Photodynamic Efficiency Research Articles

Luminescence imaging-guided triple-collaboratively enhanced photodynamic therapy by bioresponsive lanthanide-based nanomedicine

Photodynamic therapy (PDT) provides a novel sight for non-invasive tumor ablation, which, however, is still limited by low converting efficiency and short life-time of produced singlet oxygen. In this work, a bioresponsive lanthanide-based nanomedicine, FeOOH-coated and toluidine blue (TB)-loaded NaLuF4:Yb,Er,Tm@NaLuF4, is constructed for tumor microenvironment-activated photodynamic therapy with triple-collaborative enhancing strategy. In response to intratumoral reducibility and acidity, coated FeOOH decomposes, eliminating reduced glutathione (GSH) and up-regulating intratumoral oxidative stress to enhance PDT. Besides, Fe2+ is also released from this redox process, which can improve intratumoral dissolved O2 for PDT by catalytic decomposition of H2O2. Lastly, quenched upconversion luminescence of lanthanide-doped nanoparticles also recovers, which allows more efficient energy transfer to TB and hence improves PDT efficiency. By the above triple-collaborative strategy, highly efficient photodynamic tumor ablation is performed in vivo. This work proposes a rigorous method to elevate photodynamic therapeutic efficiency.

Lipid monolayer as a simple model membrane for comparative assessment of the photodynamic therapy photosensitizer efficiency via macroscopic measurements

Cellular membrane is one of the main targets of photodynamic therapy. Its high complexity has led to the study of the efficiency of photosensitizers on artificial lipid systems mimicking membranes. However, the preliminary analysis of this efficiency remains limited due to difficulty of the model construction and/or implementation of the required measurement techniques. Hereby, we propose a quite simple way for the rapid comparative assessment of novel photosensitizers in terms of membrane photodegradation, based on simple and fast measurements, such as wetting angle and surface plasmon resonance spectroscopy. As a proof of concept, we applied this methodology to two bacteriopurpurinimide derivatives. We have shown in particular that such complementary techniques can be employed not only for the multiparametric monitoring of the kinetics of the photodegradation, but also for the comparison of the damaging efficiency of the photosensitizers in the lipid structures as well.

Antimicrobial Photodynamic Therapy in the Control of Pseudomonas syringae pv. actinidiae Transmission by Kiwifruit Pollen.

Pseudomonas syringae pv. actinidiae (Psa) is a phytopathogen responsible for bacterial canker in kiwifruit plants and can be disseminated through pollen. This study aimed to evaluate the effectiveness of antimicrobial photodynamic therapy (aPDT) in the inactivation of Psa on kiwifruit pollen using New Methylene Blue (NMB) and Methylene Blue (MB) in the presence/absence of potassium iodide (KI). Pollen germination assays were also performed to evaluate if it was affected by aPDT. Higher reduction of Psa was achieved using NMB (5.0 μM) combined with KI (100 mM) in vitro (ca. 8 log CFU mL−1 after 90 min of irradiation), while NMB alone promoted a lower reduction (3.7 log CFU mL−1). The most efficient NMB concentration with KI was used to study the photodynamic efficiency of MB (5.0 μM). MB with KI photo-inactivated Psa more efficiently than NMB, causing the same bacterial reduction (ca. 8 log CFU mL−1) in half the irradiation time (45 min). Therefore, MB was selected for the subsequent ex vivo aPDT assays in pollen. Almost all the Psa cells added artificially to the pollen (3.2 log CFU mL−1) were photo-inactivated (3.1 log CFU mL−1), whereas aPDT had a low effect on pollen natural microorganisms. When KI was added, a significant increase in aPDT effectiveness was observed (4.5 log CFU mL−1). No negative effects were observed in the pollen germination after aPDT. The results show aPDT is an effective and safe method to Psa inactivation on kiwifruit pollen, and MB use is a promising alternative in the control of Psa transmission.

Investigation of LED-based photodynamic therapy efficiency on breast cancer cells.

Photodynamic therapy (PDT) is based on special light source, photosensitizer (PS), and in the presence of oxygen. Different light sources have been used for PDT applications. Recent studies have focused on LED light sources for PDT applications due to reducing the cost of laser-based PDT and providing easy access for research laboratory or clinic facilities. LED-mediated PDT applications have shown promising results for the treatment of different types of disease. However, few studies have determined the effects of LED-based PDT on cancer cells. For the first time, the aim of this study was to explore the therapeutic effects of 5-aminolevulinic acid (5-ALA)-mediated PDT after LED irradiation on two sub-types (a poorly aggressive MCF-7 and a highly aggressive MDA-MB-231) of breast cancer cell lines. The effectiveness of 5-ALA PDT treatment was evaluated by WST-1, annexin V, and acridine orange staining with different energy levels. The LED system was specially developed with optical power and wavelength stability techniques. The system consists of user interface and embedded LED controller with real-time optic power output calibration by photodiode feedback. Our results demonstrated that the cell viability of breast cancer cells was considerably decreased a LED dose-dependent manner (P < 0.05). Additionally, a significant increase in the percentage of apoptotic cells was detected in breast cancer cells after irradiation with LED at a density of 18 and 30 J/cm2 energy. Consequently, the LED system could be effectively used for irradiation of 5-ALA in the treatment of breast cancer cells.

Porphyrin-Loaded TyroSpheres for the Intracellular Delivery of Drugs and Photoinduced Oxidant Species.

In order to understand the intracellular delivery of drugs and to improve the cell killing efficiency of photosensitizers (PSs) used in photodynamic therapy (PDT), we prepared TyroSphere nanoparticles, which are triblock polymer [poly(ethylene glycol)-block-oligo(desaminotyrosyltyrosine octyl ester suberate)-block-poly(ethylene glycol)] aggregates, loaded with amphiphilic porphyrins with either positive (CisDiMPyP) or negative (TPPS2a) charges. Their physicochemical and photochemical properties were investigated, as well as the efficiency and mechanism of PDT death in a cervical cancer cell line (HeLa). The photophysical properties of both PSs were improved when loaded in the nanocarrier, with a decrease in aggregation as well as an increase in the yield of singlet oxygen generation. The physical and chemical stability of TyroSphere nanoparticles allows them to enter cells and to promote the slow intracellular delivery of part of the PSs. Confocal steady-state and lifetime-resolved fluorescence imaging microscopy data showed that the released PSs are free to target their natural intracellular targets, which are mitochondria and lysosomes for CisDiMPyP and TPPS2a, respectively. The photodynamic efficiency of cell killing was increased considerably compared with the free PSs (∼3×), but the mechanism of cell death was the same as that of the free PSs, which are acute necro-apoptosis for CisDiMPyP and autophagy malfunction for TPPS2a, reflecting the specific damage in mitochondria and lysosomes, respectively. We are confident that TyroSpheres provide a novel and efficient platform to administrate PDT photosensitizers, as well as other drugs with intracellular targets.

Assemblies of indocyanine green and chemotherapeutic drug to cure established tumors by synergistic chemo-photo therapy

Indocyanine green (ICG), a safe and clinically approved near-infrared (NIR) dye, was recently explored as a potential photosensitizer due to its excellent photophysical properties. However, ICG tends to form aggregations in physiological solution, causing fluorescence quenching, fast blood clearance and thereby inefficient tumor accumulation. Herein, we report ICG-based nanodrug delivery systems formed by self-assembly of ICG and chemotherapeutic drugs without any excipients for combined chemo- and photo-therapy. Taking advantage of the amphiphilic aromatic structure, ICG readily bounded with hydrophobic aromatic drugs such as SN38 and formed well-dispersible nanoparticles, which reduced its aggregation-induced quenching and thus greatly improved its photodynamic efficiency. The loaded hydrophobic drugs elicited chemotherapy synergizing the photodynamic therapy, giving rise to much enhanced antitumor activity in vitro and in vivo against human glioblastoma cells and breast cancer cells upon NIR irradiation. The work demonstrates the fabrication of readily translational nanoformulations of hydrophobic drugs using amphiphilic drugs.

Engineering and biological assessment of double core nanoplatform for co-delivery of hybrid fluorophores to human melanoma

We investigated new development in photodynamic therapy (PDT), aiming at enhanced tumor selectivity and biocompatibility, which included application of a third-generation photosensitizing agent, i.e. xanthene-origin Rose Bengal (RB) co-encapsulated with up-converting NaYF4 nanoparticles (NPs) co-doped with lanthanide ions: Er3+ (2%) and Yb3+ (20%). The hybrid fluorophores were applied as components of double core nanocarriers (NCs) obtained by double (multiple) emulsion solvent evaporation process. Next, to improve the biocompatibility and photodynamic activity, biodegradable polymer: poly(lactide-co-glycolide) – PLGA and non-ionic surfactants with different hydrophobicity: Span 80 and Cremophor A25, were used. After the engineering process, controlled by dynamic light scattering (DLS) measurements, ζ-potential evaluation, transmission electron and atomic force microscopy (TEM and AFM) imaging, as well as optical analysis provided by measurements of the up-conversion emission spectra and luminescence kinetics for encapsulated only NaYF4:Er3+,Yb3+ NPs and co-encapsulated RB + NaYF4:Er3+,Yb3+ molecules, spherical polyester NCs with average size <200 nm, were tested on human melanoma (Me-45 and MeWo) cells and a control human keratinocyte (HaCaT) cell line. The photodynamic action of the investigated NCs was assessed by oxidoreductive potential measurements with 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, that corresponds to percentage of the viable cells. Immunofluorescence and the NCs internalization studies were visualized by confocal laser scanning microscopy (CLSM studies). Our results indicated effective photosensitizer delivery into the cancer cells and significant photodynamic efficiency enhanced by the near infrared (NIR)-activation of the encapsulated hybrid cargo in the skin melanoma cells.

Photocyanine: A novel and effective phthalocyanine-based photosensitizer for cancer treatment

As one of the three key components of photodynamic therapy (PDT), photosensitizers (PSs) greatly influence the photodynamic efficiency in the treatment of tumors. Photosensitizers with tetrapyrrole structure, such as porphyrins, chlorins and phthalocyanines, have been extensively investigated for PDT and some of them have already received clinical approval. However, only a few of porphyrin-based photosensitizers are available for clinical applications, and PDT has not received wide recognition in clinical practice. In this regard, PSs remain a limiting factor. Our research focuses on the rational design of new PSs. Photocyanine, a Zinc (II) phthalocyanine (ZnPc) type photosensitizer with low dark toxicity and high single oxygen quantum yield, is one of the promising PSs candidates and currently being tested in clinical trials. Here, we present an overview on the development of Photocyanine, including its design, synthesis, purification, characterization and preclinical studies, wishing to contribute to the research of more promising PSs.

Synthesis of Water-Soluble Thioglycosylated trans-A2B2 Type Porphyrins: Cellular Uptake Studies and Photodynamic Efficiency.

The synthesis of water-soluble thioglycosylated A2B2 type porphyrins and their zinc(II) complexes is reported. The water-soluble trans-A2B2 porphyrins were synthesized in two steps, via [2+2] condensation between thioglycosylated dipyrromethanes and aromatic aldehydes in 15-21% yields. The thioglycosylated trans-A2B2 porphyrins showed decent in vitro singlet oxygen generation, which was supported by the intracellular DCFDA study. The in vitro cellular investigations of thioglycosylated A2B2 porphyrins were carried out in lung cancer cells (A549) to test their photodynamic therapeutic (PDT) activity. The PDT study revealed significant cytotoxicities of porphyrins with IC50 values between 23.3 and 44.2 μM in the dark, whereas, after visible light exposure, the photosensitizers exhibited IC50 values around 11.1-23.8 μM. The water-soluble thioglycosylated zinc(II) porphyrins having two meso-N-butylcarbazole groups exhibited an excellent degree of photocytotoxicity (IC50 = 4.6-8.8 μM). The flow cytometry analysis revealed that cellular uptake and ROS (reactive oxygen species) generation efficiency of water-soluble thioglycosylated zinc(II) porphyrins were considerably higher than nonmetalated porphyrins. Confocal microscopy images displayed substantial distribution in the endoplasmic reticulum with partial colocalization in mitochondria and lysosomes of water-soluble thioglycosylated zinc(II) porphyrins in A549 cells.

Imprinting Pentaphyrin on Conductive Electropolymerized Dipyrromethane Films: A New Strategy towards the Synthesis of Photokilling Materials

We report herein the synthesis and photoinduced bactericidal activity of two new polymeric materials, obtained by imprinting the photosensitizer 20-(4-carboxyphenyl)-2,13-dimethyl-3,12-diethyl-[22]pentaphyrin (PCox, 1) into suitable electropolymerized dipyrromethane films. 5-Phenyl-dipyrromethane (5-ph-DP) and 5-(4-pyridyl)dipyrromethane (5-py-DP) have been selected as the monomers for the synthesis of the materials in order to assess the correlation between the substituent in C5 and the capability in Pcox uptake. Both films have been tested in their photokilling ability toward Staphylococcus aureus by using a multi-LED blue lamp at a fluence rate of 40 W/m2 . Poly-5-py-DP/PCox, with a PCox load of 10-8 mol/cm2 , achieved a 4-log reduction in microbial viability after 60 min of irradiation. The polymeric films proved to be stable over time and under oxidation conditions; in addition, no loss of photosensitizer was observed during the experiments, thus demonstrating that the bactericidal action was effectively brought by the ROS generated by PCox immobilized in the material. After use, the films were recharged with PCox, with almost complete recovery of their photodynamic efficiency.

An insight into the synthesis of cationic porphyrin-imidazole derivatives and their photodynamic inactivation efficiency against Escherichia coli

New porphyrin-imidazole derivatives were synthesised by Radziszewski reaction between 2-formyl-5,10,15,20-tetraphenylporphyrin 1 and several (hetero)aromatic 1,2-diones, which after cationization afforded promising monocationic photosensitizers 3a-d. Singlet oxygen studies have demonstrated that all the cationic porphyrin-imidazole conjugates 3a–d were capable to produce cytotoxic species. These photosensitizers were able to photoinactivate Eschericha coli and their inactivation profile was improved in the presence of KI.

Self-Tracking Multifunctional Nanotheranostics for Sensitive miRNA Imaging Guided Photodynamic Therapy.

A theranostic system that enables monitoring the delivery process and amplified detection of low-abundance biomarkers is significant for bioimaging and biomedicine. We here develop a graphitic carbon nitride (g-C3N4) nanosheet based self-tracking multifunctional nanotherapeutic system for sensitive miRNA guided photodynamic therapy in living cells. The g-C3N4 nanosheets are employed not only as a nanocarrier for an intracellular hybridization chain reaction for sensitive miRNA imaging but also as an excellent photosensitizer for tumor therapy. Moreover, the fluorescent g-C3N4 nanosheets allow assessing the transfection efficiency to mitigate the false negative signals. In vitro experiments showed that the proposed strategy had high signal amplification efficiency. The live cell studies revealed that the g-C3N4@H1/H2 could distinguish different miRNA expression levels from tumor to normal cells. The cell viability assay demonstrated the good photodynamic therapy efficiency of g-C3N4@H1/H2. Therefore, the developed self-tracking multifunctional nanotheranostics hold great potential for biomarker detection and imaging guided photodynamic therapy in living cells.

Near-Infrared Fluorescent pH Responsive Probe for Targeted Photodynamic Cancer Therapy

We developed a pH dependent amino heptamethine cyanine based theranostic probe (I2-IR783-Mpip) that can be activated by near infrared light. I2-IR783-Mpip, in acidic condition, exhibited an intense, broad NIR absorption band (820–950 nm) with high singlet oxygen generation upon exposure to NIR light (~850 nm). Theoretical calculations showed that the protonation of the probe in an acidic environment decreased the molecular orbital energy gaps and increased the intramolecular charge transfer efficiency. I2-IR783-Mpip exhibited good photodynamic efficiency towards liver hepatocellular carcinoma cells under physiological and slightly acidic conditions while normal human embryonic kidney cells remained alive under the same conditions. Detection of intracellular reactive oxygen species (ROS) in cells treated with I2-IR783-Mpip after NIR light exposure confirmed PDT efficiency of the probe in acidic environment. Moreover, I2-IR783-Mpip also demonstrated efficient phototoxicity under deep-seated tumour cell system. We believed this is the first PDT agent that possesses intrinsic tumour binding and selectively eradicate tumour in acidic environment under 850 nm NIR lamp.

Enhanced photodynamic therapy and fluorescence imaging using gold nanorods for porphyrin delivery in a novel in vitro squamous cell carcinoma 3D model.

Nanocomposites of gold nanorods (Au NRs) with the cationic porphyrin TMPyP (5,10,15,20-tetrakis(1- methyl 4-pyridinio)porphyrin tetra(p-toluenesulfonate)) were investigated as a nanocarrier system for photodynamic therapy (PDT) and fluorescence imaging. To confer biocompatibility and facilitate the cellular uptake, the NRs were encapsulated with polyacrylic acid (PAA) and efficiently loaded with the cationic porphyrin by electrostatic interaction. The nanocomposites were tested with and without light exposure following incubation in 2D monolayer cultures and a 3D compressed collagen construct of head and neck squamous cell carcinoma (HNSCC). The results showed that Au NRs enhance the absorption and emission intensity of TMPyP and improve its photodynamic efficiency and fluorescence imaging capability in both 2D cultures and 3D cancer constructs. Au NRs are promising theranostic agents for delivery of photosensitisers for HNSCC treatment and imaging.

In the Right Light: Photodynamic Inactivation of Microorganisms Using a LED-Based Illumination Device Tailored for the Antimicrobial Application

Drug-resistant bacteria threaten the health of people world-wide and cause high costs to their health systems. According to Scientific American, the number of regrettable fatalities due to the bacteria that are resistant to conventional antibiotics will sum up to 300 million until 2050 if the problem is not tackled immediately. Photodynamic Inactivation (PDI) has proven effective against microorganisms irrespective of their resistance to conventional treatment, but for the translation into clinical practice, economic, homogenous and powerful light sources holding approval as medical devices are needed. In this study we present two novel light emitting diode (LED)-based lamps (Repuls7PDI-red and Repuls7PDI-blue) tailored for application in PDI and demonstrate their photodynamic efficiency upon using either methylene blue (MB), a photoactive compound widely used in PDI, or Sodium Magnesium Chlorophyllin (CHL), a water-soluble derivative of chlorophyll, which holds approval as food additive E140, against bacteria and fungi. Gram+ Staphylococcus aureus, Gram− Escherichia coli and the yeast Candida albicans serve as model systems. Repuls7PDI-red emits a wavelength of 635 nm and an intensity of 27.6 ± 2.4 mW·cm−2 at a distance of 13.5 cm between the light source and the target, while the Repuls7PDI-blue allows an exposure at 433 nm (within the range of violet light) (6.4 ± 0.5 mW·cm−2 at 13.5 cm). Methylene blue was photoactivated with the Repuls7PDI-red at 635 nm (25.6 J·cm−2) and allows for photokilling of E. coli by more than 6 log10 steps at a concentration of 10 µM MB. Using equal parameters, more than 99.99999% of S. aureus (20 µM MB) and 99.99% of C. albicans (50 µM MB) were killed. If blue light (Repuls7PDI-blue, 433 nm, 6.6 J·cm2) is used to trigger the production of reactive oxygen species (ROS), a photoinactivation of S. aureus (5 µM CHL, CFU reduction > 7 log10) and C. albicans (>7 log10) below the detection limit is achieved. PDI based on CHL (10 µM) using red light activation reduces the number of viable S. aureus by more than 6 log10. Our data prove that both LED-based light sources are applicable for Photodynamic Inactivation. Their easy-to-use concept, high light output and well-defined wavelength might facilitate the translation of PDI into clinical practice.

Boosting the photodynamic therapy efficiency by using stimuli-responsive and AIE-featured nanoparticles

Photosensitizers with aggregation-induced emission (AIE) characteristics are of great interest for cancer theranostics involving both fluorescence imaging and photodynamic therapy (PDT). However, in the purpose of clinical trials of PDT, the development of prominent drug delivery systems for boosting the PDT efficiency of AIE photosensitizers is highly desirable but still remain a challenging task. Herein, a novel strategy is designed and performed for boosting PDT effect based on stimuli-responsive nano-micelles as extraordinary carriers for an AIE photosensitizer, namely MeTTMN. Those presented stimuli-responsive nano-micelles loading MeTTMN exhibit good biocompatibility, excellent stability, appropriate nanoparticle size, high loading efficiency, outstanding imaging quality and significantly promoted PDT performance, eventually making them remarkably impressive and significantly superior to commercially available nano-micelles carried MeTTMN. This study thus offers an ideal template for fluorescence imaging-guided PDT, as well as a promising candidate for clinical trials.

Lipid Membrane Adsorption Determines Photodynamic Efficiency of β-Imidazolyl-Substituted Porphyrins.

Photosensitizers (PSs) represent a group of molecules capable of generating reactive oxygen species (ROS), such as singlet oxygen (SO); thus, they are considered to be promising agents for anti-cancer therapy. The enhancement of the photodynamic efficiency of these compounds requires increasing the PS activity in the cancer cell milieu and exactly at the target cells. In the present work, we report the synthesis, lipid membrane binding and photodynamic activity of three novel cationic PSs based on β-imidazolyl-substituted porphyrin and its Zn(II) and In(III) complexes (1H2, 1Zn and 1In). Comparison of the behavior of the investigated porphyrins at the bilayer lipid membrane (BLM) demonstrated the highest adsorption for the 1In complex and the lowest one for 1Zn. The photodynamic efficiency of these porphyrins was evaluated by determining the oxidation rate of the styryl dye, di-4-ANEPPS, incorporated into the lipid membrane. These rates were proportional to the surface density (SD) of the porphyrin molecules at the BLM and were roughly the same for all three porphyrins. This indicates that the adsorption of these porphyrins at the BLM determines their photodynamic efficiency rather than the extinction or quantum yield of singlet oxygen.

Effect of PVP formulation on the in vitro photodynamic efficiency of a photosensitizing phthalocyanine

The administration of photosensitizers and their biocompatibility is crucial to the success of photodynamic therapy treatment. Amongst the various strategies developed to administer photosensitizers of low water-solubility, the use of polyvinylpyrrolidone (PVP), an FDA-approved food additive, is emerging as extremely promising. Its effect on photodynamic outcome was compared to more classical formulation in DMSO and direct solubilization in water. The tetrakis (2-(2-(2-methoxyethoxy)ethoxy)ethoxy)-Zn(II) phthalocyanine chosen as the model photosensitizer for this study proved to be a powerful photosensitizer. Even if slightly less efficient than DMSO formulation, PVP formulation proved to work very well, with submicromolar IC50 and IC90 values against MDA-MB-231 human cancer cells.

Photodynamic Anti-Tumor Efficiency of Hematoporphyrin Derivative

Photodynamic therapy (PDT) is an emerging non-invasive treatment based on a combination of photochemistry and photophysics. PDT has more advantages compared with traditional...

Ultrafast discrimination of Gram-positive bacteria and highly efficient photodynamic antibacterial therapy using near-infrared photosensitizer with aggregation-induced emission characteristics

With the increase of bacterial infections in clinical practice, it becomes a public health problem which has aroused worldwide attention. Fluorescence imaging-guided photodynamic antibiosis has recently emerged as a promising protocol to solve this problem. However, developing a super powerful fluorescent material allowing facile preparation, long emission wavelength, rapid bacterial discrimination, washing-free staining, and high photodynamic antibacterial efficiency in a single entity, is highly desirable but remains challenging. In this study, we utilize for the first time a water-soluble near-infrared (NIR) emissive luminogen with aggregation-induced emission (AIE) characteristics, namely TTVP, for simultaneous dual applications of Gram-positive bacteria discrimination and photodynamic antibiosis. TTVP is able to selectively target Gram-positive bacteria over Gram-negative bacteria through a washing-free procedure after only 3 s incubation period, which is at least 100-fold shorter than those of previously reported protocols, implying ultrafast bacterial discrimination features. Meanwhile, TTVP exhibits extremely high reactive oxygen species generation efficiency, which is far superior to that of most popularly used photosensitizers, representing one of the best candidates for photodynamic antibiosis. In vitro and in vivo results demonstrate that TTVP provides extraordinary performance on photodynamic antibacterial therapy. This study thus offers a blueprint for the next generation of antibacterial materials.