Vanya Mantareva

Photodynamic efficacy of water-soluble Si(IV) and Ge(IV) phthalocyanines towards Candida albicans planktonic and biofilm cultures

Water-soluble phthalocyanine complexes of silicon (SiPc1) and germanium (GePc1) were synthesized. The absorbance of SiPc1 in water was with minor aggregation while GePc1 strongly aggregated in water. The fluorescence data in water showed low quantum yields of 0.073 (SiPc1) and 0.01 (GePc1) and similar lifetimes of 4.07 ns and 4.27 ns. The uptake of SiPc1 into Candida albicans cells was two orders of magnitude lower as compared to GePc1 and for both was dependent on the cell density. Fungal cells in suspension were completely inactivated after SiPc1 (1.8 μM) at soft light radiation (50 J cm(-2), 60 mW cm(-2)). The fungal biofilm formed on denture acrylic resin was inactivated with 3 log after fractionated light irradiation.

Antimicrobial photodynamic efficiency of novel cationic porphyrins towards periodontal Gram-positive and Gram-negative pathogenic bacteria.

The Gram‐negative Aggregatibacter actinomycetemcomitans and Fusobacterium nucleatum are major causative agents of aggressive periodontal disease. Due to increase in the number of antibiotic‐resistant bacteria, antimicrobial Photodynamic therapy (aPDT) seems to be a plausible alternative. In this work, photosensitization was performed on Gram‐positive and Gram‐negative bacteria in pure culture using new‐age cationic porphyrins, namely mesoimidazolium‐substituted porphyrin derivative (ImP) and pyridinium‐substituted porphyrin derivative (PyP). The photophysical properties of both the sensitizers including absorption, fluorescence emission, quantum yields of the triplet excited states and singlet oxygen generation efficiencies were evaluated in the context of aPDT application. The studied porphyrins exhibited high ability to accumulate into bacterial cells with complete penetration into early stage biofilms. As compared with ImP, PyP was found to be more effective for photoinactivation of bacterial strains associated with periodontitis, without any signs of dark toxicity, owing to its high photocytotoxicity.

Long wavelength absorbing cationic Zn(II)-phthalocyanines as fluorescent contrast agents for B16 pigmented melanoma

Three cationic zinc phthalocyanines (ZnPcs), tetrakis-(3-methylpyridyloxy)-, tetrakis-(3-hexyl-pyridyloxy)-, and tetrakis-(3-dodecylpyridyloxy)phthalocyaninezinc (ZnPcMe, ZnPcHe and ZnPcDo) have been studied as advanced fluorescent contrast agents for pigmented melanoma tumor. UV-vis spectroscopic properties of the monomers were investigated. Their photophysical behavior as a substantial part of dye-induced fluorescence was evaluated. The selective accumulation and labeling capacity towards B16F0 pigmented melanoma tumor were determined. Melanin containing cells were isolated and incubated with ZnPcs at several time intervals (1, 1.5 and 6 h) following the kinetics of cellular uptake. The highest accumulation was found for ZnPcHe. A lower uptake was detected for the more lipophilic ZnPcDo and more hydrophilic ZnPcMe. The fluorescence diagnostic potential of ZnPcs towards pigmented melanoma by using an argon-dye laser detection set-up was demonstrated.

Metallophthalocyanines for antimicrobial photodynamic therapy: an overview of our experience

Metal phthalocyanine complexes with different charges, hydrophobicity and metal ions were synthesized and studied for antimicrobial photodynamic therapy of pathogenic bacterial and fungal model strains. Ten positively charged complexes with the metals Zn(II), Al(III), Ga(III), In(III), Si(IV) and Ge(IV) in the center of the ligand and substituents at the ligand bearing four or eight N-alkylpyridyloxy groups were prepared. In addition, a negatively charged Zn(II)-phthalocyanine with four sulfophenoxy-groups was synthesized. The absorption spectra showed low intensity of the Soret band in the UV part of the spectrum and the intense Q-band in the red to far red region (λ = 671–697 nm). The fluorescence was determined with quantum yields between 0.1–0.33 and life-times 2.8–4.9 ns in dependence of the kind of metal ion and the substituents. In organic solvents all complexes exist in a monomeric state but in aqueous solution they show aggregation with the exception of Ga(III) phthalocyanines. The singlet oxygen...

Lutetium(III) acetate phthalocyanines for photodynamic therapy applications: Synthesis and photophysicochemical properties

BACKGROUND The development of new water-soluble photosensitizers for photodynamic therapy (PDT) applications is a very active research topic. Efforts have been made to obtain the far-red absorbing phthalocyanine complexes with molecular design that facilitates the uptake and selectivity for a high PDT efficiency. METHODS The monomolecular lutetium(III) acetate phthalocyanines (LuPcs) substituted with methylpyridyloxy groups at non-peripheral (5) and peripheral (6) positions were synthesized by following the modification of the well-known synthetical routes. The photo-physicochemical properties of the both quaternized LuPcs were evaluated by the steady-state and time-resolved spectroscopy. The photochemical technique was applied to study the generation of the singlet oxygen. RESULTS Two water-soluble and cationic LuPcs were synthesized and chemically characterized. The photo-physicochemical properties of absorption (675 and 685nm) and the red shifted fluorescence (704 and 721nm) as well as the fluorescence lifetimes (2.24 and 3.27ns) were studied. The promising values of singlet oxygen quantum yields (0.32 for 5 and 0.35 for 6) were determined. CONCLUSIONS Lutetium(III) acetate phthalocyanine complexes were synthesized and evaluated with physicochemical properties suitable for future photodynamic therapy applications.

Tumor detection by exogenous fluorescent dyes using new generation photo-multiplier tubes

The easy and non-destructive fluorescence method for quantification of early changes in biological tissues improves the possibilities of the clinical research and diagnostics. Developments in this area are moving very rapidly in part because of advances in the technology and in part because of the numerous successful examples which are appearing. New family of photomultiplier tubes with a high detection sensitivity for near-infra red light (700-900 nm) were developed as a result of project IMPECABLE, which are valuable tools for early diagnosis of cutaneous pigmented melanoma using long-wave fluorescence dyes. Several phthalocyanines that are promising fluorophores for photodiagnosis of cutaneous malignant melanoma have been studied in different solvents for concentrations from 10-5 to 10-15 mol. Argon pumped dye laser as an excitation source was used. Three different wavelengths (613, 633 and 660 nm) in the red region, corresponding to first absorption peak, minimum of the absorption and near to the Q-band maximum of Pcs were applied. Fluorescence signals in the region of 700 to 800 nm were detected using spectrometric systems (Perkin-Elmer, UK-with conventional PMT as a detector, and PC2000, Ocean Optics, USA-with CCD-array as a detector) and a newly developed red-sensitive PMT. Detectable signal from other spectrometric systems was obtain up to 10-8 mol concentrations, which could be used for significant reduction of concentrations applied for in vivo applications. Fluorescence is a highly sensitive method of distinguishing between healthy and unhealthy tissue. The results demonstrate that extremely low concentrations of photosensitizers could be used to determine initial stages of melanoma. This application of PMT detectors will reduce extremely the negative side effects of higher concentrations of these drugs applied in the skin tissue. One can achieve high accuracy in the determination of pigmented malignant melanoma lesions with wide clinical applications.

Photodynamic opening of blood-brain barrier

Photodynamic treatment (PDT) causes a significant increase in the permeability of the blood-brain barrier (BBB) in healthy mice. Using different doses of laser radiation (635 nm, 10-40 J/cm2) and photosensitizer (5-aminolevulinic acid - 5-ALA, 20 and 80 mg/kg, i.v.), we found that the optimal PDT for the reversible opening of the BBB is 15 J/cm2 and 5-ALA, 20 mg/kg, exhibiting brain tissues recovery 3 days after PDT. Further increases in the laser radiation or 5-ALA doses have no amplifying effect on the BBB permeability, but are associated with severe damage of brain tissues. These results can be an informative platform for further studies of new strategies in brain drug delivery and for better understanding of mechanisms underlying cerebrovascular effects of PDT-related fluorescence guided resection of brain tumor.

A new method for photodynamic disinfection of prosthetic constructions and impressions in prosthetic dentistry

ABSTRACT INTRODUCTION: Photodynamic therapy is a topical treatment of pathogens that involves the use of a photoactive dye (photosensitizer), which is non-toxic when not exposed to light and activated by light of a specifi c wavelength in the presence of oxygen. The highly cytotoxic oxygen species generated by the induced photophysical processes inactivate the pathogenic cells. The PURPOSE of this study was to present a new method we developed for photodynamic disinfection of prostheses and impressions in prosthetic dentistry and to assess its effectiveness in comparison with some conventional methods of disinfection. MATERIALS AND METHODS: The method was developed on the basis of series of experimental studies (30 experiments for each type of disinfectant, 30 controls with no disinfection for each material, and 30 direct cultures of each test microorganism - MRSA, P. aeruginosa and C. albicans) using standard test specimens made of prosthesis plastic and impression materials. RESULTS: The new method of photodynamic disinfection with GaPc1 as photosensitizer was 100% effi cient in C-silicones, A-silicones and polyethers, but not in alginates (40%). To plastics the photodynamic method shows the same effi ciency as the conventional disinfectants of hypochlorite solutions and denture cleansing tablets (100% effect). CONCLUSION: The method of photodynamic disinfection we developed is a good therapeutic choice against orally transmitted diseases in prosthetic dentistry.

Photodiagnosis and Photodynamic Therapy of Cutaneous Melanoma

Skin cancer is one of the most widespread tumours. However, despite the progress achieved in all clinical diagnostic techniques, the most severe of those tumours cutaneous melanoma, continues to be an important problem of social health. A large number of optical techniques have been recently applied in the clinical practice in view of obtaining qualitatively and quantitatively new data from cutaneous neoplasia. Due to their high sensitivity in detecting small changes, spectroscopic techniques are now widely used for detection of early changes in biological tissues. Fluorescence detection of normal and abnormal tissues is among the most promising such approaches as it makes use of naturally existing fluorescent molecules (in the case of autofluorescence) or added fluorescent markers (in the case of exogenous fluorescence) of high importance. Fluorescent markers are introduced wherever native fluorescence is not informative enough to be used for diagnostic goals due to the absence or non-specificity of the changes in the tumour vs. the normal tissues. The fluorescent diagnostic techniques are particularly suitable in diagnosing melaninpigmented cutaneous pathologies. Melanin is a pigment which absorbs strongly within practically entire visible spectral range. Its high content in these lesions leads to low penetration depth of the excitation light and a small amount of re-emitted fluorescent light that can be collected and used for fluorescent analysis of the pathology under investigation. Therefore, fluorescent diagnosis of melanin-pigmented neoplasia, such as cutaneous malignant melanoma and its differentiation vs. dysplastic precursors and similar benign skin pathologies, such as nevi, is an elaborate and challenging task for all researchers working in the field of biomedical photonics. Photodiagnosis (PD) and photodynamic therapy (PDT) have been established as emerging modalities for a variety of pathogenic conditions including pigmented melanoma (Awan et al., 2006; Davids and Kleemann, 2010). The number of cases of pigmented malignancies has been steadily increasing during the last decades in general, and, in particular, malignant melanoma (MM) incidence has also increased. Melanomas are the most aggressively developing form of dermatological cancers due to the difficulty of diagnosis at an early stage combined with the low rate of success of

Virus inactivation under the photodynamic effect of phthalocyanine zinc(II) complexes

Abstract Various metal phthalocyanines have been studied for their capacity for photodynamic effects on viruses. Two newly synthesized water-soluble phthalocyanine Zn(II) complexes with different charges, cationic methylpyridyloxy-substituted Zn(II)- phthalocyanine (ZnPcMe) and anionic sulfophenoxy-substituted Zn(II)-phthalocyanine (ZnPcS), were used for photoinactivation of two DNA-containing enveloped viruses (herpes simplex virus type 1 and vaccinia virus), two RNA-containing enveloped viruses (bovine viral diarrhea virus and Newcastle disease virus) and two nude viruses (the enterovirus Coxsackie B1, a RNA-containing virus, and human adenovirus 5, a DNA virus). These two differently charged phthalocyanine complexes showed an identical marked virucidal effect against herpes simplex virus type 1, which was one and the same at an irradiation lasting 5 or 20 min (Δlog=3.0 and 4.0, respectively). Towards vaccinia virus this effect was lower, Δlog=1.8 under the effect of ZnPcMe and 2.0 for ZnPcS. Bovine viral diarrhea virus manifested a moderate sensitivity to ZnPcMe (Δlog=1.8) and a pronounced one to ZnPcS at 5- and 20-min irradiation (Δlog=5.8 and 5.3, respectively). The complexes were unable to inactivate Newcastle disease virus, Coxsackievirus B1 and human adenovirus type 5.