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[Display omitted] Water-soluble nanosized systems of aluminum phthalo- cyanine, which is a promising photosensitizer for photodynamic therapy and fluorescence diagnostics, were obtained by encapsulating it in biocompatible copolymers of N -vinylpyrrolidone with mono- and dimethacrylates. The physicochemical (water solubility, stability and size of nanoparticles) and photophysical (absorption and fluorescence) properties of the resulting nanoparticles in aqueous solution were determined. Quantum chemical modeling revealed the formation of coordination bonds between the Al atom of the dye and the oxygen atoms of all monomer units. [ABSTRACT FROM AUTHOR]

This work reports for the first time on the synthesis, characterization, and photodynamic therapy efficacy of the novel aluminium (III) chloride 2(3), 9(10), 16(17), 23(24)-tetrakis-(sodium 2-mercaptoacetate) phthalocyanine (AlClPcTS41) when alone and when conjugated to PEGylated copper–gold bimetallic nanoparticles (PEG-CuAuNPs) as photosensitizers on colon cancer cells (Caco-2). The novel AlClPcTS41 was covalently linked to the PEG-CuAuNPs via an amide bond to form AlClPcTS41-PEG-CuAuNPs. The amide bond was successfully confirmed using FTIR while the crystal structures were studied using XRD. The morphological and size variations of the PEG-CuAuNPs and AlClPcTS41-PEG-CuAuNPs were studied using TEM, while the hydrodynamic sizes and polydispersity of the particles were confirmed using DLS. The ground state electron absorption spectra were also studied and confirmed the typical absorption of metallated phthalocyanines and their nanoparticle conjugates. Subsequently, the subcellular uptake, cellular proliferation, and PDT anti-tumor effect of AlClPcTS41, PEG-CuAuNPs, and AlClPcTS41-PEG-CuAuNPs were investigated within in vitro Caco-2 cells. The designed AlClPcTS41 and AlClPcTS41-PEG-CuAuNPs demonstrated significant ROS generation abilities that led to the PDT effect with a significantly decreased viable cell population after PDT treatment. These results demonstrate that the novel AlClPcTS41 and AlClPcTS41-PEG-CuAuNPs had remarkable PDT effects against Caco-2 cells and may trigger apoptosis cell death pathway, indicating the potential of the AlClPcTS41 and AlClPcTS41-PEG-CuAuNPs in enhancing the cytotoxic effect of PDT treatment. [ABSTRACT FROM AUTHOR]

In recent years, the development of methods of photodynamic therapy (PDT) and photodynamic photodiagnostics (PD) in Russia is characterized by an intensive rise, steadily growing interest of specialists from various medical specialties in the method of specialists from various medical specialties, an increase in the level of equipment number of hospitals with the necessary equipment for performing PD and PDT, the and the emergence of new photosensitizers on the pharmaceutical market, and an increasing increase in the level of patients’ confidence in these methods. This study analyzes the dynamics of the development of the clinical application and scientific developments of PD and PDT over the past decade in Russia in terms of the volume of public procurement of photosensitizers, as well as the activity of research work in the field of PD and PDT, the number of candidate and doctoral dissertations theses on this topic and the number of scientific publications in the RSCI. 688 contracts for the supply of photosensitizers for clinical use were analyzed. The analysis showed a stable annual growth in the volume of public procurement of photosensitizers, an increase in the number of subjects of the Russian Federation and clinical centers that purchase photosensitizers through the portal www.zakupki.gov.ru. From 2014 to 2020, the total volume of public procurement of all photosensitizers increased by 8 times (from 36.42 million rubles (3.58 thousand packages) to 307.37 million rubles (18.99 thousand packages)). The annual increase in the volume of public procurement in numerical terms over the previous 6 years ranged from 9.4% to 63.2% in different years. The main share of state purchases of photosensitizers falls on Moscow and St. Petersburg, h. However, in recent years there has been a noticeable trend towards an increase in sales of photosensitizers in the regions. Thus, in recent years, the share of purchases of photosensitizers in the constituent entities of the Russian Federation with a population of less than 1 million people has significantly increased (from 2.9% of the total number of purchases in 2014 to 25.3% in 2020). Also, in recent years, there has been a significant increase in the activity of research work activity in the field of PD and PDT. The number of defended candidate and doctoral dissertations theses defended in the field of PD and PDT photodynamic therapy and fluorescent diagnostics has been steadily high in recent years and, in some scientific specialties, reaches 2-3% of the total number of defended dissertations theses defended in these specialties. The increase in the total number of publications over 10 years according to the RSCI was 224% (from 218 publications in 2014 to 489 publications in 2019), according to the RSCI. The results obtained confirm the growing demand for photosensitizers for photodynamic therapy and fluorescence diagnostics in clinical practice, the expansion of the geography of the use of methods, as well and the stable interest in this topic in the research environment.

Today, fluorescent diagnostics and photodynamic therapy are promising methods for diagnosing and treating oncological diseases. The development of new photosensitizers (PS) is one of the most important tasks to improve the efficiency of both laser-induced diagnostics and therapy. In our study, we conjugated PS with AIS/ZnS triple quantum dots (QDs) to obtain non-aggregated complexes. It was shown that the conjugation of PS with QDs does not change the PS fluorescence lifetime, which is a marker of the preservation of PS photophysical properties. In particular, efficient resonant Förster energy transfer (FRET), from QDs to PS molecules in the conjugate, increases the PS luminescence response. The FRET from QD to PS molecules with different ratios of donor and acceptors are shown. It has been demonstrated that the average efficiency of FRET depends on the ratio of PS and QD and reaches a maximum value of 80% at a ratio of 6 PS molecules per 1 QD molecule. Thus, these studies could help to contribute to the development of new complexes based on QD and PS to improve the efficiency of phototheranostics. [ABSTRACT FROM AUTHOR]

The monocyte/macrophage cell lineage reveals an enormous plasticity, which is required for tissue homeostasis, but is also undermined in various disease states, leading to a functional involvement of macrophages in major human diseases such as atherosclerosis and cancer. We recently generated in vivo evidence that crystalline, nonfluorescent nanoparticles of the hydrophobic porphyrin-related photosensitizer Aluminum phthalocyanine are selectively dissolved and thus may be used for specific fluorescent labelling of rejected, but not of accepted xenotransplants. This led us to hypothesize that nanoparticles made of planar photosensitizers such as porphyrins and chlorins were preferentially taken up and dissolved by macrophages, which was verified by in vitro studies. Here, using an in vitro system for macrophage differentiation/polarization of the human monocyte THP-1 cell line, we demonstrate differential uptake/dissolution of Temoporfin-derived nanoparticles in polarized macrophages, which resulted in differential photosensitivity. More importantly, low dose photodynamic sensitization using Temoporfin nanoparticles can be used to trigger M1 re-polarization of THP-1 cells previously polarized to the M2 state. Thus, sublethal photodynamic treatment using Temoporfin nanoparticles might be applied to induce a phenotypic shift of tumor-associated macrophages for the correction of an immunosuppressive microenvironment in the treatment of cancer, which may synergize with immune checkpoint inhibition. [ABSTRACT FROM AUTHOR]

Metal phthalocyanines are promising components in photodynamic therapy. Aluminum phthalocyanine chloride (AlClPc) has been used to treat oral cancer in mice, human carious tissue, lung cancer cells and other conditions. To overcome the high hydrophobicity of AlClPc, phthalocyanine is often encapsulated in nanoformulations. Despite increased usage, little is known about the pharmacokinetics and biodistribution of AlClPc. The aim of this study was the development and validation of a UHPLC-MS method for the determination of AlClPc in solution after extraction from nanoformulations and biological matrices such as plasma and tissue. The described method has been assayed as to selectivity, linearity, limits of detection and quantification, precision and recovery. The present study is the first to describe the behavior of AlClPc in biological matrices with mass spectrometry as well as the first to describe the chromatographic behavior of AlClPc contaminants. Molecular mass analysis identified dechlorination of AlClPc by both LC/MS and MALDI-MS and an adduct formation in LC/MS. The parameters observed indicated that the method has applicability and robustness for use in biodistribution studies. [ABSTRACT FROM AUTHOR]

Considering the feasibility of the aluminum phthalocyanine chloride (AlPcCl) application in the topical photodynamic therapy of cutaneous tumors and the lack of HPLC methods capable of supporting skin permeation experiments using this compound, the aim of this study was to obtain a simple and selective chromatographic method for AlPcCl determination in skin matrices. A HPLC-UV/Vis method was developed using a normal-phase column operating at 30°C, an isocratic mobile phase of methanol : phosphoric acid (0.01 M) at 1.5 mL/min, and detection at 670 nm. The method exhibited (i) selectivity against various contaminants found in the different skin layers, (ii) high drug extraction capacity from the hair follicle (>70%) and remaining skin (>80%), and (iii) low limits of detection and of quantification (0.03 and 0.09 μg/mL, resp.). The method was also linear in the range from 0.1 to 5.0 µg/mL (r = 0.9994) and demonstrated robustness with regard to experimental chromatographic parameters according to a factorial design. Lastly, the developed method was successfully tested in in vitro skin permeation studies of AlPcCl, proving its effectiveness in the development of pharmaceutical delivery systems containing this drug for topical photodynamic therapy of skin cancers. [ABSTRACT FROM AUTHOR]

Background and Objective Emerging evidence suggests that photodynamic therapy (PDT) can exhibit immunomodulatory activity. The purpose of the present study was to analyse cytokine profiles after application of PDT in gingival tissues of rats with ligature-induced periodontal disease (PD). Study Design/Material and Methods Periodontal disease was induced through the introduction of a cotton thread around the first left mandibular molar, while the right side molars did not receive ligatures. After 7 days of PD evolution, ligatures were removed from the left side, and the animals were randomically divided into the following treatment groups: I, rats without treatment; II, rats received chloro-aluminum phthalocyanine (AlClPc); III, rats received low-level laser alone; and IV, rats received AlClPc associated with low-level laser (PDT). The animals were killed 7 days after the treatments, and the mandibles were histologically processed to assess morphological and immunohistochemical profile, while gingival tissues were removed for quantification of tumor necrosis factor (TNF)-α, interleukin (IL-)1β and IL-10 expression (by ELISA). Results Histomorphological analysis of periodontal tissues demonstrated that PDT-treated animals show tissue necrosis, as well as lower TNF- α expression, compared to ligatured animals treated with AlClPc alone. Conclusions It was concluded that PDT using AlClPc entrapped in a lipid nanoemulsion may be useful in therapies, because of immunomodulatory effects that decreased the inflammatory response and cause tissue destruction. [ABSTRACT FROM AUTHOR]

The use of lectins can play an important role for tracking modification on cell surface components, since lectins can be easily complexed with radioisotopes, biotin or fluorescein, facilitating the evaluation of carbohydrates distribution in the cell and mitochondrial activity. The aim of this study was to evaluate photodynamic therapy effects on indirect distribution of N-acetyl-glucosamine terminal glycoproteins, in human laryngeal carcinoma HEp-2 cell line surface, using lectin wheat germ agglutinin (WGA) and on mitochondrial activity, for the same cell line, using MitoTracker. The photosensitizer Aluminum Phthalocyanine Tetrasulfonate (AlPcS) was administrated at 10 μM/mL, followed by an incubation period for its accumulation in the tumor cells, which were irradiated with laser diode λ = 685 nm and energy density of 4.5 J/cm. Our results indicated that, after Photodynamic Therapy (PDT), it was observed N-acetyl glucosamine terminal glycoprotein expression and mitochondrial O production, compared to the control group. Based on these results, we suggest that PDT influences the O mitochondrial production and the presence of surface glycoproteins N-acetyl glucosamine terminals. [ABSTRACT FROM AUTHOR]

Aluminum phthalocyanine chloride (AlClPc) is a second-generation photodynamic therapy (PDT) photosensitizer characterized for its high hydrophobicity and self-aggregation tendency in aqueous media, which hamper its potential application. Aiming at AlClPc solubilization we proposed here the use of 1,2-distearoyl-sn-glycero-3-phosphocholine (DSPC) and 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) at different proportions to form mixed lipid vesicles (LVs) as a drug delivery system. LVs were prepared by ethanol injection method and formed nano-sized vesicles (about 100 nm) with suitable polydispersity index, negative zeta potential, and stable in aqueous medium for at least 50 days. AlClPc strongly interacts with LV (high binding constant values), especially due to aluminum–phosphate specific interactions, which gives a surface localization to AlClPc molecules as demonstrated by fluorescence quenching data. Anisotropy, static and time-resolved fluorescence measurements corroborated with these results and demonstrated that AlClPc self-aggregation occurred even in the liposomes. However, formulation uptake by oral squamous cell carcinoma (OSCC) the AlClPc was distributed in cellular organelles and suffered a disaggregation process demonstrated by fluorescence life-time imaging microscopy. This amazing behavior is new and increases the scientific knowledge about the intracellular mechanism of action of PDT photosensitizers. In addition, these results open a new perspective to the potential use of AlClPc-LV formulations for photodynamic treatment. [ABSTRACT FROM AUTHOR]

Aluminum phthalocyanine tetrasulphonate (AlPcS 4 ) is a well characterized water soluble phthalocyanine dye having structural similarities with porphyrin and has immense applications as a photosensitizer in photodynamic therapy (PDT). The present article embodies the exploration of physicochemical properties of PDT active AlPcS 4 and its interaction with DNA alkylating quinone in biomimicking micellar microenvironments to overcome the limitation of PDT that is caused by the hypoxic nature of solid tumor. UV–vis absorption, steady state emission and time resolved fluorescence spectroscopy reveal that the AlPcS 4 does not undergo considerable interaction with anionic SDS as well as uncharged Triton X-100 micelle, whereas in case of the series of a cationic surfactant (DTAB, TTAB, CTAB) it shows a significant columbic attraction toward the positively charged head group of the surfactant molecule. In premicellar concentration, surfactant induced aggregation of the probe molecule is observed, which subsequently disaggregates into its monomeric form above critical micellar concentration. The anionic dye localizes itself in the Stern layer of cationic micelles. The escalation of the fluorescence anisotropy value ( r ) with increase in the surfactant concentration is explained by the rise in compactness around the probe with increasing chain length of the cationic surfactant. However, the compactness has a reverse effect on the extent of water penetration or micellar hydration, which in turn decreases the polarity of microenvironment in the Stern layer. The fully micellized PDT active AlPcS 4 experiences stronger interaction with DNA alkylating quinone in confined medium as compared to the aqueous solution and the above said interaction intensifies with decrease in the micellar hydration. This spectroscopic research described herein may provide relevant addition to the usefulness of this bioactive dye–quinone system for the application in photodynamic therapy. [ABSTRACT FROM AUTHOR]

Sonodynamic therapy (SDT), or ultrasound combined with sonosensitization, is a promising approach because it is noninvasive and penetrates deeper than light does in photodynamic therapy. We examined whether bleomycin (BLM) could improve the efficacy of SDT. We performed an in vitro study using Colon-26 cells, which are derived from mouse colon cancer. SDT with BLM was significantly more cytotoxic than SDT alone both in vitro and in vivo. We also observed an ultrasound intensity-dependent cytotoxic effect of SDT with BLM. These findings suggest that SDT with BLM might provide a novel noninvasive treatment for deep-seated tumors. [ABSTRACT FROM AUTHOR]

The impact of double bonds in fatty acyl tails of unsaturated lipids on the photodynamic inactivation of ion channels formed by the pentadecapeptide gramicidin A in a planar bilayer lipid membrane was studied. The presence of unsaturated acyl tails protected gramicidin A against photodynamic inactivation, with efficacy depending on the depth of a photosensitizer in the membrane. The protective effect of double bonds was maximal with membrane-embedded chlorin e-monoethylenediamine monoamide dimethyl ester, and minimal - in the case of water-soluble tri-sulfonated aluminum phthalocyanine (AlPcS) known to reside at the membrane surface. By contrast, the protective effect of the hydrophilic singlet oxygen scavenger ascorbate was maximal for AlPcS and minimal for amide of chlorin e dimethyl ester. The depth of photosensitizer position in the lipid bilayer was estimated from the quenching of photosensitizer fluorescence by iodide. Thus, the protective effect of a singlet oxygen scavenger against photodynamic inactivation of the membrane-inserted peptide is enhanced upon location of the photosensitizer and scavenger molecules in close vicinity to each other. [ABSTRACT FROM AUTHOR]

Abstract: Targeting cancer vasculature is an emerging field in cancer treatment. Photochemical internalization (PCI) is a drug delivery technology based on photochemical lysis of drug-bearing endocytic vesicles originally designed to target cancer cells. Recent investigations have revealed a lower PCI efficacy in vascular endothelial cells (HUVECs) in vitro than in HT1080 fibrosarcoma cells. This manuscript aims to explore the limiting factor for the PCI effect in HUVECs. Cellular uptake of the photosensitizers AlPcS2a and TPPS2a, and a model compound for macromolecular drugs taken up by fluid phase endocytosis, Alexa488-dextran, was explored by flow cytometry. The uptake of AlPcS2a and TPPS2a was 3.8-fold and 37-fold higher in HUVECs than in HT1080 cells, respectively, while the Alexa488-dextran uptake was 50% lower. AlPcS2a (but not TPPS2a) was shown to reduce Alexa488-dextran uptake in a concentration-dependent manner, resulting in 66% and 33% attenuation of Alexa488-dextran uptake at 20μg/ml AlPcS2a in HUVECs and HT1080 cells respectively. Studies of intracellular localization of Alexa488-dextran and AlPcS2a by confocal microscopy in HUVECs uncovered a concentration-dependent AlPcS2a-induced inhibition of Alexa488-dextran trafficking into AlPcS2a-stained and acidic vesicles. The localization of Alexa488-dextran to AlPcS2a-localizing compartments was reduced by 40% when the AlPcS2a concentration was increased from 5 to 20μg/ml. The treatment dose of AlPcS2a was found to influence on the efficacy of PCI of saporin, but to a lesser extent than expected considering the data from cellular uptake and intracellular trafficking of Alexa488-dextran. The implications of these results for further development of vascular targeting-PCI are discussed. [Copyright &y& Elsevier]

The efficacy of transfersomes (flexible liposomes) as a novel technique for topical delivery of the hydrophilic tetra-anionic photodynamic sensitizer aluminum (III) phthalocyanine tetrasulfonate (AlPcS4) was investigated, on mammalian fibroblasts and on Balb/c mice dorsal skin. AlPcS4 was loaded in transfersomes composed of phosphatidylcholine/sodium deoxycholate (5:1, 10:1, and 15:1 w/ w, ratios), resulting in 110-, 160-, and 200-nm mean size vesicles with encapsulation efficiencies of 16, 25, and 30 %, respectively. In vitro studies on baby hamster kidney-21 fibroblasts revealed twofold enhancement of the photocytotoxicity of AlPcS4 loaded in transfersomes (Trans-AlPcS4), compared to free AlPcS4 dissolved in culture medium. The photocytotoxicity of Trans-AlPcS4 was less dependent on the incubation time with cells, compared to free AlPcS4. Topical application on the dorsal skin of Balb/c mice revealed that both free AlPcS4 and Trans-AlPcS4 exhibited evident photosensitization towards mice skin, but acquiring different regions of skin. [ABSTRACT FROM AUTHOR]

Abstract: In this work we have developed nanocapsules containing chloroaluminum phthalocyanine (ClAlPc) and assessed their phototoxic action on WM1552C, WM278, and WM1617 human melanoma cell lines. The ClAlPc-loaded nanocapsules were prepared by the nanoprecipitation method and optimized by means of a 23 full factorial design. The ClAlPc nanocapsules were characterized by particle size and distribution, zeta potential, morphology, encapsulation efficiency, singlet oxygen production, stability, and phototoxic action on melanoma cells. Both the development and optimization studies revealed that stable colloidal formulations could be obtained by using 1.75% (w/v) soybean lecithin, 1.25% (w/v) Poloxamer 188, 2.5% (v/v) soybean oil, and 0.75% (w/v) poly(D,L-lactide-co-glycolide). The nanocapsules had a mean diameter of 230nm, homogeneous size distribution (polydispersity index<0.3), and negative zeta potential (about −30mV). Their morphology was spherical, with evident polymer membrane coating droplet. The encapsulation efficiency was 70%, as expected for hydrophobic drugs, and the nanoencapsulated ClAlPc was able to produce high singlet oxygen quantum yield. ClAlPc nanocapsules exhibited good physical stability over a 12-month period. WM1552C primary melanoma cells were more sensitive (p <0.05) to the phototoxic effect elicited by ClAlPc nanocapsules (0.3μgml−1) under light irradiation at 20mJcm−2. On the other hand, the cell survival percentage for all the melanoma cell lines treated with the highest light dose (150mJcm−2) was lower than 10%. In summary, ClAlPc nanoencapsulation could enable application of this hydrophobic photosensitizer in the treatment of malignant melanoma with the use of both low sensitizer drug concentration and light dose. [Copyright &y& Elsevier]

Abstract: The combination of chemotherapy and photodynamic therapy was investigated by the synthesis and characterisation of phthalocyanine conjugates with Pt complexes. The complexes synthesized are: hydroxoaluminum trikis(diaquaplatinum) octacarboxyphthalocyanine (OHAlOCPc(Pt)3) and hydroxoaluminum tetrakis(diaquaplatinum) octacarboxyphthalocyanine (OHAlOCPc(Pt)4). The platinated phthalocyanine complexes gave long triplet lifetimes of 577 and 526 μs for OHAlOCPc(Pt)3 and OHAlOCPc(Pt)4, respectively. The triplet quantum yields were found to be 0.45 for OHAlOCPc(Pt)3 and 0.57 OHAlOCPc(Pt)4 while the singlet oxygen quantum yields were found to be 0.38 and 0.48, respectively. [Copyright &y& Elsevier]

Abstract: A photosensitive capsule consisting of aluminum phthalocyanine tetrasulfonate chloride (AlPcS4Cl) and polyelectrolytes was fabricated by assembling of oppositely charged poly(allylamine hydrochloride) (PAH) and AlPcS4Cl onto the preformed capsules composed of poly(styrene sulfonate) (PSS) and PAH. UV–visible absorption spectra, EDX spectrum and AFM images confirmed the successful deposition of AlPcS4Cl onto as-prepared hollow capsules. The assembled photosensitive capsules were found to remain intact and spherical morphology in the deposition process. The generation of cytotoxic singlet oxygen (1O2) of photosensitive capsules under visible light irradiation (670 ± 10 nm) was evidenced by ESR measurements and the oxidative reaction between the generated 1O2 and a detector. In vitro cellular experiments showed that photosensitive capsules exhibited a good biocompatibility in the dark and a higher killing efficacy against MCF-7 cancer cells under visible light irradiation as compared with free AlPcS4Cl, which implies that the assembled photosensitive capsules might be potentially applicable in photodynamic therapy. [Copyright &y& Elsevier]

Abstract: Sodium salts of sulfonated hydroxyaluminum phthalocyanines [Al(OH)Pc(SO3Na) i ] containing various numbers of sulfonate groups (i =1–4), were studied by spectroscopic techniques. The lifetimes of the singlet states were found to range between 5 and 8ns, experimentally determined fluorescence quantum yields ranging between 0.45 and 0.74. Both parameters depend on the number of sulfonate groups, the singlet lifetime depending additionally on concentration. The triplet lifetime was indirectly estimated for aqueous solutions of Al(OH)Pc(SO3Na)3 to amount to ca. 0.6μs. The decay time of singlet oxygen in the same system was also found to be close to 0.6μs. The molecules were found to dimerize in acidic and neutral solutions, the second order rate constants of the dimerization being of the order of 10mol−1 dm3 s−1, and the equilibrium constants of the order of 104. The experiments were supplemented with quantum chemical calculations allowing us to assign electronic transitions in monomers and dimers. [Copyright &y& Elsevier]

Photodynamic therapy of cancer is a promising treatment based on the tumor-specific accumulation of photosensitizers followed by irradiation with visible light which induces tumor cell death. The effect of different preincubation times on the photosensitization efficiency of the phthalocyanines AlPc and AlPcS4 was investigated in lymphoblastoid CCRF-CEM cells under conditions that allow maximal uptake of the sensitizers. First, the time course for the uptake of AlPcS4 and AlPc by CCRF-CEM cells and by the pheochromocytoma PC12 cells was compared. The uptake of AlPcS4 by CCRF-CEM cells was not significantly different after 6 h or 24 h incubation, but the photosensitization efficiency of the phthalocyanine was much higher when a 24 h preincubation period was used, with a fluence rate of 5 mW/cm2. However, for a fluence rate of 10 mW/cm2, the photosensitization efficiency of AlPcS4 was almost completely independent of the preincubation time (6 h vs. 24 h) with the phthalocyanine. When the cells were preincubated with 1 μmol/L AlPc for 10 min or 6 h, which allows the same accumulation of sensitizer by the cells, no significant effect of the incubation time on the photodynamic inactivation of CCRF-CEM cells was observed, with fluence rates of 5 mW/cm2 or 10 mW/cm2, for different light doses. Confocal fluorescence microscopy studies did not reveal differences in the localization of the phthalocyanines after maximal uptake was reached. The results show that the preincubation time with AlPcS4, after the maximal uptake is reached, affects cell growth to an extent depending on the fluence rate used, and this effect was not due to a major redistribution of the sensitizer during incubation. However, this was not observed when AlPc was used. [ABSTRACT FROM AUTHOR]

Oncological photodynamic therapy (PDT) relies on photosensitizers (PSs) to photo-oxidatively destroy tumor cells. Currently approved PSs yield satisfactory results in superficial and easy-to-access tumors but are less suited for solid cancers in internal organs such as the biliary system and the pancreas. For these malignancies, second-generation PSs such as metallated phthalocyanines are more appropriate. Presently it is not known which of the commonly employed metallated phtahlocyanines, namely aluminum phthalocyanine (AlPC) and zinc phthalocyanine (ZnPC) as well as their tetrasulfonated derivatives AlPCS4 and ZnPCS4, is most cytotoxic to tumor cells. This study therefore employed an attritional approach to ascertain the best metallated phthalocyanine for oncological PDT in a head-to-head comparative analysis and standardized experimental design. ZnPC and AlPC were encapsulated in PEGylated liposomes. Analyses were performed in cultured A431 cells as a template for tumor cells with a dysfunctional P53 tumor suppressor gene and EGFR overexpression. First, dark toxicity was assessed as a function of PS concentration using the WST-1 and sulforhodamine B assay. Second, time-dependent uptake and intracellular distribution were determined by flow cytometry and confocal microscopy, respectively, using the intrinsic fluorescence of the PSs. Third, the LC 50 values were established for each PS at 671 nm and a radiant exposure of 15 J/cm2 following 1-h PS exposure. Finally, the mode of cell death as a function of post-PDT time and cell cycle arrest at 24 h after PDT were analyzed. In the absence of illumination, AlPC and ZnPC were not toxic to cells up to a 1.5-μM PS concentration and exposure for up to 72 h. Dark toxicity was noted for AlPCS4 at 5 μM and ZnPCS4 at 2.5 μM. Uptake of all PSs was observed as early as 1 min after PS addition to cells and increased in amplitude during a 2-h incubation period. After 60 min, the entire non-nuclear space of the cell was photosensitized, with PS accumulation in multiple subcellular structures, especially in case of AlPC and AlPCS4. PDT of cells photosensitized with ZnPC, AlPC, and AlPCS4 yielded LC 50 values of 0.13 μM, 0.04 μM, and 0.81 μM, respectively, 24 h post-PDT (based on sulforhodamine B assay). ZnPCS4 did not induce notable phototoxicity, which was echoed in the mode of cell death and cell cycle arrest data. At 4 h post-PDT, the mode of cell death comprised mainly apoptosis for ZnPC and AlPC, the extent of which was gradually exacerbated in AlPC-photosensitized cells during 8 h. ZnPC-treated cells seemed to recover at 8 h post-PDT compared to 4 h post-PDT, which had been observed before in another cell line. AlPCS4 induced considerable necrosis in addition to apoptosis, whereby most of the cell death had already manifested at 2 h after PDT. During the course of 8 h, necrotic cell death transitioned into mainly late apoptotic cell death. Cell death signaling coincided with a reduction in cells in the G 0 /G 1 phase (ZnPC, AlPC, AlPCS4) and cell cycle arrest in the S-phase (ZnPC, AlPC, AlPCS4) and G 2 phase (ZnPC and AlPC). Cell cycle arrest was most profound in cells that had been photosensitized with AlPC and subjected to PDT. Liposomal AlPC is the most potent PS for oncological PDT, whereas ZnPCS4 was photodynamically inert in A431 cells. AlPC did not induce dark toxicity at PS concentrations of up to 1.5 μM, i.e. , > 37 times the LC 50 value, which is favorable in terms of clinical phototoxicity issues. AlPC photosensitized multiple intracellular loci, which was associated with extensive, irreversible cell death signaling that is expected to benefit treatment efficacy and possibly immunological long-term tumor control, granted that sufficient AlPC will reach the tumor in vivo. Given the differential pharmacokinetics, intracellular distribution, and cell death dynamics, liposomal AlPC may be combined with AlPCS4 in a PS cocktail to further improve PDT efficacy. Unlabelled Image • Zinc phthalocyanine (ZnPC) and aluminum phthalocyanine (AlPC) are lipophilic photosensitizers. • ZnPC and AlPC tetrasulfonate (S4) are hydrophilic derivatives. • Which of these is most optimal to treat cancer cells by photodynamic therapy?. • A head-to-head comparative analysis was performed; liposomal AlPC performed best. • Liposomal AlPC can be combined with AlPCS4 for multi-locus photosensitization. [ABSTRACT FROM AUTHOR]

We demonstrate effective inactivation of oral cancer cells SAS through a combination of photothermal therapy (PTT) and photodynamic therapy (PDT) effects based on localized surface plasmon resonance (LSPR) around 1064 nm in wavelength of a Au nanoring (NRI) under femtosecond (fs) laser illumination. The PTT effect is caused by the LSPR-enhanced absorption of the Au NRI. The PDT effect is generated by linking the Au NRI with the photosensitizer of sulfonated aluminum phthalocyanines (AlPcS) for producing singlet oxygen through the LSPR-enhanced two-photon absorption (TPA) excitation of AlPcS. The laser threshold intensity for cancer cell inactivation with the applied Au NRI linked with AlPcS is significantly lower when compared to that with the Au NRI not linked with AlPcS. The comparison of inactivation threshold intensity between the cases of fs and continuous laser illuminations at the same wavelength and with the same average power confirms the crucial factor of TPA under fs laser illumination for producing the PDT effect. [ABSTRACT FROM AUTHOR]