Synthesis and photodynamic activity of zinc(II) phthalocyanine derivatives bearing methoxy and trifluoromethylbenzyloxy substituents in homogeneous and biological media

Fluorinated Phthalocyanine/Silver Nanoconjugates for Multifunctional Biological Applications

In this study, a new phthalonitrile derivative namely 4-[(2,4-difluorophenyl)ethynyl]phthalonitrile (1) and its metal phthalocyanines (2 and 3) were synthesized. The resultant compounds were conjugated to silver nanoparticles and characterized using transmission electron microscopy (TEM) images. The biological properties of compounds (1-3), their nanoconjugates (4-6), and silver nanoparticles (7) were examined for the first time in this study. The antioxidant activities of biological candidates (1-7) were studied by applying the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assay. The highest antioxidant activity was obtained 97.47 % for 200 mg/L manganese phthalocyanine-silver nanoconjugates (6). The antimicrobial and antimicrobial photodynamic therapy (APDT) activities of biological candidates (1-7) were examined using a micro-dilution assay. The highest MIC value was obtained 8 mg/L for nanoconjugate 6 against E. hirae. The studied compounds and their silver nanoconjugates exhibited high APDT activities against all the studied microorganisms. The most effective APDT activities were obtained 4 mg/L for nanoconjugates (5 and 6) against L. pneumophila and E. hirae, respectively. All the studied biological candidates displayed high cell viability inhibition activities against E. coli cell growth. The biofilm inhibition activities of the tested biological candidates were also investigated against S. aureus and P. Aeruginosa. Biological candidates (1-6) can be considered efficient metal nanoparticle-based materials for multi-disciplinary biological applications.

Amphiphilic tricationic Zn(II)phthalocyanine provides effective photodynamic action to eradicate broad-spectrum microorganisms

A novel tricationic Zn(II)phthalocyanine derivative, (NCH₃)₃ZnPc³⁺, was synthesized by ring expansion reaction of boron(III) [2,9(10),16(17)-trinitrosubphthalocyaninato]chloride. First, the reaction of this subphthalocyanine with 2,3-naphthalenedicarbonitrile and Zn(CH₃COO)₂ catalyzed by 8-diazabicyclo[5.4.0]undec-7-ene was used to obtain the A₃B-type nitrophthalocyanine. After reduction of nitro groups with Na₂S and exhaustive methylation of amino groups, (NCH₃)₃ZnPc³⁺ was formed in good yields. In addition, the tetracationic analog (NCH₃)₄ZnPc⁴⁺ was synthesized to compare their properties. The absorption and fluorescence spectra showed the Q-bands and the red emission, respectively, which are characteristic of the Zn(II)phthalocyanine derivatives in N,N-dimethylformamide. Furthermore, photodynamic activity sensitized by these compounds was studied in the presence of different molecular probes to sense the formation of reactive oxygen species. (NCH₃)₃ZnPc³⁺ efficiently produced singlet molecular oxygen and also it sensitized the formation of superoxide anion radical in the presence of NADH, while the photodynamic activity of (NCH₃)₄ZnPc⁴⁺ was very poor, possibly due to the partial formation of aggregates. Furthermore, the decomposition of L-tryptophan induced by (NCH₃)₃ZnPc³⁺ was mainly mediated by a type II mechanism. Antimicrobial photodynamic inactivation sensitized by these phthalocyanines was evaluated in Staphylococcus aureus, Escherichia coli, and Candida albicans, as representative microbial cells. In cell suspensions, (NCH₃)₃ZnPc³⁺ was rapidly bound to microbial cells, showing bioimages with red fluorescence emission. After 5 min of irradiation with visible light, (NCH₃)₃ZnPc³⁺ was able to completely eliminate S. aureus, E. coli and C. albicans, using 1.0, 2.5 and 5.0 μM phthalocyanine, respectively. In contrast, a low photoinactivation activity was found with (NCH₃)₄ZnPc⁴⁺ as a photosensitizer. Therefore, the amphiphilic tricationic phthalocyanine (NCH₃)₃ZnPc³⁺ is a promising photosensitizing structure for application as a broad-spectrum antimicrobial phototherapeutic agent.

Selective Detection of Trinitrophenol by Amphiphilic Dimethylaminopyridine-Appended Zn(II)phthalocyanines at the Near-Infrared Region

Novel amphiphilic Zn(II)phthalocyanines (ZnPcs) peripherally substituted with four and eight dimethylaminopyridinium units (ZnPc1 and ZnPc2) were synthesized by cyclotetramerization of the corresponding phthalonitriles. The effect of aggregation and photophysical (fluorescence quantum yields and lifetimes) and photochemical (singlet oxygen generation and photodegradation under light irradiation) properties was investigated. The chemosensing ability of ZnPcs toward explosive nitroaromatic compounds was explored in aqueous medium. This study demonstrates that ZnPc1 and ZnPc2 show fluorescence quenching behavior upon interaction with different nitro analytes and show unprecedented selectivity toward 2,4,6-trinitrophenol with a limit of detection (LOD) of 0.7-1.1 ppm with a high quenching rate constant (K _sv) of 1.6-2.02 × 10⁵. The near-infrared (NIR) fluorescence in thin films was quenched efficiently because of the photoinduced electron-transfer process through strong intermolecular π-π and electrostatic interactions. The sensing process is highly reversible and free from the interference of other commonly encountered nitro analytes. Further, experiments were performed to demonstrate the use of ZnPcs as efficient heterogeneous photocatalysts in the reduction of nitro explosives. The smart dual performance of multicharged ZnPcs in aqueous media quantifies them as attractive candidates in developing sensor materials at the NIR region and to possibly convert the toxic explosives into useful scaffolds. These results provide an interesting perspective toward elaboration of stable fluorescent systems for the selective sensing behavior of nitro explosives and their facile heterogeneous catalytic behavior in the reduction reactions.

Functionalized photosensitive gelatin nanoparticles for drug delivery application

In this study, zinc phthalocyanine (ZnPc) was loaded onto gelatin nanoparticles functionalized with polyelectrolytes (polystyrene sulfonate/polyallylamine hydrochloride) by layer-by-layer (LbL) assembly. The process yield and the encapsulation efficiency were 76.0% ± 2.5 and 86.0% ± 1.8, respectively. The functionalized photosensitive gelatin nanoparticles (FPGN) had a mean diameter of 396.5 ± 45.8 nm, narrow distribution size with a polydispersity index of 0.106. The obvious switching of zeta potential indicates successful alternating deposition of the polyanion PSS and polycation PAH directly on the gelatin nanoparticles. The in vitro drug release investigation found that the LbL deposited polyelectrolyte bilayer is very efficient to reduce the release rate and assuage the initial burst for drugs loaded in gelatin nanoparticles. The photobiological activity of FPGN was evaluated on mouse macrophage carcinoma line J774 A-1. The cells viability decreased with the increase of the light dose in the range of 1-10.0 J.cm^-2. ZnPc-loaded in functionalized gelatin nanoparticles are the release systems that promise photodynamic therapy use.

Silica nanoparticles embedded with water insoluble phthalocyanines for the photoinactivation of microorganisms

Silica nanoparticles (SiNPs) embedded with Zn(II) 2,9,16,23-tetrakis(methoxy)phthalocyanine (SiNPZnPcOCH₃), Zn(II) 2,9,16,23-tetrakis(4-pyridyloxy) phthalocyanine (SiNPZnPcOPy) and Zn(II) 2,9,16,23-tetrakis(t-butyl) phthalocyanine (SiNPZnPctBu) were synthesized in the nonpolar core of AOT/1-butanol/water micelles using triethoxyvinylsilane and 3-aminopropyltriethoxysilane. These SiNPs-Pc presented an average diameter of about 20-25 nm. UV-vis absorption spectra presented the characteristic Soret and Q bands of phthalocyanines embedded into the nanoparticles. Moreover, red fluorescence emission of SiNPs bearing phthalocyanines was detected in water. The SiNPs-Pc produced the photodecomposition of 2,2'-(anthracene-9,10-diyl)bis(methylmalonic acid), which was used to sense the singlet molecular oxygen O₂(¹Δ_g) generation in aqueous medium. Also, the formation of superoxide anion radical was detected by nitro blue tetrazolium reduction in the presence of NADH. Photoinactivation of microorganisms was investigated in Staphylococcus aureus and Candida albicans. In vitro experiments showed that photosensitized inactivation induced by SiNPZnPcOCH₃ and SiNPZnPctBu improved with an increase of irradiation times. After 30 min irradiation, over 7 log reduction was found for S. aureus. Also, these SiNPs-Pc produced a decrease of 2.5 log in C. albicans after 60 min irradiation. In both cases, a lower photoinactivation activity was found for SiNPZnPcOPy. Studies of photodynamic action mechanism showed that the photokilling of microbial cells was protected in the presence of sodium azide and diazabicyclo[2.2.2]octane. Also, a reduction on the cell photodamage was found with the addition of D-mannitol. Therefore, the photodynamic activity sensitized by SiNPZnPcOCH₃ and SiNPZnPctBu in microbial cells was mediated by a contribution of both type I and type II photooxidative mechanisms. Thus, silica nanoparticles are interesting materials to vehicle ZnPcOCH₃ and ZnPctBu in aqueous media to photoeradicate microorganisms.

Amphiphilic zinc phthalocyanine photosensitizers: synthesis, photophysicochemical properties and in vitro studies for photodynamic therapy

Peripherally and non-peripherally tetra-substituted zinc(ii) phthalocyanines bearing 2-(2-{2-[3-(dimethylamino)phenoxy]ethoxy}ethoxy)ethoxy and 2-(2-{2-[3-(diethylamino)phenoxy]ethoxy}ethoxy)ethoxy groups (, , and ) were synthesized by cyclotetramerization of the corresponding phthalonitriles (, , and ). Their quaternized ionic derivatives (, , and ) were also synthesized by the reaction of them with methyl iodide. The novel compounds were characterized by using standard spectroscopic techniques such as FT-IR, (1)H NMR, (13)C NMR, UV-vis, mass and elemental analyses. The obtained quaternized phthalocyanines (, , and ) showed amphiphilic behaviour with excellent solubility in both organic and aqueous solutions, which makes them potential photosensitizers for use in photodynamic therapy (PDT) of cancer. The photophysical (fluorescence quantum yields and lifetimes) and photochemical (singlet oxygen and photodegradation quantum yields) properties of these novel phthalocyanines were studied in DMSO for both non-ionic and ionic quaternized derivatives. However, these properties were examined in both DMSO and phosphate buffer solution (PBS) for quaternized ionic phthalocyanines. The effects of the positions of substituents (peripheral or non-peripheral) and the quaternization of the nitrogen atoms on the substituents about their photophysical and photochemical properties were also compared in this study. The bovine serum albumin (BSA) binding behaviours of the studied quaternized ionic zinc(ii) phthalocyanines were also described in PBS solutions. The quaternized phthalocyanines (, , and ) successfully displayed light-dependent photodamage in HeLa and HuH-7 cancer cells in photodynamic therapy treatment. The photosensitivity and the intensity of damage were found directly related to the concentration of the photosensitizers.

Effect of DTPP-mediated photodynamic therapy on cell morphology, viability, cell cycle, and cytotoxicity in a murine lung adenocarcinoma cell line

Photodynamic therapy (PDT) involves the administration and activation of photosensitizing reagents in cancer tissues to induce cytotoxicity. Here we examined the effects of 5-5- (4-N, N-diacetoxylphenyl)-10,15,20- tetraphenylporphyrin (DTPP) -mediated PDT on cell morphology, viability, cell cycle, and cytotoxicity in a murine lung adenocarcinoma cell line. LA795 murine lung adenocarcinoma cell line was used in the study, with cellular uptake of DTPP being quantified by a UV-visible spectrophotometer. The subcellular localization of DTPP was detected by confocal laser scanning microscopy, alteration of cell morphology after PDT was observed by an inverted light microscope, and late-stage apoptosis was examined by terminal dUTP nick end labeling (TUNEL) . The effects of influencing factors on cytotoxicity of PDT in LA795 cells was investigated with varying concentrations of DTPP, energy densities, power densities, and antioxidants by 3- (4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assays. Effects of PDT on cell cycle and plasma membrane integrity were studied by flow cytometry analysis. The uptake of DTPP by LA795 cells reached maximum after incubation for 24 h. Confocal laser scanning microscopy showed that DTPP was mainly in the mitochondrion, and slight localization was detected in the lysosomes. Cellular inhibitory effects increased with increased irradiation dose and DTPP concentration, while unactivated DTPP had low toxicity. Flow cytometry analysis revealed that DTPP-PDT-treated cells showed S phase arrest. Cell membrane damage initiation, repair, and irreversible damage were observed at 2, 4, and 5 h after DTPP-PDT , respectively. Together, our results demonstrated cell apoptosis, compromised viability, and cell cycle S phase arrest of LA795 in response to DTPP-PDT , while no effect on the lung cancer cells was observed with irradiation or photosensitizer treatment alone.

Ecological photodynamic therapy: new trend to disrupt the intricate networks within tumor ecosystem

As with natural ecosystems, species within the tumor microenvironment are connected by pairwise interactions (e.g. mutualism, predation) leading to a strong interdependence of different populations on each other. In this review we have identified the ecological roles played by each non-neoplastic population (macrophages, endothelial cells, fibroblasts) and other abiotic components (oxygen, extracellular matrix) directly involved with neoplastic development. A way to alter an ecosystem is to affect other species within the environment that are supporting the growth and survival of the species of interest, here the tumor cells; thus, some features of ecological systems could be exploited for cancer therapy. We propose a well-known antitumor therapy called photodynamic therapy (PDT) as a novel modulator of ecological interactions. We refer to this as "ecological photodynamic therapy." The main goal of this new strategy is the improvement of therapeutic efficiency through the disruption of ecological networks with the aim of destroying the tumor ecosystem. It is therefore necessary to identify those interactions from which tumor cells get benefit and those by which it is impaired, and then design multitargeted combined photodynamic regimes in order to orchestrate non-neoplastic populations against their neoplastic counterpart. Thus, conceiving the tumor as an ecological system opens avenues for novel approaches on treatment strategies.

Synthesis and photodynamic properties of adamantylethoxy Zn(II) phthalocyanine derivatives in different media and in human red blood cells

Novel unsymmetrically substituted Zn(II) phthalocyanine bearing an adamantylethoxy group (AZnPc) was synthesized by the ring expansion reaction of boron(III) subphthalocyanine chloride with an appropriated phthalonitrile derivative (APc). Also, APc was used to obtain a new Zn(II) phthalocyanine bearing four adamantylethoxy groups (A(4)ZnPc) by cyclotetramerization reaction. The spectroscopic and photodynamic properties of these photosensitizers were compared with those of a Zn(II) phthalocyanine substituted by four methoxy groups (M(4)ZnPc) in different media. Similar results were obtained in N,N-dimethylformamide. However, a higher photodynamic activity was found for AZnPc in a biomimetic system formed by reverse micelles. This behavior was also observed in the presence of human red blood (HRB) cells, which were used as an in vitro cellular model. Thus, AZnPc was the most effective photosensitizer to produce HRB cells hemolysis. The photodynamic effect produced a decrease in the HRB cells osmotic stability leading to the release of hemoglobin. Studies of photodynamic action mechanism showed that photohemolysis of HRB cells was protected in the presence of azide ion, while the addition of mannitol produced a negligible effect on the cellular photodamage, indicating the intermediacy of O(2)((1)Δ(g)). Therefore, the presence of an adamantyl unit in the phthalocyanine macrocycle represents an interesting molecular architecture for potential phototherapeutic agents.

Synthesis, properties and photodynamic activities of some zinc(II) phthalocyanines against Escherichia coli and Staphylococcus aureus

Two new zinc phthalocyanine derivatives bearing four 3,5-di-tert-butyl-4-hydroxyphenyl (ZnPc1) and 3,5-dimethylphenoxy (ZnPc2) have been synthesized and proved by elemental analyses and UV-vis, 1H NMR, FTIR and MALDI-TOF mass spectra as spectroscopic determination. Thermal stabilities of these neutral Zn -phthalocyanines were performed by thermal gravimetric analysis and, significantly, were found stable up to 373 °C for ZnPc1 and 550 °C for ZnPc2. In addition, the photostability of the sensitizers was quite successful within 240 min. Furthermore, photodynamic therapy has been investigated using these neutral phthalocyanines. Singlet oxygen generation capacities of ZnPc1 and ZnPc2 were studied using 1,3-diphenyl-iso-benzofuran (50.0 μM) as a selective singlet oxygen trap in DMSO and both of them demonstrated very high singlet oxygen generation capacity. Photodynamic therapy is of considerable interest for its potential as an antimicrobial therapy on the grounds that the photodynamic activity of these compounds was tested against a Gram-negative bacteria, Escherichia coli and a Gram-positive bacteria, Staphylococcus aureus. Suspensions of the microorganisms were irradiated for 240 min in the presence of ZnPc1 (with hydrophilic group) and ZnPc2 phthalocyanines. In order to simulate solar radiation, we used a 750 W xenon lamp. Minimum photosensitizer concentration was used as 0.1 mg.10 mL-1 in 1% dimethylsulfoxide/phosphate buffer saline solution (DMSO/PBS). Moreover, the photostability of these compounds has been investigated and the effect of the amount of DMSO tested against selected bacteria. In the dark, with and without Pcs, bacterial inactivation did not occur. Bacterial inactivation by light with ZnPc1 was observed in response to Gram-negative bacteria E. coli and Gram-positive bacteria S. aureus, whereas the photoinactivation studies with ZnPc2 have revealed that the lack of its activity is due to its poor affinity for either of the organisms. These results suggest that a neutral amphiphilic photosensitizer may be easily used in an application concerning photoinactivation of bacterial cells as well as ionic photosensitizers.

Synthesis and photophysical properties of water-soluble dendrimers bearing a phthalocyanine core

Aggregation behaviors of phthalocyanine derivatives which have a dendritic structure were examined in an aqueous solution. We prepared the first- and second-generation dendrimers (WG1-PC and WG2-PC), having water-soluble substituents as a peripheral group, to be resolved in water. From spectroscopic measurement, WG2-PC acted in a monomeric manner, even in an aqueous solution, in contrast to WG1-PC, which exhibited spectra attributed to aggregation. This implies that a higher generation of water-soluble dendrimers can prevent a phthalocyanine core from forming an aggregation. The introduction of the second-generation dendrons to an aggregatable core may be effective to avoid self-aggregation and an undesirable deactivation process.

Photophysical behaviour and photodynamic activity of zinc phthalocyanines associated to liposomes

Phthalocyanines are macrocyclic compounds that can be employed as photosensitizers in the treatment of various infections and diseases, as well as in photodynamic therapy. Nevertheless, a disadvantage for the clinical application of these compounds is their strong tendency to form oligomers (especially dimers), a phenomenon that reduces their efficiency as photosensitizers. In the present contribution, we have studied the photophysical and photochemical properties of ZnPc and ZnF(16)Pc in an organic solvent (THF) and liposomal formulations (DMPC, DPPC and DSPC). Our results show that dye incorporation into liposomes decreases its aggregation degree, as revealed by absorption spectra, triplet quantum yield, and singlet oxygen quantum yield measurements. Additionally, we studied the photodynamic activity of both phthalocyanines in liposomal formulation on human cervical carcinoma (HeLa) cells. For ZnF(16)Pc the photophysical behavior and phototoxicity in vitro correlate with the aggregation degree. The dimers are not photoactive and the photochemistry of ZnF(16)Pc depends of the fraction present as monomer. On the other hand, ZnPc aggregation is minimal and its photophysical and photochemical properties are similar in the three liposomes studied. Nevertheless, its phototoxicity in vitro is liposome dependent.

Comparative photodynamic therapy study using two phthalocyanine derivatives

In the present study, a comparative photodynamic therapy (PDT) study was performed using the phthalocyanine derivatives, ZnPc(OCH(3))(4) and ZnPc(CF(3))(4), in a mouse tumor model, under identical experimental procedures. We studied the ablation of tumors induced by PDT. The end-point was to compare the photodynamic efficacy of ZnPc(OCH(3))(4) and ZnPc(CF(3))(4). ZnPc(OCH(3))(4) and ZnPc(CF(3))(4) were administered intraperitoneally at a dose of 0.2 mg/kg body weight. The injections of drugs were carried out in Balb/c mice bearing subcutaneously inoculated LM2 mouse mammary adenocarcinoma. Histological examination and serum biochemical parameters were used to evaluate hepatic and renal toxicity and function. Phototherapeutic studies were achieved employing a light intensity of 210 J/cm(2). After PDT, tumoral regression analyses were carried out, and the degree of tumor cell death was measured utilizing the vital stain Evan's blue. In this pilot study, we revealed that the cytotoxic effect of ZnPc(OCH(3))(4) after PDT led to a higher success rate compared to ZnPc(CF(3))(4)-PDT when both were intraperitoneally injectioned. Both phthalocynanine derivatives were able to induce ablation in the tumors. In summary, these results demonstrate the feasibility of ZnPc(OCH(3))(4)- or ZnPc(CF(3))(4)-PDT and its potential as a treatment for small tumors.

Photodynamic therapy with a new photosensitizing agent

OBJECTIVE

The aim of this study was to investigate the cytotoxicity of octal-bromide zinc phthalocyanine (ZnPcBr(8)) before and after irradiation with a low-power laser (AsGaAl) and analyze the effects of photodynamic therapy (PDT) on the nucleus of L929 cells.

BACKGROUND DATA

One of the most recent and promising applications of phthalocyanine in medicine is in the detection and cure of tumors. We studied the ZnPcBr(8) in agreement with the development of new photosensitizing agents for curing tumors.

METHODS

L929 cells were cultivated at standard conditions, incubated with ZnPcBr(8) for 1 h at different concentrations, irradiated with a semiconductor laser, and incubated in MEM medium for 1, 12, or 24 h. Cells were analyzed using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide (MTT) technique and fluorescence microscopy.

RESULTS

The results demonstrated that ZnPcBr(8) at 1 microM was the most effective concentration for PDT, with a decrease of 63% after 1 h, 99% after 12 h, and 100% after 24 h in relation to the control group. The fluorescence microscopy results showed that ZnPcBr(8) was localized in the perinuclear region when analyzed 1 h after incubation. Nucleus staining with DAPI made it possible to observe that nuclear fragmentation occurred 24 h after PDT, cytoplasm retraction at 1, 12, and 24 h after PDT, and vacuoles along the cytoplasm at 12 and 24 h after PDT.

CONCLUSION

According to the results obtained in this study, L929 cell death caused by PDT with ZnPcBr(8) possesses characteristics of apoptosis mediated by the mitochondria, due to the decrease in cells viability, the subcellular localization, and the photodamage found.

Zinc-(II) 2,9,16,23-tetrakis (methoxy) phthalocyanine: Potential photosensitizer for use in photodynamic therapy in vitro

Photodynamic therapy (PDT) is an innovative treatment for several types of malignant and non-malignant disease. In the present study, ZnPcOCH(3) was investigated on a human larynx-carcinoma cell line (Hep-2) for its use in PDT. This drug exhibited favourable properties as a photosensitizer in vitro because ZnPcOCH(3) is able to penetrate efficiently in the cytoplasm of cultured cancer cells and is partially localized in lysosomes. The results show that ZnPcOCH(3)-PDT-induced apoptosis by caspase dependent pathway. The new compound shows a good photosensitizing efficiency in vitro on Hep-2 cells, encouraging further in vivo studies.

Preparation and in vitro photodynamic activities of novel axially substituted silicon (IV) phthalocyanines and their bovine serum albumin conjugates

Two novel axially substituted phthalocyanines, namely bis(4-(4-acetylpiperazine)phenoxy)phthalocyaninatosilicon (IV) (1) and its N-methylated derivative 2, have been synthesized. The dicationic phthalocyanine 2 is non-aggregated in water and exhibits good photophysical properties. The non-covalent BSA conjugates of these compounds have also been prepared. Compound 2 and the conjugate 2-BSA show extremely high photodynamic activities toward B16 melanoma cancer cell lines. The corresponding 50% growth-inhibitory (IC50) ratios are 33 and 38 nM, respectively.