Singlet Oxygen Research Articles

Visible light-activated dye-sensitized TiO2 antibacterial film: A novel strategy for enhancing food safety and quality

Antibacterial packaging holds promise in addressing food spoilage by inactivating bacteria, but current antimicrobial packaging solutions face challenges like depletion of antibacterials and concerns of antibiotic abuse. In response to these limitations of existing packaging materials, we developed a novel antibacterial packaging film by incorporating titanium dioxide (TiO2)- tetra(4-carboxyphenyl) porphyrin (TcPP) conjugates into cellulose nanofibrils (CNF) films. Unlike conventional antimicrobial packaging, this film harnesses visible light energy to excite electrons from TcPP to TiO2, generating reactive oxygen species (ROS) that inactivate bacteria without relying on antibiotics. Results demonstrated that the film reduced 4.5, 4.6, 4.1, and 4.7-log Escherichia coli, Pseudomonas fluorescens, Leuconostoc lactis, and Listeria innocua, respectively, in phosphate-buffered saline within 72h under 6000 lux light (3.13mW/cm2). The antimicrobial efficacy decreased as the light intensity decreased. Notably, it retains significant antimicrobial properties even under an extremely low light intensity of 600 lux (0.60mW/cm2). The analysis also revealed that singlet oxygen and hydrogen peroxide are the major generated ROS from the film under light exposure. When applied to cucumbers, the film reduced E. coli by 3.5 logs after 48-hour light exposure. The designed photocatalytic antibacterial film represents a major advancement in sustainable food preservation, reducing food waste by extending the shelf life of fresh produce.

Hypoxia-Active Iridium(III) Bis-terpyridine Complexes Bearing Oligothienyl Substituents: Synthesis, Photophysics, and Phototoxicity toward Cancer Cells.

In an effort to develop hypoxia-active iridium(III) complexes with long visible-light absorption, we synthesized and characterized five bis(terpyridine) Ir(III) complexes bearing oligothienyl substituents on one of the terpyridine ligands, i.e., nT-Ir (n = 0-4). The UV-vis absorption, emission, and transient absorption spectroscopy were employed to characterize the singlet and triplet excited states of these complexes and to explore the effects of varied number of thienyl units on the photophysical parameters of the complexes. In vitro photodynamic therapeutic activities of these complexes were assessed with respect to three melanoma cell lines (SKMEL28, A375, and B16F10) and two breast cancer cell lines (MDA-MB-231 and MCF-7) under normoxia (∼18.5% oxygen tension) and hypoxia (1% oxygen tension) upon broadband visible (400-700 nm), blue (453 nm), green (523 nm), and red (633 nm) light activation. It was revealed that the increased number of thienyl units bathochromically shifted the low-energy absorption bands to the green/orange spectral regions and the emission bands to the near-infrared (NIR) regions. The lowest triplet excited-state lifetimes and the singlet oxygen generation efficiency also increased from 0T to 2T substitution but decreased in 3T and 4T substitution. All complexes exhibited low dark cytotoxicity toward all cell lines, but 2T-Ir-4T-Ir manifested high photocytotoxicity for all cell lines upon visible, blue, and green light activation under normoxia, with 2T-Ir showing the strongest photocytotoxicity toward SKMEL28, MDA-MB-231, and MCF-7 cells, and 4T-Ir being the most photocytotoxic one for B16F10 and A375 cells. Singlet oxygen, superoxide anion radicals, and peroxynitrite anions were found to likely be involved in the photocytotoxicity exhibited by the complexes. 4T-Ir also showed strong photocytotoxicity upon red-light excitation toward all cell lines under normoxia and retained its photocytotoxicity under hypoxia toward all cell lines upon visible, blue, and green light excitation. The hypoxic activity of 4T-Ir along with its green to orange light absorption, NIR emission, and low dark cytotoxicity suggest its potential as a photosensitizer for photodynamic therapy applications.

Tratamento endodôntico associado a terapia fotodinâmica em dente anterior: relato de caso

Photodynamic therapy acts on biostimulation at the cellular level, thus accelerating tissue repair and promoting analgesia. Often with conventional treatment it is not possible to achieve success and it is necessary to use alternative therapies, photodynamic therapy is used as one of these alternative therapies, demonstrating which types of photosensitizers and light can be used and how it is possible to help combat the infection. bacterial. Photosensitizers have the function of absorbing red light in the region and producing singlet oxygen. Therefore, the objective of this work was to perform endodontic treatment on element 21 with a periapical lesion, with the aid of photodynamic therapy associated with the photosensitizer Methylene Blue.

Gold Nanoparticles for Photothermal and Photodynamic Therapy.

Cancer cells exposed to 13 nm gold nanoparticles and irradiated with cw laser light at 532 nm are shown to undergo cell death via two competing causes. When cells contain relatively high quantities of gold nanoparticles and/or receive a high dose of light, photothermal effects dominate, which are independent of the cellular location of the gold nanoparticles and affect all cells in the irradiated area due to the rapid diffusion of heat. In contrast, at lower doses of nanoparticles and light, the photogeneration of singlet oxygen triggers cell death only in cells that contain a sufficient number of nanoparticles. The parallel occurrence of both effects will need to be considered carefully when designing practical therapy applications. In particular, the photodynamic effect should allow for a cell-type-specific treatment modality that can distinguish between cancer and normal cells using suitable targeting ligands on the nanoparticle surface, providing a highly selective route for cancer therapy.

Effect of Peripheral Functionalization of Pt(II) Porphyrin(2.1.2.1) on Singlet Oxygen Generation.

Four structurally bent porphyrin(2.1.2.1) Pt(II) complexes have been obtained and verified well. Main absorbance of Pt(II) porphyrin(2.1.2.1) displayed a significant red-shift compared to that of porphyrin(1.1.1.1) Pt(II) molecules. 1O2 study indicated that electron-withdrawing group and intramolecular charge transfer effect synergistically endowed Pt(II) porphyrin(2.1.2.1) with good singlet oxygen-sensitizing capacity under blue LED light irradiation. This work presents a simple synthesis way to develop a new series of efficient porphyrinoid singlet oxygen photosensitizers for PDT through molecular engineering.

A triple-mode strategy combining low-temperature photothermal, photodynamic, and chemodynamic therapies for treating infectious skin wounds.

The skin is the first natural barrier of the human body. Bacterial infections severely hinder the healing process of skin wounds and pose a great threat to human health. Therefore, it is particularly urgent to develop new antimicrobial strategies for bacterial pathogen clearance and wound healing. In this study, a metal-organic framework (MOF), Fe-MIL88B-NH2, was incorporated with the photosensitizer indocyanine green (ICG) to construct composite nanoparticles (MOF@ICG NPs) with multiple antibacterial activities. Under mild near-infrared (NIR) irradiation, the photosensitizer ICG in the MOF@ICG NPs undergoes photothermal conversion (∼45 °C) and photodynamic reactions to generate heat and singlet oxygen (1O2). In addition, the Fenton reaction of the NPs with hydrogen peroxide (H2O2) in the bacterial infection microenvironment resulted in the generation of hydroxyl radicals (˙OH), thus achieving the three-mode combination of low-temperature photothermal therapy (PTT)/photodynamic therapy (PDT)/chemodynamic therapy (CDT). The in vitro experimental results showed that MOF@ICG MPs had excellent antibacterial properties and good cytocompatibility, with some ability to promote the migration of L-929 fibroblasts. Furthermore, under NIR irradiation, MOF@ICG NPs could significantly kill bacteria and promote skin wound healing according to the results of animal experiments. The wound healing rate reached 87.1% after 7 days of treatment. The research results break through the limitations of single-mode antibacterial technology and provide certain theoretical guidance and technical support for the research and development of new antibacterial materials.

Frenkel defects facilitate oriented 1O2 formation in birnessite for enhanced catalytic oxidation of formaldehyde

Defect strategy is one of the most effective approaches for enhancing the efficiency of Mn-based catalysts in removing formaldehyde (HCHO) under ambient conditions. Herein, the interlayer Mn-O octahedra in birnessite synergistically form with Mn vacancies through proton exchange in acidic solutions, creating surface Frenkel defects. As evidenced by highly combined physicochemical characterization and density functional theory calculations, surface Frenkel defects are highly active sites on the surface of birnessite. The surface Frenkel defects can induce surface electronic reconstruction, generating strong electrophilicity, which promotes the evolution of superoxide radicals (O2•−) into singlet oxygen (1O2). In-situ quenching DRIFTS indicates that 1O2 is the most important ROS in the oxidation process of HCHO. Additionally, the surface Frenkel defects enhance the adsorption of HCHO, promoting the dehydrogenation of HCHO to form CO, which is then rapidly oxidized to CO2 and H2O under the action of 1O2. This provide a more effective kinetic and thermodynamic catalytic pathway. The defect-rich birnessite (R-Bir) achieved complete HCHO removal in the dynamic test at 10 ppm within 10 hours, significantly outperforming defect-free birnessite (F-Bir) and most previously reported catalysts. This study precisely reveals the catalytic mechanism of HCHO over R-Bir and provides valuable insights for the design of high-performance environmental catalysts.

Ball milling of pyrolytic residue from oil sands with MnO2 and reuse as PMS activator: Measurement of ROS exposure and mechanism insights

Pyrolysis is an important process to recover petroleum from oil sands, while the pyrolytic residue of oil sands (PROS) is commonly treated as solid waste. In this study, PROS was treated by ball milling with manganese dioxide and converted into Mn-loaded carbon sand (MnBMCS), which was reused as a peroxymonosulfate (PMS) activator to degrade aniline (AN) in wastewater. The AN (100 mg/L) was almost completely removed by 2 g/L MnBMCS and 1 g/L PMS. Electron paramagnetic resonance tests confirmed the existence of three reactive oxygen species (ROS) including sulfate radical (SO4∙−), hydroxyl radical (∙OH) and singlet oxygen (O21) in MnBMCS/PMS system. A probe-based kinetics model was constructed to measure the ROS exposure. The O21 exposure was 6.73 and 22.95 times of SO4∙− and ∙OH exposure, respectively. But the contribution of SO4∙− to AN degradation was much greater than that of O21 due to its higher oxidation capacity. Characterization analysis showed that Mn(Ⅳ)/Mn(Ⅲ) redox electrons could activate PMS to produce SO4∙− and ∙OH, CO activated PMS to produce O21, and π-π* was also beneficial to generate SO4∙− and ∙OH. This study proposes an innovative integrated process to promote the governance mode of PROS from harmless disposal to high-value resource utilization.

Photocatalyst-Free Transformation of C(sp3)-H Bonds to Oxime Ethers via Photoinduced Hydrogen Atom Transfer.

Herein, a direct transformation of aliphatic C-H bonds to oxime ethers has been developed via light-promoted hydrogen atom transfer (HAT) in the absence of a photocatalyst. Singlet oxygen and chlorine radical are complementary C(sp3)-H bond cleaving agents in this reaction, enabling the extraction of hydrogen atoms from a diverse range of compounds, like cycloalkanes, ethers, amines, amides, and cyclic sulfides. This method excels in transforming common aliphatic C-H bonds into valuable oxime ethers featuring abundant chemical feedstocks, good functional group tolerance, and catalyst free conditions.

Multifunctional hyaluronic acid ligand-assisted construction of CD44- and mitochondria-targeted self-assembled upconversion nanoparticles for enhanced photodynamic therapy.

Upconversion nanoparticles (UCNPs) have been used as a potential nanocarrier for photosensitizers (PSs), which have demonstrated a great deal of promise in achieving an effective photodynamic therapy (PDT) for deep-seated tumors. However, overcoming biological barriers to achieve mitochondria-targeted PDT remains a major challenge. Herein, CD44- and mitochondria-targeted photodynamic nanosystems were fabricated through the self-assembly of hyaluronic acid-conjugated-methoxy poly(ethylene glycol)-diethylenetriamine-grafted-(chlorin e6-dihydrolipoic acid-(3-carboxypropyl)triphenylphosphine bromide) polymeric ligands (HA-c-mPEG-Deta-g-(Ce6-DHLA-TPP)) and NaErF4:Tm@NaYF4 core-shell UCNPs (termed CMPNs). The CMPNs presented ideal physiological stability, a good drug loading capacity and an improved capacity for the generation of singlet oxygen (1O2) based on the FRET mechanism. Significantly, confocal images revealed that CMPNs not only facilitated cellular uptake through CD44-receptor-targeted endocytosis, subsequently enabling rapid evasion from endo-lysosomal sequestration, but also specifically targeted mitochondria, ultimately inducing a profound disruption of mitochondrial membrane potential, which triggered apoptosis upon laser irradiation, thereby significantly enhancing the therapeutic effect. Furthermore, in vitro antitumor experiments further confirmed the substantial enhancement in cancer cell killing efficiency achieved by treating with CMPNs upon near-infrared (NIR) laser irradiation. This innovative approach holds promise for the development of NIR-laser-activated photodynamic nanoagents specifically designed for mitochondria-targeted PDT, thus addressing the limitations of the current PDT treatments.

Core‐Fluorinated BODIPYs – a New Family of Highly Efficient Luminophores

AbstractA modular synthesis of novel series of 1,7‐difluorinated BODIPYs has been elaborated. First, the acid‐catalyzed condensation of ethyl 3‐aryl‐4‐fluoro‐1H‐pyrrole‐2‐carboxylates with aromatic aldehydes gives the corresponding dipyrromethane‐1,9‐dicarboxylates. The latter are subjected to the exhaustive reduction with lithium aluminum hydride to transform the ester moieties into methyl groups. The subsequent oxidation of the resulting 1,9‐dimethylated dipyrromethanes followed by the boron difluoride complexation afforded a family of novel core‐fluorinated BODIPYs in up to 74 % yield. Photophysical properties of the resulting BODIPYs were tuned by varying of the starting fluoropyrroles and aromatic aldehydes and were studied by UV‐visible and fluorescence spectroscopy. As a result, the fluorescence quantum yields of the obtained compounds reached up to 99 %. In addition, their ability to generate singlet oxygen and electrochemical properties were also evaluated. As a result, a new promising family of fluorophores with a good combination of the fluorescence and photosensitizing properties was obtained. It was found that conversion of ester groups into methyl ones at the 3,5‐positions of the BODIPY core is a crucial step toward fluorescence enhancement. In addition, DFT calculations were performed to elucidate a relationship between electronic structure, geometry and photophysical properties of these BODIPYs.

Tetraphenylethene-Based Molecular Cage with Coenzyme FAD: Conformationally Isomeric Complexation toward Photocatalysis-Assisted Photodynamic Therapy.

Flavin adenine dinucleotide (FAD), serving as a light-absorbing coenzyme factor, can undergo conformationally isomeric complexation within different enzymes to form various enzyme-coenzyme complexes, which exhibit photocatalytic functions that play a crucial role in physiological processes. Constructing an artificial photofunctional system using FAD or its derivatives can not only develop biocompatible photocatalytic systems with excellent activities but also further enhance our understanding of the role of FAD in biological systems. Here, we demonstrate a supramolecular approach for constructing an artificial enzyme-coenzyme-type host-guest complex with photoinduced catalytic function in water. First, we have designed and synthesized a water-soluble tetraphenylethene (TPE)-based octacationic molecular cage (1) with a large and flexible cavity, which can adaptively encapsulate with two FAD molecules with "U-shaped" conformation (uFAD) to form a 1:2 host-guest complex (1⊃uFAD2) in water. Second, based on the conformationally isomeric complexation of FAD within 1, the 1⊃uFAD2 complex facilitates electron and energy transfers to molecular oxygen upon the white-light illumination, efficiently producing reactive oxygen species (ROS) such as superoxide radical (O2•-) and singlet oxygen (1O2). To our knowledge, the 1⊃uFAD2 complex acts as a photocatalyst to achieve the highest turnover frequency (TOF) of 35.6 min-1 for the photocatalytic oxidation reaction of NADH via a photoinduced superoxide radical catalysis mechanism in an aqueous medium. At last, combining the cytotoxic effects of ROS and the disruption of the intracellular redox balance involving NADH, 1⊃uFAD2 as a supramolecular photosensitizer displays an excellent oxygen-independent photocatalysis-assisted photodynamic therapy in hypoxic tumors.

Iron–Cobalt Bimetallic Metal–Organic Framework-Derived Carbon Materials Activate PMS to Degrade Tetracycline Hydrochloride in Water

Organic pollutants entering water bodies lead to severe water pollution, posing a threat to human health. The activation of persulfate advanced oxidation processes using carbon materials derived from MOFs as substrates can efficiently treat wastewater contaminated with organic pollutants. This research uses NH2-MIL-101(Fe) as a substrate, doped with Fe2+ and Co2+, to prepare Fe/Co-CNs through a one-step carbonization method. The surface morphology, pore structure, and chemical composition of Fe/Co-CNs were investigated using characterization techniques such as XRD, SEM, TEM, XPS, FT-IR, BET, and Raman. A comparative study was conducted on the performance of catalysts with different Fe/Co ratios in activating PMS for the degradation of organic pollutants, as well as the effects of various influencing factors (the dosage of Fe/Co-CNs, the amount of peroxymonosulfate (PMS), the initial pH of the solution, the TC concentration, and inorganic anions) on the catalyst’s activation of persulfate for TC degradation. Through radical quenching experiments and post-degradation XPS analysis, the active radicals in the FeCo-CNs/PMS system were investigated to explain the possible mechanism of TC degradation in the Fe/Co-CNs/PMS system. The results indicate that Fe/Co-CNs-2 (with a Co2+ doping amount of 20%) achieves a degradation rate of 93.34% for TC (tetracycline hydrochloride) within 30 min when activating PMS, outperforming other Co2+ doping amounts. In addition, singlet oxygen (1O2) is the main reactive species in the reaction system.

A combination of covalent and noncovalent restricted‐intramolecular‐rotation strategy for supramolecular AIE‐type photosensitizer toward photodynamic therapy

AbstractPhotodynamic therapy (PDT) is a promising noninvasive method for targeted cancer cell destruction. Still, its effectiveness is often hindered by the aggregation‐caused quenching effect of organic photosensitizer (PS) in aqueous environments. Here, we have employed a combination of covalent and noncovalent restricted‐intramolecular‐rotation strategies to develop supramolecular PSs with aggregation‐induced emission (AIE) characteristics. Firstly, a water‐soluble octacationic molecular cage (1) with a bilayer tetraphenylethene (TPE) structure has been designed and synthesized, which minimizes intramolecular rotation of TPE moieties and achieves the single‐molecule‐level aggregation by the covalent restriction of intramolecular rotation (RIR) via molecular engineering synthesis. Compared with its single‐layer TPE analog, 1 exhibits superior efficiency in generating reactive oxygen species (ROS) including superoxide radical (O2−•) and singlet oxygen (1O2) upon white‐light irradiation. Subsequently, by forming a 1:4 host–guest complex (1@CB[8]4) between 1 and cucurbit[8]uril (CB[8]), O2−• generation can be further enhanced by the noncovalent RIR via the host–guest assembly. Additionally, 1@CB[8]4 as a photocatalyst promotes rapid oxidation of nicotinamide adenine dinucleotide (NADH) in water. Given its Type‐I ROS generation and catalytic activity for NADH oxidation, 1@CB[8]4 acts as a supramolecular AIE‐type PS to exhibit strong photo‐induced cytotoxicity upon white‐light irradiation under hypoxic conditions, showcasing its potential for synergistic PDT.

Collaboration in Contradiction: Self-Adaptive Synergistic ROS Generation and Scavenge Balancing Strategies Used for the Infected Wounds Treatment.

The rational utilization of ROS is key to treating infected wounds. Exogenous ROS can destroy bacterial structures, quickly kill bacteria, and inhibit secondary infections. However, excess ROS at the wound will cause a secondary inflammatory response. Acute infections exacerbate this damage by increasing endogenous ROS, complicating the maintenance of ROS homeostasis. Therefore, regulating the balance of ROS production and scavenging in wounds has emerged as a promising strategy for wound treatment. Conventional ROS balancing platforms are mostly based on the " all for one" strategy of functional superposition and lack self-adaptability and integration. To subvert this conventional strategy, this study proposes a "one for all" self-adaptive integrated photodynamic therapy (PDT)-antioxidant model to actively regulate the ROS balance. A gelatin-hyaluronic acid hydrogel embedded with Se-modified cerium dioxide nanoparticles (Gel-HA-Se@CeO2 NPs) is designed for treating infected wounds. The Se@CeO2 NPs serve both as nanoenzymes and photosensitizers(PS). As nanoenzymes, they exhibit catalase and superoxide dismutase activities, converting hydrogen peroxide and superoxide anions into oxygen. As a PS, it synergizes with oxygen under NIR irradiation to rapidly produce singlet oxygen. Additionally, Se modification enhances the PDT effects by disrupting bacterial antioxidant systems. In vitro and in vivo experiments revealed that the ROS balance platform polarizes M1-type macrophages to M2-type macrophages, altering the wound microenvironment from proinflammatory to prohealing. RNA sequencing revealed that this hydrogel accelerated the reconstruction of the vascular network of the wound by activating the PI3K/AKT pathway and increasing VEGF secretion.This strategy is believed to be beneficial not only for infected wounds but also for treating other conditions that involve the regulation of reactive oxygen species, such as tumors and bacterial infections.

Encapsulation of an Au25 Nanocluster inside a Porphyrin Nanoring Enhances Singlet Oxygen Generation and Photo-Electrocatalytic CO2 Reduction.

The synthesis of molecular host-guest complexes with enhanced performance, relative to those of their components, is a central theme in supramolecular chemistry. Here we explore a host-guest system consisting of an atomically precise gold nanocluster bound inside a zinc porphyrin nanoring. UV-vis absorption and fluorescence titrations with different sized nanorings revealed strong binding between a pyridinethiol-coated Au25 nanocluster and a nanoring consisting of six zinc porphyrin units, and complexation is confirmed by mass spectrometry. Formation of this assembly enhances the stability of the gold nanocluster. The host-guest complex also exhibits remarkable activity and selectivity for photochemical CO2 to CO conversion and singlet oxygen generation.

Activation of persulfate by MOF-derived MnFeOx to efficiently degrade sulfadiazine: Synergistic effects from free radicals and singlet oxygen

In this study, a facile hydrothermal approach was used to synthesize the MOFs materials [Mn-doped MIL-101(Fe)]. These materials were subsequently subjected to high temperature annealing process via calcination to generate the MOFs derivatives (MnFeOx). The synthesized materials were utilized for the removal of sulfadiazine (SDZ) removal through activated peroxymonosulfate (PMS). At the optimum Mn doping, the removal ratio of SDZ could reach 98.9 % (at natural pH) within 20 min. In addition, the study investigated the influence of PMS dosage, catalyst dosage, initial pH, various inorganic anions, and humic acid (HA) on the degradation of SDZ. The activation processes of both free and non-free radicals in the MnFeOx/PMS system were examined by free radical quenching experiments and electron paramagnetic resonance (EPR) techniques. The analysis of the degradation products of SDZ was conducted by using high performance liquid chromatography-mass spectrometry (HPLC-MS), and the breakdown pathways of SDZ in the MnFeOx/PMS system were proposed.

Fe/Mo bimetallic synergy system for ultra-highly efficient degradation of Rhodamine B

The traditional Fenton process, which depends on the use of Fe2+/H2O2, is constrained by the consumption of ferrous ions and the requirement for large amounts of H2O2. However, the assembly of bimetallic synergy systems with adjustable valence metal cations and enhanced dispersion of active sites has been evidenced to address these limitations. In this work, the Fe/Mo bimetallic synergy system in FexMo-CN materials is explored, utilized for the degradation of dyes with the assistance of H2O2. The cooperative effect of Fe/Mo bimetallic and the highly dispersed FeMoO4 as active sites make materials to achieve ultra-highly efficient degradation of dyes, approximately 100 % Rhodamine B (RhB) degradation within 6 min. And the corresponding degradation rate constant is 1.3471 min−1. Additionally, FexMo-CN materials exhibit excellent stability and versatility in solutions containing various cations, anions, or other dyes. Quenching experiments and EPR tests demonstrate that singlet oxygen (1O2) serves as the main reactive oxygen species (ROS) to degrade RhB. And the mechanism of generated 1O2 is revealed. The degradation path and mechanism of RhB are analyzed and the toxicology of intermediate products are calculated in detail. This work presents a novel approach for enhancing efficiency in Fenton-like reactions within the field of environmental remediation.

Self-Assembled BODIPY@Au Core-Shell Structures for Durable Neuroprotective Phototherapy.

BODIPY analogs are promising photosensitizers for molecular phototherapy; however, they exhibit high dark cytotoxicity and limited singlet oxygen generation capacity. In this study, we developed self-assembled core-shell nanophotosensitizers by linking a bipyridine group to BODIPY (Bpy-BODIPY) and promoting J-aggregation on gold nanourchins. This design enhances photostability and reduces the energy gap between the lowest singlet excited state and the lower triplet state, facilitating efficient singlet oxygen production. We characterized these nanophotosensitizers using UV-visible spectroscopy, transmission electron microscopy (TEM), surface-enhanced Raman spectroscopy (SERS) and dynamic light scattering (DLS), which confirmed the formation of the desired core-shell structure and J-aggregates. Notably, Bpy-BODIPY@Au significantly suppresses tau protein aggregation and enhances neuroprotective action, even in the presence of a phosphatase inhibitor. This work broadens the application of BODIPY chemistry to nanoagents for neuroprotective therapy.

Photoinactivation of Multidrug-Resistant mcr-1-Positive E. coli Using PCPDTBT Conjugated Polymer Nanoparticles under White Light.

The issue of antimicrobial resistance is an escalating concern within the scope of global health. It is predicted that the existence of antibiotic-resistant bacteria might result in an estimated annual death of up to 10 million by 2050, along with possible economic losses ranging from 100 to 210 trillion. This study reports the production of poly[2,6-(4,4-bis(2-ethylhexyl)-4H-cyclopenta[2,1-b;3,4-b']dithiophene)-alt-4,7(2,1,3-benzothiadiazole)] nanoparticles (PCPDTBT-NPs) by nanoprecipitation as an alternative to tackle this problem. The size, shape, and optical features of these conjugated polymer NPs were analyzed. Their efficacy as photosensitizers against nonresistant (ATCC) and multidrug-resistant mcr-1-positive Escherichia coli was assessed under white light doses of 250 and 375 J·cm-2. PCPDTBT-NPs inactivated both E. coli strains exposed to white light at an intensity of 375 J·cm-2, while no antimicrobial effect was observed in the group not exposed to white light. Reactive oxygen species and singlet oxygen were detected using DCFH-DA and DPBF probes, allowing the investigation of the photoinactivation pathways. This work showcases PCPDTBT-NPs as photosensitizers to eliminate multidrug-resistant bacteria through photodynamic inactivation employing visible light.