1O2 Production Research Articles

Chlorin e6-loaded goat milk-derived extracellular vesicles for Cerenkov luminescence-induced photodynamic therapy.

Photodynamic therapy (PDT) is a promising cancer treatment strategy with rapid progress in preclinical and clinical settings. However, the limitations in penetration of external light and precise delivery of photosensitizers hamper its clinical translation. As such, the internal light source such as Cerenkov luminescence (CL) from decaying radioisotopes offers new opportunities. Herein, we show that goat milk-derived extracellular vesicles (GEV) can act as a carrier to deliver photosensitizer Chlorin e6 (Ce6) and tumor-avid 18F-FDG can activate CL-induced PDT for precision cancer theranostics. GEV was isolated via differential ultracentrifugation of commercial goat milk and photosensitizer Ce6 was loaded by co-incubation to obtain Ce6@GEV. Tumor uptake of Ce6@GEV was examined using confocal microscopy and flow cytometry. To demonstrate the ability of 18F-FDG to activate photodynamic effects against cancer cells, apoptosis rates were measured using flow cytometry, and the production of 1O2 was measured by reactive oxygen species (ROS) monitoring kit. Moreover, we used the IVIS device to detect Cherenkov radiation and Cerenkov radiation energy transfer (CRET). For animal experiments, a small-animal IVIS imaging system was used to visualize the accumulation of the GEV drug delivery system in tumors. PET/CT and CL images of the tumor site were performed at 0.5, 1, and 2 h. For in vivo antitumor therapy, changes of tumor volume, survival time, and body weight in six groups of tumor-bearing mice were monitored. Furthermore, the blood sample and organs of interest (heart, liver, spleen, lungs, kidneys, and tumor) were collected for hematological analysis, immunohistochemistry, and H&E staining. Confocal microscopy of 4T1 cells incubated with Ce6@GEV for 4 h revealed strong red fluorescence signals in the cytoplasm, which demonstrated that Ce6 loaded in GEV could be efficiently delivered into tumor cells. When Ce6@GEV and 18F-FDG co-existed incubated with 4T1 cells, the cell viability plummeted from more than 88.02 ± 1.30% to 23.79 ± 1.59%, indicating excellent CL-induced PDT effects. In vivo fluorescence images showed a peak tumor/liver ratio of 1.36 ± 0.09 at 24 h after Ce6@GEV injection. For in vivo antitumor therapy, Ce6@GEV + 18F-FDG group had the best tumor inhibition rate (58.02%) compared with the other groups, with the longest survival rate (35 days, 40%). During the whole treatment process, neither blood biochemical analysis nor histological observation revealed vital organ damage, suggesting the biosafety of this treatment strategy. The simultaneous accumulation of 18F-FDG and Ce6 in tumor tissues is expected to overcome the deficiency of traditional PDT. This strategy has the potential to extend PDT to a variety of tumors, including metastases, using targeted radiotracers to provide internal excitation of light-responsive therapeutics. We expect that our method will play a critical role in precision treatment of deep solid tumors.

Fine‐Tuning Cu (II)‐Induced Self‐Assembly of Hydrophilic Cyanine Dyes for Enhanced Tumor Photothermal Therapy

AbstractSupramolecular self‐assembly of near‐infrared (NIR) dyes are believed to be a promising strategy to design effective photothermal agents for tumor photothermal therapy (PTT). However, due to the uncontrollable intermolecular interactions, accurately fine‐tuning the aggregated morphology of NIR dyes through adjusting their supramolecular self‐assembly is challenging. Here, based on organic–metal coordination interaction, a facile self‐assembly fine‐tuning strategy is proposed to adjust the aggregated morphology of heptamethine cyanine (Cy7) dyes, the well‐known NIR dyes. Three hydrophilic Cy7 derivatives Cy‐nCOOH (n = 1, 2, and 3) are synthesized, and then are coordinated with Cu2+to obtain different aggregates. Cy‐1COOH/Cu aggregates form partial J‐aggregates. Cy‐2COOH/Cu aggregates are amorphous. Noteworthily, Cy‐3COOH/Cu aggregates exhibit significant H‐type aggregation. Moreover, Cy‐3COOH/Cu aggregates show about threefold higher photothermal conversion efficiency and obviously enhanced photostability than Cy‐1COOH/Cu and Cy‐2COOH/Cu aggregates. It is demonstrated that H‐aggregates with face‐to‐face π–π stacking greatly quench fluorescence and inhibit singlet oxygen (1O2) production, which lead to the improved photothermal performances. In vitro and in vivo experiments demonstrate the remarkable tumor PTT efficiency of Cy‐3COOH/Cu H‐aggregates. This study provides a new insight into how to precisely control molecular aggregation of organic dyes in supramolecular self‐assembly for enhanced tumor phototherapy.

Surface Boronizing Can Weaken the Excitonic Effects of BiOBr Nanosheets for Efficient O2 Activation and Selective NO Oxidation under Visible Light Irradiation.

The photocatalytic O2 activation for pollutant removal highly depends on the controlled generation of desired reactive oxygen species (ROS). Herein, we demonstrate that the robust excitonic effect of BiOBr nanosheets, which is prototypical for singlet oxygen (1O2) production to partially oxidize NO into a more toxic intermediate NO2, can be weakened by surface boronizing via inducing a staggered band alignment from the surface to the bulk and simultaneously generating more surface oxygen vacancy (VO). The staggered band alignment destabilizes excitons and facilitates their dissociation into charge carriers, while surface VO traps electrons and efficiently activates O2 into a superoxide radical (•O2-) via a one-electron-transfer pathway. Different from 1O2, •O2- enables the complete oxidation of NO into nitrate with high selectivity that is more desirable for safe indoor NO remediation under visible light irradiation. This study provides a facile excitonic effect manipulating method for layered two-dimensional photocatalysts and sheds light on the importance of managing ROS production for efficient pollutant removal.

Smart Covalent Organic Framework with Proton-Initiated Switchable Photocatalytic Aerobic Oxidation

To conveniently regulate photocatalytic reactions, the design and development of smart photocatalysts, which can realize a series of controllable regulation of their structure, physicochemical properties, photocatalytic activity, and selectivity by simple external stimuli, such as chemical substances, pH, light, electric field, and heat, has aroused keen interest. However, the relevant research is still in its infancy. Herein, a smart imine covalent-organic-framework (COF) photocatalyst HP-n (n represents the pH of COF pretreatment, n = 1∼7) with proton-initiated switchable photocatalytic aerobic oxidation has been prepared. In the structure, the imine units can be reversibly protonated, which leads to the COF skeleton rearrangement from the phenolic to its quinone structure. The corresponding absorption band edge is expanded from 463 nm (HP-7) to 630 nm (HP-1). Meanwhile, the excitation energy transfer, oxygen adsorption, and activation change significantly, endowing HP-n with smartly switchable 1O2 production and interesting proton-initiated efficiency photocatalytic sulfide oxidation with both conversion and sulfoxide selectivity >99%. This work demonstrates a smart imine-COF photocatalyst, which paves the way for the development of smart photocatalysts and reveals the critical roles of protons in the structure–property–activity relationship of COF photocatalysts.

Super Light‐Sensitive Photosensitizer Nanoparticles for Improved Photodynamic Therapy against Solid Tumors

AbstractPhotodynamic therapy (PDT) is an effective method for superficial cancer treatment. However, the limited light intensity in tissues, tumor hypoxia, and the low accumulation efficiency of photosensitizers (PSs) in tumors are still major challenges. Herein, we introduce super light‐sensitive PS nanoparticles (designated HR NPs) that can increase singlet oxygen (1O2) production and improve PS accumulation in tumors. HR NPs have the ability to produce a large amount of 1O2 under ultralow power density light (0.05 mW cm−2) irradiation. More significantly, HR NPs have a long circulating time in tumor‐bearing mice and can accumulate in tumors with high efficiency. When irradiated by light with a suitable wavelength, the nanoparticles exhibit excellent antitumor efficacy. This work will make it possible to cure solid tumors by PDT by enhancing the therapeutic effects.

Drug-Induced Self-Assembly Cascade Nanoreactor for Synergistic Tumor Therapy.

The construction of completely biocompatible and biodegradable tumor suppressors by a simple and reliable method is essential for the clinical application of cancer-targeted drugs. Herein, by inserting glucose oxidase (GOx), catalase (CAT), and chlorin e6 (Ce6) into human serum albumin (HSA) assembly molecules, we constructed a cancer-targeted cascade bioreactor for synergistic starvation and photodynamic therapy (PDT). The modification of HSA could block the GOx activity and reduce the cytotoxicity of normal cells and organs. Through active targeting and passive enhanced permeability and retention effect, the loading of AS1411 could promote the cascade bioreactors to effectively target nucleolin-overexpressed tumors. Once internalized by cancer cells, as a result of catalyzing hydrogen peroxide (H2O2) to produce oxygen (O2), the protein nano-cascade reactor promoted microenvironmental oxygenation, which would subsequently lead to an increase in cytotoxic singlet oxygen (1O2) production under light irradiation as well as the decomposition of intracellular glucose. In vitro and in vivo studies showed that the cascaded nanoreactors could significantly enhance therapeutic efficacy through synergistic starvation therapy and enhanced PDT as well as chemotherapy. This cascade strategy will be demonstrated in clinical applications with huge potential.

Pauling-type adsorption of O2 induced electrocatalytic singlet oxygen production on N–CuO for organic pollutants degradation

Due to environmentally friendly operation and on-site productivity, electrocatalytic singlet oxygen (1O2) production via O2 gas is of immense interest in environment purification. However, the side-on configuration of O2 on the catalysts surface will lead to the formation of H2O, which seriously limits the selectivity and activity of 1O2 production. Herein, we show a robust N-doped CuO (N–CuO) with Pauling-type (end-on) adsorption of O2 at the N–Cu–O3 sites for the selective generation of 1O2 under direct-current electric field. We propose that Pauling-type configuration of O2 not only lowers the overall activation energy barrier, but also alters the reaction pathway to form 1O2 instead of H2O, which is the key feature determining selectivity for the dissociation of Cu–O bonds rather than the O–O bonds. The proposed N dopant strategy is applicable to a series of transition metal oxides, providing a universal electrocatalysts design scheme for existing high-performance electrocatalytic 1O2 production.

Selective production of singlet oxygen for harmful cyanobacteria inactivation and cyanotoxins degradation: Efficiency and mechanisms

Knowledge about the impact of singlet oxygen (1O2) on the characteristics and inactivation of harmful cyanobacterial organic matter is limited. In this study, the feasibility of using an improved single-iron doped graphite-like phase carbon nitride catalyst (FeCN) to activate peroxymonosulfate (PMS) catalytic production of 1O2 to inactivate four harmful cyanobacteria was investigated. The inactivation efficiencies at 30 min were 92.77%, 66.84%, 91.06%, and 93.45% for Microcystis aeruginosa (M. aeruginosa), Nodularia harveyana, Oscillatoria sp., and Nostoc sp., respectively. This was associated with adjusting experimental parameters, such as the FeCN and PMS doses and initial pH, to obtain the maximum 1O2 yield. The quenching experiment results and electron paramagnetic resonance spectra showed that 1O2 generated via the non-radical pathway might play a dominant role in inactivating harmful cyanobacteria and degrading harmful algal toxins (Microcystin-LR and Nodularin). In addition, the FeCN-PMS system not only effectively destroyed the integrity of harmful cyanobacterial cells but also effectively degraded cyanobacterial toxins, thereby preventing severe secondary contamination by cell rupture. A possible removal mechanism was proposed. This reveals the potential of 1O2 to simultaneously inactivate harmful cyanobacteria and degrade harmful cyanobacterial toxins.

Development of a Polymeric Film Entrapping Rose Bengal and Iodide Anion for the Light-Induced Generation and Release of Bactericidal Hydrogen Peroxide

A series of poly(2-hydroxyethyl methacrylate) (PHEMA) thin films entrapping photosensitizer Rose Bengal (RB) and tetrabutylammonium iodide (TBAI) have been synthetized. The materials have been characterized by means of Thermogravimetric Analysis (TGA), Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy (ATR-FTIR) and UV-vis Absorption spectroscopy. Irradiation of the materials with white light led to the generation of several bactericidal species, including singlet oxygen (1O2), triiodide anion (I3−) and hydrogen peroxide (H2O2). 1O2 production was demonstrated spectroscopically by reaction with the chemical trap 2,2′-(anthracene-9,10-diylbis(methylene))dimalonic acid (ABDA). In addition, the reaction of iodide anion with 1O2 yielded I3− inside the polymeric matrix. This reaction is accompanied by the formation of H2O2, which diffuses out the polymeric matrix. Generation of both I3− and H2O2 was demonstrated spectroscopically (directly in the case of triiodide by the absorption at 360 nm and indirectly for H2O2 using the xylenol orange test). A series of photodynamic inactivation assays were conducted with the synthesized polymers against Gram-negative bacteria Escherichia coli and Pseudomonas aeruginosa. Complete eradication (7 log10 CFU/mL) of both bacteria occurred after only 5 min of white light irradiation (400–700 nm; total energy dose 24 J/cm2) of the polymer containing both RB and TBAI. The control polymer without embedded iodide (only RB) showed only marginal reductions of ca. 0.5 log10 CFU/mL. The main novelty of the present investigation is the generation of three bactericidal species (1O2, I3− and H2O2) at the same time using a single polymeric material containing all the elements needed to produce such a bactericidal cocktail, although the most relevant antimicrobial activity is shown by H2O2. This experimental approach avoids multistep protocols involving a final step of addition of I−, as described previously for other assays in solution.

In-situ preparation of coal gangue-based catalytic material for efficient peroxymonosulfate activation and phenol degradation

Based on the urgency of comprehensive utilization of large amount of coal gangue and the demand for the treatment of organic pollution in coal chemical sites and water bodies, novel coal gangue-based persulfate catalytic material (GCM) which can effectively activate peroxymonosulfate (PMS) were prepared by using coal gangue as raw material and adding activator under inert atmosphere. Under the optimized conditions, the degradation rate of GCM-ZnCl2 material can reach 82.6% in 25min. Among different environmental impact factors, anions have little effect on the degradation rate of phenol, while the initial pH value has a greater impact. When the pH value is 9.0, it belongs to the synergistic effect of alkali activation, and the degradation effect of phenol is relatively better. The GCM-ZnCl2 material can realize the efficient adsorption of phenol through its large specific surface area and pore volume, and provide more catalytic active sites. The oxygen-containing groups CO (carboxyl, ester, ketone, etc.) on its surface can react with PMS to produce free radical SO4•− or induce the production of non-free radical 1O2, so as to realize the efficient degradation of phenol.

BODIPYs in PDT: A Journey through the Most Interesting Molecules Produced in the Last 10 Years.

Over the past 30 years, photodynamic therapy (PDT) has shown great development. In the clinical setting the few approved molecules belong almost exclusively to the porphyrin family; but in the scientific field, in recent years many researchers have been interested in other families of photosensitizers, among which BODIPY has shown particular interest. BODIPY is the acronym for 4,4-difluoro-4-bora-3a, 4a-diaza-s-indacene, and is a family of molecules well-known for their properties in the field of imaging. In order for these molecules to be used in PDT, a structural modification is necessary which involves the introduction of heavy atoms, such as bromine and iodine, in the beta positions of the pyrrole ring; this change favors the intersystem crossing, and increases the 1O2 yield. This mini review focused on a series of structural changes made to BODIPYs to further increase 1O2 production and bioavailability by improving cell targeting or photoactivity efficiency.

Detection of excited triplet species from photolysis of carbonyls: Direct evidence for single oxygen formation in atmospheric environment.

Excited triplet species play an important role in the photolytic formation of 1O2 from carbonyls, but the related mechanism is still uncertain, due to lack of direct evidence. In this study, steady-state and transient photolysis of eleven carbonyls to produce 1O2 was investigated. Dicarbonyl displayed greater 1O2 production ability than monocarbonyl, while dicarbonyl containing both ketone and carboxyl groups connected by CC bond (i.e., pyruvic acid (PA)) showed the highest 1O2 steady-state concentration ([1O2]SS). For the first time, the production of 3PA* from PA with narrow energy gap was confirmed by laser flash photolysis technique and the second-order decay rate constant of 3PA* was 2.78 × 107 M-1 s-1. Quenching results verified the dominant contribution of 3PA* to 1O2 production from PA. Addition of inorganic salt or increase in solution pH showed negligible effect on 3PA*, but significantly decreased the [1O2]SS of PA by up to two orders of magnitude, due to reduction of hydrate content. Photolysis of methylglyoxal and dimethylamine mixture led to higher content of excited triplet species at pH ≈ 11 and remarkably enhanced [1O2]SS, which was 2.3 times of that from PA and dimethylamine mixture. These findings provide direct evidence for the contribution of transient species from carbonyls or their product to 1O2 formation in atmospheric environment.

Spheroidal Model of SKBR3 and U87MG Cancer Cells for Live Imaging of Caspase-3 during Apoptosis Induced by Singlet Oxygen in Photodynamic Therapy.

Aspects related to the response of cells to photodynamic therapy (PDT) have been well studied in cell cultures, which often grow in monolayers. In this work, we propose a spheroidal model of U87MG and SKBR3 cells designed to mimic superficial tumor tissue, small spheroids (<500 µm) suitable for confocal fluorescence microscopy, and larger spheroids (>500 µm) that can be xenografted onto quail chorioallantoic membrane (CAM) to study the effects of PDT in real time. Hypericin was used as a model molecule for a hydrophobic photosensitizer that can produce singlet oxygen (1O2). 1O2 production by hypericin was detected in SKBR3 and U87MG spheroid models using a label-free technique. Vital fluorescence microscopy and flow cytometry revealed the heterogeneity of caspase-3 distribution in the cells of the spheroids. The levels of caspase-3 and apoptosis increased in the cells of spheroids 24 h after PDT. Lactate dehydrogenase activity was evaluated in the spheroids as the most reliable assay to detect differences in phototoxicity. Finally, we demonstrated the applicability of U87MG spheroids on CAM in photodiagnostics. Overall, the variability and applicability of the prepared spheroid models were demonstrated in the PDT study.

Dual-function oxygen vacancy of BiOBr intensifies pollutant adsorption and molecular oxygen activation to remove tetracycline hydrochloride

Oxygen vacancy is an important factor for pollutant adsorption and molecular oxygen activation. How to construct the dual-function oxygen vacancy is still a challenge for environmental remediation. Here, BiOBr (3D-self-assembled nanospheres) with different contents of oxygen vacancies was prepared via solvothermal method and calcination, which intensified antibiotic adsorption and molecular oxygen activation to remove tetracycline hydrochloride. Adsorption experiments and theoretical calculations revealed that oxygen vacancies enhanced the adsorption of pollutants via ion exchange. Furthermore, surface complexation due to adsorption facilitated degradation through faster charge transfer, which was proven by photoelectrochemical tests and TRPL spectroscopy. Quenching experiments, EPR and photoelectrochemical measurement indicated that oxygen vacancies facilitated charge transfer, to increase the activation of molecular oxygen and subsequent ∙O2- and 1O2 production for pollutant degradation. This study provides an in-depth explanation of the role of oxygen vacancies in tetracycline adsorption, surface complex due to the intermediate state in adsorption and molecular oxygen activation, as well as a reference for antibiotic removal via adsorption coupling degradation.

Methylene Blue/Carbon Dots Composite with Photothermal and Photodynamic Properties: Synthesis, Characterization, and Antibacterial Application.

Photodynamic therapy and photothermal therapy provide new ways to combat antibiotic resistance. In this research, methylene blue (MB) as an effective photosensitizer was conjugated with carbon quantum dots (CQDs), the composite product not only possessed good antibacterial properties against Staphylococcus aureus (S. aureus) and Escherichia coli (E.coli) due to excellent singlet oxygen (1 O2 ) production rate and light heat transfer performance, but also showed good biocompatibility. Combined with 808 nm and 660 nm laser irradiation, the minimum bactericidal concentration of CQDs-MB towards S. aureus and E.coli was 5 μm. Therefore, this study provides a potential candidate material based on CQDs for clinical applications.

Calcination temperature regulates non-radical pathways of peroxymonosulfate activation via carbon catalysts doped by iron and nitrogen

Switching the reaction routes between radical pathways and non-radical ones in peroxymonosulfate (PMS) activation has attracted much interest, however, the regulation between non-radical pathways remains elusive. Herein, we reported the regulation of the dominant non-radical routes in PMS activation with carbon catalysts doped by iron and nitrogen (Fe-N/C) through varying the calcination temperatureof conductive polymer Fe-polyaniline complexes. High calcination temperatures ranging from 300 °C to 900 °C boosted the catalytic activity and surprisingly switched the non-radical activation routes from electron transfer to singlet oxygen (1O2) and high-valent iron-oxo species (HV–FeO). Pyrrolic N and CO formed at 300 °C accounted for the electron transfer process, while graphitic N, O–CO, and Fe–Nx formed over 700 °C were key catalytic sites responsible for the production of 1O2 and HV–FeO. Moreover, the catalyst calcinated at 900 °C (900@Fe-N/C-2) maximized bisphenol A removal by 96.4% and TOC removal by 83.0%. The optimal 900@Fe-N/C-2/PMS system could work efficiently over a wide pH range or coexisting water components. This study provided a facile strategy to regulate PMS non-radical pathways for the treatment of complicated wastewater.

A convenient and economical strategy for multiple-target electrochemiluminescence detection using peroxydisulfate solution

As various aptasensors are adopted in clinical diagnosis, the development of convenient multiple-target determination is a field of ever-increasing interests. Herein, a label-free and amplified electrochemiluminescence (ECL) sensing platform was constructed to detect multiple targets of hemin, glucose and thrombin (TB) using peroxydisulfate (S2O82−) solution, which was one of the most convenient and economical ECL systems. It was worth mentioning that the target-induced bi-enzyme cascade catalysis reaction was developed to increase the ECL response strongly of S2O82− solution due to the production of (1O2)2* from the inter-reaction between reactive oxygen species (ROS) and sulfate radical (SO4•−). Specifically, with the layer-by-layer assembly of multi-walled carbon nanotubes (MWCNTs), glucose oxidase (GOx) and gold nanoparticles (AuNPs) as the interface, the guanine-rich (G-rich) thrombin aptamer (TBA) was anchored for hemin (target 1) detection, due to the electrocatalysis of hemin/G-quadruplex as a horseradish peroxidase mimicking DNAzyme (HRP-DNAzyme) towards dissolved oxygen for ROS generation. Second, in the presence of glucose (target 2), the ECL intensity was improved because glucose was the substrate of the bi-enzyme cascade catalysis reaction. Third, when TB (target 3) was sequentially incubated based on the above-mentioned aptasensor, the bi-enzyme catalysis was inhibited to decrease the ECL signal, due to the steric hindrance effect of the TB protein. As a result, the aptasensor achieved the nanomolar detection for hemin (3.33 nM), the micromolar detection for glucose (0.33 μM) and the femtomolar detection for TB (3.33 fM), respectively.

Photocatalytic Ag Nanoparticle Growth Induced Oxygen Vacancy Formation on Few-Layered BiOBr Nanosheets and Enhancements of ·O2– Generation Toward Tetracycline Photodegradation

This work indicates that the defect-free FL-BiOBr-NSs are favorable for the production of 1O2 through the energy transfer of band edge excitons from the FL-BiOBr-NSs to molecular oxygen, while the oxygen vacancies are favorable for the production of ·O2– through the transfer of the vacancy trapped electrons to molecular oxygen. The photocatalytic growth of the Ag nanoparticles can produce more oxygen vacancies in the plain FL-BiOBr-NSs. The obtained PG-Ag/FL-BiOBr-NSs therefore exhibit greatly improved activity toward TC photodegradation due to the enhancement of ·O2– generation. The physical mixing of Ag nanoparticles with the plain FL-BiOBr-NSs does not produce new oxygen vacancies on the plain FL-BiOBr-NSs. The PM-Ag/FL-BiOBr-NSs only exhibit a slightly improved activity toward TC photodegradation with respect to the plain FL-BiOBr-NSs due to the suppression of the radiative recombination of the photoexcited carriers. The plasma effect is demonstrated to be not a main reason leading to the high catalytic activity of the Ag nanoparticle deposited FL-BiOBr-NSs. It highlights the importance of the oxygen vacancy formation on the high catalytic activity of the FL-BiOBr-NSs and is useful for the rational design of the BiOBr-based photocatalysts with enhanced catalytic activity for specific applications.

Oxygen Self‐Supplying Enzymatic Nanoplatform for Precise and Enhanced Photodynamic Therapy

AbstractTraditional oxygen‐dependent photodynamic therapy (PDT) faces formidable challenges owing to abnormal angiogenesis and insufficient oxygen supply in solid tumors. Herein, a multifunctional nanoplatform (HRP‐DPBF‐Zn) consisting of photosensitizer zinc (II) phthalocyanine (ZnPc), singlet oxygen (1O2) probe 1,3‐diphenylisobenzofuran (DPBF), and hydrogen peroxide (H2O2) catalyst horseradish peroxidase (HRP) is developed. Such HRP‐DPBF‐Zn nanosystems are expected to possess catalase‐like capacity for catalyzing intracellular H2O2 to produce oxygen (O2). The enhanced O2 content further facilitates the production of cytotoxic 1O2 by ZnPc under laser irradiation. DPBF loading endows the nanoplatform with the high 1O2 sensitivity, which can promote precise PDT with fluorescent 1O2 feedback. HRP‐DPBF‐Zn exhibits excellent biocompatibility, efficient 1O2 generation, high 1O2 sensitivity, favorable H2O2‐to‐O2 decomposition, and superior fluorescence imaging properties. Both in vitro and in vivo experimental results confirm that such HRP‐DPBF‐Zn can accomplish highly specific and efficient PDT against hypoxic tumors, which shows great potential in tumor theranostics.

Fe, Co, N co-doped hollow carbon capsules as a full pH range catalyst for pollutant degradation via a non-radical path in Fenton-like reaction

Persulfate (PMS)-based Fenton-like reaction was a highly efficient technique for disposal of organic contaminants. However, high metal leaching and low environmental adaptation were the major concerns for further application. To overcome these two drawbacks, herein, Fe, Co, N atoms co-doped hollow carbon capsules (Fe-Co-N@HCCs) were prepared and used as catalysts for PMS activation. 92.6% of TC was degraded within 40 min and the mineralization efficiency was 55.7%. The degradation rate was 4.7, 3.1 and 1.4 times higher than those of activated carbon, N@HCCs, and Fe-N@HCCs, respectively. Thermodynamic study indicated the TC degradation was an exothermal, chaotic and non-spontaneous process. Radical trapping experiments, electron paramagnetic resonance spectrum, and electrochemical analysis indicated that 1O2 production and electron-transfer path worked together for PMS activation. DFT calculation indicated that the catalytic activity of Co-N4 site was higher than Fe-N4 site for 1O2 production. Fe-Co-N@HCCs were adapted well to the full pH range (0–14) and complex inorganic anions via non-radical PMS activation paths. Meanwhile, the leached Fe and Co ions were lowered to 0.201 and 0.457 mg/L, satisfying the China emission standard. This work gave a better comprehension on preparation of carbonaceous materials with high environmental adaptation and low leached metal ions for PMS activation.