Gelled oil particles: A new approach to encapsulate a hydrophobic metallophthalocyanine

Abstract

Chloroaluminum phthalocyanine (ClAlPc) is a promising sensitizer molecule for photodynamic therapy, but its hydrophobicity makes it difficult to formulate. In this study, we have efficiently encapsulated ClAlPc into gelled soybean oil particles dispersed in water. 12-Hydroxystearic acid (HSA) and polyethyleneimine (PEI) were the gelling and stabilizing agents, respectively. The preparation process involved hot emulsification above the gelation temperature (Tgel), followed by cooling to room temperature, which gave a colloidal dispersion of gelled particles of oil in aqueous medium. The gelled particles containing ClAlPc had a medium diameter of 280 nm, homogeneous size distribution (polydispersity index ≈0.3) and large positive zeta potential (about +50 mV) and showed a spherical morphology. The gelled oil particle formulations exhibited good physical stability over a 6-month period. ClAlPc interfered with the HSA self-assembly only slightly, and decreased the gelation temperature to a small extent; however it did not affect gelation process of the oil droplets. The amounts of PEI and HSA employed during the preparation allowed us to control particle size and the dispersion stability, a phenomenon that results from complex electrostatic interactions between the positively charged PEI and the negatively charged HSA fibers present on the gelled particles surface. In summary, by using the right ClAlPc, HSA, and PEI proportions, we prepared very stable dispersions of gelled soybean oil particles with excellent ClAlPc encapsulation efficiency. The obtained colloidal formulation of gelled oil particles loaded with ClAlPc shall be very useful for photodynamic therapy protocols.

Evaluation of the efficacy of systemic miltefosine associated with photodynamic therapy with liposomal chloroaluminium phthalocyanine in the treatment of cutaneous leishmaniasis caused by Leishmania (L.) amazonensis in C57BL/6 mice

“…Moreover, despite the formation of large unilamellar vesicles (> 100 nm) in the aqueous medium, these were smaller than 300 nm, which is important in that liposome sizes of more than 500 nm could compromise their use as a drug delivery vehicle, because they would be quickly removed from the bloodstream by phagocytes [35]. In the future there may be new findings with an organised lipid gellified system, known as a gelosome, which has appeared recently [18].…”

“…The concentration of the phthalocyanine was estimated spectrophotometrically using  674 = 2.41×10 5 M -1 for AlClPC in liposome. Even in a liposomal formulation, normally AlClPC associated with a drug delivey system is reorganized in a gel formulation, by associating the liposome preparation to thermosensitive Poloxamer surfactant derivatives (such as a Pluronic F-127) to increase the adhesion proproperties of the final formulation in contact with the wound at body temperature, allowing the perfect contact of the formulation with the lesion, leading to a better uptake of the photoactive compounds by the biological target [17][18][19][20]. The amount of AlClPC incorporated was analysed by absorption and the fluorescence spectra recorded on a Hitachi U-3000 spectrophotometer and a Spex Fluorog 3 (Jobin-Ivon) spectrofluorimeter, respectively, at 25C with constant stirring.…”

“…In gel formulation most of the liposome presents the same behaviour. New DDS as a gelosome formulation has emerged recently as a new proposal for drug delivery [18].…”

Encapsulation of Hydrophobic Phthalocyanine with Poly(N-isopropylacrylamide)/Lipid Composite Microspheres for Thermo-Responsive Release and Photodynamic Therapy

“…Thus, during the photodynamic therapy using Pc molecules, following the accumulation of these photosensitizers in a tumor region under the visualizing and monitoring by fluorescence imaging, PDT can be precisely applied onto the targeted tissue by selectively illuminating the tumor cells, without hurting the normal organs around [2,5]. Furthermore, belonging to the second generation of sensitizer molecules used in PDT, Pc has strong absorption and fluorescence emission in the near-infrared (NIR) light range (called “biological optical window”), among which minimal tissue autofluorescence and light scattering occur [6,7]. …”

Core–shell-type organogel–alginate hybrid microparticles: A controlled delivery vehicle

“…To achieve this, Siqueira-Moura et al (2013) have synthesized gelled oil particles using polyethleneimine as the stabilizer [13]. In the present study, an alternative approach has been proposed to solve the problem of leaching and to improve the drug encapsulation efficiency.…”