Reaction Of Singlet Oxygen Research Articles

Enhancing the Theranostic Performance of Organic Photosensitizers with Aggregation-Induced Emission

ConspectusPhotodynamic therapy has been actively explored recently to combat various physiological disorders and diseases, including bacterial infections, inflammation, and cancer. As a noninvasive modality with high spatiotemporal selectivity, photodynamic therapy leverages photosensitizers, light, and reactive oxygen species to induce cytotoxicity and cell death. Specifically, upon light irradiation, photosensitizers harvest the incident light energy to generate highly reactive singlet oxygen species through photochemical reactions to disrupt the integrity of certain cellular components of the target cells. The extent to which the target cells can be damaged depends largely on the characteristics of photosensitizers. As such, the selection and design of photosensitizers are essential to ensuring effective and safe photodynamic therapy. Unfortunately, organic photosensitizers typically used in photodynamic therapy tend to suffer from a considerable reduction in singlet oxygen production when these molecules aggregate, significantly limiting the efficacy of photodynamic therapy. To address this issue, a different class of organic photosensitizers with aggregation-induced emission (AIE) characteristics, which exhibit bright fluorescence and enhanced photosensitizing activity only when they exist in an aggregated state, has been increasingly formulated for disease theranostic applications.In general, AIE photosensitizers can be designed on the basis of several major strategies. For example, AIE photosensitizers with efficient singlet oxygen generation can be formulated by minimizing their singlet–triplet energy gap via tuning the distribution of the highest occupied molecular orbital and the lowest unoccupied molecular orbital of the molecules. Simultaneously, through donor–acceptor engineering, AIE photosensitizers can be designed to have increased molar absorptivity, red-shifted absorption and emission wavelengths, and improved body clearance. In situ click synthesis can also be adopted to formulate AIE photosensitizers with suppressed dark toxicity. These design approaches can be optimized using artificial intelligence or machine learning, leading to higher throughput discovery of AIE photosensitizers with exceptional performance. Intriguingly, the therapeutic impact of AIE photosensitizers can be further strengthened by modulating their performance-related features, notably targeting specificity, target accumulation and retention, tissue penetration depth, stimulus responsivity, and theranostic modality. By precisely controlling these elements, multifunctional and biocompatible AIE photosensitizers with superior performance can be realized.Herein, we describe our recent efforts in designing and formulating organic AIE photosensitizers with improved theranostic efficacy and safety to treat bacterial infections and cancer. We first introduce different principles that can be adopted to guide the design of AIE photosensitizers. We then present various ways to strengthen the different performance-associated features of AIE photosensitizers. These include enhancement of the targeting specificity, target accumulation, and retention of AIE photosensitizers through metabolic engineering, enhancement of the tissue penetration depth of AIE photosensitizers through chemiexcitation and ionizing irradiation, enhancement of AIE photosensitization by suppressing intrinsic oxidative resistance, enhancement of the responsivity of AIE photosensitizers through stimulus-responsive building blocks, and enhancement of the overall theranostic performance of AIE photosensitizers through combinatorial therapy. Finally, we identify current challenges, potential opportunities, and future research directions for this emerging field. Through this Account, we seek to stimulate further interest and active collaborations in the development, theranostic applications, and clinical translation of organic AIE photosensitizers to treat different diseases.

Probing the Transition State-to-Intermediate Continuum: Mechanistic Distinction between a Dry versus Wet Perepoxide in the Singlet Oxygen "Ene" Reaction at the Air-Water Interface.

A mechanistic study is reported for the reactions of singlet oxygen (1O2) with alkene surfactants of tunable properties. Singlet oxygen was generated either top-down (photochemically) by delivery as a gas to an air-water interface or bottom-up (chemically) by transport to the air-water interface as a solvated species. In both cases, reactions were carried out in the presence of 7-carbon (7C), 9-carbon (9C), or 11-carbon (11C) prenylsurfactants [(CH3)2C═CH(CH2)nSO3- Na+ (n = 4, 6, 8)]. Higher "ene" hydroperoxide regioselectivities (secondary ROOH 2 to tertiary ROOH 3) were reached in delivering 1O2 top-down through air as compared to bottom-up via aqueous solution. In the photochemical reaction, ratios of 2:3 increased from 2.5:1 for 7C, to 2.8:1 for 9C, and to 3.2:1 for 11C. In contrast, in the bubbling system that generated 1O2 chemically, the selectivity was all but lost, ranging only from 1.3:1 to 1:1. The phase-dependent regioselectivities appear to be correlated with the "ene" reaction with photochemically generated, drier 1O2 at the air-water interface vs those with wetter 1O2 from the bubbling reactor. Density functional theory-calculated reaction potential energy surfaces (PESs) were used to help rationalize the reaction phase dependence. The reactions in the gas phase are mediated by perepoxide transition states with 32-41 kJ/mol binding energy for C═C(π)···1O2. The perepoxide species, however, evolve to well-defined stationary structures in the aqueous phase, with covalent C-O bonds and 85-88 kJ/mol binding energy. The combined experimental and computational evidence points to a unique mechanism for 1O2 "ene" tunability in a perepoxide continuum from a transition state to an intermediate.

Characterization and Quantification of Tryptophan- and Tyrosine-derived Hydroperoxides.

The reaction of singlet oxygen (1 O2 ) with the amino acids tryptophan and tyrosine, either free or inserted in peptides or proteins, gives rise to hydroperoxides. To understand the impact of these hydroperoxides in complex biological systems, methods allowing their characterization and accurate quantification must be available. In this work, hydroperoxides derived from tryptophan and tyrosine and from peptides containing these amino acids were synthesized by photooxidation, and characterized by high-resolution mass spectrometry. In addition, experiments were carried out to compare two colorimetric methods commonly used for quantification of peroxides, namely the iodometric and the ferric-xylenol orange assays. For the tryptophan hydroperoxide, the quantifications obtained by colorimetric methods were then compared to that obtained by NMR. The results showed that for the ferric-xylenol orange method, the stoichiometry between peroxide and Fe3+ ions varies considerably. On the other hand, for the iodometric assay, the stoichiometry peroxide:I3 - ions is always 1:1. However, the kinetics of the reactions of peroxides with I- vary, and the assay must be performed in anaerobic conditions. Thus, the iodometric method is more appropriate for precise quantification of a given peroxide. The characterization and accurate quantification of biological peroxides iskey to understand the mechanisms involved in redox processes.

Highly stable tetradentate phosphonate-based green fluorescent Cu-MOF for anticancer therapy and antibacterial activity

Metal-organic frameworks (MOFs) have attracted huge attention in drug delivery, cellular imaging, and anticancer therapy due to their exceptionally high surface area, large internal void space, and the possibility of building the frameworks with fluorescent ligands. Here we demonstrate the synthesis of a highly stable tetradentate phosphonate ligand-based green fluorescent bioactive Cu-MOF (H8L-Cu-Crystal) in a water medium. This new MOF displayed monoclinic crystal structure [empirical formula: C13H13CuO7P2, H2O; space group C2/c; a = 27.9337 Å, b = 12.094 Å, c = 10.560 Å; α = γ = 90°, β = 99.607° unit cell volume = 3517.3 Å3; CCDC No. 1922965] having theoretical surface area of 164 m2/g with optimized energy 1475.9634 a.u. and HOMO-LUMO gap at 3.6 eV. Upon visible light irradiation, Cu-MOF generates highly reactive singlet oxygen (1O2) species, which exhibits a superior photocytotoxic effect against human lung epithelial cancer cells (A549) with respective IC50 value = 15.96 μg/mL and nominal dark toxicity of IC50 = 225 μg/mL. Notably, the tetradentate phosphonate moiety in the MOF crystal acts as a fluorophore, which is beneficial for cancer cell imaging. Due to active surface area, reactive oxygen species (ROS) generation, porosity, and Cu-ion metal center, the MOF exerts excellent antibacterial efficacy against both Gram-positive and Gram-negative microorganisms. Minimum inhibitory concentrations (MICs) are recorded at 300 μg/mL and 350 μg/mL for Escherichia coli (ATCC8739) and Staphylococcus aureus (ATCC25923), respectively. SEM images reveal dead and deformed bacterial cellular morphologies. What's more, the MOF crystal shows a good binding affinity coefficient value (KBSA = 4.8 × 104 M−1) with bovine serum albumin (BSA) protein interaction. Overall, these results suggest that this Cu-phosphonate MOF is a promising aspirant for anti-cancer photodynamic therapy and bacterial eradication.

Membrane reactors accelerate polymer photosensitizer-based singlet oxygen reactions

Polymer photosensitizers have gained a growing interest as singlet oxygen (1O2) generators. Although they provide a route to sustainable chemistry, their efficiency in bulk reactions is restricted by a limited oxygen supply and a short lifetime. Herein, we report membrane reactors that support a range of organic reactions using 1O2 generated from polymer photosensitizers. The porous nature of the membrane support, a nylon fabric membrane functionalized with poly(fluorenthiophen thiadiazothiophen) (PFOTTzT), allows highly efficient trapping of a thin membrane of reagents that is in close proximity to the 1O2 source. We demonstrate that oxidation reactions are accelerated by 10 – 100 folds, and polymerization reactions are rapidly initiated and accelerated and reach a nearly 2-fold increase in the degree of polymerization. The method is compatible with a range of solvents upon protection of the polymeric photosensitizers with a porous layer of polytetrafluoroethylene (PTFE) fabric that prevents solvent transport but allows 1O2 diffusion through. Summarizing, our membrane reactors are sustainable, low-cost, robust-in-use and overcome current limitations in reactions involving 1O2 from polymer photosensitizers and show strong potential for green industrial use.

Construction of dual active sites on diatomic metal (FeCo−N/C-x) catalysts for enhanced Fenton-like catalysis

High metal loading of single-atom catalysts enables excellent catalytic activity, but possibly causes serious aggregation problem. Herein, a series of diatomic FeCo−N/C-x (x represents metal content) were skillfully designed and applied to improve the catalytic activity for peroxymonosulfate (PMS) activation toward degrading organic micropollutants. The unprecedented dual active sites, referring to Fe(N3)−Co(N3) moiety and FeCo alloy, are constructed on the obtained FeCo−N/C-x, thereby exhibiting significantly greater performance toward degrading aqueous phenol (e.g., 0.316 min−1 for FeCo−N/C-3) via PMS activation, compared with those of traditional single-atom Co−N/C (0.011 min−1) and Fe−N/C (0.018 min−1). Combined experimental and theoretical calculations demonstrate the independent functions of dual active sites, in which Fe(N3)−Co(N3) and FeCo alloy can decrease the energy barrier of O−O bond cleaving resulting in the formation of high-valent FeCoO reactive species and singlet oxygen, respectively. This study opens up a new platform toward constructing dual active sites for enhanced Fenton-like catalytic activity.

Self-Rectifiable and Hypoxia-Assisted Chemo-Photodynamic Nanoinhibitor for Synergistic Cancer Therapy.

Photodynamic therapy (PDT) can eradicate cancer cells under light irradiation, mainly because of reactive singlet oxygen (1O2) being transformed from intratumoral oxygen. Nonetheless, the consumption of oxygen during PDT results in serious hypoxic conditions and an elevated hypoxia-inducing factor-1α (HIF-1α) level that hamper further photodynamic efficacy and induce tumor metastasis. To address this problem, we developed hypoxia-assisted NP-co-encapsulating Ce6 (photosensitizer) and YC-1 (HIF-1α inhibitor) as a self-rectifiable nanoinhibitor for synergistic antitumor treatment. PDT-aggravated intracellular hypoxic stress facilitated NP dissociation to release the drug (YC-1), which achieved tumor killing and HIF-1α inhibition to further enhance the therapeutic effect of PDT and prevent tumor metastasis. Besides, in vivo studies revealed that the HC/PI@YC-1 NPs afforded synergistic anticancer efficacy with minimal toxicity. Therefore, this study provides a prospective approach against PDT drawbacks and combination cancer therapy.

Enhanced peroxymonosulfate activation by Cu-doped LaFeO3 with rich oxygen vacancies: Compound-specific mechanisms

The degradation reaction mechanisms of organic pollutants by peroxymonosulfate (PMS) activation processes remain controversial. In this study, Cu-doped LaFeO3 samples were prepared and used as heterogeneous catalysts of PMS for the degradation of pharmaceuticals. Compared to LaFeO3 (LFO), the increased catalytic activity of LaFe1-xCuxO3 (LFCO) samples was observed, among which LFCO-7.5 exhibited the best performance. The enhanced catalytic activity of LFCO-7.5 was attributable to the generation of abundant oxygen vacancies. Hydroxyl radicals, sulfate radicals, superoxide and singlet oxygen were detected in the LFCO-7.5/PMS system. However, selective effects of radical scavengers on the degradation of different pharmaceuticals and selective reactivity of singlet oxygen toward different pharmaceuticals indicate the existence of compound-specific degradation mechanisms in the LFCO-7.5/PMS system. Furthermore, possible degradation pathways of SDZ and the toxicity evolution were investigated during sulfadiazine (SDZ) degradation. This study further enhances our knowledge on the degradation reaction mechanisms of organic pollutants in PMS activation processes.

Reactivity of Singlet Oxygen with DNA, an Update.

The reactivity of singlet oxygen with DNA constituents and in particular with the guanine base has been studied during more than four decades but the exact mechanisms by which such a reactive oxygen species reacts with DNA is still a matter of debate. In this review article, a summary of the data that were obtained from several laboratories and using complementary experimental and theoretical approaches are presented. Reaction mechanisms of 1 O2 with guanine and its oxidation product 8-oxo7,8-dihydroguanine are presented both at the nucleoside level and when the base is inserted into DNA since significant differences have been observed. Efforts have been made to propose tentative mechanisms to explain the conflicting results that were sometimes reported and hypotheses have been put forward to tentatively explain still contradictory observations.

Photoinactivation of bacteriophage MS2, Tulane virus and Vibrio parahaemolyticus in oysters by microencapsulated rose bengal

Abstract Bivalve molluscan shellfish such as oysters are important vectors for the transmission of foodborne pathogens including both viruses and bacteria. Photoinactivation provides a cold-sterilization option against the contamination as excited photosensitizers could transfer electronic energy to oxygen molecules producing reactive oxygen species such as singlet oxygen, leading to oxidative damage and death of the pathogens. However, the efficacy of photoinactivation is very often compromised by the presence of food matrix due to the nonselective reactions of short-lived singlet oxygen with organic matter other than the target pathogens. In order to address this issue, we encapsulated a food-grade photosensitizer rose bengal (RB) in alginate microbeads. An extra coating of chitosan effectively prevented the release of RB from the microbeads in seawater, and more importantly, enhanced the selectivity of the photoinactivation via the electrostatic interactions between cationic chitosan and anionic charge of the virus particles (bacteriophage MS2 and Tulane virus) and the Gram-negative bacteria Vibrio parahaemolyticus (V. parahaemolyticus). The treatment of oysters with microencapsulated RB resulted in significantly higher reductions of MS2 phage, Tulane virus and V. parahaemolyticus than free RB and non-RB carrying microbeads (P<0.05) tested with both in vitro and in vivo experimental set-ups. This study demonstrated a new strategy in delivering comprehensively formulated biochemical sanitizers in bivalve shellfish through their natural filter-feeding activity and thereby enhancing the mitigation efficiency of foodborne pathogen contamination.

Electronic couplings for singlet oxygen photosensitization and its molecular orbital overlap description

The reaction of triplet fusion, also named triplet-triplet annihilation, has attracted a lot of research interests because of its wide applications in photocatalytic, solar cells, and bioimaging. As for the singlet oxygen photosensitization, the reactive singlet oxygen species are generated through the energy transfers from photosensitizer (PS) to ground triplet oxygen molecule. In this work, we computed the electronic coupling for singlet oxygen photosensitization using the nonadiabatic coupling from the quantum chemical calculation. Then we utilized the molecular orbital (MO) overlaps to approximate it, where the MOs were computed from isolated single molecules. As demonstrated with quantitative results, this approach well describes the distribution of the coupling strength as the function of the intermolecular distance between the sensitizer and O2, providing us a simple but effective way to predict the coupling of triplet fusion reactions.

Direct and Indirect Chemiluminescence: Reactions, Mechanisms and Challenges.

Emission of light by matter can occur through a variety of mechanisms. When it results from an electronically excited state of a species produced by a chemical reaction, it is called chemiluminescence (CL). The phenomenon can take place both in natural and artificial chemical systems and it has been utilized in a variety of applications. In this review, we aim to revisit some of the latest CL applications based on direct and indirect production modes. The characteristics of the chemical reactions and the underpinning CL mechanisms are thoroughly discussed in view of studies from the very recent bibliography. Different methodologies aiming at higher CL efficiencies are summarized and presented in detail, including CL type and scaffolds used in each study. The CL role in the development of efficient therapeutic platforms is also discussed in relation to the Reactive Oxygen Species (ROS) and singlet oxygen (1O2) produced, as final products. Moreover, recent research results from our team are included regarding the behavior of commonly used photosensitizers upon chemical activation under CL conditions. The CL prospects in imaging, biomimetic organic and radical chemistry, and therapeutics are critically presented in respect to the persisting challenges and limitations of the existing strategies to date.

Merging of a Perylene Moiety Enables a RuII Photosensitizer with Long-Lived Excited States and the Efficient Production of Singlet Oxygen.

Multichromophoric systems based on a RuII polypyridine moiety containing an additional organic chromophore are of increasing interest with respect to different light‐driven applications. Here, we present the synthesis and detailed characterization of a novel RuII photosensitizer, namely [(tbbpy)2Ru((2‐(perylen‐3‐yl)‐1H‐imidazo[4,5‐f][1,10]‐phenanthrolline))](PF6)2 RuipPer, that includes a merged perylene dye in the back of the ip ligand. This complex features two emissive excited states as well as a long‐lived (8 μs) dark state in acetonitrile solution. Compared to prototype [(bpy)3Ru]2+‐like complexes, a strongly altered absorption (ϵ=50.3×103 M−1 cm−1 at 467 nm) and emission behavior caused by the introduction of the perylene unit is found. A combination of spectro‐electrochemistry and time‐resolved spectroscopy was used to elucidate the nature of the excited states. Finally, this photosensitizer was successfully used for the efficient formation of reactive singlet oxygen.

Synthesis of Some Substituted Furans and Endoperoxides Via Singlet Oxygen Reactions

Cinnamaldehyde was used to condense with substituted acetophenone then with acetone to form substituted 2,4- diene -1- pentanone (1- 4), after two moles of cinnamaldehyde condense with one mole of acetone to form 1, 5- diphenyl nona- 8- tetraene -5 – one (5), for these reactions, sodium hydroxide was used as a catalyst, the resulted compounds reduced by Luche (specific reduction agent use cerium chloride as a catalyst with sodium borohydride to protect double bond) reaction to form 2,4- diene-1- methoxy pentane (6-9) and -5- methoxy nona- 1,3,6,8 – tetraene – 1,9 - diyl dibenzene (10), the resulted dienes compound converted to endoperoxides (11- 15) via singlet oxygen reaction in the present of Rose Bengal as a catalyst with light in chlorinated solvent and finally by appling of Appel reaction condition these compounds converted to furans (16- 20). All mechanisms of the reaction were listed. These compounds were identified by thin layer chromatography TLC, and by their physical properties in addition, the IR spectroscopy and 1HNMR.

Visualising UV-A light-induced damage to plasma membranes of eye lens.

An eye lens is constantly exposed to the solar UV radiation, which is considered the most important external source of age-related changes to eye lens constituents. The accumulation of modifications of proteins and lipids with age can eventually lead to the development of progressive lens opacifications, such as cataracts. Though the impact of solar UV radiation on the structure and function of proteins is actively studied, little is known about the effect of photodamage on plasma membranes of lens cells. In this work we exploit Fluorescence Lifetime Imaging Microscopy (FLIM), together with viscosity-sensitive fluorophores termed molecular rotors, to study the changes in viscosity of plasma membranes of porcine eye lens resulting from two different types of photodamage: Type I (electron transfer) and Type II (singlet oxygen) reactions. We demonstrate that these two types of photodamage result in clearly distinct changes in viscosity - a decrease in the case of Type I damage and an increase in the case of Type II processes. Finally, to simulate age-related changes that occur in vivo, we expose an intact eye lens to UV-A light under anaerobic conditions. The observed decrease in viscosity within plasma membranes is consistent with the ability of eye lens constituents to sensitize Type I photodamage under natural irradiation conditions. These changes are likely to alter the transport of metabolites and predispose the whole tissue to the development of pathological processes such as cataracts.

The Reactive Oxygen Species Singlet Oxygen, Hydroxy Radicals, and the Superoxide Radical Anion—Examples of Their Roles in Biology and Medicine

Reactive oxygen species comprise oxygen-based free radicals and non-radical species such as peroxynitrite and electronically excited (singlet) oxygen. These reactive species often have short lifetimes, and much of our understanding of their formation and reactivity in biological and especially medical environments has come from complimentary fast reaction methods involving pulsed lasers and high-energy radiation techniques. These and related methods, such as EPR, are discussed with particular reference to singlet oxygen, hydroxy radicals, the superoxide radical anion, and their roles in medical aspects, such as cancer, vision and skin disorders, and especially pro- and anti-oxidative processes.

Iron-Based Dual Active Site-Mediated Peroxymonosulfate Activation for the Degradation of Emerging Organic Pollutants.

It is still a challenge to synthesize highly efficient and stable catalysts for the Fenton-like reaction. In this study, we constructed an integrated catalyst with highly dispersed iron-based dual active sites, in which Fe2N and single-atom Fe (SA-Fe) were embedded into nitrogen- and oxygen-co-doped graphitic carbon (Fe-N-O-GC-350). Extended X-ray absorption fine structure (EXAFS) confirmed the coordination structure of iron, and line combination fitting (LCF) demonstrated the coexistence of Fe2N and SA-Fe with percentages of 75 and 25%, respectively. Iron-based dual active sites endowed Fe-N-O-GC-350 with superior catalytic activity to activate peroxymonosulfate (PMS) as evidenced by the fast degradation rate of sulfamethoxazole (SMX) (0.24 min-1) in the presence of 0.4 mM PMS and 0.1 g/L Fe-N-O-GC-350. Unlike the reported singlet oxygen and high-valent iron oxo-mediated degradation induced by the SA-Fe catalyst, both surface-bound reactive species and singlet oxygen contributed to SMX degradation, while surface-bound reactive species dominated. Density functional theory (DFT) simulation indicated that Fe2N and SA-Fe enhanced the adsorption of PMS, which played a key role in PMS activation. The Fe-N-O-GC-350/PMS system had resistance to the interference of common inorganic anions and high oxidation capacity to recalcitrant organic contaminants. This study elucidated the important role of Fe2N in PMS activation and provide a clue to design rationally catalysts with iron-based dual active sites to activate PMS for the degradation of emerging organic pollutants.

Suppressing Singlet Oxygen Formation during the Charge Process of Li-O2 Batteries with a Co3O4 Solid Catalyst Revealed by Operando Electron Paramagnetic Resonance.

Aprotic lithium-oxygen (Li-O2) batteries promise high energy, but the cycle life has been plagued by two major obstacles, the insulating products and highly reactive singlet oxygen (1O2), which cause higher overpotential and parasitic reactions, respectively. A solid-state catalyst is known to reduce overpotential; however, it is unclear whether it affects 1O2 generation. Herein, Co3O4 was employed as the representative catalyst in Li-O2 batteries, and 1O2 generation was investigated by ex-situ and operando electron paramagnetic resonance (EPR) spectroscopy. By comparing a carbon nanotube (CNT) cathode with a Co3O4/CNT cathode, we find that 1O2 generation in the charge process can be suppressed by the Co3O4 catalyst. After carefully studying the discharge products on the two electrodes and the corresponding decomposition processes, we conclude that a LiO2-like species is responsible for the 1O2 generation during the early charge stage. The Co3O4 catalyst reduces the amount of LiO2-like species in discharge products, and thus the 1O2 formation is suppressed.

Local DNA microviscosity converts ruthenium polypyridyl complexes to ultrasensitive photosensitizers

In this manuscript, we have reported how DNA binding of ruthenium polypyridyl complexes (RPCs) make them more efficient photosensitizer. The DNA binding of RPCs results in a significant enhancement of their emission intensity and excited-state lifetime. As a result, upon visible-light irradiation, these complexes generate reactive singlet oxygen, which causes selective DNA damage and kills cancer cells. This investigation also demonstrates the effect of light-driven RPCs on bacterial growth arrest through DNA nicking and differential localization in cancer and non-cancer cells. The local DNA microviscosity suppresses the non-radiative pathways which causes a large enhancement in the emission intensity and the excited state lifetime. The visible-light-triggered singlet-oxygen efficiently produces nick in DNA and inhibits bacterial growth. RPCs also localize inside the cancer cell nucleus and in the vicinity of the nuclear membrane of non-cancerous cells, confirmed by live-cell confocal microscopy. The results provide a facile platform for the novel antibiotic intended discovery combined with cancer therapy.

Graphene Oxide and Graphene Quantum Dots as Delivery Systems of Cationic Porphyrins: Photo-Antiproliferative Activity Evaluation towards T24 Human Bladder Cancer Cells.

The development of new photodynamic therapy (PDT) agents designed for bladder cancer (BC) treatments is of utmost importance to prevent its recurrence and progression towards more invasive forms. Here, three different porphyrinic photosensitizers (PS) (TMPyP, Zn-TMPyP, and P1-C5) were non-covalently loaded onto graphene oxide (GO) or graphene quantum dots (GQDs) in a one-step process. The cytotoxic effects of the free PS and of the corresponding hybrids were compared upon blue (BL) and red-light (RL) exposure on T24 human BC cells. In addition, intracellular reactive oxygen species (ROS) and singlet oxygen generation were measured. TMPyP and Zn-TMPyP showed higher efficiency under BL (IC50: 0.42 and 0.22 μm, respectively), while P1-C5 was more active under RL (IC50: 0.14 μm). In general, these PS could induce apoptotic cell death through lysosomes damage. The in vitro photosensitizing activity of the PS was not compromised after their immobilization onto graphene-based nanomaterials, with Zn-TMPyP@GQDs being the most promising hybrid system under RL (IC50: 0.37 μg/mL). Overall, our data confirm that GO and GQDs may represent valid platforms for PS delivery, without altering their performance for PDT on BC cells.