Singlet Oxygen Sensor Green Research Articles

Baicalein induces apoptosis by targeting ribosomes in Candida auris.

The emergence of the "super fungus" Candida auris poses a significant threat to human health, given its multidrug resistance and high mortality rates. Therefore, developing a new antifungal strategy is necessary. Our previous research showed that Baicalein (BE), a key bioactive compound from the dried root of the perennial herb Scutellaria baicalensis Georgi, has strong fungistatic properties against C. auris. Nevertheless, the antifungal activity of BE against C. auris and its mechanism of action requires further investigation. In this study, we explored how BE affects this fungus using various techniques, including scanning electron microscopy (SEM), Annexin V-FITC apoptosis detection, CaspACE FITC-VAD-FMK In Situ Marker, reactive oxygen species (ROS) assay, singlet oxygen sensor green (SOSG) fluorescent probe, enhanced mitochondrial membrane potential (MMP) assay with JC-1, DAPI staining, TUNEL assay and reverse transcription-quantitative polymerase chain reaction (RT-qPCR). Our findings revealed that BE induced several apoptotic features, including phosphatidylserine (PS) externalization, metacaspase activation, nuclear condensation and DNA fragmentation. BE also increased intracellular ROS levels and altered mitochondrial functions. Additionally, transcriptomic analysis and RT-qPCR validation indicated that BE may induce apoptosis in C. auris by affecting ribosome-related pathways, suggesting that ribosomes could be new targets for antifungal agents, in addition to cell walls, membranes, and DNA. This study emphasizes the antifungal activity and mechanism of BE against C. auris, offering a promising treatment strategy for C. auris infection.

Singlet oxygen detection in vivo is hindered by nonspecific SOSG staining

Singlet oxygen is considered an important cell damaging agent due to its propensity to react with organic compounds. This drives the interest in developing methods for determination of 1O2. Simplicity of application and high sensitivity makes fluorescent probes a popular choice for in vivo 1O2 detection. Despite its proclaimed cell-impermeability, the commercially available Singlet Oxygen Sensor Green (SOSG) is widely applied to support assertions of 1O2 involvement in cell and tissue damage. Our investigation, however, demonstrate that different microbial species and cancer cells become fluorescent when exposed to SOSG under conditions which exclude generation of 1O2. Cells, permeabilized with chlorhexidine or by heat exposure under anaerobic conditions, exhibited SOSG fluorescence. Permeabilized cells could be stained with SOSG even 24 h post-permeabilization. Since SOSG is cell impermeable, the main factor that led to fluorescent staining was plasma membrane damage. Spectral analyses of different batches of SOSG revealed that SOSG endoperoxide (SOSG-EP) did not increase even after prolonged storage under the recommended conditions. The commercial preparations of SOSG, however, were not SOSG-EP free, which can produce erroneous results when SOSG staining is used as a proof of singlet oxygen production in vivo.

Assessment of Photoactivated Chlorophyllin Production of Singlet Oxygen and Inactivation of Foodborne Pathogens

Singlet oxygen (1O2) is known to have antibacterial activity; however, production can involve complex processes with expensive chemical precursors and/or significant energy input. Recent studies have confirmed the generation of 1O2 through the activation of photosensitizer molecules (PSs) with visible light in the presence of oxygen. Given the increase in the incidence of foodborne diseases associated with cross-contamination in food-processing industries, which is becoming a major concern, food-safe additives, such as chlorophyllins, have been studied for their ability to act as PSs. The fluorescent probe Singlet Oxygen Sensor Green (SOSG®) was used to estimate 1O2 formation upon the irradiation of traditional PSs (rose bengal (RB), chlorin 6 (ce6)) and novel chlorophyllins, sodium magnesium (NaChl) and sodium copper (NaCuChl), with both simulated-solar and visible light. NaChl gave rise to a similar 1O2 production rate when compared to RB and ce6. Basic mixing was shown to introduce sufficient oxygen to the PS solutions, preventing the limitation of the 1O2 production rate. The NaChl-based inactivation of Gram-positive S. aureus and Gram-negative E. coli was demonstrated with a 5-log reduction with UV–Vis light. The NaChl-based inactivation of Gram-positive S. aureus was accomplished with a 2-log reduction after 105 min of visible-light irradiation and a 3-log reduction following 150 min of exposure from an initial viable bacterial concentration of 106 CFU mL−1. CHS-NaChl-based photosensitization under visible light enhanced Gram-negative E. coli inactivation and provided a strong bacteriostatic effect preventing E. coli proliferation. The difference in the ability of NaChl and CHS-NaChl complexes to inactivate Gram-positive and Gram-negative bacteria was confirmed to result from the cell wall structure, which impacted PS–bacteria attachment and therefore the production of localized singlet oxygen.

Tumor Targeting with Apatinib-loaded Nanoparticles and Sonodynamic Combined Therapy.

This study implies the enhancement of apatinib killing effect in 4T1 tumor cells through constructing drug-loaded nanoparticles apatinib/Ce6@ZIF- 8@Membranes (aCZM) to enhance tumor therapeutic targeting and reduce toxic side following sonodynamic therapy (SDT). apatinib/Ce6@ZIF-8 (aCZ) were synthesized by in situ encapsulation, and aCZM were constructed by encapsulating the nanoparticles with extracted breast cancer 4T1 cell membranes. aCZM were characterized and tested for the stability by electron microscopy, and the membrane proteins on the nanoparticles' surface were assessed using SDS-PAGE gel electrophoresis. The cell viability of 4T1 cells following treatment with aCZM was tested using cell counting kit-8 (CCK-8). The uptake of nanoparticles was detected by laser confocal microscopy and flow cytometry, and the SDT-mediated production of reactive oxygen species (ROS) was verified by singlet oxygen sensor green (SOSG), electron spin resonance (ESR), and DCFH-DA fluorescent probes. The CCK-8 assay and flow cytometry using Calcein/PI were used to assess the antitumoral effect of aCZM nanoparticles under SDT. The biosafety of aCZM was further verified in vitro and in vivo using the hemolysis assay, routine blood test and H&E staining of vital organs in Balb/c mice. aCZM with an average particle size of about 210.26 nm were successfully synthesized. The results of the SDS-PAGE gel electrophoresis experiment showed that aCZM have a band similar to that of pure cell membrane proteins. The CCK-8 assay demonstrated the absence of effects on cell viability at a low concentration range, and the relative cell survival rate reached more than 95%. Laser confocal microscopy and flow cytometry analysis showed that aCZM treated group has the strongest fluorescence and the highest cellular uptake of nanoparticles. SOSG, ESR, and DCFH-DA fluorescent probes all indicated that the aCZM + SDT treated group has the highest ROS production. The CCK-8 assay also showed that when the ultrasound intensity was fixed at 0.5 W/cm2, the relative cell survival rates in the medium concentration group (10 μg/ml) (5.54 ± 1.26%) and the high concentration group (20 μg/ml) (2.14 ± 1.63%) were significantly lower than those in the low concentration group (5 μg/ml) (53.40 ± 4.25%). Moreover, there was a concentration and intensity dependence associated with the cellkilling effect. The mortality rate of the aCZM in the ultrasound group (44.95 ± 3.03%) was significantly higher than that of the non-ultrasound (17.00 ± 2.26%) group and aCZ + SDT group (24.85 ± 3.08%) (P<0.0001). The live and dead cells' staining (Calcein/PI) also supported this result. Finally, in vitro hemolysis test at 4 and 24 hours showed that the hemolysis rate of the highest concentration group was less than 1%. The blood routine, biochemistry, and H&E staining results of major organs in Balb/c mice undergoing nano-treatments showed no obvious functional abnormalities and tissue damage in 30 days. In this study, a multifunctional bionic drug delivery nanoparticles (aCZM) system with good biosafety and compatibility in response to acoustic dynamics was successfully constructed and characterized. This system enhanced apatinib killing effect on tumor cells and reduced toxic side effects under SDT.

Potential of Ruthenium as a photosensitizer in radiation-activated Photodynamic Therapy (radioPDT)

In Photodynamic Therapy (PDT), light is used to activate photosensitizers (PS) to generate reactive oxygen species (ROS) as a cell-killing mechanism. However, PDT's application is limited to the surface and small size tumors because of the inefficiency of light in penetrating larger and deep-seated tumors. We have developed novel nanoparticles (NPs) that can be activated by radiation, a process known as the radiation-activated PDT (radioPDT). In our studies we developed a new variant of pegylated poly-lactic-co-glycolic (PEG-PLGA) encapsulated nanoscintillators (NSC) and ruthenium-based photosensitizer (Ru/rPDT) that exhibits minimal cell toxicity while having significant cell killing effect upon radiation activation. Our data suggest that radioPDT with Ru/rPDT can be a more effective strategy than previous protoporphyrin-based iterations in treating many deep-seated tumors.Introduction and Background: Toxicity and normal tissue damage are limiting factors for the application of radiotherapy (RT) where higher doses of radiation is required to cure deep-seated tumor such as prostate cancer. In Photodynamic Therapy (PDT), photosensitizers (PS) are activated by light to generate reactive oxygen species (ROS) to kill tumor cells. However, the main limitation of the current PDT is the limited tissue penetration of PS-activating light. Thus, PDT cannot be effectively used to treat deep-seated and larger size tumors. RT has higher tissue penetration depth, making the radiation-activated PDT (radioPDT) advantageous in treating deep seated tumors.We aim to develop novel radioPDT nanoparticles (NP) with more efficient anti-cancer therapeutic effect in vitro and in vivo to enhance targeted radiotherapy.Methods: LaF3:Ce3+ nanoscintillators (NSCs) were synthesized in a single step wet chemistry technique. The NSCs along with Ruthenium-based PS (Ru) with matching excitation/emission spectra were successfully encapsulated in PEG-PLGA. UV-Vis spectrometry and inductively coupled plasma mass spectrometry (ICP-MS) were used to confirm the presence of NSCs and Ru, and dynamic light scattering (DLS) and transmission electron microscopy (TEM) were used to determine the size of NP. Singlet oxygen generation was measured by Singlet Oxygen Sensor Green (SOSG) and direct singlet oxygen fluorescence. RadioPDT therapeutic potential was evaluated in PC3 prostate cancer cell under radiation by Alamar Blue cell viability assay.Results: UV-Vis spectrometry and ICP-MS determined the successful PEG-PLGA encapsulation of NSC and Ru. The TEM imaging confirmed the encapsulation NSC inside the nanocarrier PEG-PLGA. TEM and DLS measurements showed the size of radioNP ranged from 90nm to 150nm with polydispersity index of <0.3. Singlet oxygen generation by Ru/rPDT NPs was greater than PPIX based radioPDT (PPIX/rPDT) NPs. Furthermore, the direct measurement of singlet oxygen generation with fluorescence spectroscopy of Ru/rPDT showed preserved singlet oxygen yield and no evidence of quenching. The Ru/rPDT and PPIX/rPDT showed minimal PC3 cell cytotoxicity in dark conditions. The PC3 cell killing efficiency was comparable between Ru/rPDT and PPIX/rPDT either under light or radiation activation.Conclusion: Our in vitro studies show Ru/rPDT significantly increases anti-cancer therapeutic effect of RT, with minimal toxicity. Future studies will refine in vivo NP biodistribution, dosing, and RT dose/fractionation schemes.

New Insights into the Phototoxicity of Anthracene-Based Chromophores: The Chloride Salt Effect†.

Unraveling the causes underlying polycyclic aromatic hydrocarbon phototoxicity is an essential step in understanding the harmful effects of these compounds in nature. Toward this end, we have studied the DNA interactions and photochemistry of N1-(anthracen-9-ylmethyl)ethane-1,2-diaminium dichloride in the presence and absence of NaF, KF, NaCl, KCl, NaBr, KBr, NaI, and KI (350 nm hν, pH 7.0). Exposing pUC19 plasmid to UV light in solutions containing 400 mM KCl formed significantly more direct strand breaks in DNA compared to no-salt control reactions. In contrast, NaCl increased DNA damage moderately, while the sodium(I) and potassium(I) fluoride, bromide, and iodide salts generally inhibited cleavage (I- > Br- > F-). A halide anion-induced heavy-atom effect was indicated by monitoring anthracene photodegradation and by employing the hydroxyl radical (•OH) probe hydroxyphenyl fluorescein (HPF). These studies revealed that among no-salt controls and the eight halide salts, only NaCl and KCl enabled the anthracene to photosensitize the production of high levels of DNA-damaging reactive oxygen species (ROS). Pre-irradiation of N1-(anthracen-9-ylmethyl)ethane-1,2-diaminium dichloride at 350 nm increased the amounts of chloride salt-induced •OH detected by HPF in subsequent anthracene photoactivation experiments. Taking into consideration that •OH and other highly reactive ROS are extremely short-lived, this result suggests that the pre-irradiation step might lead to the formation of oxidized anthracene photoproducts that are exceedingly redox-active. The fluorometric probes HPF and Singlet Oxygen Sensor Green revealed that KCl concentrations ranging from 150 to 400 mM and from 100 to 400 mM, respectively, enhanced N1-(anthracen-9-ylmethyl)ethane-1,2-diaminium dichloride photosensitized •OH and singlet oxygen (1O2) production over no-salt controls. Considering the relatively high levels of Na+, K+, and Cl- ions that exist in the environment and in living organisms, our findings may be relevant to the phototoxic effects exhibited by anthracenes and other polycyclic hydrocarbons in vivo.

Bright photon upconversion in LiYbF4:Tm3+@LiYF4 nanoparticles and their application for singlet oxygen generation and in immunoassay for SARS-CoV-2 nucleoprotein

Photon upconversion is an intensively investigated phenomenon in the materials sciences due to its unique applications, mainly in biomedicine for disease prevention and treatment. This study reports the synthesis and properties of tetragonal LiYbF4:Tm3+@LiYF4 core@shell nanoparticles (NPs) and their applications. The NPs had sizes ranging from 18.5 to 23.7 nm. As a result of the energy transfer between Yb3+ and Tm3+ ions, the synthesized NPs show intense emission in the ultraviolet (UV) range up to 347 nm under 975 nm excitation. The bright emission in the UV range allows for singlet oxygen generation in the presence of hematoporphyrin on the surface of NPs. Our studies show that irradiation with a 975 nm laser of the functionalized NPs allows for the production of amounts of singlet oxygen easily detectable by Singlet Oxygen Sensor Green. The high emission intensity of NPs at 800 nm allowed the application of the synthesized NPs in an upconversion-linked immunosorbent assay (ULISA) for highly sensitive detection of the nucleoprotein from SARS-CoV-2, the causative agent of Covid-19. This article proves that LiYbF4:Tm3+@LiYF4 core@shell nanoparticles can be perfect alternatives for the most commonly studied upconverting NPs based on the NaYF4 host compound and are good candidates for biomedical applications.

Lysosome directed red light photodynamic therapy using glycosylated iron-(III) conjugates of boron-dipyrromethene

To overcome the drawbacks associated with chemotherapeutic and porphyrin-based photodynamic therapy (PDT) agents, the use of BODIPY (boron-dipyrromethene) scaffold has gained prominence in designing a new generation of photosensitizers-cum-cellular imaging agents. However, their poor cell permeability and limited solubility in aqueous medium inhibits the in-vitro application of their organic form. This necessitates the development of metal-BODIPY conjugates with improved physiological stability and enhanced therapeutic efficacy. We have designed two iron(III)-BODIPY conjugates, [Fe(L1/2)(L3)Cl] derived from benzyl-dipicolylamine and its glycosylated analogue along with a BODIPY-tagged catecholate. The complexes showed intense absorption bands (ε ∼ 55,000 M−1 cm−1) and demonstrated apoptotic PDT activity upon red-light irradiation (30 J/cm2, 600–720 nm). The complex with singlet oxygen quantum yield value of ∼0.34 gave sub-micromolar IC50 (half-maximal inhibitory concentration) value (∼0.08 μM) in both HeLa and H1299 cancer cells with a photocytotoxicity index value of >1200. Both the complexes were found to have significantly lower cytotoxic effects in non-cancerous HPL1D (human peripheral lung epithelial) cells. Singlet oxygen was determined to be the prime reactive oxygen species (ROS) responsible for cell damage from pUC19 DNA photo-cleavage studies, 1,3-diphenylisobenzofuran and SOSG (Singlet Oxygen Sensor Green) assays. Cellular imaging studies showed excellent fluorescence from complex 2 within 4 h, with localization in lysosomes. Significant drug accumulation into the core of 3D multicellular tumor spheroids was observed within 8 h from intense in-vitro emission. The complexes exemplify iron-based targeted PDT agents and show promising results as potential transition metal-based drugs for ROS mediated red light photocytotoxicity with low dosage requirement.

Salvianolic acid B as a potent nano-agent for enhanced ALA-PDT of oral cancer and leukoplakia cells.

Photodynamic therapy (PDT) relies on the light activation of a photosensitizers to generate reactive oxygen species such as singlet oxygen, but its effect on cancer therapy is limited dramatically by hypoxia in the tumor microenvironment. To determine the potential of a nano-photosensitizer loaded salvianolic acid B (SalB) and 5-aminolevulinic acid (ALA) for enhancing the efficacy of PDT in oral squamous cell carcinoma Cal27 cells and leukoplakia Leuk1 cells. Singlet oxygen sensor green (SOSG) assay showed that nano-SalB-ALA generated higher levels of singlet oxygen, compared to nano-SalB and nano-ALA. Cellular uptake assay showed that nano-SalB-ALA effectively absorbed by Leuk1 cells. Importantly, cell counting kit-8 and flow cytometry revealed that PDT with nano-SalB-ALA effectively inhibited the viability and induced the apoptosis of Cal27 and Leuk1 cells, respectively. Moreover, the tumor xenograft study revealed that PDT with nano-SalB-ALA had a stronger inhibitory effect on tumor growth of nude mice, compared to control groups. The novel photosensitizer nano-SalB-ALA remarkably enhanced the efficacy of PDT by improving singlet oxygen production, inhibiting cell proliferation, promoting cell apoptosis, and suppressing tumor growth. These suggest PDT with nano-SalB-ALA could be a clinically significant and potent treatment for oral cancer and leukoplakia.

Efficiency of direct photoinduced generation of singlet oxygen at different wavelengths, power density and exposure time of laser irradiation.

This work investigates the influence of laser irradiation parameters (wavelength, power density and exposure time) on singlet oxygen (1O2) generation efficiency. Chemical trap (L-histidine) and fluorescent probe (Singlet Oxygen Sensor Green, SOSG) detection methods were used. Studies have been conducted for 1267, 1244, 1122 and 1064 nm laser wavelengths. 1267 nm had the highest efficiency of 1O2 generation, but 1064 nm demonstrated almost the same efficiency. We also observed that the 1244 nm wavelength can generate some amount of 1O2. It was demonstrated that laser exposure time can generate 1O2 more efficiently than an increase of power. Additionally, the SOSG fluorescence intensity measurements method for acute brain slices was studied. This allowed us to evaluate the approach's potential for in vivo detection of 1O2 concentrations.

Generation of singlet oxygen by porphyrin and phthalocyanine derivatives regarding the oxygen level

Background. The principle of photodynamic effect is based on the combined action of photosensitiser, molecular oxygen and light, which produce various reactive oxygen species and are associated with significant cellular damage. Singlet oxygen is one of the most serious representatives, which is characterised by powerful oxidising properties. Moreover, concomitant hyperbaric oxygen treatment can support these effects. Therefore, the subject of our study was to compare the yields of singlet oxygen for four different photosensitizers in dependency on the oxygen concentration. Material and methods. Four different photosensitizers 5,10,15,20-tetrakis(1-methyl-4-pyridinio)porphyrin tetra(p-toluenesulfonate), tetramethylthionine chloride, 5,10,15,20-tetrakis(4-sulfonatophenyl)porphyrin zinc(II) and zinc phthalocyanine disulfonate were investigated to determine the yield of singlet oxygen in PBS by Singlet Oxygen Sensor Green reagent under different partial pressures of oxygen (0.4 and 36 mg/l). Results. There were no noticeable shifts in the excitation and emission fluorescence spectra regarding the oxygen concentration. Concerning the same molar concentration of photosensitizers the production of singlet oxygen was highest for 5,10,15,20-tetrakis(4-sulfonatophenyl)porphyrin zinc(II), where the rate of the fluorescence change was more than 3 times higher than that obtained for 5,10,15,20-tetrakis(1-methyl-4-pyridinio)porphyrin tetra(p-toluenesulfonate). On the other hand, zinc phthalocyanine disulfonate showed the lowest yield in singlet oxygen production. Conclusions. Singlet oxygen production, within the range of oxygen concentrations achievable in tissues under normoxia or hyperoxia, does not depend on these concentrations. However, the singlet oxygen generation is significantly influenced by the type of photosensitizer, with the highest yield belonging to 5,10,15,20-tetrakis(4-sulfonatophenyl)porphyrin zinc(II).

Excitation-Wavelength-Dependent Functionalities of Temporally Controlled Sensing and Generation of Singlet Oxygen by a Photoexcited State Engineered Rhodamine 6G-Anthracene Conjugate.

The present study provides design guidance for unique multipotent molecules that sense and generate singlet oxygen (1 O2 ). A rhodamine 6G-aminomethylanthracene-linked donor-acceptor molecule (RA) is designed and synthesized for demonstrating wavelength-dependent functionalities as follows; (i) RA acts as a conventional fluorogenic 1 O2 sensor molecule like the commercially available reagent, singlet oxygen sensor green (SOSG), when it absorbs ultraviolet (UV)-visible light and reacts with 1 O2 . (ii) RA acts as a temporally controlled 1 O2 sensing reagent under the longer wavelength (∼700 nm) photosensitization. RA enters an intermediate state after capturing 1 O2 and does not become strongly fluorescent until it is exposed to UV, blue, or green light. (iii) RA acts as an efficient photosensitizer to generate 1 O2 under green light illumination. The spin-orbit charge transfer mediated intersystem crossing (SOCT-ISC) process achieves this function, and RA shows a potential cancer-killing effect on pancreatic cancer cells. The wavelength-switchable functionalities in RA offer to promise molecular tools to apply 1 O2 in a spatiotemporal manner.

X-Ray Triggered Nanoscintillators Photosensitize Pancreatic Cancer and Stimulate a Robust Systemic Immune Response

<h3>Purpose/Objective(s)</h3> X-ray excited photodynamic therapy (XPDT) utilizes X-ray excited nano-scintillators as a light source for photodynamic therapy to treat solid tumors in deep tissues and stimulate immunogenic tumor necrosis. The goals of our study were twofold: (1) to assess the efficacy of a novel XPDT agent, pYSM, in enhancing the regression of murine pancreatic tumors using low doses of radiation, and (2) to evaluate the immunogenic effects of XPDT and immunotherapy in stimulating a systemic anti-tumor immune response. <h3>Materials/Methods</h3> pYSM was synthesized by coating Y₂O₃:Eu nanoparticles in a mesoporous silica shell before loading the shell with methylene blue dye as a photosensitizer and encapsulating the complex in polyethylene glycol to improve systemic circulation. The generation of reactive oxygen species from irradiating pYSM in solution was measured by a singlet oxygen sensor green (SOSG) assay. In vitro studies were conducted using Panc02, a murine pancreatic cell line, by culturing cells with pYSM and measuring the cell viability after irradiation. In vivo studies were performed using C57BL/6 mice with subcutaneous bilateral flank injections of Panc02 cells. A biodistribution assay was performed to confirm that the intravenous tail-vein injection of pYSM resulted in the accumulation of the XPDT agent within the tumor microenvironment. Only right-sided tumors were treated with either XPDT+immunotherapy, XPDT only, radiotherapy only, or pYSM only, and left-sided tumors were left untreated. Tumor growth delay curves were measured for both treated and untreated tumors, and flow cytometry was performed on both tumors to measure the immune response in all treatment groups. <h3>Results</h3> XPDT mediated by pYSM resulted in the greater generation of reactive oxygen species generation under a 10 Gy dose when compared to controls. And in vitro studies confirmed the greater cytotoxic effects of pYSM under X-ray irradiation as compared to controls. Additionally, in vivo studies showed the enhanced tumor regression of pYSM-mediated XPDT+immunotherapy as compared to controls in both right-sided (treated) and left-sided (untreated) tumors, suggesting an abscopal effect, as well as an increase in immune responses within the microenvironment of both right-sided and left-sided tumors. <h3>Conclusion</h3> pYSM is a novel, viable construct capable of performing XPDT to treat solid tumors. Additionally, XPDT mediated by pYSM combined with immunotherapy can generate a systemic anti-tumor immune response that leads to the regression of treated tumors as well as an abscopal effect. This combined treatment modality can be used to treat deep-seated solid tumors with poor immunogenic profiles.

Photonic Crystal-Enhanced Photodynamic Antibacterial Therapy

Photonic Crystal-Enhanced Photodynamic Antibacterial Therapy

Gemini Surfactant Mediated Catansomes for Enhanced Singlet Oxygen Generation of Rose Bengal and Their Phototoxicity against Cancer Cells.

Photodynamic therapy (PDT) is an innovative technique for cancer treatment with minimal side effects, based on the use of a photosensitizer, oxygen, and light. Photosensitizers (PSs) have several limitations, that may limit their clinical use, like poor solubilization, self-aggregation, and lack of specific targeting, which can be addressed with the use of nanomaterials. Herein, a unique type of catansomes (CaSs) was prepared using a gemini imidazolium-based surfactant (1,3-bis[(3-octadecyl-1-imidazolio)methyl]benzene dibromide (GBIB) and a double chain surfactant, diaoctyl sodium sulfosuccinate or Aerosol OT (AOT). The formation of CaS GBIB/AOT was optimized in various ethanol/water (E/W) solvent ratios by employing a facile, quick, and most reliable solution-solution mixing method. The CaS was characterized by dynamic light scattering (DLS) and field emission gun scanning electron microscopy (FEG-SEM) techniques. The experimental results reveal that stable CaSs with a spherical shape were obtained at lower concentration (100 μM). Rose Bengal (RB), a PS of the xanthene family, was incorporated into these prepared CaSs, as proven by fluorescence spectroscopy, UV-visible absorption spectroscopy, and confocal laser scanning microscopy. Singlet oxygen (1O2) generation studies revealed the relevant role of the E/W solvent ratio as there was a 4-fold boost in the 1O2 production for GBIB/AOT in E/W = 50:50 and around 3-fold in E/W = 30:70. Also, the GBIB-rich 80:20 fraction was more efficient in increasing the 1O2 generation as compared to the AOT rich fraction (20:80). Further, their phototoxicity was tested in a water-rich solvent ratio (E/W = 30:70) against MCF-7 cells. Upon irradiation with a 532 nm laser (50 mW) for 5 min, RB@GBIB/AOT(20:80) fraction caused 50% decrease in the metabolic activity of MCF-7 cells, and RB@GBIB/AOT(80:20) fraction produced a maximum 85% decrease in cell viability. Furthermore, the enhancement in intracellular 1O2 generation by RB@GBIB/AOT, as compared to pure RB, was confirmed with singlet oxygen sensor green (SOSG). This new type of CaS based on gemini surfactants exhibiting a large amount of 1O2 generation, holds great interest for several applications, such as use in photomedicine in future.

Red light active Pt(iv)-BODIPY prodrug as a mitochondria and endoplasmic reticulum targeted chemo-PDT agent.

A cisplatin-based platinum(iv) prodrug, [Pt(NH3)2Cl2(OH)(L 1 )], having L 1 as a red-light active boron-dipyrromethene (BODIPY) pendant, was synthesized and characterized and its application as a chemo-cum-photodynamic therapy agent was studied. Me-L 1 as the ligand precursor is structurally characterized. The complex displayed an intense absorption band near 650 nm (ε ∼ 8.8 × 104 dm3 mol-1 cm-1) in 1 : 1 (v/v) DMSO/DPBS. It showed an emission band at 674 nm (λ ex = 630 nm) with a fluorescence quantum yield (Φ F) value of 0.37. In red light (600-720 nm), it generated singlet oxygen as evidenced from the 1,3-diphenylisobenzofuran (DPBF) titration experiment giving a singlet oxygen quantum yield (Φ Δ) value of 0.28 in DMSO. The mechanistic pUC19 DNA photocleavage study and singlet oxygen sensor green (SOSG) assay ascertained its ability to generate singlet oxygen in both extracellular and intracellular media by a type-II photo-process. The complex exhibited high stability in the dark, but on red-light irradiation, it displayed rapid activation in the presence of a reducing environment. It displayed remarkable apoptotic photocytotoxicity with half-maximal inhibitory concentration (IC50) ranging from 0.58 to 0.76 μM in human cervical cancer (HeLa) and breast cancer (MCF-7) cells with a respective photo-cytotoxicity index value of >172 and >131. The photodynamic activity was significantly less in non-cancerous human peripheral lung epithelial (HPL1D) cells. The emissive complex showed localization in the mitochondria and endoplasmic reticulum (ER) with a similar Pearson's correlation coefficient value, making it a dual organelle-targeted therapeutic agent. JC-1, fluo-4-AM and annexin V-FITC/propidium iodide assays in HeLa cells showed cellular apoptosis by arresting cells in the sub-G1 phase via mitochondrial dysfunction and ER stress.

Enhancing Intersystem Crossing by Intermolecular Dimer-Stacking of Cyanine as Photosensitizer for Cancer Therapy

Enhancing Intersystem Crossing by Intermolecular Dimer-Stacking of Cyanine as Photosensitizer for Cancer Therapy

BODIPY-Ruthenium(II) Bis-Terpyridine Complexes for Cellular Imaging and Type-I/-II Photodynamic Therapy.

A series of multichromophoric ruthenium(II) complexes with the formulation [Ru(tpy-BODIPY)(tpy-R)]Cl2 (1-4), having a heteroleptic Ru(II)-bis-tpy (tpy = 4'-phenyl-2,2':6',2″-terpyridine) moiety covalently linked to a boron-dipyrromethene (BODIPY) pendant, have been prepared and characterized and their application as a phototherapeutic and photodetection agent in cancer therapy has been explored. Ligand L1 with a terpyridine-BODIPY moiety and complex 1 as its PF6 salt (1a) have been structurally characterized by a single-crystal X-ray diffraction study. Complex 1a has a distorted-octahedral RuN6 core with a Ru(II)-bis-terpyridine unit that is covalently linked to one photoactive BODIPY unit. The complexes exhibit strong absorbance near 502 nm (ε ≈ (3.7-7.8) × 104 M-1 cm-1) and high singlet oxygen sensitization ability, giving singlet oxygen quantum yield (ΦΔ) values ranging from 0.57 to 0.75 in DMSO. An emission-based study using complex 4 and Singlet Oxygen Sensor Green (SOSG) displays the formation of singlet oxygen inside the cells and also in the buffer medium upon light irradiation. DNA (pUC19) photocleavage experiments using ROS scavengers/stabilizers reveal photoinduced generation of singlet oxygen by a type-II process and of the superoxide anion radical by a type-I process. Complex 4 having a pendant biotin moiety as a cancer cell targeting group shows high photocytotoxicity with a remarkable phototherapeutic index (PI) value of >1400 in HeLa cancer cells with a low light dose activation (400-700 nm, 2.2 J cm-2). The complexes display reduced activity in noncancerous HPL1D cells. The emission property of the complexes is used for cellular imaging, thus making them suitable as next-generation theranostic PDT agents.

Emerging Designs of Aggregation-Induced Emission Agents for Enhanced Phototherapy Applications

Emerging Designs of Aggregation-Induced Emission Agents for Enhanced Phototherapy Applications

Antimicrobial photodynamic therapeutic effects of cationic amino acid-porphyrin conjugate 4i on Porphyromonas gingivalis in vitro

BackgroundPorphyromonas gingivalis (P. gingivalis) is considered to be among the principal pathogens in periodontal disease. The present study aimed to investigate the effect of antimicrobial photodynamic therapy (aPDT) mediated by cationic amino acid-porphyrin conjugate 4i on P. gingivalis MethodsThe uptake of 4i by P. gingivalis over different times of incubation was evaluated by optical density using a microplate reader. Laser radiation at λ=650nm-660nm with I =50 mW/cm2 at doses of 0, 3.0, 6.0, 9.0, and 12 J/cm2 was used for aPDT. A colony-counting method and confocal laser scanning microscopy (CLSM) were used to observe the neutralization of P. gingivalis. The fluorescent molecular probe 3’(p-hydroxyphenyl)-fluorescein and the reagent Singlet Oxygen Sensor Green were used to measure the quantities of •OH and 1O2 produced by 4i after irradiation with different light energies. ResultsThe 4i conjugate was absorbed gradually by P. gingivalis, reaching a maximum at 30 min. A clear cytotoxic effect on P. gingivalis was observed with aPDT using 62.5 µM 4i, with colony counts dropping by a factor of 3.35 log10, indicating a sterilization rate of 99.95%. Light irradiation resulted principally in the production of • OHby 4i. A live/dead viability assay demonstrated substantial red fluorescence in P. gingivalis treated with aPDT. ConclusionsThe results suggest that 4i-aPDT caused substantial cytotoxicity in P. gingivalis.