Search Results (235)

Singlet oxygen is produced by light-dependent excitation of molecular oxygen using photosensitizers. Using blue light and riboflavin (RF) or riboflavin phosphate (RFP) as photosensitizers, we studied the reaction of singlet oxygen with tertiary amines in aqueous solution because many are used as biochemical buffers and as electron donors in photoreduction reactions. The reactions of singlet oxygen with multiple tertiary amines, including ethylenediamine tetraacetic acid (EDTA), bicine, and triethanolamine (TEOA), produced micromolar hydrogen peroxide (H₂O₂) as the stable end product. For bicine and TEOA, but not EDTA, H₂O₂ yield increased as pH increased due to their higher amine pKa values. A white LED used in conjunction with riboflavin and tertiary amines also produced H₂O₂, a contaminant likely to form during tissue culture manipulations. Direct photoreduction of 2,6-dichlorophenolindophenol and 2,3-dimethoxy-5-methyl-p-benzoquinone was achieved using blue light, RF or RFP, and tertiary amines as electron donors. With RF, EDTA was the optimal electron donor for both substrates, whereas with RFP, bicine and TEOA were superior to EDTA. Photochemical redox cycling of both quinones produced H₂O₂ via singlet oxygen-dependent re-oxidation of reduced quinols. Several amine buffers, including HEPES and PIPES, reacted with singlet oxygen to produce H₂O₂ but did not function as electron donors in quinone photoreduction assays. Full article

Tomato (Solanum lycopersicum L.) is the world’s second-most cultivated vegetable. Production reached 192 million tonnes in 2023; approximately 23% is industrially processed, leaving 4.3 to 10.2 million tonnes of pomace each year. Despite its high content of lycopene, tocopherols, polyphenols, dietary fibre, and seed oil, most of this residue is composted, landfilled, or fed without prior processing. This narrative review examines how the chemistry of tomato by-products maps onto their effects in farm animals, and how green-extraction biorefinery fits within the European Green Deal. Reported pomace lycopene runs from 36.7 to 50.2 mg/100 g DM, with phenolics near 161.8 mg GAE/g. Lycopene is an efficient singlet-oxygen quencher; it activates Keap1–Nrf2–ARE signaling while dampening NF-κB. Supercritical CO₂, ultrasound, microwave, pressurized-liquid, and NADES extractions can now recover up to 91% of peel lycopene using green, food-grade solvents. In broilers, 5 to 10% pomace or 30 to 400 mg/kg purified lycopene improves antioxidant status and lessens heat stress; in dairy ruminants, ensiled pomace at 10 to 40% maintains milk yield while improving milk PUFA. In finishing pigs and rabbits, dietary pomace or lycopene improves tissue oxidative stability, with growth benefits reported in heat-stressed rabbits. Standardized bioactive reporting and clearer inclusion limits remain the main research priorities. Full article

The oxygen reduction reaction (ORR) is the cathode cornerstone of fuel cells and metal-air batteries. Its inherent spin mismatch between triplet O₂ and singlet products causes sluggish kinetics that conventional catalyst designs cannot fully overcome. This review critically summarizes the past three years’ breakthroughs in spin-regulated ORR electrocatalysis and offers a fresh perspective beyond traditional electronic and geometric optimization. We first dissect the physical mechanism of spin-selective electron transfer required for the 4e⁻ pathway. We then systematically present four strategies for modulating the spin state of transition-metal active sites, namely strain engineering, defect engineering, heteroatom doping, and interfacial heterostructures. Subsequently, we highlight the emerging chirality-induced spin selectivity effect, where chiral organic molecules or intrinsically chiral inorganic materials act as spin filters without an external magnetic field, enabling spin-matched electron transfer and enhanced ORR performance. At the end of our review, we identify several key challenges, including the lack of in situ techniques to dynamically track spin states under operating conditions, the limited stability and universality of chiral catalysts, and the insufficient understanding of synergistic effects between spin control and traditional design parameters. We also outline future research directions, such as developing operando spin characterization, constructing robust chiral inorganic nanostructures, and employing high-throughput computational screening to integrate spin, geometric, and electronic level design. Our review provides a timely and comprehensive framework that bridges spin physics with electrocatalyst design, offering critical mechanistic insights and practical guidelines. Full article

Natural product-based upconversion photosensitizers (PSs) have emerged as innovative agents in photodynamic therapy (PDT). Lanthanide ions such as Yb³⁺, Er³⁺, Nd³⁺, Gd³⁺, and Tm³⁺ have unique photophysical properties and biocompatibility, exhibiting sharp 4f–4f transitions and long-lived excited states involving the dual luminescence processes, upconversion and downshifting. Natural product photosensitizers (PSs), including coumarin, riboflavin, curcumin, chlorophyll derivatives, and hypocrellin, offer superior safety profiles compared with synthetic PSs. Recent advances in upconversion nanoparticles (UCNPs) and upconversion–downshifting nanoparticles (UDNPs) for the generation of ROS in PDT have been evaluated. This narrative review surveyed the literature published between 1995 and 2026 across multiple electronic databases, including WanFang Data, PubMed, ScienceDirect, Scopus, Web of Science, Springer Link, SciFinder, and the China National Knowledge Infrastructure (CNKI), without language restrictions. The search focused on studies related to photodynamic therapy, lanthanide photophysics, and natural product photosensitizers such as coumarin, riboflavin, curcumin, chlorophyll derivatives, and hypocrellin, as well as nanoplatforms involving upconversion (UCNPs) and upconversion–downshifting nanoparticles (UDNPs). Relevant publications were identified and synthesized to integrate advances in lanthanide photophysics, natural product PSs, and nanoplatform design into a conceptual framework. Natural product-based upconversion PSs for PDT have the advantages of low dark toxicity, biocompatibility, and multimodal actions. Lanthanide-enhanced systems overcome these issues, including shallow tissue penetration, photobleaching, and relatively low singlet oxygen quantum yields. Thus, natural product-based upconversion PSs in PDT are an innovative strategy, but bridging preclinical promise with clinical translation remains a critical future challenge. Full article

Advanced oxidation processes based on peracetic acid (PAA) have emerged as a sustainable strategy for water treatment; however, developing efficient, stable, and environmentally friendly catalysts remains challenging. In this study, a functional cobalt-based catalyst (CPBC_x) was fabricated by immobilizing cobalt ions onto phytic-acid-modified biochar to active PAA for the degradation of sulfamethoxazole (SMX). The effect of pyrolysis temperature on the catalytic performance was investigated, with CPBC₈ showing the highest SMX degradation efficiency, under the conditions of a CPBC8 dosage of 200 mg/L, a PAA concentration of 0.2 mM, and an initial SMX concentration of 5 mg/L, and a 99.0% removal of SMX was achieved within 10 min. Moreover, the removal efficiency remained above 90% after five consecutive cycles. Mechanistic analysis revealed that biochar, acting as an efficient electron shuttle, enhanced electron transfer and accelerated the Co²⁺/Co³⁺ redox cycle, thereby shifting the SMX degradation pathway from a radical-dominated route to a non-radical one dominated by singlet oxygen (¹O₂). Density functional theory (DFT) calculations identified the vulnerable attack site (N11) on the SMX molecule. Transformation products and degradation pathways were elucidated using ultra-performance liquid chromatography coupled with time-of-flight mass spectrometry (UPLC-TOF-MS), and the identified intermediates exhibited low ecotoxicity. Furthermore, the CPBC₈ composite demonstrated sustained degradation rates, good stability, and environmental compatibility for practical application. This study provides a sustainable and efficient solution for applying biochar-based PAA advanced oxidation processes in water treatment. Full article

Thiopurines are efficient triplet-state photosensitisers; however, the practical application of canonical derivatives such as 6-thioguanine (6TG) and 6-thioguanosine (6TGuo) is limited by competing deactivation pathways that reduce the fraction of triplet states available for productive interaction with molecular oxygen. In this work, we investigated how structural modification of the thiopurine scaffold through introducing of an additional five-membered etheno ring affects triplet-state energetics, deactivation pathways, and singlet oxygen sensitisation. The photophysical properties of four tricyclic thiopurine analogues—9-thio-1,N²-ethenoguanine (TEGua), 9-thio-1,N²-ethenoguanosine (TEGuo), 6-methyl-9-thio-1,N²-ethenoguanine (6MeTEGua), and 6-methyl-9-thio-1,N²-ethenoguanosine (6MeTEGuo)—were investigated using steady-state spectroscopy, low-temperature phosphorescence, nanosecond transient absorption spectroscopy, and direct detection of singlet oxygen phosphorescence. All investigated compounds exhibited efficient intersystem crossing and microsecond-lived triplet states. Compared with canonical thiopurines, the tricyclic analogues displayed lower triplet-state energies and significantly enhanced singlet oxygen generation. Quantum yields of singlet oxygen sensitisation reached ~0.56 in acetonitrile, approximately twofold higher than those observed for 6TG and 6TGuo under identical conditions. Analysis of triplet-state deactivation pathways showed that the enhanced photosensitising efficiency does not result from increased triplet formation, but from more effective use of the triplet-state population for energy transfer to molecular oxygen leading to singlet oxygen formation. These findings demonstrate that structural modification of the thiopurine scaffold enables control over triplet-state reactivity and provides a strategy for designing improved thiopurine-based photosensitisers for photodynamic therapy applications (PDT). Full article

Reactive oxygen species (ROS)-mediated cancer therapy has attracted extensive attention due to its high spatiotemporal selectivity and minimal side effects. Herein, we report a nonanuclear Pd-based coordination cage of Pd₆-TMPP(Ni), constructed from Ni-chelated TMPP(Ni) as the metalloligand and Pd²⁺ ions (H₂TMPP = meso-tetrakis (6-methylpyridin-3-yl) porphyrin). Pd₆-TMPP(Ni) integrates dual ROS-generation for cancer therapy, viz., hydroxyl radical (•OH) production and photoinduced singlet oxygen (¹O₂) generation. In vitro cytotoxicity assays against cancer cell lines NCI-H82 (lung cancer), A549 (lung cancer), KYSE-510 (esophageal cancer), and Te-1 (esophageal cancer) reveal its potent dark toxicity (IC₅₀: 1.9–2.1 μmol L⁻¹) and phototoxicity (IC₅₀: 0.8–1.5 μmol L⁻¹), which is attributed to enhanced intracellular ROS accumulation. This work develops a versatile therapeutic platform that harnesses Ni-induced •OH for chemodynamic therapy (CDT) and porphyrin-generated ¹O₂ for photodynamic therapy (PDT), thereby mitigating the oxygen dependence of conventional PDT. Full article

The Oxygen Radical Absorbance Capacity (ORAC) assay is one of the most popular assays of antioxidant activity/capacity. It has several advantages over other common assays, including the use of an oxidant (peroxyl radicals) relevant in physiology and food storage and processing, as well as reactions in the physiological pH range and temperature. These advantages make ORAC the method of choice for the determination of antioxidant activity/capacity. This review presents the methodology and application of ORAC to the analysis of food products, various versions of the assay, including the lipophilic ORAC-related assays like the Hydroxyl Radical Absorbance Capacity (HORAC), Peroxynitrite Absorbance Capacity (NORAC), Superoxide Anion Absorbance Capacity (SORAC), and Singlet Oxygen Absorbance Capacity (SOAC); discusses the pros and cons, nd technical details affecting the reproducibility of ORAC. Examples of applications of the assay are given, including ORAC values [mol Trolox equivalent/mol, and mmol Trolox equivalents/kg or per L, respectively] for over 90 antioxidants and over 900 food products and medicinal plants. Full article

Hypoxia is one of the most important factors limiting the effectiveness of modern anticancer therapies, particularly photodynamic therapy (PDT). The hypoxia of the tumor microenvironment results from abnormal angiogenesis and the high metabolic demand of cancer cells, which leads to reduced oxygen availability necessary for generating reactive oxygen species (ROS). Consequently, conventional therapeutic approaches, mainly based on the type II PDT mechanism, show limited effectiveness under hypoxic conditions. In response to these limitations, strategies are being developed to increase oxygen availability within the tumor. Of particular importance are nanocarriers based on perfluorocarbons (PFCs), which, due to their high gas solubility, can effectively transport and release oxygen in the tumor microenvironment. Research indicates that the use of such systems leads to improved PDT efficiency by increasing the production of singlet oxygen and enhancing cancer cell damage. Parallelly, alternative approaches independent of high oxygen concentration, including type I photosensitizers, are being developed. Unlike classical type II mechanisms, they generate free radicals through electron transfer reactions, which allows effective action even under conditions of significant hypoxia. This approach significantly expands the possibilities of using PDT in the treatment of tumors with low oxygen levels. Current research directions focus on integrating various therapeutic strategies to achieve a synergistic effect. Hybrid systems combining oxygen delivery (e.g., using PFCs) with the use of type I photosensitizers and other treatment methods, such as chemotherapy or immunotherapy, show the greatest clinical potential. Such multifunctional approaches simultaneously allow improving tumor oxygenation and increasing the efficiency of ROS generation, which makes them a promising strategy for the future of anticancer therapies. Full article

Heterogeneous catalytic ozonation has attracted increasing research attention as a strategy for advanced wastewater polishing; yet the recent literature has advanced the attribution of non-radical pathways at a pace that has outstripped rigorous demonstration of their practical process advantage. This article constitutes an evidence-centered critical review—rather than a formal systematic review—organized around a central evaluative question: under what conditions are non-radical mechanistic claims in catalytic ozonation sufficiently persuasive, wastewater-relevant, and defensible to warrant consideration for process translation. Recent studies, drawn primarily from the period 2023–2026, are evaluated through an explicit evidence-grading framework that distinguishes among radical, singlet-oxygen-mediated, surface-bound oxygen-transfer, direct electron-transfer, and high-valent metal-oxo pathways. The review further examines whether reported parent-compound removal is corroborated by complementary lines of evidence encompassing bromate formation, transformation product characterization, effluent toxicity assessment, catalyst leaching quantification, operational durability, and reactor-scale performance. The synthesis reveals that single-atom catalysts currently provide the most robust active-site mechanistic evidence; however, even these systems remain constrained by their reliance on simplified aqueous matrices, incomplete transformation byproduct accounting, and unresolved long-term stability. Accordingly, the article proposes standardized reporting protocols and benchmark performance metrics—including a bromate-normalized treatment benefit index—to delineate mechanistic elegance from process realism. Full article

In recent years, accelerated industrialization has made water pollution a major challenge, bisphenol pollutants being one of the most typical examples. Advanced oxidation processes (AOPs) based on peroxymonosulfate (PMS) activation have been applied in environmental remediation due to their broad applicability and high pollutant removal efficiency. The key to AOPs lies in developing low-cost, highly active catalysts. This study utilized waste biomass of baijiu distillers’ grains (DSGs) as precursor to prepare biochar materials for bisphenol pollutant removal. Through high-temperature pyrolysis at 900 °C for 2 h in the presence of NaCl and KCl as activator, biochar-based materials (BC-x) were prepared, which possessed advantageous features of large specific surface area and high nitrogen doping content. When applied for typical bisphenol pollutant removal, the selected BC-900 biochar exhibited almost 100% bisphenol AF (BPAF) removal efficiency after a 30 min adsorption and following a 5 min PMS activation process under reaction conditions of 200 mg L⁻¹ of BC-900, 200 mg L⁻¹ of PMS, and 20 mg L⁻¹ of BPAF. Reactive species of sulfate radicals (SO₄⦁⁻), hydroxyl radicals (⦁OH) and singlet oxygen (¹O₂) were responsible for BPAF degradation, among which ¹O₂ played the major role. Further toxicity prediction of the BPAF degradation intermediate products implied the low ecological risk of the constructed BC-900/PMS catalytic system for BPAF removal. The findings in this study may provide useful guidance for waste biomass conversion and organic contamination remediation in water. Full article

Biochar (BC)-activated peracetic acid (PAA)-based advanced oxidation processes (AOPs) were increasingly considered as cost-efficient and eco-friendly water treatment technologies for the removal of organic pollutants. However, the specific role of intrinsic carbon, nitrogen species and structure properties played in activation mechanism is still vague. In this study, the waste tea residues-based biochar (WTBC) was prepared by thermal carbonization and applied to activate PAA for the degradation of bisphenol A (BPA). The product carbonized at 800 °C (WTBC800) possessed larger specific surface area (342.57 m²/g), more abundant porous structure and massive defects state (I_D/I_G = 3.53), and exhibited a superior activation performance with 83.7% BPA removal within 120 min. Adsorption and non-radical oxidation pathways [e.g., the mediated electron transfer process (ETP) and singlet oxygen (¹O₂) generation] were evidenced to play the dominant roles in the BPA degradation through the formation of metastable complex WTBC-PAA*. The graphitic carbon, functional nitrogen species, defects structure and persistent free radicals (PFRs) in WTBC were proposed to contribute to the activation of PAA. Overall, relatively higher dosages of WTBC (0–0.5 g/L) and PAA (0–1.5 mM) facilitated the BPA degradation. The solution pH and water matrix (e.g., Cl⁻, NO₃⁻, HCO₃⁻ and SO₄²⁻) presented a negligible effect on the BPA degradation in WTBC/PAA system. This study not only proposes a sustainable approach for organic pollutants removal in wastewater, but also promotes the resource re-utilization of agricultural waste. Full article

Background/Objectives: Photodynamic therapy (PDT) relies on light activation of photosensitizers to generate reactive oxygen species for tumor ablation; however, limited tumor selectivity and systemic toxicity of free photosensitizers remain challenges. This study aimed to develop polymer-based nanotheranostics carrying tetraphenylporphyrin (TPPc) derivatives and to evaluate how linker structure impacts their performance. Methods: TPPc derivatives were covalently conjugated to N-(2-hydroxypropyl)methacrylamide (HPMA)-based polymers via either pH-sensitive hydrazone linkages (using aliphatic 5-hydroxy-2-pentanone or aromatic 1-(4-hydroxymethyl)phenyl)ethanone spacer) or stable amide bonds, forming amphiphilic polymer conjugates. The conjugates were characterized based on their physicochemical and in vitro and in vivo biological behavior. Results: Polymer conjugation reduced dark toxicity while preserving photodynamic activity. Linker structure influenced intracellular behavior and singlet oxygen production, with hydrazone systems showing faster activation-related responses under acidic conditions in vitro. All conjugates accumulated in tumors and induced significant tumor growth inhibition after irradiation at low doses (2.5 mg kg⁻¹ TPPc equivalent), while the amide-linked conjugate showed the strongest overall in vivo therapeutic effect, likely due to more favorable biodistribution and sustained delivery. Conclusions: The developed HPMA-based polymer–TPPc conjugates improve the therapeutic profile of photosensitizers by reducing toxicity and enabling effective PDT. These findings highlight the importance of linker design in balancing photosensitizer activation, circulation stability, and biodistribution, which together determine the overall therapeutic outcome. Full article

The increasing prevalence of antimicrobial resistance, together with recurring infectious disease outbreaks, has intensified the need for alternative strategies to control microbial infections beyond conventional antibiotic therapies. Antimicrobial photodynamic therapy has emerged as a promising non-antibiotic approach in which light-activated photosensitising compounds generate reactive oxygen species that induce oxidative damage to microbial cells. Plant-derived photosensitisers have attracted increasing attention due to their structural diversity, biocompatibility, natural abundance, and potential for sustainability. Natural compounds such as curcumin, hypericin, chlorophyll derivatives, flavonoids, anthraquinones, and riboflavin exhibit favourable photochemical properties that enable efficient production of reactive oxygen species upon irradiation with visible light. Through radical- and singlet-oxygen-mediated photochemical pathways, these molecules exhibit broad-spectrum antimicrobial activity against bacteria, fungi, viruses, and biofilm-associated microorganisms. This review examines the photophysical properties and mechanisms of reactive oxygen species generation associated with plant-derived photosensitisers, together with key factors influencing their antimicrobial performance. Recent advances in nanocarrier-based delivery systems, dual-wavelength activation strategies, and synergistic combination therapies are also discussed for their potential to improve photostability, enhance reactive oxygen species generation, and increase microbial inactivation efficiency. Finally, current progress, challenges, and future research directions for advancing plant-derived photosensitisers in antimicrobial photodynamic therapy are discussed. Full article

The damage caused by herbivores is generally measured as the amount of leaf tissue consumed, without accounting for the fate of the leftover tissue. As a result, the plant defense mechanisms that promote resistance to herbivore feeding by photosynthetically acclimating the rest of the plant to the feeding spot leaf area have not been well exploited. Plant-insect interactions are now becoming better defined with the development of visualization methods that permit spatial whole-leaf assessment of photosynthetic efficiency after herbivore attack. The purpose of our study was to evaluate the spatial heterogeneity of photosystem II (PSII) function at the whole-leaf level before and after herbivory by the Colorado potato beetles. Twenty minutes after Colorado potato beetle (Leptinotarsa decemlineata) feeding, the maximum efficiency of PSII photochemistry (Fv/Fm) decreased significantly, suggesting photoinhibition due to reduced efficiency of the oxygen-evolving complex (OEC). The decreased quantum yield of PSII photochemistry (Φ_PSII) after feeding, at the neighboring area of the feeding spot and at the rest of the leaf area, was attributed to the reduced efficiency of the open PSII reaction centers (Fv′/Fm′), since there was no change in the fraction of open PSII reaction centers (qp). Nevertheless, plant defense elicitation was activated by the photoprotective mechanism of non-photochemical quenching (NPQ) that reduced the singlet oxygen (¹O₂) formation in potato plants in the neighboring area of the feeding spot and at the rest of the leaf area. In addition, the increased production of hydrogen peroxide (H₂O₂) triggered by this increase suggests that it acted as a signaling molecule in the biotic stress defense response. Full article