Synthesis and characterization of photosensitive gelatin-based hydrogels for photodynamic therapy in HeLa-CCL2 cell line.

BACKGROUND: Hydrogel systems are increasingly gaining visibility involving biomedicine, tissue engineering, environmental treatments, and drug delivery systems. These systems have a three-dimensional network composition and high-water absorption capacity, are biocompatible, allowing them to become an option as photosensitizer carriers (PS) for applications in Photodynamic Therapy (PDT) protocols. METHODS: A nanohydrogel system (NAHI), encapsulated with chloroaluminium phthalocyanine (ClAlPc) was synthesized for drug delivery.. NAHI was synthesized using gelatin as based polymer by the chemical cross-linking technique. The drug was encapsulated by immersing the hydrogel in a 1.0 mg.mL-1 ClAlPc solution. The external morphology of NAHI was examined by scanning electron microscopy (SEM). The degree of swelling of the synthesized system was evaluated to determine the water absorption potential. The produced nanohydrogel system was characterized by photochemical, photophysical and photobiologial studies. RESULTS: The images from the SEM analysis showed the presence of three-dimensional networks in the formulation. The swelling test demonstrated that the nanohydrogel freeze-drying process increases its water holding capacity. All spectroscopic results showed excellent photophysical parameters of the drug studied when served in the NAHI system. The incorporation efficiency was 70%. The results of trypan blue exclusion test have shown significant reduction (p < 0.05) in the cell viability for all groups treated with PDT, in all concentrations tested. In HeLa cells, PDT mediated by 0,5 mg.mL-1 ClAlPc encapsulated in NAHI showed a decrease in survival close to 95%. In the internalization cell study was possible to observe the internalization of phthalocyanine after one hour of incubation, at 37 °C, with the the accumulation of PS in the cytoplasm and inside the nucleus at both concentrations tested. CONCLUSIONS: Given the peculiar performance of the selected system, the resulting nanohydrogel is a versatile platform and display potential applications as controlled delivery systems of photosensitizer for photodynamic therapy application.

Polyelectrolytic gelatin nanoparticles as a drug delivery system for the promastigote form of Leishmania amazonensis treatment.

In this study, phthalocianato[bis(dimethylaminoethanoxy)] silicon (NzPC) was loaded onto gelatin nanoparticles functionalized with polyelectrolytes (polystyrene sulfonate/polyallylamine hydrochloride) by layer-by-layer (LbL) assembly for photodynamic therapy (PDT) application in promastigote form of Leishmania amazonensis treatment. The process yield, and encapsulation efficiency were 80.0% ± 1.8 and EE = 87.0% ± 1.1, respectively. The polyelectrolytic gelatin nanoparticles (PGN) had a mean diameter of 437.4 ± 72.85 nm, narrow distribution size with a polydispersity index of 0.086. The obvious switching of zeta potential indicates successful alternating deposition of the polyanion PSS and polycation PAH directly on the gelatin nanoparticles. Photosensitizer photophysical properties were shown to be preserved after gelatin nanoparticle encapsulation. The impact of the PDT in the viability and morphology of Leishmania amazonensis promastigote in culture medium was evaluated. The PGN-NzPc presented low toxicity at the dark and the PDT was capable of decreasing the viability in more than 80% in 0.1 µmol.L-1 concentration tested. The PDT also triggered significant morphological alterations in the Leishmania promastigotes. These results reinforce the idea that the use of PGN as photosensitizers carriers is useful for PDT of Leishmania promastigotes.

Polyelectrolytic BSA nanoparticles containing silicon dihydroxide phthalocyanine as a promising candidate for drug delivery systems for anticancer photodynamic therapy.

Recently several scientific-technological advances in the health area have developed. Among them, we can highlight research addressing nanoscience and nanotechnology focusing on the development of formulations for the cancer treatment. This work describes the synthesis and characterization of bovine serum albumin (BSA) polyelectrolytic nanoparticles for controlled release using silicon dihydroxide phthalocyanine [SiPc (OH)2] as a photosensitizer model for application in Photodynamic Therapy (PDT). BSA nanoparticles were prepared by the one-step desolvation process and the nanoparticulate system was coated with polyelectrolytes using poly-(4-styrene sulfonate - PSS) as a strong polyanion and polyallylamine hydrochloride (PAH) as a weak polycation by the technique self-assembling layer-by-layer (LbL). The formulation was characterized and available in cellular culture. The profile of drug release was investigated and compared to that of free [SiPc (OH)2]. The nanoparticles have a mean diameter of 226.9 nm, a narrow size distribution with polydispersive index of 0.153, smooth surface and spherical shape. [SiPc(OH)2] loaded nanoparticles maintain its photophysical behaviour after encapsulation. The polyelectrolytic nanoparticles improved efficiency in release and photocytotoxicity assay when compared to pure drug. The results demonstrate that photosensitizer adsorption on BSA nanoparticles together with biopolymer layer-by-layer assembly provides a way to manufacture biocompatible nanostructured materials that are intended for use as biomaterials for Photodynamic Therapy applications.

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.

Cellular changes after photodynamic therapy on HEp-2 cells using the new ZnPcBr(8) phthalocyanine.

OBJECTIVE: This study investigated the effects of photodynamic therapy (PDT) by using the new photosensitizer Octal-Bromide Zinc Phthalocyanine (ZnPcBr(8)) on the nucleus, mitochondria, and cytoskeleton of HEp-2 cells. BACKGROUND DATA: PDT has been widely used as a therapeutic method for tumor-selective treatment and for other diseases. The therapy requires a photosensitizer, molecular oxygen, and visible light. Different studies have demonstrated that cellular organelles are potential targets for PDT, and the results are dependent on the photosensitizer used in the treatment. In this study, we investigated changes in the nucleus, mitochondria, and cytoskeleton of HEp-2 cells after PDT with the new ZnPcBr(8) phthalocyanine. MATERIAL AND METHODS: HEp-2 cells were cultivated under standard conditions, and then incubated with ZnPcBr(8) (1 micromol/L) for 1 h, and subsequently irradiated with a diode laser light (676 nm, 30 mW, 4.5 J/cm(2)). The cells were further cultured for 1 and 24 h at 37 degrees C in a 5% CO(2) and analyzed with fluorescence microscopy by using specific probes for the investigated organelles. RESULTS: Before PDT, the photosensitizer showed a cytoplasmic diffuse distribution. After PDT, cells showed multinucleation, a punctuated mitochondrial distribution in the perinuclear region, and cellular retraction due to the cytoskeleton changes. All those cellular alterations disrupted homeostasis, contributing to cellular death, which is the major goal of PDT. CONCLUSION: Based on our results and the characteristics of the new ZnPcBr(8) phthalocyanine, mechanistic and biochemical studies must be performed, but it is tempting to consider the chemical as a promising agent for PDT.