Characterization and stability of liposomes containing ovalbumin and metal nanoparticles

• Grant number: 13/06482-7
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: July 01, 2013
• End date: June 30, 2014
• Field of knowledge: Health Sciences - Pharmacy - Pharmaceutical Technology
• Principal Investigator: Renata Fonseca Vianna Lopez
• Grantee: Beatriz Triano Perusso
• Host Institution: Faculdade de Ciências Farmacêuticas de Ribeirão Preto (FCFRP). Universidade de São Paulo (USP). Ribeirão Preto , SP, Brazil

Abstract

The transcutaneous administration of antigens is a promising strategy for vaccination that is painless and avoids the risks associated with parenteral administrations. The success of this type of immunization depends, however, on the penetration of the antigen into the viable epidermis, where the antigen-presenting cells are located. As antigens are mostly hydrophilic macromolecules, their diffusion to the viable epidermis is hampered by the stratum corneum (SC). SC is a powerful barrier, with lipophilic characteristics, which protects the skin against the entry and exit of substances. To overcome this barrier, applying an electrical pulse of approximately 1000 V on the skin, known as electroporation, has been studied as a way to change the SC and facilitate penetration of antigens. However, this strategy causes discomfort to the patient and does not target the antigen release to the skin, but to the bloodstream. Iontophoresis, which is the application of an electrical current of low intensity, which causes a variation in electrical potential of up to 6 V, could be used for this purpose without causing discomfort or irreversible alterations in the SC. However, despite the success of iontophoresis in transdermal drug administration, it has been little explored in transcutaneous immunization. Adequate control of formulation and iontophoretic parameters (such as time of application of current, polarity, and conductivity) could target antigens to viable epidermis and increase the potential for success of transcutaneous immunization. Some recent studies show that the application of iontophoresis in liposomal formulations appears to increase drug retention in the skin and decrease its dissemination into the bloodstream. Therefore, the overall objective of this project (Proc. 12/05177-3 FAPESP) is to study the influence of the composition of liposomal formulations containing ovalbumin (OVA), a model antigen, in the immune response after iontophoretic administration. This undergraduate research project is part of this larger proposal and aims to specifically prepare liposomes with different surface charges. Furthermore, the influence of metal nanoparticles on the conductivity and stability of the liposomes formulations obtained will be evaluated. These formulations will be characterized for size, zeta potential, encapsulation efficiency of OVA, conductivity, and stability to electrical current. It is expected that positively charged liposomes conduced better the electrical current when placed in contact with the positive electrode (anode). If this happens, OVA transport should be improved, together with a better immune response. Furthermore, it is expected that the presence of metal nanoparticles increases the physical stability of the liposomes in the presence of the electrical current. (AU)