to generate different N-doped CNDs. The level of N doping can be tuned through the selection of a single liquid solvent containing N as carbon precursor. This liquid precursor can be alternatively enriched with additional N sources co-fed in the form of gas (i.e. NH3) or disolved solid precursors (i.e. phtalocyanine-Ph). We demonstrate that the N-CNDs retrieved after the additional N cofeeding treatments improve their photoactivity when assembled to P25 nanoparticles towards the conversion of methyl orange (MO) under white LED illumination. All the N-CNDs act as photosensitizers expanding the response of P25 beyond the UV region and exhibit an active role generating different types of Reactive Oxygen Species (ROS) via singlet oxygen, superoxide and hydroxyl radicals that can pave the way for multiple potential applications in environmental and green processes.

Au-sensitised TiO2 and ZnO nanoparticles for broadband pharmaceuticals photocatalytic degradation in water remediation

A large number of contaminants of emerging concerns, such as most pharmaceuticals, exhibit high persistency in water bodies due to the difficulty of their removal by conventional treatment methods, causing severe environmental issues. Semiconductor-based photocatalysis has become an exciting solution to remove these pollutants through photocatalytic degradation. However, the high diversity of chemical composition of pharmaceutic pollutants hinders the selection of an adequate photocatalyst for efficient and broadband pollutants removal, making necessary the development of systematic studies that link the physicochemical photocatalyst and pollutant properties with the degradation performance. Here, four different photocatalysts have been synthesised, physical-chemically characterised and systematically compared in the photocatalytic degradation of four highly abundant and chemically different pharmaceuticals in water remediation field: chloroquine phosphate (CLQ), paracetamol (PAR), diclofenac sodium (DCF), and ciprofloxacin (CIP). The photocatalysts were selected to be easily accessible, cost-effective, and scalable, including the well-known TiO2 and ZnO, and the plasmonic photocatalysts versions TiO2:Au and ZnO:Au, which were synthesised, characterised, and assayed under UV and visible light. The results show that the photocatalytic degradation correlated with the amount and type of reactive oxygen species generated by photocatalysts, electrostatic interaction between pollutants and photocatalysts. High degradation efficiencies were shown for all photocatalysts and differences were observed as a function of the pollutant for the ZnO- and TiO2-based photocatalysis. Finally, the Au nanoparticle sensitising displayed remarkable improvement concerning the homocomponent counterparts under visible radiation opening the door for degrading pollutants in a cost-effective way.

Mechanism of NO removal in selective catalytic reduction based on γ‐Fe2O3 catalyst doped with Mg element

AbstractThe doping of different elements will make the Fe2O3 catalyst show different catalytic characteristics and improve the activity of the Fe2O3 catalyst in selective catalytic reduction (SCR), mainly by increasing the types of reactive oxygen species and the specific surface area of the catalyst. In this paper, density functional theory (DFT) was used to reveal the reaction path and adsorption behaviour of the Mg‐doped γ‐Fe2O3 catalyst. The results show that the doping of Mg ions can contribute electrons and lead to electron migration on the catalyst surface, which changes the acidity of some sites on the catalyst surface. The adsorption energy of NH3 is related to the binding sites of N atoms on the catalyst surface, and different adsorption sites will be enhanced or weakened due to Mg doping. NH2 reacts with NO to form N2 and H2O, so the dehydrogenation of NH3 to the NH2 radical is a key step in SCR. With doping, this process becomes more likely to occur. In addition, the activation energy barrier of NH2 formation in the aerobic environment is lower than that in the anaerobic condition, which contributes to NH3 dehydrogenation. Therefore, doping Mg on the surface of γ‐Fe2O3 catalyst can improve the catalytic activity of NO removal.

Effect and mechanism of norfloxacin removal by guava leaf extract in the ZVI/H2O2 system

To overcome the bottlenecks of the conventional zero-valent iron Fenton-like (ZVI/H2O2) process, such as low reagent utilization, low applicable pH, and iron sludge contamination, guava leaf extract (GLE) was used as a green promoter to enhance ZVI/H2O2 process in this study. Compared with the ZVI/H2O2 system, the removal rate and kobs of norfloxacin by the ZVI/H2O2/GLE system were increased by 33.76% and 2.19 times, respectively. The experimental investigation of the mechanism showed that the attack of reactive oxygen species was the main pathway for the removal of pollutants, and three types of reactive oxygen species (1O2, O2−,·OH) generations in the ZVI/H2O2/GLE system were effectively promoted by the introduction of GLE. The reactivity improvement was mainly due to the decrease of pH. At the same time, the chelation of iron ions by GLE promoted the Fe(III)/Fe(II) cycle on the catalyst surface was also a minor mechanism to improve the reactivity. This study provides a crucial reference for the practical application of guava leaf to promote the ZVI/H2O2 process in environmental pollution control.