Light-induced effects in sulfonated aluminum phthalocyanines — potential photosensitizers in the photodynamic therapy

On the Synergism of Biogenic Gold Nanoparticles and Hydroxyaluminum Phthalocyanines in the Photoeradication of Staphylococcus aureus

Due to the unusual properties of gold nanoparticles, these structures are widely used in medicine and biology. This paper describes for the first time the synthesis of colloidal gold nanoparticles by the cell-free filtrate obtained from the Coriolus versicolor biomass and the use of these biogenic nanostructures to increase the photosensitizing efficiency of di- (AlPcS₂) and tetrasulfonated (AlPcS₄) hydroxyaluminum phthalocyanines in antibacterial photodynamic therapy. The obtained monodisperse particles were extremely stable, and this remarkable stability was due to the presence of phosphoprotein as a capping agent. The studied gold nanoparticles had a spherical shape, were uniformly distributed, and were characterized by a single plasmon band at wavelength of 514-517 nm. Almost 60% of the gold particles were found to be in the range of 13 to 15 nm. In accordance with the regulations of the American Microbiological Society, indicating that any antimicrobial technique must kill at least 3 log CFU (99.9%) to be accepted as "antimicrobial", this mortality of Staphylococcus aureus was shown to be achieved in the presence of AlPcS₄ + AuNPs mixture and 4.8 J cm^-2 light dose compared to AlPcS₄ alone, which required a light dose of 24 J cm^-2. The best effect of increasing the effectiveness of combating this pathogen was observed in the case of AlPcS₂ + AuNPs as a photosensitizing mixture. The light dose of 24 J cm^-2 caused a lethal effect of the studied coccus in the planktonic culture.

Sulfonated hydroxyaluminum phthalocyanine-biogenic Au/Ag alloy nanoparticles mixtures for effective photo-eradication of Candida albicans

In response to the increasingly widespread resistance of fungi to traditional treatment, we have reported successful photodynamic inactivation of Candida albicans planktonic cells using di-(AlPcS₂) and trisulfonated (AlPcS₃) hydroxyaluminum phthalocyanines in combination with Au/Ag alloy nanoparticles synthesized by the cell-free filtrate of Trichoderma koningii. These nanostructures with Au:Ag molar ratios 2:1, 1:1 and 1:2 have individual plasmonic band at 513-515 nm, 505-509 nm and 486-489 nm, respectively. XPS analysis of the ratio of gold to silver on the surface of these alloys indicated that Au and Ag formed a bimetallic system, wherein Au was coated with Ag. The XRD pattern revealed the angles at 38.2, 44.5, 64.9 and 78.0°. TEM analysis indicated that the average diameter of the synthesized alloys was 9 ± 3 nm, 8 ± 3 nm and 16 ± 3 nm for structures with Au:Ag molar ratios 1:1, 1:2 and 2:1, respectively. The FTIR band absorption, SEM-EDS analysis and basic elemental composition obtained by XPS confirmed that these nanostructures are stabilized by protein(s). Diode laser with the peak-power wavelength ʎ = 650 nm (output power of 40 mW; power density of 105 mW cm^-2) was used as a light source. The mixture of AlPcS₂+Au/Ag-NPs (Au:Ag = 2:1) can be considered as an effective photosensitizer, because eradication of C. albicans, as required by the American Society of Microbiology (99.9 %), was achieved at a low dose of light of 31.5 J cm^-2. It was postulated that this low dose of light applied to the photo-induced fungicidal effect may be painless for potential patients.

Porphyrinoid-based photosensitizers for diagnostic and therapeutic applications: An update

Porphyrin-based molecules are actively studied as dual function theranostics: fluorescence-based imaging for diagnostics and fluorescence-guided therapeutic treatment of cancers. The intrinsic fluorescent and photodynamic properties of the bimodal molecules allows for these theranostic approaches. Several porphyrinoids bearing both hydrophilic and/or hydrophobic units at their periphery have been developed for the aforementioned applications, but better tumor selectivity and high efficacy to destroy tumor cells is always a key setback for their use. Another issue related to their effective clinical use is that, most of these chromophores form aggregates under physiological conditions. Nanomaterials that are known to possess incredible properties that cannot be achieved from their bulk systems can serve as carriers for these chromophores. Porphyrinoids, when conjugated with nanomaterials, can be enabled to perform as multifunctional nanomedicine devices. The integrated properties of these porphyrinoid-nanomaterial conjugated systems make them useful for selective drug delivery, theranostic capabilities, and multimodal bioimaging. This review highlights the use of porphyrins, chlorins, bacteriochlorins, phthalocyanines and naphthalocyanines as well as their multifunctional nanodevices in various biomedical theranostic platforms.

Evaluation of aluminum phthalocyanine chloride and DNA interactions for the design of an advanced drug delivery system in photodynamic therapy

The aim of this study was to evaluate the interaction of aluminum phthalocyanine chloride (AlClPc) with double-stranded DNA. Absorption and fluorescence spectra, resonance light scattering, and circular dichroism were evaluated in water and water/ethanol mixtures with different concentrations of DNA or AlClPc. AlClPc showed a high ability to bind to DNA in both water and 4/6 water/ethanol mixture (v/v), with a majority of monomeric and aggregated initial forms of AlClPc, respectively. In this interaction, AlClPc bound preferentially to the grooves of DNA. The monomeric/aggregate state of AlClPc in DNA was dependent on the AlClPc/DNA ratio. At low concentrations of AlClPc, the interaction of AlClPc with few DNA sites caused a curvature in the DNA structure that provided a favorable environment for the intercalation of AlClPc aggregates. Increase in AlClPc concentration induced interactions with a high number of binding sites on DNA, which prevented bending and therefore aggregation of AlClPc molecules throughout the double-stranded DNA. These results are relevant to the understanding of the behavior and interaction of AlClPc with double-stranded DNA in the design of novel drug delivery systems for clinical application in photodynamic therapy as a new approach to treat skin or oral cancer, scars, or wound healing.

Enhancement of photo-bactericidal effect of tetrasulfonated hydroxyaluminum phthalocyanine on Pseudomonas aeruginosa

At the present time, photodynamic inactivation (PDI) is receiving considerable interest for its potential as an antimicrobial therapy. The results of our study indicate that enhancement of the phototoxic effect on Pseudomonas aeruginosa can be achieved by combination of tetrasulfonated hydroxyaluminum phthalocyanine (AlPcS₄) and bimetallic gold/silver nanoparticles (Au/Ag-NPs) synthesized by the cell-free filtrate of Aureobasidium pullulans. The bimetallic nanoparticles were characterized by a number of techniques including UV-vis, XPS, TEM, and SEM-EDS to be 14 ± 3 nm spherical particles coated with proteins. The effect of diode lasers with the peak-power wavelength ʎ = 650 nm (output power of 10 and 40 mW; radiation intensity of 26 and 105 mW/cm²) in combination with the AlPcS₄ and the bimetallic nanoparticles mixture on the viability of P. aeruginosa rods was shown. Particularly high efficiency of killing bacterial cells was obtained for the light intensity of 105 mW/cm², after 20, 30, and 40 min of irradiation corresponding to 126, 189^, and 252 J/cm² energy fluences. For AlPcS₄+Au/Ag-NPs treatment, the viable count reduction were equal to 99.90, 99.96, and 99.975%, respectively. These results were significantly better than those accomplished for irradiated separated assays of AlPcS₄ and Au/Ag-NPs.

Protein microarray for complex apoptosis monitoring of dysplastic oral keratinocytes in experimental photodynamic therapy

Background

Photodynamic therapy is an alternative treatment of muco-cutaneous tumors that uses a light source able to photoactivate a chemical compound that acts as a photosensitizer. The phthalocyanines append to a wide chemical class that encompasses a large range of compounds; out of them aluminium-substituted disulphonated phthalocyanine possesses a good photosensitizing potential.

Results

The destructive effects of PDT with aluminium-substituted disulphonated phthalocyanine are achieved by induction of apoptosis in tumoral cells as assessed by flow cytometry analysis. Using protein microarray we evaluate the possible molecular pathways by which photodynamic therapy activates apoptosis in dysplastic oral keratinocytes cells, leading to the tumoral cells destruction. Among assessed analytes, Bcl-2, P70S6K kinase, Raf-1 and Bad proteins represent the apoptosis related biomolecules that showed expression variations with the greatest amplitude.

Conclusions

Up to date, the intimate molecular apoptotic mechanisms activated by photodynamic therapy with this type of phthalocyanine in dysplastic human oral keratinocytes are not completely elucidated. With protein microarray as high-throughput proteomic approach a better understanding of the manner in which photodynamic therapy leads to tumoral cell destruction can be obtained, by depicting apoptotic molecules that can be potentially triggered in future anti-tumoral therapies.

Photophysical efficiency-boost of aqueous aluminium phthalocyanine by hybrid formation with nano-clays

Aluminium phthalocyanines, solubilized by nano-clay shuttles, retain high fluorescence efficiencies and singlet oxygen generation capabilities in aqueous ambience, qualifying them for photodynamic therapies.

Poly(amidoamine) dendrimer-grafted porous hollow silica nanoparticles for enhanced intracellular photodynamic therapy

We report a novel photodynamic therapy (PDT) drug-carrier system, whereby third-generation (G3) polyamidoamine (PAMAM) was successfully grafted to the surface of porous hollow silica nanoparticles (PHSNPs), followed by the attachment of gluconic acid (GA) for surface charge tuning. The composite G3-PAMAM-grafted PHSNPs (denoted as G3-PHSNPs) with a diameter range of 100-200 nm and about 30 nm sized shell thickness retain bimodal pore structures (e.g. inner voids and porous structure of the shells) and PAMAM-functionalized outer layer with a large number of amino groups, allowing high loading efficacy of aluminum phthalocyanine tetrasulfonate (AlPcS4) and its effective release to target tissue. The GA-induced G3-PHSNPs were evidenced to be able to favorably cross tumor cell walls and enter into the cell interior. The generation of singlet oxygen ((1)O2) from AlPcS4-GA-G3-PHSNPs under visible light excitation was detected by the in situ electron spin resonance measurements and the oxidative reaction between the generated (1)O2 and a chemical probe. In vitro cellular experiments showed that the photosensitive GA-G3-PHSNPs exhibited a good biocompatibility in the dark and a higher killing efficacy against MCF-7 tumor cells upon irradiation as compared with free AlPcS4, which implies that the preformed photosensitive drug-carrier system might be potentially applicable in PDT.

Synthesis and characterization of NIR-responsive Aurod@pNIPAAm-PEGMA nanogels as vehicles for delivery of photodynamic therapy agents

A near-infrared (NIR)-responsive Aurod@pNIPAAm-PEGMA nanogel was synthesized in two steps, growing a PEGMA monolayer on the surface of gold nanorods (AuNRs), followed by in situ polymerization and cross-linking of N-iso-propylacrylamide (NIPAAm) and poly-(ethylene glycol)-methacrylate (PEGMA). The AuNRs and Aurod@pNIPAAm-PEGMA nanogel were characterized by UV-vis spectroscopy, Raman spectroscopy, Fourier transform infrared spectroscopy, and transmission electron microscopy, respectively. The lower critical solution temperature of the Aurod@pNIPAAm-PEGMA nanogel could be tuned by changing the molar ratio of NIPAAm/PEGMA. The NIR-mediated drug release behavior of the Aurod@pNIPAAm-PEGMA nanogel was studied with zinc phthalocyanines (ZnPc4) as a drug model. It was also demonstrated that the loaded ZnPc4 could keep the capability of generating singlet oxygen, and the in vitro study showed a great photodynamic therapy (PDT) effect on Hela cells. It thus indicated the potential of this Aurod@pNIPAAm-PEGMA nanogel for application as a drug carrier in PDT, which might make contributions to oncotherapy.

Distribution of phthalocyanines and Raman reporters in human cancerous and noncancerous breast tissue as studied by Raman imaging

There is a considerable interest in the developing new diagnostic techniques allowing noninvasive tracking of the progress of therapies used to treat a cancer. Raman imaging of distribution of phthalocyanine photosensitizers may open new possibilities of Photodynamic Therapy (PDT) to treat a wide range of neoplastic lesions with improved effectiveness of treatment through precise identification of malignant areas. We have employed Raman imaging and Raman spectroscopy to analyze human breast cancer tissue that interacts with photosensitizers used in the photodynamic therapy of cancer. PCA (Principal Component Analysis) has been employed to analyze various areas of the noncancerous and cancerous breast tissues. The results show that the emission spectra combined with the Raman images are very sensitive indicators to specify the aggregation state and the distribution of phthalocyanines in the cancerous and noncancerous breast tissues. Our results provide experimental evidence on the role of aggregation of phthalocyanines as a factor of particular significance in differentiation of the normal and tumourous (cancerous or benign pathology) breast tissues. We conclude that the Raman imaging reported here has a potential to be a novel and effective photodynamic therapeutic method with improved selectivity for the treatment of breast cancer.

Spectral properties of binaphthalene-coumarins interconnected through hydrazone linkage

Photophysical properties of new coumarin-3-carbaldehyde (dihydrodinaphtho[2,1-c:1',2'-e]azepin-N-yl)imines bearing dimethylamino and methoxy groups at position 7 of coumarin were investigated. Dimethylamino derivative exhibits different solvent polarity dependence of fluorescent characteristics for nonpolar, medium polar and highly polar solvents. This effect can be rationalized by diverse charge distribution in the singlet excited state due to its different stabilization by solvation in the solvents of particular group. While 2-fold higher values of Stokes shift were observed for methoxy derivative, its quantum yield of fluorescence is much lower due to high nonradiative decay rate constant of the excited state.

Photophysical properties and photostability of novel benzothiazole-based D-π-A-π-D systems

The photophysical properties and photochemical stability of two novel D-π-A-π-D systems based on a benzothiazole core and terminal N,N-dimethylaminophenyl and N,N-diphenylaminophenyl groups were investigated. The quantum yield of photoreactions (Φ) was determined for various oxygen concentrations in the solvent (CH2Cl2) and various irradiation wavelengths. Trans-cis photoisomerization is proposed as a photobleaching mechanism during irradiation at longer wavelength due to charge-transfer transitions. Solution deoxygenation led to an unusual decrease in the photostability of the compounds investigated, most likely because of cation radical formation. The population of higher excited states for short-wavelength irradiation opened another degradation pathway and the overall degradation percentage decreased in comparison with long-wavelength irradiation. We assume that photoisomerization of the second double bond and electron transfer to CH2Cl2 (and subsequent oxidation reactions) contribute to this slower degradation branch. Singlet oxygen contributes significantly, albeit to the smallest values of Φ, to the overall photodegradation for both types of irradiation.