Photodynamic Action Research Articles

Fluorescent Nitric Oxide Photodonors Based on BODIPY and Rhodamine Antennae.

Two novel NO photodonors (NOPDs) based on BODIPY and Rhodamine antennae activatable with the highly biocompatible green light are reported. Both NOPDs exhibit considerable fluorescence emission and release NO with remarkable quantum efficiencies. The combination of the photoreleasing and emissive performance for both compounds is superior to those exhibited by other NOPDs based on similar light-harvesting centres, making them very intriguing for image-guided phototherapeutic applications. Preliminary biological data prove their easy visualization in cell environment due to the intense green and orange-red fluorescence and their photodynamic action on cancer cells due to the NO photo-liberated.

Stimuli-Responsive Reversible Switching of Intersystem Crossing in Pure Organic Material for Smart Photodynamic Therapy.

Photosensitizers (PSs) with stimuli-responsive reversible switching of intersystem crossing (ISC) are highly promising for smart photodynamic therapy (PDT), but achieving this goal remains a tremendous challenge. This study introduces a strategy to obtain such reversible switching of ISC in a new class of PSs, which exhibit stimuli-initiated twisting of conjugated backbone. We present a multidisciplinary approach that includes femtosecond transient absorption spectroscopy and quantum chemical calculations. The organic structures reported show remarkably enhanced ISC efficiency (ΦISC ), switching from nearly 0 to 90 %, through an increase in the degree of twisting, providing an innovative mechanism to promote ISC. This leads us to propose here and demonstrate the concept of smart PDT, where pH-induced reversible twisting maximizes the ISC rate, and thus enables strong photodynamic action only under pathological stimulus (such as change in pH, hypoxia, or exposure to enzymes). The ISC process is turned off to deactivate PDT ability, when the PS is transferred or metabolized away from pathological region.

Stimuli‐Responsive Reversible Switching of Intersystem Crossing in Pure Organic Material for Smart Photodynamic Therapy

AbstractPhotosensitizers (PSs) with stimuli‐responsive reversible switching of intersystem crossing (ISC) are highly promising for smart photodynamic therapy (PDT), but achieving this goal remains a tremendous challenge. This study introduces a strategy to obtain such reversible switching of ISC in a new class of PSs, which exhibit stimuli‐initiated twisting of conjugated backbone. We present a multidisciplinary approach that includes femtosecond transient absorption spectroscopy and quantum chemical calculations. The organic structures reported show remarkably enhanced ISC efficiency (ΦISC), switching from nearly 0 to 90 %, through an increase in the degree of twisting, providing an innovative mechanism to promote ISC. This leads us to propose here and demonstrate the concept of smart PDT, where pH‐induced reversible twisting maximizes the ISC rate, and thus enables strong photodynamic action only under pathological stimulus (such as change in pH, hypoxia, or exposure to enzymes). The ISC process is turned off to deactivate PDT ability, when the PS is transferred or metabolized away from pathological region.

Video-endoscopy system for photodynamic theranostics of central lung cancer

Theranostics is a new medical specialization that combines therapy with diagnostics. This paper describes a video-endoscopy system intended for the photodynamic theranostics of malignant tumors of the respiratory passages, in which treatment consists of photodynamic therapy, using photosensitizers of the chlorin series (visible region) and indocyanine green (near-IR region), while diagnosis is performed using the same agents, but now as fluorescence markers of the tumor. The system is based on a standard brochofibroscope that uses several diode lasers as light sources to provide photodynamic action, to excite fluorescence, and for observation in reflected white light. Visualization is carried out by a multispectral video system that relies on the fluorescence pattern to perform targeted irradiation of the tumor and to monitor the irradiation-energy dosage from the attenuation of the photosensitizer’s luminescence brightness. The possibilities of the system are illustrated by clinical examples.

Poisonous Caterpillar-Inspired Chitosan Nanofiber Enabling Dual Photothermal and Photodynamic Tumor Ablation.

As caterpillars detect the presence of predators and secrete poison, herein, we show an innovative and highly effective cancer therapeutic system using biocompatible chitosan nanofiber (CNf) installed with a pH-responsive motif that senses tumor extracellular pH, pHe, prior to delivering dual-modal light-activatable materials for tumor reduction. The filamentous nanostructure of CNf is dynamic during cell interaction and durable in blood circulation. Due to its amine group, CNf uptakes a large amount of photothermal gold nanoparticles (AuNPs, >25 wt %) and photodynamic chlorin e6 (Ce6, >5 wt %). As the innovative CNf approaches tumors, cationic CNf effectively discharges AuNPs connected to the pH-responsive motif via electrostatic repulsion and selectively binds to tumor cells that are generally anionic, via the electrostatic attraction accompanied by CNf. We demonstrated via these actions that the endocytosed Ce6 (on CNf) and AuNPs (free from CNf) significantly elicited tumor cell death under light irradiation. As a result, the synergistic interplay of thermogenesis and photodynamic action was observed to switch on at the pHe, resulting in a striking reduction in tumor formation and growth rate upon light exposure.

Determination of the Diffusion Coefficient of Methylene Blue Solutions in Dentin of a Human Tooth using Reflectance Spectroscopy and Their Antibacterial Activity during Laser Exposure

This study is devoted to the determination of the diffusion coefficients of methylene blue in an aqueous solution and in a micellar solution of the cationic surfactant in dentin sections of a human tooth in vitro using a method of diffuse reflectance optical spectroscopy and a model of free diffusion. The average diffusion coefficient was (6.74 ± 1.32) × 10−6 cm2/s for an aqueous solution of methylene blue and (1.93 ± 0.24) × 10−6 cm2/s for a micellar solution of the dye. The toxicity of methylene blue solutions in water and in a solution of cetylpyridinium chloride in daylight in the absence of laser radiation on the cells of Candida albicans, Staphylococcus aureus FDA 209P, and Lactobacillus, as well as the photodynamic effect of laser radiation (662 nm) on them, were studied. The photodynamic action of laser radiation was shown to have a pronounced suppressive effect on all the studied microbial strains.

Exploration of interfacial dynamics in squaraine based nanohybrids for potential photodynamic action

Photodynamic therapy (PDT) is a clinically approved, minimally invasive therapeutic procedure exhibiting cytotoxic effects toward malignant cells. Hydrophobic nature of most photosensitizers used in PDT with lower light absorption ability restricts practical use of PDT. Herein, we have employed a squaraine drug (SQ) with 665 nm absorbance peak maxima as the photosensitizing agent and evaluate its photo-physical properties. The tendency of aggregation formation in aqueous media limits its practical usefulness. Thus, we have synthesised wide band gap semiconductor zinc oxide (ZnO) nanoparticles and functionalized the surface using squaraine molecules. The molecular cross-talking was evaluated using excited state fluorescence lifetime decay profiles and by employing Fӧrster resonance energy transfer (FRET) technique. The nanohybrids show improvement in three aspects compared to bare SQ molecule such as lesser aggregate formation in aqueous media, pH responsive precipitation of the drug and improvement of photo-induced reactive oxygen species (ROS) generation. Ultrafast dynamical study at the inorganic (ZnO) - organic (SQ) interface depicts presence of photo-induced charge transfer process at the junction which indeed improves the ROS generation capability. Finally, the photodynamic action has been evaluated in human breast cancer cell line MCF-7. The nanohybrids depict enhanced photo toxicity in cancer cell with loss of adherence and typical morphology of cancerous cell depicting controlled cell death. The present study employ characterisation of nanohybrids for potential use in PDT for cancer treatment.

Light-Harvesting Antenna and Proton-Activated Photodynamic Effect of a Novel BODIPY-Fullerene C60 Dyad as Potential Antimicrobial Agent.

A covalently linked BODIPY-fullerene C60 dyad (BDP-C60 ) was synthesized as a two-segment structure, which consists of a visible light-harvesting antenna attached to an energy or electron acceptor moiety. This structure was designed to improve the photodynamic action of fullerene C60 to inactivate bacteria. The absorption spectrum of BDP-C60 was found to be a superposition of the spectra of its constitutional moieties, whereas the fluorescence emission of the BODIPY unit was strongly quenched by the fullerene C60 . Spectroscopic, calculations, and redox studies indicate a competence between photoinduced energy and electron transfer. Protonating the dimethylaminophenyl substituent through addition of an acidic medium led to a substantial increase in the fluorescence emission, triplet excited state formation, and singlet molecular oxygen production. At physiological pH, photosensitized inactivation of Staphylococcus aureus mediated by 1 μM BDP-C60 exhibited a 4.5 log decrease of cell survival (>99.997 %) after 15 min irradiation. A similar result was obtained with Escherichia coli using 30 min irradiation. Moreover, proton-activated photodynamic action of BDP-C60 turned this dyad into a highly effective photosensitizer to eradicate E. coli. Therefore, BDP-C60 is an interesting photosensitizing structure in which the light-harvesting antenna effect of the BODIPY unit combined with the protonation of dimethylaminophenyl group can be used to improve the photoinactivation of bacteria.

CCK1 ‐ a Very Peculiar G Protein‐Coupled Receptor

The class A G protein‐coupled receptor cholecystokinin 1 (CCK1) plays a predominant role in regulating exocrine pancreatic secretion both in mammals and in birds. CCK1R supra‐maximal stimulation leads to one of the most commonly used murine models of acute pancreatitis. The CCK‐CCK1R system is a well conserved feeding regulator in evolution from worms, insects, other invertebrates, vertebrates, to primates. In the murine brain, CCK1R is mainly expressed in the hippocampus and a few highly defined extracortical regions. These expression patterns determine that CCK1R modulation is important in both biology and medicine. Indeed some special characteristics revealed recently have made CCK1 stand out among all the class A GPCR. Although CCK1 is not susceptible to superoxide or hydrogen peroxide oxidative regulation, it is permanently activated by singlet oxygen (1O2) which can be generated conveniently in a Type II photodynamic action. We have used Fura‐2 fluorescent calcium imaging to show that CCK1R is activated permanently by photodynamic action with photosensitiser sulphonated aluminium phthalocyanine (SALPC) in the freshly isolated rat pancreatic acini. Such permanent photodynamic activation of CCK1R with SALPC could be reproduced in rat pancreatic acinar tumor cell AR4‐2J, and in cell lines ectopically expressing human hCCK1R. Both CCK1R in AR4‐2J and ectopically expressed in other cell lines (CHO, HEK) could be permanently activated by photodynamic action with the genetically encoded protein photosensitisers KillerRed and miniSOG. Other than permanent activation by 1O2, CCK1R activation by CCK in the freshly isolated rat pancreatic acini is quenched by mixed reactive oxygen species generated by neutrophil respiratory burst, and by neutrophil extracellular trap component histones. Further, CCK1R activation by CCK or by 1O2 in AR4‐2J is sensitized by histones. Our ongoing work is examining the potential for CCK1R analogues from invertebrates to be permanently activated by photodynamic action with SALPC, KillerRed, miniSOG or their variants. We are also looking at the possibility to extend the permanent activation by 1O2 (pAb1O2) property of CCK1R to other GPCR by the generation of chimeric receptors. The outcomes of such experiments will provide useful toolkits for remote photon‐driven activations of the CCK1R system in vivo from invertebrates to vertebrates, birds, mammals and non‐human primates.Support or Funding InformationThis work was supported by The Natural Science Foundation of China (31670856).This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Effect of dose responses of hydrophilic aluminium (III) phthalocyanine chloride tetrasulphonate based photosensitizer on lung cancer cells

Photodynamic therapy (PDT) is a promising approach for the treatment of different types of cancer and has been brought into focus for its synergy, compatibility, repeatability, relatively inexpensive cost and it's typically more efficacious nature. Photosensitizers (PSs) play a major role in PDT and are the core of this specific therapy. Al (III) Phthalocyanine Chloride Tetra sulfonic Acid (AlPcS4Cl) PS is an aromatic macrocyclic metal-based compound that is synthetically derived. It aids in deep tissue penetration due to its far red light activation wavelength, low photo bleaching, increased quantum yields and stability. Lung cancer is a leading cause of cancer related deaths worldwide accounting for approximately 1 in 5 of all cancer-related deaths. In this study, we explored the photochemical properties of AlPcS4Cl, its uptake into lung cancer, the intracellular localization and photodynamic action on lung cancer (A549 cells). Results indicated that AlPcS4Cl is a stable PS that localizes in intracellular organelles including the mitochondrion and lysosomes. PDT using AlPcS4Cl indicated an increase in cell death and decrease in cell proliferation and viability. AlPcS4Cl showed to be effective in treating lung cancer in vitro, however the resulting PDT efficacy will finally depend on the biological features such as tumour vasculature and tumour specific accumulation when used as a clinical application. It is noted that PDT can be considered as an adjunct therapy until standard protocols for various tumour types along with a relevant PS has been validated.

Theoretical and experimental studies concerning monomer/aggregates equilibrium of zinc phthalocyanine for future photodynamic action.

Monomeric zinc phthalocyanine has been studied as a promising active photosensitizer in photodynamic therapy against cancer, in which its aggregate form is non-active. This paper aimed to describe the monomer/aggregates equilibrium of zinc phthalocyanine in binary water/DMSO mixtures. To reach this aim theoretical calculation, electronic absorption, static and time-resolved fluorescence, and resonance light scattering was used. Zinc phthalocyanine shows a complex water dependence behavior in the mixture. At least three distinct steps were observed: (i) until 30% water zinc phthalocyanine is essentially in the monomeric form, changing to (ii) small slipped cofacial-aggregates around 30% to 40% water and finally to (iii) a staircase arrangement of large aggregates at higher water percent. The staircase arrangement is driven by the intermolecular coordination between the pyrrolic nitrogen lone-pairs and the central metal zinc. The water-Zn coordination governs the fluorescence quenching by a static mechanism. These results have direct relevance in the better understanding on the behavior of zinc phthalocyanine in vivo and when incorporated in drug delivery systems for clinical applications in photodynamic therapy.

Selectivity in Photodynamic Action: Higher Activity of Mitochondria Targeting Photosensitizers in Cancer Cells

AbstractAmong the pathways for improving the practice of photodynamic therapy of cancer, increasing the selectivity of photodynamic action is an obvious choice. Considering the different characteristics of mitochondria in normal cells and cancer cells, we designed mitochondria‐targeting photosensitizers. We now demonstrate for the first time that mitochondria‐targeted photosensitizers by triphenylphosphonium (TPP) derivatization are more selective for cancer cells compared to normal cells, presumably due to the larger membrane potential of cancer‐cell mitochondria allowing more efficient accumulation of the photosensitizer.

Development of Photo-Activated ROS-Responsive Nanoplatform as a Dual-Functional Drug Carrier in Combinational Chemo-Photodynamic Therapy.

Dual functional drug carrier has been a modern strategy in cancer therapy because it is a platform to elicit additive and synergistic effects through combination therapy. Photo-activated external stimuli such as reactive oxygen species (ROS) also ensure adequate drug delivery in a precise temporal and spatial manner. However, current ROS-responsive drug delivery systems usually require tedious synthetic procedures. A facile one-pot approach has been reported herein, to obtain self-assembled polymeric nanocarriers (NCs) for simultaneous paclitaxel (PTX)- and Rose Bengal (RB)-loading to achieve combined chemo-photodynamic therapy and controlled drug release in responsive to a light-induced ROS stimulus. To encapsulate these hydrophobic and hydrophilic drugs, chitosan (CTS), branched polyethylenimine (bPEI) and polyvinyl alcohol (PVA) were selected and fabricated into nanoblended matrices through an oil-in-water emulsion method. The amphiphilic properties of CTS permit simultaneous entrapment of PTX and RB, while the encapsulation efficiency of RB was further improved by increasing the amount of short-chain bPEI. During the one-step assembly process, bovine serum albumin (BSA) was also added to condense the cationic tripolymer mixtures into more stable nanocarriers (BNCs). Hyaluronic acid (HA) was subsequently grafted onto the surface of BNCs through electrostatic interaction, leading to the formation of HA-BSA/CTS/PVA/bPEI-blended nanocarriers (HBNCs) to achieve an efficient prostate-cancer-cell uptake. Importantly, in response to external light irradiation, HBNCs become destabilized owing to the RB-mediated photodynamic action. It allows an on-demand dual-payload release to evoke a simultaneous photodynamic and chemo treatment for cancer cell eradication. Thus, HBNCs present a new promising approach that exhibits a specific vulnerability to RB-induced photosensitization. The consequent dual-cargo release is also expected to successfully combat cancer through a synergistic anti-tumor effect.

Мониторинг изменения содержания кислорода в тканях по кинетике замедленной флуоресценции экзогенных красителей

The dynamics of oxygen consumption during photodynamic processes and its subsequent restoration in malignant tumors and healthy tissues of mice were studied in vitro by kinetics of long-term luminescence of xanthene dyes. It was shown that to estimate changes in tissue oxygen tension, specific type of delayed fluorescence can be used which caused by singlet-triplet annihilation of singlet oxygen and a sensitizer in triplet state. In tumors under pulse excitation of sensitizers, reversible quenching of delayed fluorescence was observed, which is associated with a decrease in the tissue oxygen tension during photodynamic processes. Method for visualizing the restoration of the initial oxygen level in tissues after photodynamic action is proposed.

Theoretical insight into joint photodynamic action of a gold(i) complex and a BODIPY chromophore for singlet oxygen generation.

Density functional theory is herein employed to provide theoretical insight into the mechanism involved in 1O2 photosensitization by a gold-BODIPY combined complex proposed as a promising photodynamic therapy agent. The protocol is thus used to compute the non-radiative rate constants for the S1 → Tj intersystem crossing transitions. Calculations show that while the incorporation of an iodine atom into the core skeleton of BODIPY enhances the singlet-triplet intersystem crossing (ISC) efficiency due to the occurrence of the singlet-triplet transition between states with different orbital characters (ππ* → πn*), the presence of a gold atom, even if not directly anchored to the chromophore core but through a triplet bond, equally entails an increase of the spin-orbit coupling constant due to the heavy atom effect. In this way, the system is able to generate singlet molecular oxygen, the key cytotoxic agent in PDT. Our results fit well with the experimental singlet oxygen quantum yield and cytotoxicity determination.

Benefits of hypericin transport and delivery by low- and high-density lipoproteins to cancer cells: From in vitro to ex ovo.

Lipoproteins are very attractive natural-based transport systems suitable for applications in diagnostics and cancer therapy. Low- and high-density lipoproteins (LDL, HDL) were selected for hypericin (hyp) delivery in cancer cells. Hyp was used, as it is a well-known model for hydrophobic molecules, in order to estimate the LDL and HDL transport efficacy. We applied fluorescence techniques, absorption and Raman spectroscopy to characterize the state and alteration of LDL and HDL in the absence and presence of hyp. The fluorescence intensity of hyp loaded in lipoproteins was two times weaker in HDL than LDL. We demonstrated that there are faster redistribution kinetics of hyp from HDL than from LDL. As a consequence, hyp uptake by glioma and breast cancer cells was driven more via endocytosis when hyp was delivered by LDL than by HDL. Hyp induced photodynamic action was stronger when hyp was delivered by HDL than LDL. Ex ovo hyp fluorescence pharmacokinetics demonstrated differences in biodistributions of hyp in lipoproteins topical applications. However, hyp was successfully delivered to cancer cells grafted on quail's chorioallantoic membrane. The results presented in this paper could provide strategies to develop adequate and targeted anticancer therapy.

Hypocrellin A-based photodynamic action induces apoptosis in A549 cells through ROS-mediated mitochondrial signaling pathway

Over recent decades, many studies have reported that hypocrellin A (HA) can eliminate cancer cells with proper irradiation in several cancer cell lines. However, the precise molecular mechanism underlying its anticancer effect has not been fully defined. HA-mediated cytotoxicity and apoptosis in human lung adenocarcinoma A549 cells were evaluated after photodynamic therapy (PDT). A temporal quantitative proteomics approach by isobaric tag for relative and absolute quantitation (iTRAQ) 2D liquid chromatography with tandem mass spectrometric (LC–MS/MS) was introduced to help clarify molecular cytotoxic mechanisms and identify candidate targets of HA-induced apoptotic cell death. Specific caspase inhibitors were used to further elucidate the molecular pathway underlying apoptosis in PDT-treated A549 cells. Finally, down-stream apoptosis-related protein was evaluated. Apoptosis induced by HA was associated with cell shrinkage, externalization of cell membrane phosphatidylserine, DNA fragmentation, and mitochondrial disruption, which were preceded by increased intracellular reactive oxygen species (ROS) generations. Further studies showed that PDT treatment with 0.08 µmol/L HA resulted in mitochondrial disruption, pronounced release of cytochrome c, and activation of caspase-3, -9, and -7. Together, HA may be a possible therapeutic agent directed toward mitochondria and a promising photodynamic anticancer candidate for further evaluation.

Enhanced efficacy of chemo-photodynamic therapy of rhabdomyosarcoma cells by using vitamin K3 as a neoadjuvant agent

Nowadays combination of various therapeutic modalities is an attractive strategy in cancer treatment. In order to develop more efficient combinational therapy, we investigated the effect of Vitamin K3 (menadione) to enhance the cytotoxic action of chemo-photodynamic therapy against Rhabdomyosarcoma (RD) cell line, using Photosense as a photosensitizer and different chemo therapeutic agents. RD cell line was cultured for the evaluation of efficacy in the presence and absence of vitamin K3 with other chemotherapeutic agents. Diode laser (λ = 635 nm) was used for initializing the photodynamic action of Photosense mediated photodynamic therapy (PDT). Cytotoxicity was measured by using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. Pre-treatment for 24 h to RD cells with K3 significantly potentiates sensitivity of chemotherapy. Chemotherapeutic agents and K3 showed significant killing effect when combined with PDT, at very low doses. These results suggest that this procedure could be the basis for an improved chemo-PDT protocol for cancer control.

Inorganic Salts and Antimicrobial Photodynamic Therapy: Mechanistic Conundrums?

We have recently discovered that the photodynamic action of many different photosensitizers (PSs) can be dramatically potentiated by addition of a solution containing a range of different inorganic salts. Most of these studies have centered around antimicrobial photodynamic inactivation that kills Gram-negative and Gram-positive bacteria in suspension. Addition of non-toxic water-soluble salts during illumination can kill up to six additional logs of bacterial cells (one million-fold improvement). The PSs investigated range from those that undergo mainly Type I photochemical mechanisms (electron transfer to produce superoxide, hydrogen peroxide, and hydroxyl radicals), such as phenothiazinium dyes, fullerenes, and titanium dioxide, to those that are mainly Type II (energy transfer to produce singlet oxygen), such as porphyrins, and Rose Bengal. At one extreme of the salts is sodium azide, that quenches singlet oxygen but can produce azide radicals (presumed to be highly reactive) via electron transfer from photoexcited phenothiazinium dyes. Potassium iodide is oxidized to molecular iodine by both Type I and Type II PSs, but may also form reactive iodine species. Potassium bromide is oxidized to hypobromite, but only by titanium dioxide photocatalysis (Type I). Potassium thiocyanate appears to require a mixture of Type I and Type II photochemistry to first produce sulfite, that can then form the sulfur trioxide radical anion. Potassium selenocyanate can react with either Type I or Type II (or indeed with other oxidizing agents) to produce the semi-stable selenocyanogen (SCN)2. Finally, sodium nitrite may react with either Type I or Type II PSs to produce peroxynitrate (again, semi-stable) that can kill bacteria and nitrate tyrosine. Many of these salts (except azide) are non-toxic, and may be clinically applicable.

Supramolecular Adducts of Anionic Porphyrins and a Biocompatible Polyamine: Effect of Photodamage-on Human Red Blood Cells.

Supramolecular adducts obtained by interaction between the anionic porphyrin meso-tetrakis(4-carboxyphenyl)porphyrin (TPPC) or its zinc(II) derivative (ZnTPPC) with a biocompatible amino-terminated polypropylene or poly(ethylene oxide)s (Jeffamines) has been investigated. The interaction with the polymer allows the stabilization of the porphyrins in their monomeric form under physiological conditions. The photodynamic properties of the supramolecular adducts were explored by typical 1O2 indirect detection. Their photodynamic action were evaluated in vitro using human red blood cells (HRBCs) under different experimental conditions. The morphology of erythrocytes was investigated by optical microscopy after incubation with porphyrin compounds and light irradiation. The images show loss of their normal biconcave profile and an incoming spiny configuration with blebs evident on their surfaces.