Singlet Oxygen Generation Research Articles

Shining light on carbon dots: Toward enhanced antibacterial activity for biofilm disruption.

In spite of tremendous efforts dedicated to addressing bacterial infections and biofilm formation, the post-antibiotic ear continues to witness a gap between the established materials and an easily accessible yet biocompatible antibacterial reagent. Here we show carbon dots (CDs) synthesized via a single hydrothermal process can afford promising antibacterial activity that can be further enhanced by exposure to light. By using citric acid and polyethyleneimine as the precursors, the photoluminescence CDs can be produced within a one-pot, one-step hydrothermal reaction in only 2 h. The CDs demonstrate robust antibacterial properties against both Gram-positive and Gram-negative bacteria and, notably, a considerable enhancement of antibacterial effect can be observed upon photo-irradiation. Mechanistic insights reveal that the CDs generate singlet oxygen (1O2) when exposed to light, leading to an augmented reactive oxygen species level. The approach for disruption of biofilms and inhibition of biofilm formation by using the CDs has also been established. Our findings present a potential solution to combat antibacterial resistance and offer a path to reduce dependence on traditional antibiotics.

D‐cysteine‐Derived Carbon Dots for Selective Discrimination, Imaging, and Synergistic Elimination of Gram‐Positive Bacteria and Fungi

AbstractMicrobial infections pose a significant threat to public health, exacerbated by the escalating issue of antibiotic resistance resulting from their overuse. Chiral carbon dots (CDs) not only inherit the antibacterial properties of CDs but also demonstrate highly selective chiral bactericidal activity. This study focuses on the development of chiral CDs synthesized from D‐ and L‐cysteine, to selectively identify and synergistically eradicate Gram‐positive bacteria and fungi. Chiral CDs exhibit high efficacy in staining Gram‐positive bacteria and fungi while demonstrating minimal to no fluorescence with Gram‐negative bacteria, attributable to variances in the membrane structures of these pathogens. D‐CDs exhibit stronger fluorescence signals and greater antibacterial efficacy against Gram‐positive bacteria and fungi compared to L‐CDs. Under dual light irradiation, D‐CDs bolster antibacterial activity through a triple‐modal mechanism, involving membrane disruption in the absence of light, singlet oxygen generation during photodynamic therapy, and elevated temperature during photothermal treatment. Animal studies additionally showcase that D‐CDs notably enhanced the healing of wounds infected with S. aureus under laser light exposure. This investigation underscores the chiral‐specific imaging and antibacterial potentials of D‐CDs, paving the way for the advancement of chiral nanomaterials in bacterial diagnostics and therapy.

Size-Dependent Blue Emission from Europium-Doped Strontium Fluoride Nanoscintillators for X-Ray-Activated Photodynamic Therapy.

Successful implementation of X-ray-activated photodynamic therapy (X-PDT) is challenging because most photosensitizers (PSs) absorb light in the blue region, but few nanoscintillators produce efficient blue scintillation. Here, efficient blue-emitting SrF2:Eu scintillating nanoparticles (ScNPs) are developed. The optimized synthesis conditions result in cubic nanoparticles with ≈32nm diameter and blue emission at 416nm. Coating them with the meso-tetra(n-methyl-4-pyridyl) porphyrin (TMPyP) in a core-shell structure (SrF@TMPyP) results in maximum singlet oxygen (1O2) generation upon X-ray irradiation for nanoparticles with 6TMPyP depositions (SrF@6TMPyP). The 1O2 generation is directly proportional to the dose, does not vary in the low-energy X-ray range (48-160 kVp), but is 21% higher when irradiated with low-energy X-rays than irradiations with higher energy gamma rays. In the clonogenic assay, cancer cells treated with SrF@6TMPyP and exposed to X-rays present a significantly reduced survival fraction compared to the controls. The SrF2:Eu ScNPs and their conjugates stand out as tunable nanoplatforms for X-PDT due to the efficient blue emission from the SrF2:Eu cores; the ability to adjust the scintillation emission in terms of color and intensity by controlling the nanoparticle size; the efficient 1O2 production when conjugated to a PS and the efficacy of killing cancer cells.

Distyryl Carboxylic Acid Substituted BODIPY and BODIPY‐C60 Systems for Generation of Singlet Oxygen

AbstractBODIPY based molecules functionalized with water soluble moieties have been developed and recognized as liable triplet photosensitizers for phototherapeutic applications. In this work, we have prepared BODIPY analogues with dicarboxylic acid groups and bearing iodine or fullerene moieties for efficient intersystem crossing which display far‐red absorption band and high singlet oxygen production both in organic and aqueous media. In this perspective by using similar design the effect of the halogenation of the dyes versus spin converter on the skeleton were compared. The structures of the synthesized BODIPYs and BODIPY‐C60 (6–10) were elucidated by mass, 1H and 13C NMR spectroscopic techniques. Photophysical and photochemical properties of the compounds were examined using UV‐Vis. absorption and fluorescence emission spectrophotometers. The absorption intensities of the trap molecules (DPBF and ADBA) reduced because of singlet oxygen generation in the media. This study may provide useful infrastructure to elucidate the relationship between the use of fullerene (9) or iodine (10) where singlet oxygen quantum yield of 9 and 10 are determined as 0.87 and 0.97 respectively.

Targeted pH-Activated Peptide-Based Nanomaterials for Combined Photodynamic Therapy with Immunotherapy.

Photodynamic therapy (PDT) has demonstrated efficacy in eliminating local tumors, yet its effectiveness against metastasis is constrained. While immunotherapy has exhibited promise in a clinical context, its capacity to elicit significant systemic antitumor responses across diverse cancers is often limited by the insufficient activation of the host immune system. Consequently, the combination of PDT and immunotherapy has garnered considerable attention. In this study, we developed pH-responsive porphyrin-peptide nanosheets with tumor-targeting capabilities (PRGD) that were loaded with the IDO inhibitor NLG919 for a dual application involving PDT and immunotherapy (PRGD/NLG919). In vitro experiments revealed the heightened cellular uptake of PRGD/NLG919 nanosheets in tumor cells overexpressing αvβ3 integrins. The pH-responsive PRGD/NLG919 nanosheets demonstrated remarkable singlet oxygen generation and photocytotoxicity in HeLa cells in an acidic tumor microenvironment. When treating HeLa cells with PRGD/NLG919 nanosheets followed by laser irradiation, a more robust adaptive immune response occurred, leading to a substantial proliferation of CD3+CD8+ T cells and CD3+CD4+ T cells compared to control groups. Our pH-responsive targeted PRGD/NLG919 nanosheets therefore represent a promising nanosystem for combination therapy, offering effective PDT and an enhanced host immune response.

DFT and TD DFT study of oxodiboron(III) phthalocyanine and peculiarities of spectral behavior and acid–base properties of its tert-butyl substituted derivative in solutions

Molecular and electronic structures of transoid and cisoid forms of oxodi(fluoroboron(III)) complex of phthalocyanine [O(FB)2Pc] in the ground and excited states were studied using DFT and TD DFT methods. The peculiarities of the electrochemical and spectral properties of the tetra-tert-butyl substituted complex existing in the transoid form in organic solvents and in acid medium were considered in comparison with 1:1 complexes formed by aluminum subgroup metals and boron(III) subphthalocyanine. Coordination of two boron atoms in the coordination cavity of the phthalocyanine macrocycle leads to its tetragonal distortion both in the cisoid and especially in the transoid forms and stabilizes the frontier π-molecular orbitals, especially the lowest unoccupied MO. This results in the bathochromic shift of the long-wave Q band and strongly facilitates the reduction of macrocycle occurring for the transoid form at −0.19 V versus Ag/AgCl in dimethylformamide (DMF). Spectrophotometric titration in CH2Cl2-CF3COOH medium showed that the basicity of the meso-nitrogens is decreased upon coordination of two boron atoms. Slow deborylation can occur either in a strongly acid medium (96% H2SO4) or in the presence of water in DMF. The absence of fluorescence and ability to generate singlet oxygen is explained by quenching of the excited state due to conformation flexibility of the macrocycle and inversion of the coordination center in the transoid form.

Cyrene- and water-based exfoliation of black phosphorus for potential nanolayer-mediated disaggregation of insulin fibrils

Liquid suspensions of phosphorene nanolayers (2D-bP) obtained through liquid phase exfoliation (LPE) of elemental black phosphorus (bP) have been prepared and extensively characterized. The exfoliating ability of deionized water (DI water), dihydrolevoglucosenone, (Cyrene), and N-methyl-2-pyrrolidone (NMP) has been investigated and compared along with the differences in the structure, concentration, and stability of the collected nanoflakes. Water was chosen as an exfoliating medium due to its harmlessness and cost-effectiveness and because it is the safest solvent for further potential biomedical applications. Cyrene is a new bio-based solvent still under study. NMP, which is among the most widely used solvents for the exfoliation of 2D systems including bP, has been employed for comparison. The obtained suspensions have been characterized by Dynamic Light Scattering (DLS), Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES), Phosphorus 31 Nuclear Magnetic Resonance (31P NMR), Transmission Electron Microscopy (TEM), Ultraviolet -Visible (UV–Vis), and Raman spectroscopies. The stability of 2D-bP suspensions over time and their photoactivity, i.e., their ability to generate singlet oxygen species as a photosensitizer, have been investigated. The collected results evidenced that the exfoliation of bP in different solvents, including DI water, resulted in satisfactory and comparable nanoflake structures and features. The singlet oxygen generation through irradiation of 2D-bP in DI water suspensions, advantageously obtained directly from LPE, showed promising potential for use in photodynamic therapy (PDT). Preliminary data on the potential biomedical application of 2D-bP to inhibit the insulin self-assembly into amyloid aggregates as well as to cause fibrils disassembling through simple incubation or photoactivity, are also discussed.

Fine tuning of BODIPY’s properties via structural modifications at the 1,7-positions of BODIPY-3,5-dicarboxylates

A comprehensive evaluation of 2,6,8-triphenyl-BODIPY-3,5-dicarboxylates was carried out to reveal the effect of substitution at 1,7-positions on properties of this structural type of BODIPY. For this purpose, a series of different 1,7-substituted ethyl 2,6,8-triphenyl-BODIPY-3,5-dicarboxylates (unsubstituted 3a, difluoro- 3b, dimethyl- 3c and dichloro- 3d) was synthesized. The resulting BODIPYs were characterized by UV–visible and fluorescence spectroscopies, cyclic voltammetry and DFT calculations. In addition, their ability to generate singlet oxygen and photostability were evaluated. The data from this investigation are summarized, compared, analyzed and discussed herein. It was found that 1,7- dimethyl derivative 3c is the most promising photosensitizer for further application in the context of balance between photophysical properties and photostability.

Halogen-substituted meso-BODIPY ethers as effective photosensitizers for antimycotic photodynamic therapy

We conducted a comprehensive study of the influence of the molecular structure and solvent nature on the photophysical properties of the halogen-substituted meso-BODIPY ethers. The compounds were found to be stable over a wide range of pH values and exhibited intense chromophoric properties (lgε ∼ 4.60–5.02) at 497–536 nm. The halogenation at the 2,6-positions of the pyrrole rings of dyes causes a noticeable (up to 36 nm and 44 nm) red shift of the maximum of the absorption and fluorescence bands, respectively, and sharp fluorescence quenching up to φfl ∼ 2–32 %. The introduction of a bulky ester substituent into the meso-position of the dipyrromethene core increases the photostability of the dyes up to ∼ 2.7 times due to screening of the methine spacer. Moreover, the halogen-substituted BODIPYs demonstrated a high ability to generate singlet oxygen (up to ФΔ ∼50–78 %) regardless of the nature of the solvent. Among the studied dyes, the diiodo-substituted meso-BODIPY ether has an appreciable inhibitory effect on the vital activity of fungal cells. In summary, the combination of the meso-substitution and halogenation of the BODIPY core is an excellent way to enhance the affinity of dyes to biostructures and to increase the possibilities of the practical application of dyes as effective photosensitizers for antibacterial photodynamic therapy.

Photodynamic effect of vascular-targeted polyphenol nanoparticles on Endothelial cells

BackgroundPort wine stains (PWS) are vascular malformations, and photodynamic therapy (PDT) is a promising treatment. Emerging drug delivery methods employ nanoparticles (NPs) to enhance drug permeability and retention in diseased blood vessels and improve drug bioavailability. (-) -epigallocatechin-3-gallate glycine (EGCG) has anti-angiogenetic effects and boosts photodynamic therapy. Chlorin e6 (Ce6) is capable of efficiently producing singlet oxygen, rendering it a very promising photosensitizer for utilization in nanomedicine. Material and MethodsEGCG-Ce6-NPs were synthesized and characterized using various techniques. The photodynamic effects of EGCG-Ce6-NPs on endothelial cells were evaluated. The compatibility and toxicity of the nanoparticle was tested using the CCK-8 assay. The intracellular uptake of the nanoparticle was observed using an inverted fluorescence microscope, and the intracellular fluorescence intensity was detected using flow cytometry. The ROS generation and apoptosis induced by EGCG-Ce6-NPs was observed using confocal laser scanning microscopy and flow cytometry respectively. ResultsEGCG-Ce6-NPs exhibited stability, spherical shape of uniform size while reducing the particle diameter, low polydisperse profile and retaining the ability to effectively generate singlet oxygen. These characteristics suggest promising potential for enhancing drug permeability and retention. Additionally, EGCG-Ce6-NPs demonstrated good compatibility with endothelial cells and enhanced intracellular uptake of Ce6. Furthermore, EGCG-Ce6-NPs increased activation efficiency, induced significant toxicity, more reactive oxygen species, and a higher rate of late apoptosis after laser irradiation. ConclusionThis in vitro study showed the potentials EGCG-Ce6-NPs for the destruction of endothelial cells in vasculature.

Shedding light on imaging safety: Decoding the origin of photocytotoxicity in RhB-assisted fluorescence imaging.

Photocytotoxicity represents a significant limitation in the application of dye-assisted fluorescence imaging (FI), often resulting in undesirable cellular damage or even cell death, thereby restricting their practical utility. The prevalence of Rhodamine B (RhB) in FI underscores the importance of elucidating its photocytotoxicity effects to minimize photodamage. This study identifies the primary cause of photocytotoxicity stems from the generation of cytotoxic singlet oxygen in RhB, utilizing femtosecond transient absorption spectroscopy coupled with quantum chemical calculations. The Laser power-dependent cellular viability reveals a threshold at about 50 mW cm-2, surpassing which produces pronounced photocytotoxicity in vitro and in vivo. Notably, this threshold significantly falls below the safety limits (<200 mW cm-2) for laser use in health care, implying a huge risk of photodamage. This study provides valuable insights into the photocytotoxicity and offers essential guidelines for developing safer imaging protocols.

Quasi-intrinsic thiobase derivatives as potential targeted photosensitizers in two-photon photodynamic therapy

In this study, a set of potential quasi-intrinsic photosensitizers for two-photon photodynamic therapy (PDT) are proposed based on the unnatural 2-amino-8-(1′-β-ᴅ-2′-deoxyribofuranosyl)-imidazo[1,2-ɑ]-1,3,5-triazin-4(8H)-one (P), which is paired with the 6-amino-5-nitro-3-(1′-β-ᴅ-2′-deoxyribofuranosyl)-2(1H)-pyridone (Z) and can specifically recognize breast and liver cancer cells. Herein, the effects of sulfur substitution and electron-donating/electron-withdrawing groups on the photophysical properties in aqueous solution are systematically investigated. The one- and two-photon absorption spectra evidence that the modifications could result in red-shifted absorption wavelength and large two-photon absorption cross-section, which contributes to selective excitation and provides effective PDT for deep-seated tissues. To ensure the efficient triplet state population, the singlet–triplet energy gaps and spin–orbit coupling constants were examined, which is responsible for a rapid intersystem crossing rate. Furthermore, these thiobase derivatives are characterized by the long-lived T1 state and the large energy gap for radiationless transition to ensure the generation of cytotoxic singlet oxygen.

Preparation of AIEgen-based near-infrared afterglow luminescence nanoprobes for tumor imaging and image-guided tumor resection.

Fluorescence imaging represents a vital tool in modern biology, oncology and biomedical applications. Afterglow luminescence (AGL), which circumvents the light scattering and tissue autofluorescence interference associated with real-time excitation source, shows remarkably increased imaging sensitivity and depth. Here we present a protocol for the design and synthesis of AGL nanoprobes with an aggregation-induced emission (AIE) effect to simultaneously red shift and amplify the afterglow signal for tumor imaging and image-guided tumor resection. The nanoprobe (AGL AIE dot) is composed of an enol ether format of Schaap's agent and a near-infrared AIE fluorogen (AIEgen) (tetraphenylethylene-phenyl-dicyanomethylene-4H-chromene, TPE-Ph-DCM) to suppress the nonradiative dissipation pathway. Pre-irradiating AGL AIE dots with white light could generate singlet oxygen to convert Schaap's agent to its 1,2-dioxetane format, thus initializing the AGL process. With the aid of AIEgen, the AGL shows simultaneously red shifted emission maximum (from ~540 nm to ~625 nm) and enhanced intensity (by 3.2-fold), facilitating better signal-to-background ratio, imaging sensitivity and depth. Intriguingly, the activated AGL can last for over 10 days. Compared with conventional approaches, our method provides a new solution to concurrently red shift and amplify afterglow signals for better in vivo imaging outcomes. The preparation of AGL AIE dots takes ~2 days, the in vitro characterization takes ~10 days (less than 1 day if not involving afterglow kinetic profile study) and the tumor imaging and image-guided tumor resection takes ~7 days. These procedures can be easily reproduced and amended after standard laboratory training in chemical synthesis and animal handling.

Dual-functional nano-photosensitizers: Eosin-Y decorated gold nanorods for plasmon-enhanced fluorescence and singlet oxygen generation.

Photosensitizer (PS) with enhanced fluorescence is attractive for image-guided photodynamic therapy (PDT) due to its dual functional role in Singlet Oxygen Generation (SOG) and producing high fluorescence signals. Here, Eosin-Y (Ey) decorated polymer coated gold nanorods (GNRs) of different aspect ratios are synthesized and introduced as novel plasmon-enhanced nano-photosensitizers for this purpose. We show, upon excitation at 519 nm, simultaneous enhancement in fluorescence and SOG was achieved for the hybrid nanostructure. The best enhancement factors of 110 and 18 for metal-enhanced fluorescence and metal-enhanced SOG, respectively, are obtained with GNRs of length 133 nm and width 45 nm, where Ey is positioned at 12.6 nm from the metal core using layer-by-layer assembly of oppositely charged polymers. The observed plasmonic effect is critically analysed by comparing the near field damping rate along with decay length, far field scattering and nonradiative energy transfer of the nanohybrids.

Pyrene doped silica nanoparticles: Synthesis, oxygen sensing, and singlet oxygen generation

Dye-doped silica nanoparticles have garnered attention from researchers owing to their beneficial properties, such as signal amplification, surface modification, and biocompatibility. In this study, pyrene-doped silica nanoparticles (PSNPs) were prepared using the reverse microemulsion approach. Pyrenebutyric acid conjugated with aminopropyltriethoxysilane was synthesized to obtain durable PSNPs with low dye leaching via the covalent encapsulation of pyrene inside a silica matrix. The PSNPs were spherical, with a diameter of 72 nm. The PSNPs exhibited excimer fluorescence upon photoexcitation. To demonstrate the applicability of the synthesized PSNPs in biological applications, including photodynamic therapy (PDT) and oxygen sensing, the influence of oxygen on the fluorescence spectrum was investigated. The excimer fluorescence intensity was quenched by oxygen, along with a decrease in fluorescence lifetime. Ratiometric fluorescence sensing and fluorescence lifetime sensing of oxygen concentration were demonstrated. The biomolecular quenching rate constant was evaluated using the Stern–Volmer plot of the fluorescence lifetime. Moreover, utilizing a chemical trap of singlet oxygen molecules, it was demonstrated that singlet oxygen was generated by the photosensitization of PSNP. The PSNPs synthesized in this study are potentially capable of oxygen sensing, PDT, and bioimaging for various biological applications.

Exploiting G-Quadruplex-DNA Damage as a Tool to Quantify Singlet Oxygen Production.

G-Quadruplexes (G4s) are highly dynamic and polymorphic nucleic acid structures that can adopt a variety of conformations. When exposed to oxidative conditions, more specifically singlet oxygen, the guanosine nucleobases can be oxidized, which in turn can affect the conformation and folding of the G4. Based on this peculiar phenomenon, it is rationalized that G4s can serve as quantification sensors for the production of singlet oxygen. Here, a method for determining the quantum yield of singlet oxygen generation for visible as well as UV-light excited photosensitizers, using a short G4 DNA sequence, readily available from common DNA companies, as a biological and water-soluble probe, is presented.

Solvent-free oxidation of benzylic C(sp3)–H bond over MA3Bi2Br9 perovskite photocatalyst by efficient singlet oxygen generation

Photocatalytic selective oxidation under solvent-free conditions plays a pivotal role in green chemistry, which can diminish pollutant production and minimize resource consumption in chemical reactions. In this process, the activation of molecular oxygen (O2) plays a crucial role. Here, we demonstrate the efficient oxidation of C(sp3)–H bond in pure toluene to produce oxygenated products of benzaldehyde (BAD) and benzyl alcohol (BA) using O2 as an oxidant over lead-free MA3Bi2Br9 perovskite. Systematic spectroscopic characterizations and controlled experiments validate that MA3Bi2Br9 enables the activation of O2 to superoxide radical (•O2−) and singlet oxygen (1O2) via charged electron transfer and excitonic energy transfer, respectively. Significantly, 1O2 emerges as an important active species. The optimal photocatalytic performance delivered by MA3Bi2Br9 reaches a BAD generation rate of 10756 µmol g−1h−1, with a BAD product selectivity of 81.5 %. The performance is greater than most classical photocatalysts, representing one of the best photocatalytic activities available in the literature. The lead-free feature of MA3Bi2Br9 perovskite coupled with its impressive catalytic performance makes it promising for practical applications.

Compounding Methylene Blue with Selenium-decorated Graphene Quantum Dots to Improve Singlet Oxygen Production for Photodynamic Therapy Application.

Graphene quantum dots (GQDs) are known as suitable material to be applied in different fields such as photodynamic therapy (PDT). Herein, GQDs were synthesized by the pyrolysis method and then decorated with selenium (Se). Afterward, they were combined with methylene blue (MB) to increase singlet oxygen generation as well as to apply them more effectively in the PDT method. Furthermore, GQDs were investigated by transmission electron microscope (TEM), photoluminescence spectrum (PL), Fourier-transform infrared spectroscopy (FTIR), field emission scanning electron microscope (FESEM), reactive oxygen species (ROS) measurement, and cytotoxicity measurement. GQDs showed no dependence on the excitation wavelength. The result of ROS measurement proves that the combination of GQD-Se and MB increases singlet oxygen production. Moreover, afterglow measurement approved the beneficial effect of GQD-Se on even deep and near skin tumor treatment. Cytotoxicity measurements under dark conditions, cell viability, and the side effects on human cells were determined by (3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide) (MTT) assay. Our findings show that under dark conditions, even high concentrations of nanoparticles have no significant effect on cell viability. These findings and the high biocompatibility of GQDs indicate the effective application of GQD-Se-MB in PDT.

Ruthenium-Cathepsin Inhibitor Conjugates for Green Light-Activated Photodynamic Therapy and Photochemotherapy.

Dysregulated cathepsin activity is linked to various human diseases including metabolic disorders, autoimmune conditions, and cancer. Given the overexpression of cathepsin in the tumor microenvironment, cathepsin inhibitors are promising pharmacological agents and drug delivery vehicles for cancer treatment. In this study, we describe the synthesis and photochemical and biological assessment of a dual-action agent based on ruthenium that is conjugated with a cathepsin inhibitor, designed for both photodynamic therapy (PDT) and photochemotherapy (PCT). The ruthenium-cathepsin inhibitor conjugate was synthesized through an oxime click reaction, combining a pan-cathepsin inhibitor based on E64d with the Ru(II) PCT/PDT fragment [Ru(dqpy)(dppn)], where dqpy = 2,6-di(quinoline-2-yl)pyridine and dppn = benzo[i]dipyrido[3,2-a:2',3'-c]phenazine. Photochemical investigations validated the conjugate's ability to release a triazole-containing cathepsin inhibitor for PCT and to generate singlet oxygen for PDT upon exposure to green light. Inhibition studies demonstrated the conjugate's potent and irreversible inactivation of purified and intracellular cysteine cathepsins. Two Ru(II) PCT/PDT agents based on the [Ru(dqpy)(dppn)] moiety were evaluated for photoinduced cytotoxicity in 4T1 murine triple-negative breast cancer cells, L929 fibroblasts, and M0, M1, and M2 macrophages. The cathepsin inhibitor conjugate displayed notable selectivity for inducing cell death under irradiation compared to dark conditions, mitigating toxicity in the dark observed with the triazole control complex [Ru(dqpy)(dppn)(MeTz)]2+ (MeTz = 1-methyl-1H-1,2,4-triazole). Notably, our lead complex is among a limited number of dual PCT/PDT agents activated with green light.

Solar photocatalytic CeO2/g-C3N4 removal of micropollutants in the water environment through the generation of singlet oxygen

The synthesis of photocatalysts with good photocatalytic performance to selectively oxidize micropollutants in complex water environments has received widespread attention. This study successfully synthesized a CeO2/g-C3N4 composite, which could degrade sulfamethoxazole (SMX) up to 95 % under simulated sunlight (SSL) in 60 min. Additionally, it exhibited favorable selective oxidation characteristics in complex water environments. EPR and radical scavenging experiments proved the main oxidation contributions of singlet oxygen (1O2) in the system. Photoluminescence spectroscopy demonstrated that the composite material could generate more triplet excitons to generate 1O2 with ground-state oxygen (3O2) through an energy transfer pathway. The product analysis of the two models of micropollutants, SMX and carbamazepine, indicated an overall rise in the biodegradability of the majority of intermediates, accompanied by a decrease in acute toxicity. The composite showed high stability even after 5 cycles. Various micropollutants have degradation of varying degrees in different natural water matrices. In summary, this study introduced a novel photocatalytic oxidation strategy with selective oxidation capability, providing possibilities for practical applications and environmentally friendly photocatalytic processes.