Spectroscopic studies of photobleaching and photoproduct formation of meta(tetrahydroxyphenyl)chlorin (m-THPC) used in photodynamic therapy. The production of singlet oxygen by m-THPC

Photodynamic inactivation of methicillin-resistant Staphylococcus aureus by using Giemsa dye as a photosensitizer

The rise of antibiotic-resistant bacteria calls for innovative approaches to combat multidrug-resistant strains. Here, the potential of the standard histological stain, Giemsa, to act as a photosensitizer (PS) for antimicrobial photodynamic inactivation (aPDI) against methicillin-sensitive Staphylococcus aureus (MSSA) and methicillin-resistant Staphylococcus aureus (MRSA) strains is reported. Bioassays were performed using various Giemsa concentrations (ranging from 0.0 to 20.0 µM) under 625 nm illumination at a light dose of 30 J cm-2. Remarkably, Giemsa completely inhibited the growth of MSSA and MRSA bacterial colonies for concentrations at 10 µM and higher but exhibited no inhibitory effect without light exposure. Partition coefficient analysis revealed Giemsa's affinity for membranes. Furthermore, we quantified the production of reactive oxygen species (ROS) and singlet oxygen (1O2) to elucidate the aPDI mechanisms underlying bacterial inactivation mediated by Giemsa. These findings highlight Giemsa stain's potential as a PS in aPDI for targeting multidrug-resistant bacteria.

C60 adduct with L-arginine as a promising nanomaterial for treating cerebral ischemic stroke

The work aimed to investigate the biocompatibility and biological activity of the water-soluble fullerene adduct C60-Arg. It was found that the material is haemocompatible, is not cyto- and genotoxic, possesses pronounced antioxidant activity. Additionally, this paper outlines the direction of application of water-soluble fullerene adducts in the creation of neuroprotectors. It has been suggested that a putative mechanism of the protective action of the C60-Arg adduct is associated with its antioxidant properties, the ability to penetrate the blood-brain barrier, and release nitrogen monoxide as a result of the catabolism of L-arginine residues, which promote vascular relaxation. The action of the C60-Arg adduct was compared with the action of such an antioxidant as Edaravone, which is approved in Japan for the treatment of ischemic and haemorrhagic strokes.

Analysis of Radachlorin localization in living cells by fluorescence lifetime imaging microscopy

Intracellular localization of photosensitizer molecules is influential on cell death pathway at photodynamic treatment and is thus an important aspect in achieving enhanced efficacy of photodynamic therapy. In this paper we performed thorough studies of the distribution of Radachlorin photosensitizer in three established cell lines: HeLa, A549, and 3T3 with fluorescence lifetime imaging microscopy through the analysis of lifetime distributions. Experiments carried out in Radachlorin solutions in phosphate buffered saline revealed the pronounced dependence of the fluorescence quantum yield and lifetime on solution pH. This finding was used for analysis of lifetime images of living cells and their phasor plot representations and allowed us to suggest that Radachlorin localized predominantly in lysosomes, known to have acidic pH values. Experiments on co-localization of Radachlorin fluorescence lifetimes and LysoTracker fluorescence intensity supported this suggestion. The results obtained show that the inhomogeneity of fluorescence quantum yield within a cell can be significant due to lower pH values in lysosomes than in other intracellular compartments. This finding suggests that the actual amount of accumulated Radachlorin can be underestimated if being evaluated solely by comparison of fluorescence intensities.

Synchronized Microbubble Photodynamic Activation to Disinfect Minimally Prepared Root Canals

INTRODUCTION

The purpose of this study was to evaluate the antimicrobial efficacy of a novel irrigation strategy using synchronized microbubble photodynamic activation (SYMPA) in a minimally prepared single canal.

METHODS

Single-canal mandibular incisors were inoculated with Enterococcus faecalis for 3 weeks and randomly allocated to 4 groups based on the irrigation protocols: (1) control (saline), (2) conventional needle irrigation (CI), (3) ultrasonic-assisted irrigation (UI), and (4) irrigation with SYMPA. The first 3 groups were instrumented to size 25.07v (WaveOne Gold Primary; Dentsply Sirona, Johnson City, TN), and the SYMPA group was minimally prepared to size 20.07v (WaveOne Gold Small, Dentsply Sirona). The apical 5 mm was resected for microbiological assessment using the culture technique (colony-forming unit), adenosine-5'-triphosphate-based viability assay (relative luminescence units), and the percentage of live bacteria using confocal laser scanning microscopy.

RESULTS

Log colony-forming units from the UI (2.37 ± 0.66) and SYMPA (2.21 ± 0.86) groups showed a reduction compared with the control (5.16 ± 0.75) and CI (4.08 ± 1.19) groups. Relative luminescence unit reduction was significant for UI (619.08 ± 352.78) and SYMPA (415.25 ± 329.51) compared with the control (1213.2 ± 880.03) (P < .05). The percentage of live bacteria was significantly lower in the UI and SYMPA groups compared with the control and CI groups. Although higher microbial reduction was observed in SYMPA compared with UI, there was no statistical significance (P > .05).

CONCLUSION

SYMPA in minimally prepared canals showed significant antimicrobial efficacy. The novel irrigation strategy using SYMPA could be an effective disinfection strategy for minimally prepared root canals.

Comparative Analysis of Tetra(2-naphthyl)tetracyano-porphyrazine and Its Iron Complex as Photosensitizers for Anticancer Photodynamic Therapy

Photodynamic therapy (PDT) is a rapidly developing modality of primary and adjuvant anticancer treatment. The main trends today are the search for new effective photodynamic agents and the creation of targeted delivery systems with the function of controlling the release of the agent in the tumor. Recently, the new group of cyanoarylporphyrazine dyes was reported, which combine the properties of photosensitizers and sensors of the local microenvironment. Such unique characteristics allow the release of the photosensitizer from the transport carrier to be assessed in real time in vivo. The aim of the present work was to compare the photophysical and photobiological properties of tetra(2-naphthyl)tetracyanoporphyrazine and its newly synthesized Fe(II) complex. We have shown that the chelation of the Fe(II) cation with the porphyrazine macrocycle leads to a decrease in molar extinction and an increase in the quantum yield of fluorescence and photostability. We demonstrate that the iron cation significantly affects the rate of dye accumulation in cells, the dark toxicity and photodynamic activity, and the direction of the changes depends on the particular cell line. However, in all the cases, the photodynamic index of a metal complex was higher than that of a metal-free base. In general, both of the compounds were found to be very promising for PDT, including for the use with transport delivery systems, and can be recommended for further in vivo studies.

Photosubstitution in a trisheteroleptic ruthenium complex inhibits conjunctival melanoma growth in a zebrafish orthotopic xenograft model

In vivo data are rare but essential for establishing the clinical potential of ruthenium-based photoactivated chemotherapy (PACT) compounds, a new family of phototherapeutic drugs that are activated via ligand photosubstitution. Here a novel trisheteroleptic ruthenium complex [Ru(dpp)(bpy)(mtmp)](PF₆)₂ ([2](PF₆)₂, dpp = 4,7-diphenyl-1,10-phenanthroline, bpy = 2,2′-bipyridine, mtmp = 2-methylthiomethylpyridine) was synthesized and its light-activated anticancer properties were validated in cancer cell monolayers, 3D tumor spheroids, and in embryonic zebrafish cancer models. Upon green light irradiation, the non-toxic mtmp ligand is selectively cleaved off, thereby releasing a phototoxic ruthenium-based photoproduct capable notably of binding to nuclear DNA and triggering DNA damage and apoptosis within 24–48 h. In vitro, fifteen minutes of green light irradiation (21 mW cm⁻², 19 J cm⁻², 520 nm) were sufficient to generate high phototherapeutic indexes (PI) for this compound in a range of cancer cell lines including lung (A549), prostate (PC3Pro4), conjunctival melanoma (CRMM1, CRMM2, CM2005.1) and uveal melanoma (OMM1, OMM2.5, Mel270) cancer cell lines. The therapeutic potential of [2](PF₆)₂ was further evaluated in zebrafish embryo ectopic (PC3Pro4) or orthotopic (CRMM1, CRMM2) tumour models. The ectopic model consisted of red fluorescent PC3Pro4-mCherry cells injected intravenously (IV) into zebrafish, that formed perivascular metastatic lesions at the posterior ventral end of caudal hematopoietic tissue (CHT). By contrast, in the orthotopic model, CRMM1- and CRMM2-mCherry cells were injected behind the eye where they developed primary lesions. The maximally-tolerated dose (MTD) of [2](PF₆)₂ was first determined for three different modes of compound administration: (i) incubating the fish in prodrug-containing water (WA); (ii) injecting the prodrug intravenously (IV) into the fish; or (iii) injecting the prodrug retro-orbitally (RO) into the fish. To test the anticancer efficiency of [2](PF₆)₂, the embryos were treated 24 h after engraftment at the MTD. Optimally, four consecutive PACT treatments were performed on engrafted embryos using 60 min drug-to-light intervals and 90 min green light irradiation (21 mW cm⁻², 114 J cm⁻², 520 nm). Most importantly, this PACT protocol was not toxic to the zebrafish. In the ectopic prostate tumour models, where [2](PF₆)₂ showed the highest photoindex in vitro (PI > 31), the PACT treatment did not significantly diminish the growth of primary lesions, while in both conjunctival melanoma orthotopic tumour models, where [2](PF₆)₂ showed more modest photoindexes (PI ∼ 9), retro-orbitally administered PACT treatment significantly inhibited growth of the engrafted tumors. Overall, this study represents the first demonstration in zebrafish cancer models of the clinical potential of ruthenium-based PACT, here against conjunctival melanoma.

A new tris-heteroleptic photoactivated chemotherapy ruthenium complex induces apoptosis upon green light activation in a zebrafish orthothopic conjunctival melanoma xenograft model.

Modified Titanium Dioxide as a Potential Visible-Light-Activated Photosensitizer for Bladder Cancer Treatment

Low oxygen concentration inside the tumor microenvironment represents a major barrier for photodynamic therapy of many malignant tumors, especially urothelial bladder cancer. In this context, titanium dioxide, which has a low cost and can generate high ROS levels regardless of local O₂ concentrations, could be a potential type of photosensitizer for treating this type of cancer. However, the use of UV can be a major disadvantage, since it promotes breakage of the chemical bonds of the DNA molecule on normal tissues. In the present study, we focused on the cytotoxic activities of a new material (Ti(OH)₄) capable of absorbing visible light and producing high amounts of ROS. We used the malignant bladder cell line MB49 to evaluate the effects of multiple concentrations of Ti(OH)₄ on the cytotoxicity, proliferation, migration, and production of ROS. In addition, the mechanisms of cell death were investigated using FACS, accumulation of lysosomal acid vacuoles, caspase-3 activity, and mitochondrial electrical potential assays. The results showed that exposure of Ti(OH)₄ to visible light stimulates the production of ROS and causes dose-dependent necrosis in tumor cells. Also, Ti(OH)₄ was capable of inhibiting the proliferation and migration of MB49 in low concentrations. An increase in the mitochondrial membrane potential associated with the accumulation of acid lysosomes and low caspase-3 activity suggests that type II cell death could be initiated by autophagic dysfunction mechanisms associated with high ROS production. In conclusion, the characteristics of Ti(OH)₄ make it a potential photosensitizer against bladder cancer.

Photosensitized Oxidation of Intracellular Targets: Understanding the Mechanisms to Improve the Efficiency of Photodynamic Therapy

The development of improved photosensitizers is a key aspect in the establishment of photodynamic therapy (PDT) as a reliable treatment modality. In this chapter, we discuss how molecular design can lead to photosensitizers with higher selectivity and better efficiency, with focus on the importance of specific intracellular targeting in determining the cell death mechanism and, consequently, the PDT outcome.

Hypocrellin B-based activatable photosensitizers for specific photodynamic effects against high H2O2-expressing cancer cells

A novel tumor-related biomarker, a H₂O₂-activatable photosensitizer 4 based on the 1,3-dicarbonyl enol moieties of hypocrellin B (3), was designed and synthesized. The photosensitizer 4 showed a blue-shifted absorption band compared with 3, and showed negligible photosensitizing ability without H₂O₂. However, the release of 3 from 4 by the reaction with H₂O₂ regenerated the photosensitizing ability. Furthermore, 4 exhibited selective and effective photo-cytotoxicity against high H₂O₂-expressing cancer cells upon photo-irradiation with 660 nm light, which is inside the phototherapeutic window.

Graphene oxide enriched with oxygen-containing groups: on the way to an increase of antioxidant activity and biocompatibility

The article is dedicated to the comprehensive biocompatibility investigation of synthesised graphene oxide (GO) enriched with oxygen-containing functional groups (⁓85%). GO was synthesised through a modified Hummers and Offeman's method and characterised using ¹³C NMR, Raman, and IR spectroscopy, XRD, HRTEM, along with size dimensions and ζ-potentials in aqueous dispersions. Biocompatibility study included tests on haemocompatibility (haemolysis, platelet aggregation, binding to human serum albumin and its esterase activity), antioxidant activity (2,2-diphenyl-1-picrylhydrazyl reaction, NO-radical uptake, Radachlorin photobleaching, photo-induced haemolysis), genotoxicity using DNA comet assay, as well as metabolic activity and proliferation of HEK293 cells.

In Vitro and In Silico Investigation of Water-Soluble Fullerenol C60(OH)24: Bioactivity and Biocompatibility

Light fullerenes, C₆₀ and C₇₀, have significant potential in biomedical applications due to their ability to absorb reactive oxygen species, inhibit the development of tumors, inactivate viruses and bacteria, and as the basis for developing systems for targeted drug delivery. However, the hydrophobicity of individual fullerenes complicates their practical use; therefore, creating water-soluble derivatives of fullerenes is increasingly important. Currently, the most studied soluble adducts of fullerenes are polyhydroxy fullerenes or fullerenols. Unfortunately, investigations of fullerenol biocompatibility are fragmental. They often lack reproducibility both in the synthesis of the compounds and their biological action. We here investigate the biocompatibility of a well-defined fullerenol C₆₀(OH)₂₄ obtained using methods that minimize the content of impurities and quantitatively characterize the product's composition. We carry out comprehensive biochemical and biophysical investigations of C₆₀(OH)₂₄ that include photodynamic properties, cyto- and genotoxicity, hemocompatibility (spontaneous and photo-induced hemolysis, platelet aggregation), and the thermodynamic characteristics of C₆₀(OH)₂₄ binding to human serum albumin and DNA. The performed studies show good biocompatibility of fullerenol C₆₀(OH)₂₄, which makes it a promising object for potential use in biomedicine.

Curcumin-loaded Pluronic® F-127 Micelles as a Drug Delivery System for Curcumin-mediated Photodynamic Therapy for Oral Application

Antimicrobial photodynamic therapy (aPDT) is promising for oral decontamination. Curcumin has been used as photosensitizer; however, the hydrophobic properties can negatively affect aPDT. This study evaluated the aPDT efficacy using Cur-loaded Pluronic^® F-127 micelles against Streptococcus mutans and Candida albicans biofilms. Micelles characterization was performed by zeta potential, dynamic light scattering, transmission electron microscopy, absorption and fluorescence spectroscopy. Cur concentrations, cell viability by CFU mL^-1 and confocal microscopy were determined. Data were analyzed by parametric and nonparametric tests under 5%. Cur-loaded Pluronic^® F-127 exhibited spherical shape, suitable particle size (≤100 nm), adequate polydispersity index, best stability, lower photodegradation and autoaggregation compared to unloaded-Cur. Both microorganisms were sensitive to Cur-loaded Pluronic^® F-127 micelles aPDT, with minimum inhibitory concentration (MIC) of 270 μm and 2.1093 μm for S. mutans and C. albicans suspended culture, respectively. Cur-loaded Pluronic^® F-127 aPDT exhibited antibacterial/antifungal effect against the biofilms (~3 log₁₀ reduction; P ≤ 0.05); however, similar to unloaded (P ≥ 0.05). Confocal images confirmed these results. Cur-loaded Pluronic^® F-127 micelles exhibited good photo-chemical properties and may be a viable alternative to deliver Cur and to improve aPDT effect during the treatment of dental caries. Moreover, Pluronic^® micelles can enhance the solubility, stability, permeability and control the release of Cur.

Biocompatibility of a nanocomposite based on Aerosil 380 and carboxylated fullerene C60[C(COOH)2]3

Silica is silicon dioxide, which, depending on the production method, can exist in various amorphous forms with varying specific surface area, particle size, pore volume and size, and, as a result, with different physicochemical and sorption characteristics. The presence of silanol groups on the surface of silicas provides the possibility of its further functionalisation. In addition, the developed specific surface of Aerosil allows to obtain composites with a high content of biologically active substances. In this work, we studied the biocompatibility of a composite based on Aerosil 380 and carboxylated fullerene C₆₀[C(COOH)₂]₃, namely: haemolysis (spontaneous and photoinduced), platelet aggregation, binding to HSA, cyto- and genotoxicity, antiradical activity. Interest in the creation of this nanomaterial is due to the fact that carboxylated fullerenes have potential applications in various fields of biomedicine, including the ability to bind reactive oxygen species, inhibition of tumour development, inactivation of viruses and bacteria. The obtained composite can be used for the immobilisation of various drugs and the further development of drugs for theranostics.

2-Naphthol Moiety of Neocarzinostatin Chromophore as a Novel Protein-Photodegrading Agent and Its Application as a H2 O2 -Activatable Photosensitizer

A 2-naphthol derivative 2 corresponding to the aromatic ring moiety of neocarzinostatin chromophore was found to degrade proteins under photo-irradiation with long-wavelength UV light without any additives under neutral conditions. Structure-activity relationship studies of the derivative revealed that methylation of the hydroxyl group at the C2 position of 2 significantly suppressed its photodegradation ability. Furthermore, a purpose-designed synthetic tumor-related biomarker, a H₂ O₂ -activatable photosensitizer 8 possessing a H₂ O₂ -responsive arylboronic ester moiety conjugated to the hydroxyl group at the C2 position of 2, showed significantly lower photodegradation ability compared to 2. However, release of the 2 from 8 by reaction with H₂ O₂ regenerated the photodegradation ability. Compound 8 exhibited selective photo-cytotoxicity against high H₂ O₂ -expressing cancer cells upon irradiation with long-wavelength UV light.

Anti-tumor evaluation of a novel methoxyphenyl substituted chlorin photosensitizer for photodynamic therapy

Photodynamic therapy (PDT) is a non-invasive and innovative therapeutic approach which has been increasingly applied in clinical cancer therapy. As the central element of PDT, the development of novel photosensitizers (PSs) with longer absorption wavelength, proper lipophilic/hydrophilic profiles, target tissue selectivity, and higher photo-/lowest dark-cytotoxicity is a challenging task. Previously, we designed and synthesized a series of novel long-wavelength chlorin e6 (Ce6)-based PSs via introducing aromatic groups to the vinyl of Ce6 skeleton. The new formed compounds with π-extension system exhibited improved photodynamic effects and spectral characteristics. Among these π-conjugated chlorin PSs, (E)-3²-(4-methoxyphenyl)-chlorin e6, named A15, was expected to be a potent antitumor candidate as a PDT agent due to its good photobiological properties. Herein, in this work, we evaluated the effectiveness of A15 in cancer PDT. In vitro, a novel rare earth probe, ATTA-Eu³⁺ was applied to detect the singlet oxygen (¹O₂) production of A15 in solution and human hepatoma HepG2 cells, respectively. Moreover, A15 exhibited strong phototoxicity and weak dark cytotoxity to HepG2 cells. In H22 tumor bearing mice, A15 showed excellent tumor accumulation ability via i.v. administration and induced tumor regression, followed by laser treatment. These results indicated that A15 is a potential novel π-extension chlorin-type PS for PDT applications.

Physicochemical properties, biological activity and biocompatibility of water-soluble C60-Hyp adduct

Amino acid adducts of light fullerenes have a potential of application in a variety of fields of biomedicine, that is reactive oxygen species scavenging activity, anticancer activity, viruses and bacteria inactivation etc. In this work, the water-soluble C₆₀ fullerene derivative with l-hydroxyproline (C₆₀(C₅H₉NO₃)₂, C₆₀-Hyp) was studied. Extensive biomedical investigation of this compound, namely, antiradical activity in the reaction with stable diphenylpicrylhydrazyl radical, the binding to human serum albumin, photodynamic properties, cytotoxicity in glioblastoma A172 and lung carcinoma A549 cell lines, erythrocytes haemolysis, platelet aggregation, genotoxicity on human peripheral blood mononuclear cells was conducted. Moreover, the dynamic and structural characteristics of C₆₀-Hyp-H₂O binary system were obtained using molecular dynamic (MD) method, and size distribution along with ζ-potentials of C₆₀-Hyp associates was measured.

Spectroscopic and photostability study of water-soluble hypericin encapsulated with polyvinylpyrrolidone

Hypericin has gained great attention as a powerful photosensitizing and fluorescent agent for photodynamic therapy (PDT) and fluorescence diagnosis (FD) of cancer. However, native hypericin is hydrophobic and nearly insoluble in aqueous media which hinders its photobiological activity. Herein, we demonstrate the encapsulation of hypericin and polyvinylpyrrolidone (hypericin@PVP) as an attractive class of water-soluble formula of hypericin with improved absorption and emission characteristics in water. The absorption and fluorescence properties of the water-soluble hypericin@PVP were studied at room temperature. Also, the photostability of the prepared hypericin@PVP was studied under visible light irradiation. The absorbance and emission measurements confirm the association and binding of hypericin and PVP with a binding constant (K_b) of 1.2 × 10⁵ M^-1. The interaction between hypericin and PVP in water could lead to the dissociation of aggregated hypericin into their monomeric state which is crucial for effective photobiological implementation in PDT and FD. Upon encapsulation with PVP, hypericin showed a significant increase in the fluorescence properties with an enhanced emission intensity of 300% at a PVP concentration of 1 × 10^-4 M. Moreover, water-soluble hypericin@PVP demonstrated high photostability under visible light irradiation with an irradiance of 15 mW/cm² and exposure time up to 150 min. This enhancement in the absorption, emission, and photostability of hypericin in water is related to the effects of encapsulation with PVP and the unique spectroscopic properties of the formulated hypericin@PVP.

Reduction and functionalization of graphene oxide with L-cysteine: Synthesis, characterization and biocompatibility

This article presents data on the synthesis, identification, computer simulation and biocompatibility of graphene oxide (GO) functionalized with L-cysteine (GFC). It was determined that GO reacts with L-cysteine in two different ways: in an alkaline medium, L-cysteine reduces functional groups on the surface and at the boundaries of GO; with heating and the use of thionyl chloride, L-cysteine covalently attaches to GO through carboxylic groups only at the boundaries. The identification of GO, reduced graphene oxide and GFC was performed using various physicochemical methods, including infrared spectroscopy, Raman spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, thermogravimetric analysis, scanning electron microscopy and high-resolution transmission electron microscopy. Biocompatibility experiments included erythrocyte hemolysis, platelet aggregation, photodynamic and antiradical activity, binding to human serum albumin, and geno- and cytotoxicity studies. Applying density functional theory and molecular dynamics allowed us to obtain the structural and dynamic characteristics of a GFC-water binary system.

Magnetic Targeting of mTHPC To Improve the Selectivity and Efficiency of Photodynamic Therapy

Photodynamic therapy (PDT) is a promising recognized treatment for cancer. To date, PDT drugs are injected systemically, and the tumor area is irradiated to induce cell death. Current clinical protocols have several drawbacks, including limited accessibility to solid tumors and insufficient selectivity of drugs. Herein, we propose an alternative approach to improve PDT effectiveness by magnetic targeting of responsive carriers conjugated to the PDT drug. We coordinatively attached a meso-tetrahydroxyphenylchlorin (mTHPC) photosensitizer to Ce-doped-γ-Fe₂O₃ maghemite nanoparticles (MNPs). These MNPs are superparamagnetic and biocompatible, and the resulting mTHPC-MNPs nanocomposites are stable in aqueous suspensions. MDA-MB231 (human breast cancer) cells incubated with the mTHPC-MNPs showed high uptake and high death rates in cell population after PDT. The exposure to external magnetic forces during the incubation period directed the nanocomposites to selected sites enhancing drug accumulation that was double that of cells with no magnetic exposure. Next, breast cancer tumors were induced subcutaneously in mice and treated magnetically. In vivo results showed accelerated drug accumulation in tumors of mice injected with mTHPC-MNP nanocomposites, compared to the free drug. PDT irradiation led to a decrease in tumor size of both groups, whereas treatment with the focused magnetic nanocomposites led to significant tumor regression. Our results demonstrate a method to improve the current PDT treatments by applying magnetic forces to effectively direct the drug to cancerous tissue. This approach leads to a highly localized and effective PDT process, opening new directions for clinical PDT protocols.

Biological evaluation and molecular dynamics simulation of water-soluble fullerene derivative C60[C(COOH)2]3

One of the most studied fullerene members, C₆₀, has a potential of application in various fields of biomedicine including reactive oxygen species (ROS) scavenging activity, inhibiting of tumours development, inactivating of viruses and bacteria, as well as elaboration of diagnostic and targeted drug delivery tools. However, the hydrophobicity of this molecule impedes its practical use, therefore the actuality of the research devoted to functionalisation of fullerenes leading to amphiphilic derivatives remains important. In this work, the water-soluble carboxylated fullerene derivative C₆₀[C(COOH)₂]₃ was studied. Extensive biomedical investigation of this compound, namely, the binding with human serum albumin (HSA), radical scavenging activity in the reaction with diphenylpicrylhydrazyl (DPPH) radical, photodynamic properties, cytotoxicity in human embryonic kidney (HEK293) cell line, erythrocytes' haemolysis, platelet aggregation, and genotoxicity in human peripheral mononuclear cells (PBMC) was conducted. Moreover, the dynamic and structural characteristics of C₆₀[C(COOH)₂]₃-H₂O binary system were obtained using molecular dynamic (MD) method, and size distribution of C₆₀[C(COOH)₂]₃ associates was measured.

Liposome and polymeric micelle-based delivery systems for chlorophylls: Photodamage effects on Staphylococcus aureus

Chlorophyll derivatives (Chls), loaded in F-127 polymeric micelles and DPPC liposomes as drug delivery systems (DDS), have been shown to be remarkable photosensitizers for photodynamic inactivation (PDI). Assays of photoinactivation of Staphylococcus aureus bacteria (as biological models) showed that the effectiveness of Chls in these nanocarriers is dependent on photobleaching processes, photosensitizer locations in DDS, singlet oxygen quantum yields, and Chl uptake to bacteria. These are factors related to changes in Chl structure, such as the presence of metals, charge, and the phytyl chain. The photodynamic activity was significantly greater for Chls without the phytyl chain, i.e., phorbides derivatives. Furthermore, the inactivation of S. aureus was increased by the use of liposomes compared to micelles. Therefore, this research details and shows the high significance of the Chl structure and delivery system to enhance the photodynamic activity. It also highlights the chlorophylls (particularly phorbides) in liposomes as promising photosensitizers for PDI.

Lipid vesicle-loaded meso-substituted chlorins of high in vitro antimicrobial photodynamic activity

Photodynamic inactivation potential against bacteria of four chlorin derivatives with phenyl or fluorophenyl substituents was evaluated. The quantum yield values of singlet oxygen formation were in the range of 0.16-0.86. Compounds were characterized by high quantum yields of fluorescence (0.15-0.44) and moderate photostability in DMF solutions. Irradiation of chlorins in DMSO resulted in their phototransformation and then photodecomposition. Photodynamic inactivation of bacteria was performed after the compounds had been loaded into lipid vesicles. The following log reductions of growth values were obtained: Enterococcus faecalis >5.44; Staphylococcus aureus 2.74-5.34; Escherichia coli 0.01-2.14. No activity of meso-substituted chlorins was noticed against Pseudomonas aeruginosa and fungi Candida albicans and Trichophyton mentagrophytes.

Theranostics of Triple-Negative Breast Cancer Based on Conjugated Polymer Nanoparticles

Triple-negative breast cancer (TNBC) does not respond to many targeted drugs due to the lack of three receptors (i.e., estrogen receptor, progesterone receptor, and human epidermal growth factor receptor-2), which makes it difficult for TNBC detection and treatment. As compared to traditional breast cancer treatments such as surgery and chemotherapy, photodynamic therapy (PDT) has emerged as a promising approach for treating TNBC due to its precise controllability, high spatiotemporal accuracy, and minimal invasive nature. However, traditional photosensitizers used in PDT are associated with limitations of aggregation-caused quenching (ACQ), and the ACQ induced a significant decrease in reactive oxygen species (ROS) generation. To address these, we synthesized a cyclic arginine-glycine-aspartic acid (cRGD) peptide-decorated conjugated polymer (CP) nanoparticles with poly[2-methoxy-5-(2-ethyl-hexyloxy)-1,4-phenylenevinylene] (MEH-PPV) as the photosensitizer for the theranostics of TNBC. The synthesized CP nanoparticles show bright fluorescence with high stability and could effectively produce ROS under light irradiation. Cell viability studies showed that the CP nanoparticles have negligible dark cytotoxicity and could efficiently kill the α_vβ₃ integrin-overexpressed MDA-MB-231 cells (one subtype of TNBC cells) in a selective way. With the use of cRGD-modified MEH-PPV nanoparticles as the theranostic agent, it permits targeted imaging and PDT of TNBC both in the in vitro 3D tumor model and in living mice. The application of CP nanoparticles in the successful theranostics of TNBC could pave the way for future development of CP-based photosensitizers for clinical applications.

meso-Tetrahydroxyphenylchlorin-Conjugated Gold Nanoparticles as a Tool To Improve Photodynamic Therapy

Photodynamic therapy (PDT) is a promising therapeutic modality for cancer. However, current protocols using bare drugs suffer from several limitations that impede its beneficial clinical effects. Here, we introduce a new approach for an efficient PDT treatment. It involves conjugating a PDT agent, meso-tetrahydroxyphenylchlorin (mTHPC) photosensitizer, to gold nanoparticles (AuNPs) that serve as carriers for the drug. AuNPs have a number of characteristics that make them highly suitable to function as drug carriers: they are biocompatible, serve as biomarkers, and function as contrast agents in vitro and in vivo. We synthesized AuNPs and covalently conjugated the mTHPC drug molecules through a linker. The resultant functional complex, AuNP-mTHPC, is a stable, soluble compound. SH-SY5Y human neuroblastoma cells were incubated with the complex, showing possible administration of higher doses of drug when conjugated to the AuNPs. Then cells were irradiated with a laser beam at 650 nm to mimic the PDT procedure. Our study shows higher rates of cell death in cells incubated with the AuNP-mTHPC complex compared to the incubation with the free drug. Using the new complex may form the basis for a better PDT strategy for a wide range of cancers.

Photodynamic Therapy

Photodynamic therapy is a clinical technique for the treatment of cancers, microbial infections and other medical conditions by means of light-induced generation of reactive oxygen species using photosensitising drugs. The intrinsic fluorescence of many such drugs make them potential theranostic agents for simultaneous diagnosis and therapy. This chapter reviews the basic chemical and biological aspects of photodynamic therapy with an emphasis on its applications in theranostics. The roles of nanotechnology is highlighted, as well as emerging trends such as photoimmunotherapy, image-guided surgery and light- and singlet-oxygen dosimetry.

On the in vivo photochemical rate parameters for PDT reactive oxygen species modeling

Photosensitizer photochemical parameters are crucial data in accurate dosimetry for photodynamic therapy (PDT) based on photochemical modeling. Progress has been made in the last few decades in determining the photochemical properties of commonly used photosensitizers (PS), but mostly in solution or in vitro. Recent developments allow for the estimation of some of these photochemical parameters in vivo. This review will cover the currently available in vivo photochemical properties of photosensitizers as well as the techniques for measuring those parameters. Furthermore, photochemical parameters that are independent of environmental factors or are universal for different photosensitizers will be examined. Most photosensitizers discussed in this review are of the type II (singlet oxygen) photooxidation category, although type I photosensitizers that involve other reactive oxygen species (ROS) will be discussed as well. The compilation of these parameters will be essential for ROS modeling of PDT.

WO3/Pt nanoparticles are NADPH oxidase biomimetics that mimic effector cells in vitro and in vivo

To provide a means of delivering an artificial immune effector cell-like attack on tumor cells, we report the tumoricidal ability of inorganic WO3/Pt nanoparticles that mimic a leukocyte's functional abilities. These nanoparticles route electrons from organic structures and electron carriers to form hydroxyl radicals within tumor cells. During visible light exposure, WO3/Pt nanoparticles manufacture hydroxyl radicals, degrade organic compounds, use NADPH, trigger lipid peroxidation, promote lysosomal membrane disruption, promote the loss of reduced glutathione, and activate apoptosis. In a model of advanced breast cancer metastasis to the eye's anterior chamber, we show that WO3/Pt nanoparticles prolong the survival of 4T1 tumor-bearing Balb/c mice. This new generation of inorganic photosensitizers do not photobleach, and therefore should provide an important therapeutic advance in photodynamic therapy. As biomimetic nanoparticles destroy targeted cells, they may be useful in treating ocular and other forms of cancer.

Bacterial Motility Reveals Unknown Molecular Organization

The water solubility of lyotropic liquid crystals (LCs) makes them very attractive to study the behavior of biological microorganisms in an environment where local symmetry is broken (as often encountered in nature). Several recent studies have shown a dramatic change in the behavior of flagellated bacteria when swimming in solutions of the lyotropic LC disodium cromoglycate (DSCG). In this study, the movements of Escherichia coli bacteria in DSCG-water solutions of different concentrations are observed to improve our understanding of this phenomenon. In addition, the viscosity of DSCG aqueous solutions is measured as a function of concentration at room temperature. We also experimentally identify a previously undescribed isotropic pretransition zone where bacteria start sticking to each other and to surfaces. Simple estimations show that the unbalanced osmotic pressure induced depletion force might be responsible for this sticking phenomenon. An estimate of the bacteria propulsive force and the DSCG aggregates length (versus concentration) are calculated from the measured viscosity of the medium. All these quantities are found to undergo a strong increase in the pretransition zone, starting at a threshold concentration of 6±1 wt % DSCG that is well below the known isotropic-LC transition (∼10 wt %). This study also shines light on the motility of flagellated bacteria in realistic environments, and it opens new avenues for interesting applications such as the use of motile microorganisms to probe the physical properties of their host or smart bandages that could guide bacteria out of wounds.

Photodynamic Efficiency: From Molecular Photochemistry to Cell Death

Photodynamic therapy (PDT) is a clinical modality used to treat cancer and infectious diseases. The main agent is the photosensitizer (PS), which is excited by light and converted to a triplet excited state. This latter species leads to the formation of singlet oxygen and radicals that oxidize biomolecules. The main motivation for this review is to suggest alternatives for achieving high-efficiency PDT protocols, by taking advantage of knowledge on the chemical and biological processes taking place during and after photosensitization. We defend that in order to obtain specific mechanisms of cell death and maximize PDT efficiency, PSes should oxidize specific molecular targets. We consider the role of subcellular localization, how PS photochemistry and photophysics can change according to its nanoenvironment, and how can all these trigger specific cell death mechanisms. We propose that in order to develop PSes that will cause a breakthrough enhancement in the efficiency of PDT, researchers should first consider tissue and intracellular localization, instead of trying to maximize singlet oxygen quantum yields in in vitro tests. In addition to this, we also indicate many open questions and challenges remaining in this field, hoping to encourage future research.

Physicochemical properties of potential porphyrin photosensitizers for photodynamic therapy

This research evaluated the suitability of synthetic photosensitizers for their use as potential photosensitizers in photodynamic therapy using steady state and time-resolved spectroscopic techniques. Four tetraphenylporphyrin derivatives were studied in ethanol and dimethyl sulfoxide. The spectroscopic properties namely electronic absorption and emission spectra, ability to generate singlet oxygen, lifetimes of the triplet state, as well as their fluorescence quantum yield were determined. Also time-correlated single photon counting method was used to precisely determine fluorescence lifetimes for all four compounds. Tested compounds exhibit high generation of singlet oxygen, low generation of fluorescence and they are chemical stable during irradiation. The studies show that the tested porphyrins satisfy the conditions of a potential drug in terms of physicochemical properties.

Synthesis of new porphyrin/4-quinolone conjugates and evaluation of their efficiency in the photoinactivation of Staphylococcus aureus

The synthesis of new porphyrin/4-quinolone conjugates and their evaluation as potential photosensitizers in the photoinactivation of Staphylococcus aureus is described.

Photoactivated rose bengal functionalized chitosan nanoparticles produce antibacterial/biofilm activity and stabilize dentin-collagen

Treatment of infected teeth presents two major challenges: persistence of the bacterial-biofilm within root canals after treatment and compromised structural integrity of the dentin hard-tissue. In this study bioactive polymeric chitosan nanoparticles functionalized with rose-bengal, CSRBnp were developed to produce antibiofilm effects as well as stabilize structural-integrity by photocrosslinking dentin-collagen. CSRBnp were less toxic to fibroblasts and had significant antibacterial activity even in the presence of bovine serum albumin. CSRBnp exerted antibacterial mechanism by adhering to bacterial cell surface, permeabilizing the membrane and lysing the cells subsequent to photodynamic treatment. Photoactivated CSRBnp resulted in reduced viability of Enterococcus faecalis biofilms and disruption of biofilm structure. Incorporation of CSRBnp and photocrosslinking significantly improved resistance to degradation and mechanical strength of dentin-collagen (P<0.05). The functionalized chitosan nanoparticles provided a single-step treatment of infected root dentin by combining the properties of chitosan and that of photosensitizer to eliminate bacterial-biofilms and stabilize dentin-matrix.

FROM THE CLINICAL EDITOR

In this study, bioactive polymeric chitosan nanoparticles functionalized with rose-bengal (a photosensitizer), CSRBnp were developed to produce antibiofilm effects as well as stabilize structural-integrity of dental root dentin by photocrosslinking dentin-collagen, leading to efficient elimination of bacterial-biofilms and stabilization of dentin-matrix.

Photodynamic therapy with the novel photosensitizer chlorophyllin f induces apoptosis and autophagy in human bladder cancer cells

BACKGROUND AND OBJECTIVES

Our group recently synthesized a new, low-cost photosensitizer, chlorophyllin f. In this study, the effects of chlorophyllin f-mediated photodynamic therapy (PDT) and its potential mechanisms were examined in human bladder cancer cells.

MATERIALS AND METHODS

MitoTracker® Green probe and LysoTracker® Green probe were used to label mitochondria and lysosomes, revealing the intracellular localization of chlorophyllin f in 5637 and T24 cells by confocal laser scanning microscopy (CLSM). The cells were treated with chlorophyllin f-mediated PDT; the photo-cytotoxicity of chlorophyllin f was monitored using the Cell Counting Kit-8 assay, and apoptosis was measured by Annexin V-FITC/PI dual staining. Western blotting, transmission electron microscopy (TEM), and staining with Cyto-ID® Autophagy Detection dye, monodansylcadaverine (MDC) and acridine orange were performed to assess autophagy. The role of autophagy was examined by measuring cell viability and apoptosis in both cell lines pretreated with the autophagy inhibitor 3-methyladenine (3-MA).

RESULTS

Chlorophyllin f showed affinity for mitochondria and lysosomes. It exhibited significant photocytotoxicity, resulting in a maximum of 86.51% and 84.88% cell death in 5637 and T24 cells, respectively. Additionally, chlorophyllin f-mediated PDT (f-PDT) also induced a significantly higher percentage of apoptosis in treated cells compared to the control groups (P < 0.05). Moreover, the expression of Beclin1 protein and the proportion of LC3-II:LC3-I in both cell lines significantly increased after f-PDT. Autophagy, characterized by an increase in the formation of Cyto-ID® Autophagy Detection dye-labeled autophagosomes, MDC fluorescent dye-labeled autophagic vacuoles and acridine orange-labeled acidic vesicular organelles (AVOs), was observed in f-PDT-treated cells. TEM also revealed double-membrane autophagosome structures 1 hour after f-PDT. Most importantly, when pretreated with 3-MA, the two cell lines showed more significant photo-cytotoxicity and apoptotic cell death compared to those exposed to f-PDT alone (P < 0.05).

CONCLUSION

Chlorophyllin f-mediated PDT exerts anti-tumor activity by inducing apoptosis and autophagy, and most importantly, autophagy inhibition enhances f-PDT-mediated apoptotic cell death. These results suggest that chlorophyllin f is a new, effective photosensitizer and that the combination of f-PDT with autophagy inhibitors may be an attractive therapeutic strategy against human non-muscle invasive bladder cancer.

The conjugates of gold nanorods and chlorin e6 for enhancing the fluorescence detection and photodynamic therapy of cancers

Gold nanorods (AuNRs) were conjugated with chlorin e6 (Ce6), a commonly used photosensitizer, to form AuNRs-Ce6 by electrostatic binding. Due to the strong surface plasmon resonance coupling, the fluorescence of conjugated Ce6 was enhanced 3-fold and the production of singlet oxygen was increased 1.4-fold. AuNRs-Ce6 were taken up by the HeLa and KB cell lines more easily than free Ce6, enhancing the intracellular delivery of Ce6. The increased cellular amount of Ce6 leads to a 3-fold more efficient photodynamic killing of these two cell lines. This demonstrates the potential of this approach to improve photodynamic detection and therapy of cancers.

BODIPY dyes in photodynamic therapy

BODIPY dyes tend to be highly fluorescent, but their emissions can be attenuated by adding substituents with appropriate oxidation potentials. Substituents like these have electrons to feed into photoexcited BODIPYs, quenching their fluorescence, thereby generating relatively long-lived triplet states. Singlet oxygen is formed when these triplet states interact with (3)O(2). In tissues, this causes cell damage in regions that are illuminated, and this is the basis of photodynamic therapy (PDT). The PDT agents that are currently approved for clinical use do not feature BODIPYs, but there are many reasons to believe that this situation will change. This review summarizes the attributes of BODIPY dyes for PDT, and in some related areas.

Photodynamic mechanisms induced by a combination of hypericin and a chlorin based-photosensitizer in head and neck squamous cell carcinoma cells

The aim of this study was to elucidate photodynamic therapy (PDT) effects mediated by hypericin and a liposomal meso-tetrahydroxyphenyl chlorin (mTHPC) derivative, with focus on their 1:1 mixture, on head and neck squamous cell carcinoma cell lines. Absorption, excitation and photobleaching were monitored using fluorescence spectrometry, showing the same spectral patterns for the mixture as measured for single photosensitizers. In the mixture mTHPC showed a prolonged photo-stability. Singlet oxygen yield for light-activated mTHPC was Φ(Δ) = 0.66, for hypericin Φ(Δ) = 0.25 and for the mixture Φ(Δ) = ~0.4. A linear increase of singlet oxygen yield for mTHPC and the mixture was found, whereas hypericin achieved saturation after 35 min. Reactive oxygen species fluorescence was only visible after hypericin and mixture-induced PDT. Cell viability was also more affected with these two treatment options under the selected conditions. Examination of death pathways showed that hypericin-mediated cell death was apoptotic, with mTHPC necrotic and the 1:1 mixture showed features of both. Changes in gene expression after PDT indicated strong up-regulation of selected heat-shock proteins. The application of photosensitizer mixtures with the features of reduced dark toxicity and combined apoptotic and necrotic cell death may be beneficial in clinical PDT. This will be the focus of our future investigations.

Heavy metal effects on physicochemical properties of non-aggregated azaphthalocyanine derivatives

Two series of peripherally substituted azaphthalocyanines (AzaPcs) containing different transition metals ( Al(III), Zn(II), Ga(III), In(III) and Fe(II) ) were synthesized and studied for their photophysical properties. As confirmed by UV-vis and1H NMR analyses, the non-aggregation behavior was effectively induced by the applied bulky peripheral substituents which had no effect on the photophysical properties. Tuning the Q-band position was clearly achievable by using different central heavy metals which have considerable effects on the fluorescence quantum yield and singlet oxygen generation efficiency. This comparative study showed an interesting linear relationship between the former and atomic number of the central metal. The indium containing complexes exhibited the best result due to the heavy metal effect and therefore could be promoted as a potential photosensitizer in photodynamic therapy (PDT) application.

Characterization of a conjugate between Rose Bengal and chitosan for targeted antibiofilm and tissue stabilization effects as a potential treatment of infected dentin

Bacterial biofilms and dentin structural changes are some of the major challenges in the management of infected dentin tissue. This study characterized a photosensitizer-conjugated chitosan with enhanced photodynamic efficacy against dental biofilms, as well as the ability to reinforce the postinfected dentin matrix in order to improve its mechanical and chemical stability. Rose Bengal-conjugated chitosan (CSRB) was synthesized using a chemical cross-linking method and characterized for photophysical, photobiological, and cytotoxicity properties. Its potential as an antibacterial and matrix-reinforcing agent on dentin collagen was also evaluated. Enterococcus faecalis as planktonic and in vitro biofilms was treated with CSRB and photodynamically activated with 5 to 60 J/cm(2) green light. Dentin collagen was used for the CSRB cross-linking experiments and evaluated for chemical changes, resistance to enzymatic degradation, and mechanical properties. CSRB was a photosensitizer with efficient singlet oxygen yield. In vitro photoactivation gave higher fibroblast cell survival than did RB alone. CSRB showed significant antibiofilm photoinactivation (P < 0.01). The CSRB-cross-linked dentin collagen showed higher resistance to collagenase degradation and superior mechanical properties (P < 0.05). In summary, the photoactivated CSRB particles synthesized in this study may be a synergistic multifunctional treatment approach with lower cytotoxicity and effective antibiofilm activity as well as the ability to reinforce the dentin collagen to enhance resistance to degradation and improve mechanical properties. This may be a targeted treatment strategy to deal with infected dentin hard tissues in a clinical scenario, where both disinfection and structural integrity need to be addressed concomitantly.

Physical and chemical studies related to the development of m-THPC (FOSCAN®) for the photodynamic therapy (PDT) of tumours

Aggregation of 5,10,15,20-tetrakis(m-hydroxyphenyl)chlorin (m-THPC) is observed not to occur in methanol or in ethanol:polyethyleneglycol 300:water = 2:3:5 (v/v) in the concentration range of 0.46–73.4 × 10-5M and 0.92–29.4 × 10-5M , respectively. However, aggregation occurs for 4.59 × 10-5M solutions in methanol–water mixtures for compositions >50% water (v/v). The Soret band broadens and εmaxdecreases; λmaxshows a red shift, consistent with a J-type structure. Possible aggregate structures are considered based on the known hydrogen bonding patterns in crystalline solvates of the closely related 5,10,15,20-tetrakis(3,5-dihydroxyphenyl)porphyrin. Spectrophotometric titration of m-THPC in methanol–buffer mixtures gives apparent p Kavalues of p K3= 3.45 and p K4= 1.45. The phenolic groups have p Ka= 10.0. Comparisons are made with the corresponding porphyrin and with literature values on related systems. Singlet oxygen chemistry. The photobleaching of bilirubin is shown to be accelerated fivefold in the presence of a 0.05 mol proportion of m-THPC. The accelerated reaction is slowed down in the presence of 2,5-dimethylfuran and of β-carotene, providing further evidence by chemical reaction for the ability of m-THPC to photogenerate singlet oxygen. The relevance of these observations to clinical usage is discussed briefly.