New Generation Of Photosensitizers Research Articles

Atomically precise metal nanoclusters combine with MXene towards solar CO2 conversion.

Atomically precise metal nanoclusters (NCs) have been deemed a new generation of photosensitizers for light harvesting on account of their quantum confinement effect, peculiar atom-stacking mode, and enriched catalytic active sites. Nonetheless, to date, precise charge modulation over metal NCs has still been challenging considering their ultra-short carrier lifetime and poor stability. In this work, we conceptually demonstrate the integration of metal NCs with MXene in transition metal chalcogenide (TMC) photosystems via a progressive, exquisite, and elegant interface design to trigger tunable, precise and high-efficiency charge motion over metal NCs, stimulating a directional carrier transport pathway. In this customized ternary heterostructured photosystem, metal NCs function as light-harvesting antennas, MXene serves as a terminal electron reservoir, and the TMC substrate provides suitable energy level alignment for retracting photocarriers of metal NCs, giving rise to a spatial cascade charge transport route and markedly boosting charge separation efficiency. The interface configuration and energy level alignment engineering synergistically contribute to the considerably enhanced visible-light-driven photocatalytic CO2-to-CO reduction performance of the metal NCs/TMCs/MXene heterostructure. The intermediate active species during the photocatalytic CO2 reduction are unambiguously determined, based on which the photocatalytic mechanism is elucidated. Our work will provide an inspiring idea to bridge the gap between atomically precise metal NCs and MXene in terms of controllable charge migration for solar-to-fuel conversion.

Aspects of the interaction of pectin-coated Ag nanoparticles with methylene blue with regard to photodynamic applications

The promising future of photodynamic therapy has led to progress in the design of highly effective new-generation photosensitizers based on the combination of plasmonic metal nanoparticles and fluorescent molecules to kill cancer cells and bacteria. In this work, the details of the interaction of pectin-coated Ag nanocomposites (NCs) of different sizes (8, 10, 13, and 28 nm) and various types of pectin shells with the classical photosensitizer methylene blue (MB) were investigated. Pectin-Ag NCs were characterized by UV–vis spectroscopy, DLS, TEM, and XPS. The enhanced singlet oxygen generation effect of pectin-Ag@MB complexes was size-dependent (the smaller the size of the plasmonic particles, the higher the 1O2 generation) and associated with the local concentration of the dye in different molecular forms in the pectin shell of nanoparticles. In cell experiments, the pectin-Ag@MB complexes did not show enhanced phototoxicity or cellular uptake towards cancer cells, compared to free MB. The prolonged release of MB from the complex in a phosphate-buffered saline solution (pH 7.4) was observed. The amount of irreversibly bound MB depended on the type of pectin shell and equaled 1.13, 1.45, and 2.57 µg per mg pectin for Citrus25-Ag, Classic25-Ag, and Classic10-Ag NCs, respectively. The obtained physicochemical insights supplement the present understanding of the fundamental aspects of the interaction between plasmonic polymer-capped nanoparticles and MB and could be important for the rational design of new theranostic agents.

A dual therapeutic system based on corrole-siRNA conjugates.

Corrole molecules are a new generation of photosensitizers (PS) due to their ease of tunability for different medical applications. Their ability to initiate cellular death using a wide range of non-toxic wavelengths allows for the creation of non-invasive treatments. This work focuses on creating potent and non-invasive treatments by advancing siRNA therapeutics by directly conjugating siRNAs with the photosensitizer, corrole. Combining gene silencing with photodynamic therapy (PDT) creates a non-invasive dual therapy system. Basic synthetic designs were explored to create novel corrole-phosphoramidites and from these, a small library of corrole-functionalized short interfering RNAs (corrole-siRNAs) were synthesized. Corrole-siRNA conjugates showed promising results when evaluated for gene silencing and PDT therapy in vitro. Gene silencing effects were evaluated in cells by measuring the knockdown activity of the firefly luciferase reporter gene. Gene silencing studies from four siRNAs showed promising dose dependent knockdown with IC50s of 387.8, 77.8, 60.0, and 49.4 pM in the absence of red light, and 101.0, 57.2, 55.3, and 23.8 pM in the presence of red light. Furthermore, PDT showed approximately a 50% decrease in cell viability for red-light irradiated cells treated with corrole-siRNAs, demonstrating the effective role of corrole to act as a photosensitizer while still maintaining robust siRNA activity. In conclusion, corrole-siRNAs show a promising path for developing novel siRNA combination therapy.

New Generation of Photosensitizers Based on Inorganic Nanomaterials.

Advance of nanomaterials and nanotechnology has offered new possibilities for photodynamic therapy (PDT). Large amount of different kinds of sensitizers and targeting moieties can now be loaded in nanometer's volume, which not only results in the improvement of the efficacy of PDT, but also enables the control of image-guided PDT with unprecedented precision and variation. This chapter shall overview the recently most studied inorganic nanomaterials for PDT.

Rational Design of Near-Infrared-Absorbing Pt(II)-Chelated Azadipyrromethene Dyes as a New Generation of Photosensitizers for Synergistic Phototherapy

Pt(II) photosensitizers are emerging as novel Pt anticancer agents for cancer photodynamic therapy (PDT) to avoid uncontrollable toxicity of cisplatin. However, the application of Pt(II) photosensitizers is limited by tumor hypoxia and the poor penetration depth of excitation light. To overcome these drawbacks, exploiting the next generation of Pt anticancer agents is of urgent need. According to theoretical calculations, novel near-infrared (NIR)-absorbing Pt(II)-chelated azadipyrromethene dyes (PtDP-X, where X = N, C, and S) were designed. Importantly, spin-orbit coupling of the Pt atom could promote the intersystem crossing of a singlet-to-triplet transition for converting oxygen to singlet oxygen (1O2), and the azadipyrromethene skeleton could provide a strong photothermal effect. As expected, PtDP-X exhibited intense NIR absorption and synergistic PDT and photothermal effects with low dark cytotoxicity. Furthermore, water-soluble and biocompatible PtDP-N nanoparticles (PtDP-N NPs) were prepared that achieved effective tumor cell elimination with low side effects under 730 nm light irradiation in vitro and in vivo. This pioneering work could push the exploitation of NIR-absorbing metal-chelated azadipyrromethene dyes, so as to promote the positive evolution of phototherapy agents.

Anisotropy and Spectroscopic Properties of the Complexes of meso-Tetra(4-Carboxyphenyl)Porphyrin Molecules with Diamond Nanoparticles

The complexes of meso-tetra(4-carboxyphenyl)porphyrin with nanoscale diamonds were studied by spectroscopic methods. The polarization characteristics of their steady-state fluorescence indicate the formation of a covalently bound complex between porphyrin molecules and diamond nanoparticles. Using the data of steady-state fluorescence anisotropy, the hydrodynamic volumes of the studied complexes were estimated. The measurements showed that the photophysical properties of porphyrin barely change upon the formation of an organic–inorganic hybrid complex with nanodiamonds. The studied complexes can be promising in the field of biomedical research, in particular, in diagnosing and developing a new generation of photosensitizers for practical medicine.

A multilayered cancer-on-a-chip model to analyze the effectiveness of new-generation photosensitizers.

Three-dimensional (3D) cellular models of cancer tissue are necessary tools to analyze new anticancer drugs under in vitro conditions. Diagnostics and treatment of ovarian cancer are major challenges for current medicine. In our report we propose a new three-dimensional (3D) cellular model of ovarian cancer which can mimic a fragment of heterogeneous cancer tissue. We used Lab-on-a-chip technology to create a microfluidic system that allows cellular multilayer to be cultured. Cellular multilayer mimics the structure of two important elements of cancer tissue: flesh and stroma. For this reason, it has an advantage over other in vitro cellular models. We used human ovarian fibroblasts (HOF) and human ovarian cancer cells in our research (A2780). In the first stage of the study, we proved that the presence of non-malignant fibroblasts in co-culture with ovarian cancer cells stimulates the proliferation of cancer cells, which is important in the progression of ovarian cancer. In the next stage of the research, we tested the usefulness of the newly-developed cellular model in the analysis of anticancer drugs and therapies under in vitro conditions. We tested two photosensitizers (PS): free and nanoencapsulated meso-tetrafenylporphyrin, and we evaluated the potential of these drugs in anticancer photodynamic therapy (PDT) of ovarian cancer. We also studied the mechanism of PDT based on the analysis of the level of reactive oxygen species (ROS) in cell cultures. Our research confirmed that the use of new-generation PS can significantly increase the efficacy of PDT in the treatment of ovarian cancer. We also proved that the newly-developed 3D cellular model is suitable for rapid screening of anticancer drugs and has the potential to be used clinically in the future, e.g. in the selection of treatment methods for anticancer personalized medicine.

Hypocrellin B Encapsulated in Triphenyl Phosphonium-Modified Cationic Liposomes for Photodynamic Treatment of Exudative Age-Related Macular Degeneration.

Verteporfin photodynamic therapy (PDT) has been approved for the treatment of exudative age-related macular degeneration (AMD) for over a decade. However, its extensive application has been impeded by inevitably collateral tissue damage and immediate induction of angiogenesis, in addition to the need of multiple treatments. In order to develop prospective photosensitizers for clinical use, a triphenyl phosphonium-modified cationic liposomal hypocrellin B (TPP cationic LHB) for angiogenic targeting and endothelial internalization was constructed. With optimal PDT parameters, TPP cationic LHB can lead to death of choroid-retinal vascular endothelial cells while cause negligible damage to collateral retinal pigment epithelium cells. This is likely due to the mitochondria targeting and effective intracellular singlet oxygen generation of TPP cationic LHB in vascular endothelial cells. Additionally, in vivo chick chorioallantoic membrane assay indicated the elevated neovessel-targeting ability and photo-induced anti-angiogenic activity of TPP cationic LHB. Furthermore, TPP cationic LHB PDT is able to maintain neovessel occlusion for an extended period of time compared with verteporfin PDT, without inducing significant increased expression of some angiogenic factors, such as vascular endothelial growth factor and integrin αvβ₃. This study describes a facile strategy that may be useful for developing new-generation photosensitizers to circumvent the limitations of PDT treatment of exudative AMD.

In Situ Monitoring Apoptosis Process by a Self-Reporting Photosensitizer.

Although photodynamic therapy (PDT) has thrived as a promising treatment, highly active photosensitizers (PSs) and intense light power can cause treatment overdose. However, extra therapeutic response probes make the monitoring process complicated, ex situ and delayed. Now, this challenge is addressed by a self-reporting cationic PS, named TPE-4EP+, with aggregation-induced emission characteristic. The molecule undergoes mitochondria-to-nucleus translocation during apoptosis induced by PDT, thus enabling the in situ real-time monitoring via fluorescence migration. Moreover, by molecular charge engineering, we prove that the in situ translocation of TPE-4EP+ is mainly attributed to the enhanced interaction with DNA imposed by its multivalent positive charge. The ability of PS to provide PDT with real-time diagnosis help control the treatment dose that can avoid excessive phototoxicity and minimize potential side effect. Future development of new generation of PS is envisioned.

New Generation of Photosensitizers: The Conjugate of Folic Acid with Nanoparticles and Chlorine E6

Synthesis of chlorine e6 conjugates with diamond nanoparticles and folic acid. was developed. In the result of the conducted experimental investigations it was shown that chlorine e6 in a composition of chlorine e6-diamond nanoparticles-folic acid nanocomplex posess photodynamic activity, conjugated Che6 is capable of effective photosensitizing of necrotic death of tumor Hela cells in vitro at relatively low concentration and folic acid provides binding of the nanocomplex with cells expressing the folate receptor.

New Generation of Photosensitizers: Conjugates of Chlorin e 6 With Diamond Nanoparticles

Conjugates of chlorin e 6 with diamond nanoparticles were synthesized by two methods. The spectral and luminescent properties of the obtained conjugates were studied. It was shown that chlorin e 6 retained its photosensitizing activity in the conjugate. It was established that chlorin e 6 immobilized directly on diamond nanoparticles had higher photosensitizing activity than that conjugated using a spacer. It was observed that chlorin e 6 in the conjugate had higher photolytic stability than the free form.

GO/TiO2 Hybrid Nanoparticles as New Photosensitizers in Photodynamic Therapy of A375 Melanoma Cancer Cells

: Photodynamic therapy (PDT) by nanoparticles (NPs) has been proposed as a new emerging therapeutic approach for the treatment of melanoma. In this study, the researchers investigate potential of photodynamic graphene oxide (GO)/TiO2 hybrid (GOT) NPs as new photosensitizers (PSs) in A375 melanoma cancer cell line. The results showed that while different concentrations of GOT NPs (1 - 100 μg/mL) were inert, their irradiation with visible-light induced growth arrest and cell death in A375 cells in a dose-despondent manner. These anti-cancer effects were accompanied by significant morphological changes, suggesting GOT NPs have a potential for further evaluation as new generation of PSs for cancer therapy.

Evaluation of nanoencapsulated verteporfin’s cytotoxicity using a microfluidic system

A new-generation of nanoencapsulated photosensitizers could be a good solution to perform effective photodynamic therapy (PDT). In this paper, we present physicochemical characterization and cellular investigation of newly prepared long-sustained release oil-core polyelectrolyte nanocarriers loaded with verteporfin (nano VP) in relation to free VP. For this purpose, a macroscale multiwell plates and multifunctional microfluidic system (for three types of cell cultures: monoculture, coculture and mixed culture) were used. A physical analysis of nano VP showed its high stability, monodispersity with unimodal shape and highly positive charge, what made them good candidates for cancer treatment. Biological properties (cellular internalization and uptake as well as cytotoxicity) of nano and free VP were evaluated using both carcinoma (A549) and normal (MRC-5) human lung cells. It was investigated that verteporfin was accumulated in cancer cells preferentially. Low cytotoxicity of the tested photosensitizer was observed in both macro, and microscale. However, in experiments performed in the microsystem, nano VP allowed the reduction of cytotoxic effect, especially in relation to the normal cells. It could result from the specific environment of cell growth in the microsystem which can quite closely mimic the in vivo conditions. Our results suggest that the presented microsystem could be a very useful microtool for testing of new generation of photosensitizers in various configurations of cell cultures, which are difficult to perform in the macroscale. Moreover, the prepared nano VP could be successfully used for further research i.e. evaluation of PDT procedures.

Synthesis of Glycoconjugated Phthalonitriles for New Phthalocyanine-Based Photosensitizers

GRAPHICAL ABSTRACTExcellent photophysical and photochemical properties completed by magnificent take-up rates in malignant tissues attracted a great deal of interest to the application of glycosylated and glycoconjugated phthalocyanines in photodynamic therapy. In this study we describe the concise synthesis and full characterization of 16 differently 3,6-bisglycoconjugated phthalonitriles 3, 5, 6, 8, and 48–59, which are precursors for a new generation of photosensitizers, namely, nonperipheral glycoconjugated phthalocyanines. The first example for the synthesis of a nonperipheral glycoconjugated zinc phthalocyanine 60 from phthalonitrile 48 is also presented in this work.

Synthesis of Glycoconjugated Phthalonitriles for New Phthalocyanine-Based Photosensitizers

GRAPHICAL ABSTRACTExcellent photophysical and photochemical properties completed by magnificent take-up rates in malignant tissues attracted a great deal of interest to the application of glycosylated and glycoconjugated phthalocyanines in photodynamic therapy. In this study we describe the concise synthesis and full characterization of 16 differently 3,6-bisglycoconjugated phthalonitriles 3, 5, 6, 8, and 48–59, which are precursors for a new generation of photosensitizers, namely, nonperipheral glycoconjugated phthalocyanines. The first example for the synthesis of a nonperipheral glycoconjugated zinc phthalocyanine 60 from phthalonitrile 48 is also presented in this work.

A novel set of symmetric methylene blue derivatives exhibits effective bacteria photokilling - a structure-response study.

This study focuses on the structure-response relationship of symmetrically substituted phenothiazinium dyes. Four hydrophilic derivatives with the ability of additional hydrogen bonding (, ) or additional electrostatic interaction (, ) were synthesized, photophysically characterized and compared to the parent compound methylene blue (MB, ) and a lipophilic derivative () without additional coordination sites. Derivative was most effective against Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli reaching a maximum photodynamic efficacy of >5log10 steps (≥99.999%) of bacteria killing in 10 minutes (5 μM, 30 J cm(-2)) without inherent dark toxicity after one single treatment with the incoherent light source PDT1200 (λmax = 660 nm, 50 mW cm(-2)). Interestingly, one derivative with two additional primary positive charges () showed selective killing of Escherichia coli (5 μM, 30 J cm(-2), 4log10 steps inactivation (≥99.99%)) and no antimicrobial effect on Staphylococcus aureus. This might allow the development of a new generation of photosensitizers with higher antimicrobial efficacy and selectivity for future applications.

In vitro photodynamic inactivation of Candida albicans by phenothiazine dye (new methylene blue) and Indocyanine green (EmunDo®)

The application of a new generation of photosensitizers to increase the efficacy of antifungal photodynamic therapy (aPDT) is an important aspect of PDT. Thus, this in vitro study is aimed to evaluate the antifungal efficacy of the photo-elimination of Candida albicans with photothermal and antifungal photodynamic therapy. aPDT with new methylene blue and photothermal therapy with EmunDo® were applied to a fungal suspension, which was then subcultured in Sabouraud dextrose agar (SDA). The C. albicans colonies were counted and are expressed as colony-forming unit per milliliter (CFU/ml). aPDT with either EmunDo® or new methylene blue (NMB) considerably diminished the viability of inoculated C. albicans (P<0.001) by log reduction of 1.9 and 3.37, respectively, compared with the control group respectively, compared with the control group. The antifungal potency or dark toxicity of the two photosensitizers alone did not significantly differ (P=0.70). The same trend was observed for the light sources (λ: 810nm vs. λ: 630nm), which also did not significantly differ (P=0.78). The photo-elimination of C. albicans with either new methylene blue or EmunDo® as a photosensitizer can reduce the viability of fungal cells. Although the result of this study is encouraging, further investigations are warranted to determine clear protocols for the reliable and safe application of this method in clinical practice.

Improving photodynamic inactivation of bacteria in dentistry: highly effective and fast killing of oral key pathogens with novel tooth-colored type-II photosensitizers.

Increasing antibiotic resistances in microorganisms create serious problems in public health. This demands alternative approaches for killing pathogens to supplement standard treatment methods. Photodynamic inactivation of bacteria (PIB) uses light activated photosensitizers (PS) to generate reactive oxygen species immediately upon illumination, inducing lethal phototoxicity. Positively charged phenalen-1-one derivatives are a new generation of PS for light-mediated killing of pathogens with outstanding singlet oxygen quantum yield ΦΔ of >97%. Upon irradiation with a standard photopolymerizer light (bluephase C8, 1260 ± 50 mW/cm(2)) the PS showed high activity against the oral key pathogens Enterococcus faecalis, Actinomyces naeslundii, Streptococcus mutans, and Aggregatibacter actinomycetemcomitans. At a concentration of 10 μM, a maximum efficacy of more than 6 log10 steps (≥ 99.9999%) of bacteria killing is reached in less than 1 min (light dose 50 J/cm(2)) after one single treatment. The pyridinium substituent as positively charged moiety is especially advantageous for antimicrobial action.

Photodynamic biofilm inactivation by SAPYR—An exclusive singlet oxygen photosensitizer

Prevention and control of biofilm-growing microorganisms are serious problems in public health due to increasing resistances of some pathogens against antimicrobial drugs and the potential of these microorganisms to cause severe infections in patients. Therefore, alternative approaches that are capable of killing pathogens are needed to supplement standard treatment modalities. One alternative is the photodynamic inactivation of bacteria (PIB). The lethal effect of PIB is based on the principle that visible light activates a photosensitizer, leading to the formation of reactive oxygen species, e.g., singlet oxygen, which induces phototoxicity immediately during illumination. SAPYR is a new generation of photosensitizers. Based on a 7-perinaphthenone structure, it shows a singlet oxygen quantum yield ΦΔ of 99% and is water soluble and photostable. Moreover, it contains a positive charge for good adherence to cell walls of pathogens. In this study, the PIB properties of SAPYR were investigated against monospecies and polyspecies biofilms formed in vitro by oral key pathogens. SAPYR showed a dual mechanism of action against biofilms: (I) it disrupts the structure of the biofilm even without illumination; (II) when irradiated, it inactivates bacteria in a polymicrobial biofilm after one single treatment with an efficacy of ≥99.99%. These results encourage further investigation on the potential of PIB using SAPYR for the treatment of localized infectious diseases.

New aspects of photodynamic therapy for central type early stage lung cancer

and Objective Photodynamic therapy (PDT) has come to be considered as the first choice of treatment for central type early stage lung cancer (CELC). Recent advances in the ability to diagnose CELC, and in photosensitizers, as well as sophisticated clinical management, may improve the therapeutic outcome and expand the indications of PDT. We made the search for papers on PDT for lung cancer to select the most relevant articles. Based on this review and our recent data, we discussed the best available evidence for the diagnosis, the definition of indications, photosensitizers, and clinical management with regard to PDT. To obtain complete response (CR) by PDT, the selection of the indications is extremely important, including the extent of the tumor on the bronchial surface and the depth of invasion in the bronchial wall. The development of autofluorescence bronchoscopy (AFB) and endobronchial ultrasonography (EBUS) have had a large impact on diagnostic bronchoscopy for CELC. CELCs less than 1 cm in diameter showed a favorable cure rate by PDT, thus this is a good indication for PDT. The relatively newer photosensitizer NPe6, which has a stronger antitumor effect than Photofrin, showed similar treatment outcome even for large tumors >1.0 cm in diameter. Furthermore, comprehensive management including photodynamic diagnosis before and after PDT should be effective to minimize the possibility of local recurrence after PDT. The present guidelines of PDT for CELC were established based on the data obtained from studies in the 1980's. We postulate that comprehensive diagnosis and the new generation of photosensitizers may increase the CR rate and expand the indications of PDT for larger tumors.