A TME-enlightened protein-binding photodynamic nanoinhibitor for highly effective oncology treatment.

The efficiency of photodynamic therapy (PDT) is greatly dependent on intrinsic features of photosensitizers (PSs), but most PSs suffer from narrow diffusion distances and short life span of singlet oxygen (1O2). Here, to conquer this issue, we propose a strategy for in situ formation of complexes between PSs and proteins to deactivate proteins, leading to highly effective PDT. The tetrafluorophenyl bacteriochlorin (FBC), a strong near-infrared absorbing photosensitizer, can tightly bind to intracellular proteins to form stable complexes, which breaks through the space-time constraints of PSs and proteins. The generated singlet oxygen directly causes the protein dysfunction, leading to high efficiency of PSs. To enable efficient delivery of PSs, a charge-conversional and redox-responsive block copolymer POEGMA-b-(PAEMA/DMMA-co-BMA) (PB) was designed to construct a protein-binding photodynamic nanoinhibitor (FBC@PB), which not only prolongs blood circulation and enhances cellular uptake but also releases FBC on demand in tumor microenvironment (TME). Meanwhile, PDT-induced destruction of cancer cells could produce tumor-associated antigens which were capable to trigger robust antitumor immune responses, facilitating the eradication of residual cancer cells. A series of experiments in vitro and in vivo demonstrated that this multifunctional nanoinhibitor provides a promising strategy to extend photodynamic immunotherapy.

Third-Generation Anticancer Photodynamic Therapy Systems Based on Star-like Anionic Polyacrylamide Polymer, Gold Nanoparticles, and Temoporfin Photosensitizer.

Photodynamic therapy (PDT) is a non-invasive anticancer treatment that uses special photosensitizer molecules (PS) to generate singlet oxygen and other reactive oxygen species (ROS) in a tissue under excitation with red or infrared light. Though the method has been known for decades, it has become more popular recently with the development of new efficient organic dyes and LED light sources. Here we introduce a ternary nanocomposite: water-soluble star-like polymer/gold nanoparticles (AuNP)/temoporfin PS, which can be considered as a third-generation PDT system. AuNPs were synthesized in situ inside the polymer molecules, and the latter were then loaded with PS molecules in an aqueous solution. The applied method of synthesis allows precise control of the size and architecture of polymer nanoparticles as well as the concentration of the components. Dynamic light scattering confirmed the formation of isolated particles (120 nm diameter) with AuNPs and PS molecules incorporated inside the polymer shell. Absorption and photoluminescence spectroscopies revealed optimal concentrations of the components that can simultaneously reduce the side effects of dark toxicity and enhance singlet oxygen generation to increase cancer cell mortality. Here, we report on the optical properties of the system and detailed mechanisms of the observed enhancement of the phototherapeutic effect. Combinations of organic dyes with gold nanoparticles allow significant enhancement of the effect of ROS generation due to surface plasmonic resonance in the latter, while the application of a biocompatible star-like polymer vehicle with a dextran core and anionic polyacrylamide arms allows better local integration of the components and targeted delivery of the PS molecules to cancer cells. In this study, we demonstrate, as proof of concept, a successful application of the developed PDT system for in vitro treatment of triple-negative breast cancer cells under irradiation with a low-power LED lamp (660 nm). We consider the developed nanocomposite to be a promising PDT system for application to other types of cancer.

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.

Polyphosphoester-stabilized cubosomes encapsulating a Ru(II) complex for the photodynamic treatment of lung adenocarcinoma.

The clinical translation of photosensitizers based on ruthenium(II) polypyridyl complexes (RPCs) in photodynamic therapy of cancer faces several challenges. To address these limitations, we conducted an investigation to assess the potential of a cubosome formulation stabilized in water against coalescence utilizing a polyphosphoester analog of Pluronic F127 as a stabilizer and loaded with newly synthesized RPC-based photosensitizer [Ru(dppn)2(bpy-morph)](PF6)2 (bpy-morph = 2,2'-bipyridine-4,4'-diylbis(morpholinomethanone)), PS-Ru. The photophysical characterization of PS-Ru revealed its robust capacity to induce the formation of singlet oxygen (1O2). Furthermore, the physicochemical analysis of the PS-Ru-loaded cubosomes dispersion demonstrated that the encapsulation of the photosensitizer within the nanoparticles did not disrupt the three-dimensional arrangement of the lipid bilayer. The biological tests showed that PS-Ru-loaded cubosomes exhibited significant phototoxic activity when exposed to the light source, in stark contrast to empty cubosomes and to the same formulation without irradiation. This promising outcome suggests the potential of the formulation in overcoming the drawbacks associated with the clinical use of RPCs in photodynamic therapy for anticancer treatments.

Investigating the mechanism of chloroplast singlet oxygen signaling in the Arabidopsis thaliana accelerated cell death 2 mutant.

As sessile organisms, plants have evolved complex signaling mechanisms to sense stress and acclimate. This includes the use of reactive oxygen species (ROS) generated during dysfunctional photosynthesis to initiate signaling. One such ROS, singlet oxygen (1O2), can trigger retrograde signaling, chloroplast degradation, and programmed cell death. However, the signaling mechanisms are largely unknown. Several proteins (e.g. PUB4, OXI1, EX1) are proposed to play signaling roles across three Arabidopsis thaliana mutants that conditionally accumulate chloroplast 1O2 (fluorescent in blue light (flu), chlorina 1 (ch1), and plastid ferrochelatase 2 (fc2)). We previously demonstrated that these mutants reveal at least two chloroplast 1O2 signaling pathways (represented by flu and fc2/ch1). Here, we test if the 1O2-accumulating lesion mimic mutant, accelerated cell death 2 (acd2), also utilizes these pathways. The pub4-6 allele delayed lesion formation in acd2 and restored photosynthetic efficiency and biomass. Conversely, an oxi1 mutation had no measurable effect on these phenotypes. acd2 mutants were not sensitive to excess light (EL) stress, yet pub4-6 and oxi1 both conferred EL tolerance within the acd2 background, suggesting that EL-induced 1O2 signaling pathways are independent from spontaneous lesion formation. Thus, 1O2 signaling in acd2 may represent a third (partially overlapping) pathway to control cellular degradation.

Monitoring of singlet oxygen generation of a novel Schiff-base substituted silicon phthalocyanines by sono-photochemical studies and in vitro activities on prostate cancer cell.

This study demonstrates the potential of sono-photodynamic therapy as an effective approach for enhancing singlet oxygen generation using the synthesized Schiff-base diaxially substituted silicon phthalocyanines. In photochemical studies, the singlet oxygen quantum yields (Φ∆) were determined as 0.43 for Si1a, 0.94 for Q-Si1a, 0.58 for S-Si1a, and 0.49 for B-Sia1. In sono-photochemical studies, the Φ∆ values were reached to 0.67 for Si1a, 1.06 for Q-Si1a, 0.65 for S-Si1a, and 0.67 for B-Sia1. In addition, this study demonstrates the therapeutic efficacy of phthalocyanines synthesized as sensitizers on the PC3 prostate cancer cell line through in vitro experiments. The application of these treatment modalities exhibited notable outcomes, leading to a substantial decrease in cell viability within the PC3 prostate cancer cell line. These findings highlight the potential of utilizing these synthesized phthalocyanines as promising therapeutic agents for prostate cancer treatment.

Enhancing antitumor efficacy of NIR-I region zinc phthalocyanine@upconversion nanoparticle through lysosomal escape and mitochondria targeting.

Accurately visualizing the intracellular trafficking of upconversion nanoparticles (UCNPs) loaded with phthalocyanines and achieving precise photodynamic therapy (PDT) using near-infrared (NIR) laser irradiation still present challenges. In this study, a novel NIR laser-triggered upconversion luminescence (UCL) imaging-guided nanoparticle called FA@TPA-NH-ZnPc@UCNPs (FTU) was developed for PDT. FTU consisted of UCNPs, folic acid (FA), and triphenylamino-phenylaniline zinc phthalocyanine (TPA-NH-ZnPc). Notably, TPA-NH-ZnPc showcases aggregation-induced emission (AIE) characteristic and NIR absorption properties at 741 nm, synthesized initially via molybdenum-catalyzed condensation reaction. The UCL emitted by FTU enable real-time visualization of their subcellular localization and intracellular trafficking within ovarian cancer HO-8910 cells. Fluorescence images revealed that FTU managed to escape from lysosomes due to the "proton sponge" effect of TPA-NH-ZnPc. The FA ligands on the surface of FTU further directed their transport and accumulation within mitochondria. When excited by a 980 nm laser, FTU exhibited UCL and activated TPA-NH-ZnPc, consequently generating cytotoxic singlet oxygen (1O2), disrupted mitochondrial function and induced apoptosis in cancer cells, which demonstrated great potential for tumor ablation.

Redesign of a thioflavin-T-binding protein with a flat ß-sheet to evaluate a thioflavin-T-derived photocatalyst with enhanced affinity.

Amyloids, proteinous aggregates with ß-sheet-rich fibrils, are involved in several neurodegenerative diseases such as Alzheimer's disease; thus, their detection is critically important. The most common fluorescent dye for amyloid detection is thioflavin-T (ThT), which shows on/off fluorescence upon amyloid binding. We previously reported that an engineered globular protein with a flat ß-sheet, peptide self-assembly mimic (PSAM), can be used as an amyloid binding model. In this study, we further explored the residue-specific properties of ThT-binding to the flat ß-sheet by introducing systematic mutations. We found that site-specific mutations at the ThT-binding channel enhanced affinity. We also evaluated the binding of a ThT-based photocatalyst, which showed the photooxygenation activity on the amyloid fibril upon light radiation. Upon binding of the photocatalyst to the PSAM variant, singlet oxygen-generating activity was observed. The results of this study expand our understanding of the detailed binding mechanism of amyloid-specific molecules.

On-Site Quantitative Visualization of Singlet Oxygen in Crops via an Organic Small Molecule-Based Ratiometric Fluorescent Probe and a Mobile Fluorescence Analysis Device.

Singlet oxygen (1O2) plays imperative roles in a variety of biotic or abiotic stresses in crops. The change of its concentration within a crop is closely related to the crop growth and development. Accordingly, there is an urgent need to develop an efficient analytical method for on-site quantitative detection of 1O2 in crops. Here, we judiciously constructed a novel ratiometric fluorescent probe, SX-2, for the detection of 1O2 in crops. Upon treating with 1O2, probe SX-2 displayed highly selective ratiometric fluorescence response, which is favorable for the quantitative detection of 1O2. Concurrently, the fluorescence solution color of probe SX-2 was varied, obviously from blue to yellow, indicating that the probe is beneficial for on-site detection by the naked eye. Sensing reaction mechanism studies showed that the 2,3-diphenyl imidazole group in SX-2 could function as a new selective recognition group for 1O2. Probe SX-2 was utilized for the detection of photoirradiation-induced 1O2 and endogenous 1O2 in living cells. The changes in the 1O2 level in zebrafish were also tracked by fluorescence imaging. In addition, the production of 1O2 in crop leaves under a light source of different wavelengths was studied. The results demonstrated more 1O2 were produced under a light source of 365 nm. Furthermore, to achieve on-site quantitative detection, a mobile fluorescence analysis device has been made. Probe SX-2 and mobile fluorescence analysis device were capable of on-site quantitative detecting of 1O2 in crops. The method developed herein will be convenient for the on-site quantitative measurement of 1O2 in distinct crops.

Triphenylphosphonium-functionalized dimeric BODIPY-based nanoparticles for mitochondria-targeting photodynamic therapy.

The dimerization of boron dipyrromethene (BODIPY) moieties is an appealing molecular design approach for developing heavy-atom-free triplet photosensitizers (PSs). However, BODIPY dimer-based PSs generally lack target specificity, which limits their clinical use for photodynamic therapy. This study reports the synthesis of two mitochondria-targeting triphenylphosphonium (TPP)-functionalized meso-ß directly linked BODIPY dimers (BTPP and BeTPP). Both BODIPY dimers exhibited solvent-polarity-dependent singlet oxygen (1O2) quantum yields, with maximum values of 0.84 and 0.55 for BTPP and BeTPP, respectively, in tetrahydrofuran. The compact orthogonal geometry of the BODIPY dimers facilitated the generation of triplet excited states via photoinduced charge separation (CS) and subsequent spin-orbit charge-transfer intersystem crossing (SOCT-ISC) processes and their rates were dependent on the energetic configuration between the frontier molecular orbitals of the two BODIPY subunits. The as-synthesized compounds were amphiphilic and hence formed stable nanoparticles (∼36 nm in diameter) in aqueous solutions, with a zeta potential of ∼33 mV beneficial for mitochondrial targeting. In vitro experiments with MCF-7 and HeLa cancer cells indicated the effective localization of BTPP and BeTPP within cancer-cell mitochondria. Under light irradiation, BTPP and BeTPP exhibited robust photo-induced therapeutic effects in both cell lines, with half-maximal inhibitory concentration (IC50) values of ∼30 and ∼55 nM, respectively.

PEGylated chitosan-coated nanophotosensitizers for effective cancer treatment by photothermal-photodynamic therapy combined with glutathione depletion.

The combination of photothermal therapy (PTT) and photodynamic therapy (PDT) has emerged as a promising strategy for cancer treatment. However, the poor photostability and photothermal conversion efficiency (PCE) of organic small-molecule photosensitizers, and the intracellular glutathione (GSH)-mediated singlet oxygen scavenging largely decline the antitumor efficacy of PTT and PDT. Herein, a versatile nanophotosensitizer (NPS) system is developed by ingenious incorporation of indocyanine green (ICG) into the PEGylated chitosan (PEG-CS)-coated polydopamine (PDA) nanoparticles via multiple π-π stacking, hydrophobic and electrostatic interactions. The PEG-CS-covered NPS showed prominent colloidal and photothermal stability as well as high PCE (ca 62.8 %). Meanwhile, the Michael addition between NPS and GSH can consume GSH, thus reducing the GSH-induced singlet oxygen scavenging. After being internalized by CT26 cells, the NPS under near-infrared laser irradiation produced massive singlet oxygen with the aid of thermo-enhanced intracellular GSH depletion to elicit mitochondrial damage and lipid peroxide formation, thus leading to ferroptosis and apoptosis. Importantly, the combined PTT and PDT delivered by NPS effectively inhibited CT26 tumor growth in vivo by light-activated intense hyperthermia and redox homeostasis disturbance. Overall, this work presents a new tactic of boosting antitumor potency of ICG-mediated phototherapy by PEG-CS-covered NPS.

Trinuclear ruthenium(II) polypyridyl complexes: Evaluation as photosensitizers for enhanced cervical cancer treatment.

Trinuclear ruthenium(II) polypyridyl complexes anchored to benzimidazole-triazine / trisamine scaffolds were investigated as photosensitizers for photodynamic therapy. The trinuclear complexes were noted to produce a significant amount of singlet oxygen in both DMF and aqueous media, are photostable and show appreciable emission quantum yields (ɸem). In our experimental setting, despite the moderate phototoxic activity in the HeLa cervical cancer cell line, the phototoxic indices (PI) of the trinuclear complexes are superior relative to the PIs of a clinically approved photosensitizer, Photofrin®, and the pro-drug 5-aminolevulinic acid (PI: >7 relative to PI: >1 and PI: 4.4 for 5-aminolevulinic acid and Photofrin®, respectively). Furthermore, the ruthenium complexes were noted to show appreciable long-term cytotoxicity upon light irradiation in HeLa cells in a concentration-dependent manner. Consequently, this long-term activity of the ruthenium(II) polypyridyl complexes embodies their ability to reduce the probability of the recurrence of cervical cancer. Taken together, this presents a strong motivation for the development of polymetallic complexes as anticancer agents.

Anticancer photodynamic activities of triphenylphosphine-labelled phthalocyanines and their bovine serum albumin-gold nanoparticles- complexes on melanoma A375 cell lines in vitro.

This work reports on the synthesis of triphenylphosphine-labelled cationic phthalocyanines (Pc) complexed with bovine serum albumin (BSA) and gold nanoparticles (Au NPs). This nano-complex (Pc-BSA-Au) is studied for its photodynamic therapy (PDT) activity compared to the non-complexed Pc counterpart. The photochemical properties and in vitro PDT efficacies of the Pc and the nano-complex were determined and are compared herein. The singlet oxygen (1O2) yields of the Pcs were determined and are reported in DMF. A singlet oxygen quantum yield of 0.47 was obtained for the Pcs. The PDT efficacies of the complexes were thereafter determined using malignant melanoma A375 cancer cell line in vitro. An increase in the cell toxicity was observed for cells treated with Pc-BSA-Au compared to those treated with the Pc alone. The cell survival percentages were 23.1% for cells treated with Pc-BSA-Au and 48.7% for those treated with Pc alone under PDT treatments.

Correlation of in vitro cell viability and cumulative singlet oxygen luminescence from protoporphyrin IX in mitochondria and plasma membrane.

SIGNIFICANCE: Photodynamic therapy (PDT) can be targeted toward different subcellular localizations, and it is proposed that different subcellular targets vary in their sensitivity to photobiological damage. Since singlet oxygen (1O2) has a very short lifetime with a limited diffusion length in cellular environments, measurement of cumulative 1O2 luminescence is the most direct approach to compare the PDT sensitivity of mitochondria and plasma membrane. APPROACH: PDT-generated near-infrared 1O2 luminescence at 1270 nm was measured together with cell viability for 5-aminolevulinic acid (ALA)-induced protoporphyrin IX (PpIX) and exogenous PpIX, at different incubation times. Confocal fluorescence microscopy indicated that ALA-induced PpIX (2 h) localized in the mitochondria, whereas exogenous PpIX (1 h) mainly localized to the plasma membrane. Cell viability was determined at several time points during PDT treatments using colony-forming assays, and the surviving fraction correlated well with cumulative 1O2 luminescence counts from PpIX in mitochondria and plasmas membrane, respectively. RESULTS: The mitochondria are more sensitive than the plasma membrane by a factor of 1.7. CONCLUSIONS: Direct 1O2 luminescence dosimetry's potential value for comparing the PDT sensitivity of different subcellular organelles was demonstrated. This could be useful for developing subcellular targeted novel photosensitizers to enhance PDT efficiency.

Novel photocatalytic carbon dots: efficiently inhibiting amyloid aggregation and quickly disaggregating amyloid aggregates.

Amyloid aggregation is implicated in the pathogenesis of various neurodegenerative disorders, such as Alzheimer's disease (AD) and Parkinson's disease (PD). It is critical to develop high-performance drugs to combat amyloid-related diseases. Most identified nanomaterials exhibit limited biocompatibility and therapeutic efficacy. In this work, we used a solvent-free carbonization process to prepare new photo-responsive carbon nanodots (CNDs). The surface of the CNDs is densely packed with chemical groups. CNDs with large, conjugated domains can interact with proteins through π-π stacking and hydrophobic interactions. Furthermore, CNDs possess the ability to generate singlet oxygen species (1O2) and can be used to oxidize amyloid. The hydrophobic interaction and photo-oxidation can both influence amyloid aggregation and disaggregation. Thioflavin T (ThT) fluorescence analysis and circular dichroism (CD) spectroscopy indicate that CNDs can block the transition of amyloid from an α-helix structure to a ß-sheet structure. CNDs demonstrate efficacy in alleviating cytotoxicity induced by Aß42 and exhibit promising blood-brain barrier (BBB) permeability. CNDs have small size, low biotoxicity, good fluorescence and photocatalytic properties, and provide new ideas for the diagnosis and treatment of amyloid-related diseases.

Photodynamic Therapy with Targeted Release of Boron-Dipyrromethene Dye from Cobalt(III) Prodrugs in Red Light.

Boron-dipyrromethene (BODIPY) dyes are promising photosensitizers for cellular imaging and photodynamic therapy (PDT) owing to their excellent photophysical properties and the synthetically tunable core. Metalation provides a convenient way to overcome the drawbacks arising from their low aqueous solubility. New photo-/redox-responsive Co(III) prodrug chaperones are developed as anticancer PDT agents for efficient cellular delivery of red-light-active BODIPY dyes. The photobiological activity of heteroleptic Co(III) complexes derived from tris(2-pyridylmethyl)amine (TPA) and acetylacetone-conjugated PEGylated distyryl BODIPY (HL1) or its dibromo analogue (HL2), [CoIII(TPA)(L1/L2)](ClO4)2 (1 and 2), are investigated. The Co(III)/Co(II) redox potential is tuned using the Co(III)-TPA scaffold. Complex 1 displays the in vitro release of BODIPY on red light irradiation. Complex 2, having good singlet oxygen quantum yield (ΦΔ âˆ¼ 0.28 in DMSO), demonstrates submicromolar photocytotoxicity to HeLa cancer cells (IC50 ≈ 0.23 µM) while being less toxic to HPL1D normal cells in red light. Cellular imaging using the emissive complex 1 shows mitochondrial localization and significant penetration into the HeLa tumor spheroids. Complex 2 shows supercoiled DNA photocleavage activity and apoptotic cell death through phototriggered generation of reactive oxygen species. The Co(III)-BODIPY prodrug conjugates exemplify new type of phototherapeutic agents with better efficacy than the organic dyes alone in the phototherapeutic window.

Investigation of the Nanoparticulation Method and Cell-Killing Effect following the Mitochondrial Delivery of Hydrophobic Porphyrin-Based Photosensitizers.

Photodynamic therapy is expected to be a less invasive treatment, and strategies for targeting mitochondria, the main sources of singlet oxygen, are attracting attention to increase the efficacy of photodynamic therapy and reduce its side effects. To date, we have succeeded in encapsulating the photosensitizer rTPA into MITO-Porter (MP), a mitochondria-targeted Drug Delivery System (DDS), aimed at mitochondrial delivery of the photosensitizer while maintaining its activity. In this study, we report the results of our studies to alleviate rTPA aggregation in an effort to improve drug efficacy and assess the usefulness of modifying the rTPA side chain to improve the mitochondrial retention of MITO-Porter, which exhibits high therapeutic efficacy. Conventional rTPA with anionic side chains and two rTPA analogs with side chains that were converted to neutral or cationic side chains were encapsulated into MITO-Porter. Low-MP (MITO-Porter with Low Drug/Lipid) exhibited high drug efficacy for all three types of rTPA, and in Low-MP, charged rTPA-encapsulated MP exhibited high drug efficacy. The cellular uptake and mitochondrial translocation capacities were similar for all particles, suggesting that differences in aggregation rates during the incorporation of rTPA into MITO-Porter resulted in differences in drug efficacy.

The photophysical, photobiological, and DNA/HSA-binding properties of corroles containing carbazole and phenothiazine moieties.

This study characterized four corrole derivatives, namely Cbz-Cor, MetCbz-Cor, PTz-Cor, and PTzEt-Cor, examining their photophysical, electrochemical, photobiological, and biomolecule-binding properties. Experimental photophysical data of absorption and emission elements correlated with a theoretical analysis obtained through time-dependent density functional theory (TD-DFT). As for the photophysical properties, we observed lower fluorescence quantum yields and discernible differences between the excited and ground states, as indicated by Stokes shift values. Natural Transition Orbit (NTO) plots presented high occupied molecular orbital - low unoccupied molecular orbital (HOMO-LUMO) densities around the tetrapyrrolic macrocycle in all examples. Our findings demonstrate that corroles maintain stability in solution and offer photostability (<20 %), predominantly in DMSO(5 %)/Tris-HCl (pH 7.4) buffer solution. Furthermore, the singlet oxygen (1O2) quantum yield and log POW values underscore their potential application in photoinactivation approaches, as these corroles serve as effective ROS generators with more lipophilic features. We also evaluated their biomolecular binding capacity towards salmon sperm DNA and human serum albumin using spectroscopic techniques and molecular docking analysis for sustenance. Concerning biomolecule interaction profiles, the corrole derivatives showed a propensity for interacting in the minor grooves of the double helix DNA due to secondary forces, which were more pronounced in site III of the human serum protein.

EPR Spin-Trapping for Monitoring Temporal Dynamics of Singlet Oxygen during Photoprotection in Photosynthesis.

A central goal of photoprotective energy dissipation processes is the regulation of singlet oxygen (1O2*) and reactive oxygen species in the photosynthetic apparatus. Despite the involvement of 1O2* in photodamage and cell signaling, few studies directly correlate 1O2* formation to nonphotochemical quenching (NPQ) or lack thereof. Here, we combine spin-trapping electron paramagnetic resonance (EPR) and time-resolved fluorescence spectroscopies to track in real time the involvement of 1O2* during photoprotection in plant thylakoid membranes. The EPR spin-trapping method for detection of 1O2* was first optimized for photosensitization in dye-based chemical systems and then used to establish methods for monitoring the temporal dynamics of 1O2* in chlorophyll-containing photosynthetic membranes. We find that the apparent 1O2* concentration in membranes changes throughout a 1 h period of continuous illumination. During an initial response to high light intensity, the concentration of 1O2* decreased in parallel with a decrease in the chlorophyll fluorescence lifetime via NPQ. Treatment of membranes with nigericin, an uncoupler of the transmembrane proton gradient, delayed the activation of NPQ and the associated quenching of 1O2* during high light. Upon saturation of NPQ, the concentration of 1O2* increased in both untreated and nigericin-treated membranes, reflecting the utility of excess energy dissipation in mitigating photooxidative stress in the short term (i.e., the initial ∼10 min of high light).

Orchestrating apoptosis and ferroptosis through enhanced sonodynamic therapy using amorphous UIO-66-CoOx.

The development of efficient and multifunctional sonosensitizers is crucial for enhancing the efficacy of sonodynamic therapy (SDT). Herein, we have successfully constructed a CoOx-loaded amorphous metal-organic framework (MOF) UIO-66 (A-UIO-66-CoOx) sonosensitizer with excellent catalase (CAT)- and glutathione-oxidase (GSH-OXD)-like activities. The A-UIO-66-CoOx exhibits a 2.6-fold increase in singlet oxygen (1O2) generation under ultrasound (US) exposure compared to crystalline UIO-66 sonosensitizer, which is attributed to its superior charge transfer efficiency and consistent oxygen (O2) supply. Additionally, the A-UIO-66-CoOx composite reduces the expression of glutathione peroxidase (GPX4) by depleting glutathione (GSH) through Co3+ and Co2+ valence changes. The high levels of highly cytotoxic 1O2 and deactivation of GPX4 can lead to lethal lipid peroxidation, resulting in concurrent apoptosis and ferroptosis. Both in vitro and vivo tumor models comprehensively confirmed the enhanced SDT antitumor effect using A-UIO-66-CoOx sonosensitizer. Overall, this study emphasizes the possibility of utilizing amorphization engineering to improve the effectiveness of MOFs-based sonosensitizers for combined cancer therapies.