Photodynamic Therapy In Cells Research Articles

Exploring Thioxanthone Derivatives as Singlet Oxygen Photosensitizers for Photodynamic Therapy at the Near-IR Region.

In the lowest excited triplet state, the excited photosensitizer reacts with tissue oxygen and forms reactive oxygen species (ROS), which kills tissue cells in photodynamic therapy (PDT). Metal-free thio-based pure organic molecules and analogous nucleobases can be used as photosensitizers for PDT applications. Using quantum chemical methods, we studied one- and two-photon optical absorptions, fluorescence, and other excited-state properties of substituted thioxanthone derivatives for their potential as photosensitizers for PDT. Our calculated values were compared with the available experimental data. The calculation of the intersystem crossing rate constant for these photosensitizers explains the high quantum yield of the formation of ROS, as reported experimentally. The excited triplet-state population of the photosensitizer occurs through the 1π-π* → 3n-π* channel of intersystem crossing and increases in the presence of halogen substitution.

A novel heavy-atom-free lysosome-targeted BODIPY as triplet photosensitizer based on SOCT-ISC mechanism for photodynamic therapy

As important organelles in biological cells, lysosomes are closely associated with cell signaling, necrosis and apoptosis. Herein, we report a novel lysosome-targeted boron dipyrromethene (BODIPY) photosensitizer, Lyso-BDP, which has the advantage of lower side effects and higher phototoxicity for 4T1 cells in photodynamic therapy (PDT). Lyso-BDP possesses the lysosomal targeting treatment through the production of the singlet oxygen under the light excitation at 600 nm. We combine the anthracenyl group and BODIPY to form a D-A binary compound. The orthogonal configuration is confirmed by density functional theory (DFT) and time-dependent density functional theory (TDDFT). The molecular orbitals and the energies of the triplet state explain the spin-orbit charge transfer inter-system crossing (SOCT-ISC) mechanism. Due to SOCT-ISC mechanism, Lyso-BDP has the high singlet oxygen (1O2) quantum yield of 62% in DCM without heavy atoms. In this way, the dark toxicity of photosensitizer can be reduced. Meanwhile, the 1O2 ″afterglow” can be achieved to enhance the phototherapeutic effect because of the anthracene group. Compared to classical photosensitizers, Lyso-BDP shows the low half maximum inhibitory concentration (IC50) of 2.5 μM for 4T1 cells in vitro cytotoxicity assays. Therefore, this work provides a strategy to solve the problem of high cellular dark toxicity and no organelle targeting of classical photosensitizers.

Activation of ALOX12 by a multi-organelle-orienting photosensitizer drives ACSL4-independent cell ferroptosis

Ferroptosis is a recently-defined tumor suppression mechanism, but the sensitivity of many tumorigenic cells to ferroptosis is limited by their deficient expression of acyl-CoA synthetase long-chain family member 4 (ACSL4). Here, we report the discovery of a photosensitizer, namely TPCI, which can evoke ACSL4-independent ferroptosis of cancer cells in photodynamic therapy. Through co-localization with 12-lipoxygenase (ALOX12) in multiple subcellular organelles, TPCI activates ALOX12 to generate lipid reactive oxygen species in large quantity and trigger cell ferroptosis. Intriguingly, confining TPCI exclusively in lysosomes switches the cell death from ferroptosis to apoptosis. More strikingly, the ferroptosis mediated by TPCI-induced ALOX12 activation does not require the participation of ACSL4. Therefore, our study identifies TPCI as the first ALOX12 activator to induce ferroptosis independent of ACSL4, which renders a viable therapeutic approach on the basis of distinct ferroptosis of cancer cells, regardless their ACSL4 expressions.

Activation of ALOX12 by a Multi-Organelle-Orienting Photosensitizer Drives ACSL4-Independent Cell Ferroptosis

Ferroptosis is a recently-defined tumor suppression mechanism, but the sensitivity of many tumorigenic cells to ferroptosis is limited by their deficient expression of acyl-CoA synthetase long-chain family member 4 (ACSL4). Here, we report the discovery of a photosensitizer, namely TPCI, which can evoke ACSL4-independent ferroptosis of cancer cells in photodynamic therapy. Through co-localization with 12-lipoxygenase (ALOX12) in multiple subcellular organelles, TPCI activates ALOX12 to generate lipid reactive oxygen species in large quantity and trigger cell ferroptosis. Interestingly, confining TPCI exclusively in lysosomes switches the cell death from ferroptosis to apoptosis. More strikingly, the ferroptosis mediated by TPCI-induced ALOX12 activation does not require the participation of ACSL4. Therefore, our study identifies TPCI as the first ALOX12 activator to induce ferroptosis independent of ACSL4, which renders a viable therapeutic approach on the basis of distinct ferroptosis of cancer cells, regardless their ACSL4 expressions.

Effect of low power lasers on prokaryotic and eukaryotic cells under different stress condition: a review of the literature.

Radiations emitted by low power radiation sources have been applied for therapeutic proposals due to their capacity of inactivating bacteria and cancer cells in photodynamic therapy and stimulating tissue cells in photobiomodulation. Exposure to these radiations could increase cell proliferation in bacterial cultures under stressful conditions. Cells in infected or not infected tissue injuries are also under stressful conditions and photobiomodulation-induced regenerative effect on tissue injuries could be related to effects on stressed cells. The understanding of the effects on cells under stressful conditions could render therapies based on photobiomodulation more efficient as well as expand them. Thus, the objective of this review was to update the studies reporting photobiomodulation on prokaryotic and eukaryotic cells under stress conditions. Exposure to radiations emitted by low power radiation sources could induce adaptive responses enabling cells to survive in stressful conditions, such as those experienced by bacteria in their host and by eukaryotic cells in injured tissues. Adaptive responses could be the basis for clinical photobiomodulation applications, either considering their contraindication for treatment of infected injuries or indication for treatment of injuries, inflammatory process resolution, or tissue regeneration.

Vaterite submicron particles designed for photodynamic therapy in cells.

Calcium carbonate (CaCO3) is one of the most abundant materials in the world. It has several different crystalline phases as present in the minerals: calcite, aragonite and vaterite, which are anhydrous crystalline polymorphs. Regarding the preparation of these microparticles, the most important aspect is the control of the polymorphism, particle size and material morphology. This study aimed to develop porous microparticles of calcium carbonate in the vaterite phase for the encapsulation of chloro-aluminum phthalocyanine (ClAlPc) as a photosensitizer (PS) for application in Photodynamic Therapy (TFD). In this study, spherical vaterite composed of microparticles are synthesized by precipitation route assisted by polycarboxylate superplasticizer (PSS). The calcium carbonate was prepared by reacting a mixed solution of Na2CO3 with a CaCl2 solution at an ambient temperature, 25 °C, in the presence of polycarboxylate superplasticizer as a stabilizer. The photosensitizer was incorporated by adsorption technique in the CaCO3 microparticles. The CaCO3 microparticles were studied by scanning electron microscopy, steady-state, and their biological activity was evaluated using in vitro cancer cell lines by trypan blue exclusion method. The intracellular localization of ClAlPc was examined by confocal microscopy. The CaCO3 microparticles obtained are uniform and homogeneously sized, non-aggregated, and highly porous microparticles. The calcium carbonate microparticles show an average size of 3 μm average pore size of about 30-40 nm. The phthalocyanine derivative loaded-microparticles maintained their photophysical behavior after encapsulation. The captured carriers have provided dye localization inside cells. The in vitro experiments with ClAlPc-loaded CaCO3 microparticles showed that the system is not cytotoxic in darkness, but exhibits a substantial phototoxicity at 3 μmol.L-1 of photosensitizer concentration and 10 J.cm-2 of light. These conditions are sufficient to kill about 80 % of the cells. All the performed physical-chemical, photophysical, and photobiological measurements indicated that the phthalocyanine-loaded CaCO3 microparticles are a promising drug delivery system for photodynamic therapy and photoprocesses.

TiO2 Nanoparticles Co-doped with Nitrogen and Fluorine as Visible-Light-Activated Antifungal Agents

Nanoparticles are widely used in photocatalytic degradation of toxic chemicals and photodynamic therapy of cells that involve light-induced generation of reactive oxygen species (ROS) followed by R...

Induction of ferroptosis by singlet oxygen generated from naphthalene endoperoxide

Singlet oxygen causes a cytotoxic process in tumor cells in photodynamic therapy (PDT) and skin photoaging. The mechanism responsible for this cytotoxicity is, however, not fully understood. 1-Methylnaphthalene-4-propionate endoperoxide (MNPE) is a cell-permeable endoperoxide that generates pure singlet oxygen. We previously reported that cell death induced by MNPE did not show the typical profile of apoptosis, and the cause of this cell death remains elusive. We report herein on an investigation of the mechanism for MNPE-induced cell death from the view point of ferroptosis. The findings indicate that the MNPE treatment decreased the viabilities of mouse hepatoma Hepa 1-6 cells in vitro, and that this decrease was accompanied by increases in the concentrations of both intracellular ferrous iron and the level of lipid peroxidation, but that the caspase-mediated apoptotic pathway was not activated. The intracellular levels of cysteine and glutathione were not affected by the MNPE treatment. Importantly, an assay of lactate dehydrogenase activity revealed that the cell death caused by MNPE was suppressed by ferrostatin-1, a ferroptosis-specific inhibitor. Collectively, these results strongly indicate that ferroptosis is the main cell death pathway induced by singlet oxygen.

Sensitive, Real-Time, and In-Vivo Oxygen Monitoring for Photodynamic Therapy by Multifunctional Mesoporous Nanosensors.

Real-time monitoring of oxygen consumption is beneficial to predict treatment responses and optimize therapeutic protocols for photodynamic therapy (PDT). In this work, we first demonstrate that deformable hollow mesoporous organosilica nanoparticles (HMONs) can be used to load [(Ru(dpp)3)]Cl2 for detecting oxygen (denoted as HMON-[(Ru(dpp)3)]Cl2). This nanoprobe shows significantly improved biocompatibility and high cellular uptake. In-vitro experiments demonstrate that the HMON-[(Ru(dpp)3)]Cl2 can sensitively detect oxygen changes between 1% and 20%. On this basis, photosensitizer chlorin e6 (Ce6) and [(Ru(dpp)3)]Cl2 are simultaneously loaded in the HMONs (denoted as HMON-Ce6-[(Ru(dpp)3)]Cl2) for real-time oxygen monitoring during photodynamic therapy. The HMON-Ce6-[(Ru(dpp)3)]Cl2 can reflects oxygen consumption in solution and cells in photodynamic therapy. Furthermore, the ability of the HMON-Ce6-[(Ru(dpp)3)]Cl2 nanosensor to monitor oxygen changes is demonstrated in tumor-bearing nude mice.

A novel pro-apoptotic role of zinc octacarboxyphthalocyanine in melanoma me45 cancer cell's photodynamic therapy (PDT)

Zn-based phthalocyanine acts as drug or photosensitizer in photodynamic therapy (PDT) for the treatment of cancer cells. The activated zinc octacarboxyphthalocyanine (ZnPcOC) reacts with oxygen, to generate reactive oxygen species for the damage of melanoma cancer cells, Me45. This in vitro study aimed at investigating the cytotoxic effects of different concentrations of ZnPcOC activated with a diode laser (λ = 685 nm) on Me45, and normal human fibroblast cells, NHDF. To perform this study 104 cells/ml were seeded in 96-well plates and allowed to attach overnight, after which cells were treated with different concentrations of ZnPcOC (10, 20 and 30 μM). After 4 h, cells were irradiated with a constant light dose of 2.5; 4.5 and 7.5 J/cm2. Post-irradiated cells were incubated for 24 h before cell viability was measured using the MTT viability assay. Data indicated that high concentrations of ZnPcOC (30 μM) in its inactive state are not cytotoxic to the melanoma cancer cells and normal fibroblasts. Moreover, the results showed that photoactivated ZnPcOC (30 μM) was able to reduce the cell viability of melanoma and fibroblast to about 50%, respectively. At this photosensitizing concentration the efficacy the treatment light dose of 2.5; 4.5 and 7.5 J/cm2 was evaluated against Me45 cells. ZnPcOC at a concentration of 30 μM activated with a light dose of 2.5; 4.5 and 7.5 J/cm2 was the most efficient for the killing of melanoma cancer cells. Melanoma cancer cells after PDT with a photosensitizing concentration of 30 μM ZnPcOC and a treatment light dose of 2.5; 4.5 and 7.5 J/cm2 showed certain pro-apoptotic characteristics, such as direct inducer (early apoptosis) and long-term inducer, also (late apoptosis). This concludes that low concentrations of ZnPcOC, activated with the appropriate light dose, can be used to induce cell death in melanoma cells via ROS-induces apoptosis pathway, what was confirmed with cytometric ROS measurements.Our in vitro study showed that ZnPcOC mediated photodynamic therapy is an effective treatment option for melanoma Me45 cancer cells. 30 μM of ZnPcOC with the treatment light dose of 2.5 J/cm2 from a LED diode laser source, with a wavelength of 685 nm, was adequate to destroy melanoma cancer cells via ROS-induced apoptosis pathway, with low killing effects on healthy NHDF normal fibroblasts.

Layer-by-layer hollow photosensitizer microcapsule design via a manganese carbonate hard template for photodynamic therapy in cells

Microcapsules fabricated using layer-by-layer self-assembly have unique properties, making them attractive for drug delivery applications. The technique has been improved, allowing the deposition of multiple layers of oppositely charged polyelectrolytes on spherical, colloidal templates. These templates can be decomposed by coating multiple layers, resulting in hollow shells. In this paper, we describe a novel drug delivery system for loading photosensitizer drugs into hollow multilayered microcapsules for photoprocess applications. Manganese carbonate particles were prepared by mixing NH4HCO3 and MnSO4 and performing consecutive polyelectrolyte adsorption processes onto these templates using poly-(sodium 4-styrene sulfonate) and poly-(allylamine hydrocholoride). A photosensitizer was also incorporated into the layers. Hollow spheres were fabricated by removing the cores in the acidic solution. The hollow, multilayered microcapsules were studied by scanning electron microscopy, steady-state, and time-resolved techniques. Their biological activity was evaluated in vitro with cancer cells using a conventional MTT assay. The synthesized CaCO3 microparticles were uniform, non-aggregated, and highly porous spheres. The phthalocyanine derivatives loaded in the microcapsules maintained their photophysical behaviour after encapsulation. The spectroscopic results presented here showed excellent photophysical behaviour of the studied drug. We observed a desirable increase in singlet oxygen production, which is favourable for the PDT protocol. Cell viability after treatment was determined and the proposed microcapsules caused 80% cell death compared to the control. The results demonstrate that photosensitizer adsorption into the CaCO3 microparticle voids together with the layer-by-layer assembly of biopolymers provide a method for the fabrication of biocompatible microcapsules for use as biomaterials.

Plasma membrane activatable polymeric nanotheranostics with self-enhanced light-triggered photosensitizer cellular influx for photodynamic cancer therapy

To address the issue of low cellular uptake of photosensitizers by cancer cells in photodynamic therapy (PDT), we designed a smart plasma membrane-activatable polymeric nanodrug by conjugating the photosensitizer protoporphyrin IX (PpIX) and polyethylene glycol (PEG) with glycol chitosan (GC). The as-prepared GC-PEG-PpIX can self-assemble into core-shell nanoparticles (NPs) in aqueous solution and the fluorescence of PpIX moieties in the inner core is highly quenched due to strong π–π stacking. Interestingly, when encountering plasma membranes, the GC-PEG-PpIX NPs can disassemble and stably attach to plasma membranes due to the membrane affinity of PpIX moieties, which effectively suppresses the self-quenching of PpIX, leading to significantly enhanced fluorescence and singlet oxygen (1O2) production upon laser irradiation. The massively produced 1O2 can compromise the integrity of the plasma membrane, enabling the influx of extracellular nanoagents into cells to promote cell death upon further laser irradiation. Through local injection, the membrane anchored GC-PEG-PpIX enables strong physical association with tumor cells and exhibits highly enhanced in vivo fluorescence at the tumor site. Besides, excellent tumor accumulation and prolonged tumor retention of GC-PEG-PpIX were realized after intravenous injection, which ensured its effective imaging-guided PDT.

Fluorescent periodic mesoporous organosilica nanoparticles dual-functionalized via click chemistry for two-photon photodynamic therapy in cells.

The synthesis of ethenylene-based periodic mesoporous organosilica nanoparticles for two-photon imaging and photodynamic therapy of breast cancer cells is described. A dedicated two-photon absorbing fluorophore possessing four triethoxysilyl groups and having large two-photon absorption in the near IR region, and azidopropyltriethoxysilane were incorporated into the structure. The mesoporous nanoparticles of 100 nm diameter were further functionalized by means of click chemistry with a propargylated fluorescent bromo-quinoline photosensitizer able to generate singlet oxygen. The photophysical properties and two-photon absorption properties of the nanoparticles were investigated evidencing complementary contribution of the two dyes. Both dyes contribute to the two-photon absorption response of the mesoporous nanoparticles while efficient FRET from the two-photon fluorophore to the quinoline sensitizer is observed. The dual-functionalized nanoparticles were incubated with MCF-7 breast cancer cells. Two-photon confocal imaging demonstrated the endocytosis of the nanoparticles within cancer cells. Moreover, brief two-photon irradiation (3 scans of 1.57 s) at 760 nm at high laser power (3 W) was shown to induce 40% of cancer cell death demonstrating the potential of the dual-functionalized mesoporous organosilica nanoparticles for two-photon photodynamic therapy.

Evaluation of Silicon Phthalocyanine 4 Photodynamic Therapy Against Human Cervical Cancer Cells In Vitro and in Mice.

Cervical cancer is the second most common cancer in women worldwide [1]. Photodynamic therapy has been used for cervical intraepithelial neoplasia with good responses, but few studies have used newer phototherapeutics. We evaluated the effectiveness of photodynamic therapy using Pc 4 in vitro and in vivo against human cervical cancer cells. CaSki and ME-180 cancer cells were grown as monolayers and spheroids. Cell growth and cytotoxicity were measured using a methylthiazol tetrazolium assay. Pc 4 cellular uptake and intracellular distrubtion were determined. For in vitro Pc 4 photodynamic therapy cells were irradiated at 667nm at a fluence of 2.5 J/cm2 at 48 h. SCID mice were implanted with CaSki and ME-180 cells both subcutaneously and intracervically. Forty-eight h after Pc 4 photodynamic therapy was administered at 75 and 150 J/cm2. The IC50s for Pc 4 and Pc 4 photodynamic therapy for CaSki and ME-180 cells as monolayers were, 7.6μM and 0.016μM and >10μM and 0.026μM; as spheroids, IC50s of Pc 4 photodynamic therapy were, 0.26μM and 0.01μM. Pc 4 was taken up within cells and widely distributed in tumors and tissues. Intracervical photodynamic therapy resulted in tumor death, however mice died due to gastrointestinal toxicity. Photodynamic therapy resulted in subcutaneous tumor death and growth delay. Pc 4 photodynamic therapy caused death within cervical cancer cells and xenografts, supporting development of Pc 4 photodynamic therapy for treatment of cervical cancer. Support: P30-CA47904, CTSI BaCCoR Pilot Program.

G-quadruplex/protoporphyrin IX-functionalized silver nanoconjugates for targeted cancer cell photodynamic therapy

A new type of G-quadruplex/protoporphyrin IX-functionalized silver nanoconjugate was prepared and used for the targeted photodynamic therapy of cancer cells via the specific interaction between AS1411 and the nucleolin on the cell surface.

Demethoxycurcumin induces autophagic and apoptotic responses on breast cancer cells in photodynamic therapy

Curcuminoids, including curcumin (CUR), demethoxycurcumin (DMC), and bisdemethoxycurcumin (BDMC), show the maximum absorption wavelength near blue light. Photodynamic therapy (PDT) has been developed as a therapeutic modality, which could induce cell death via the formation of ROS under illumination. Recently, it has been suggested that curcuminoids may be developed as potential photosensitizers. Here we found that curcuminoids-PDT significantly inhibited cell viability in breast cancer cell lines; in particular DMC-PDT has the highest anti-proliferative effect. A comprehensive analysis of cell response to DMC-PDT showed that autophagy was an early event and apoptosis was a late event. The generation of ROS by exciting the photosensitizer in PDT can activate MAPK pathway. Pre-treatment with a singlet oxygen scavenger or JNK inhibitor in DMC-PDT resulted in the reversion of cell viability, a reduced LC3 conversion and PARP cleavage. These results indicate that DMC may be considered as a new photosensitizer in PDT for cancer treatment.

Development of a new LDL-based transport system for hydrophobic/amphiphilic drug delivery to cancer cells

Low-density lipoproteins (LDL), a natural in vivo carrier of cholesterol in the vascular system, play a key role in the delivery of hydrophobic/amphiphilic photosensitizers to tumor cells in photodynamic therapy of cancer. To make this delivery system even more efficient, we have constructed a nano-delivery system by coating of LDL surface by dextran. Fluorescence spectroscopy, confocal fluorescence imaging, stopped-flow experiments and flow-cytometry were used to characterize redistribution of hypericin (Hyp), a natural occurring potent photosensitizer, loaded in LDL/dextran complex to free LDL molecules as well as to monitor cellular uptake of Hyp by U87-MG cells. It is shown that the redistribution process of Hyp between LDL molecules is significantly suppressed by dextran coating of LDL surface. The modification of LDL molecules by dextran does not inhibit their recognition by cellular LDL receptors and U-87 MG cellular uptake of Hyp loaded in LDL/dextran complex appears to be similar to that one observed for Hyp transported by unmodified LDL particles. Thus, it is proposed that dextran modified LDL molecules could be used as a basis for construction of a drug transport system for targeted delivery of hydrophobic/amphiphilic drugs to cancer cells expressing high level of LDL receptors.

Chemical determination of singlet oxygen from photosensitizers illuminated with LED: New calculation methodology considering the influence of photobleaching

Abstract The singlet oxygen ( 1 O 2 ) is one of the reactive species responsible for the destruction of target cells in Photodynamic Therapy (PDT). However, the quantification of 1 O 2 yields ( Φ Δ ) involves lifetime measurements with very expensive equipment. An alternative methodology is the use of a chemical trap, in the present case uric acid (UA), which promptly reacts with 1 O 2 providing the evaluation of Φ Δ . On the other hand, in the quantification of the photons absorbed by the PS employing LED as irradiation sources in this kind of experiments, it is important to evaluate the overlap of the light source in the PS spectrum. Additionally, while some PS are photostable, others may undergo photobleaching leading the amount of absorbed photons to vary with the illumination time due to PS degradation. The proposed methodology corrects this problem. The proposed dosimetry method employing UA and the absorbed photon calculations taking into account chlorophyll and xanthene dyes photobleaching resulted in Φ Δ values that agree with the literature.

Targeting cancer cells by using an antireceptor antibody-photosensitizer fusion protein

Antibody-photosensitizer chemical conjugates are used successfully to kill cancer cells in photodynamic therapy. However, chemical conjugation of photosensitizers presents several limitations, such as poor reproducibility, aggregation, and free photosensitizer impurities. Here, we report a fully genetically encoded immunophotosensitizer, consisting of a specific anti-p185(HER-2-ECD) antibody fragment 4D5scFv fused with the phototoxic fluorescent protein KillerRed. Both parts of the recombinant protein preserved their functional properties: high affinity to antigen and light activation of sensitizer. 4D5scFv-KillerRed showed fine targeting properties and efficiently killed p185(HER-2-ECD)-expressing cancer cells upon light irradiation. It also showed a remarkable additive effect with the commonly used antitumor agent cisplatin, further demonstrating the potential of the approach.

Water‐Soluble Self‐Assembled Butadiyne‐Bridged Bisporphyrin: A Potential Two‐Photon‐Absorbing Photosensitizer for Photodynamic Therapy

We have synthesized a novel, two-photon-absorbing photosensitizer for two-photon-absorption photodynamic therapy (2PA-PDT). The molecule is a butadiyne-bridged porphyrin dimer terminated with two water-soluble porphyrin monomers connected through Zn-imidazolyl self-assembly and covalently linked through olefin metathesis. It has an effective two-photon-absorption (2PA) cross-section value, sigma((2)), of 33 000+/-4600 GM with 5-ns pulses at 890 nm measured by using the open-aperture Z-scan technique. The compound was found to generate singlet oxygen, cytotoxic for tumor cells in photodynamic therapy (PDT), under 2PA conditions by conducting photobleaching experiments with anthracene-9,10-dipropionic acid sodium salt (ADPA).