Design of hybrid systems based on porous silica and alginate for medical applications

• Grant number: 12/08677-7
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• Start date: September 01, 2012
• End date: September 30, 2013
• Field of knowledge: Physical Sciences and Mathematics - Chemistry
• Principal Investigator: Nelson Eduardo Duran Caballero
• Grantee: Amauri Jardim de Paula
• Host Institution: Instituto de Química (IQ). Universidade Estadual de Campinas (UNICAMP). Campinas , SP, Brazil

Abstract

Silica porous nanostructures acting as molecular vehicles are considered as protagonists of a possible revolution in several areas related to biology and medicine, which are actually incorporated in the term "nanobiotechnology". The great challenges initially presented for the compatibilization of these nanomaterials with the aqueous medium (base of biological media) were recently surpassed with the synthesis of porous and colloidal nanoparticles, hierarchically functionalized with hydrophilic and hydrophobic chemical groups, with a high surface area (~1000 m2/g), volume of pores (~1,5 cm3/g) and high colloidal stability. This set of characteristics and properties presented opened up perspectives involving the use of this system for several applications, as a vehicle for dispersion and liberation of hydrophobic molecules in the aqueous medium. Considering these nanostructures as technological platforms and following the development of nanobiotechnology, we are entering now in a new paradigm which addresses the construction of complex architectures, and it is based on the production of nanomaterials under the focus of the application. In this new paradigm of nanobiotechnology, the relevance of phenomena manifested on the nanostructure/biological medium interface is being recognized, and their consequences will be necessarily evaluated for each possible application. Therefore, the surface chemical microenvironment is now as much or more important than the intrinsic characteristics of the nanomaterial used: crystallinity, morphology, purity, porosity, etc. Consequently, in this step, the nanostructure surface functionalization emerges as a central process for the advancement of the area. Observing the size order and the fluidic and dynamic behavior of the chemical entities which make up the soft matter, the production of hybrid systems containing porous silica nanoparticles coated with biopolymers arises as a promising route for the compatibilization of the nanostructures in biological applications. In this context, alginic acid (a polysaccharide extracted from algae) is a natural candidate for such finality. Among the possibilities, the present project focuses on the formation of silica nanoparticles coated with this biopolymer (core-shell nanostructures) and alginate hydrogels incorporated with silica nanoparticles (composites). The choices are justified by several scientific and technological arguments: increase of the biocompatibility of silica nanoparticles; wide range of options of chemical bonds (covalent and non-covalent) between silica and alginate; extensive control of rheological properties of the suspensions containing core-shell nanostructures and mechanical properties of the hydrogel composites; and possibility of controlling the liberation of the molecular agent (hydrophobic molecule) present in the pores of silica nanoparticles as a function of the parameters used for the formation of the hybrid systems. Materials will be produced aiming their utilization for the treatment of cutaneous melanomas (kind of skin cancer). For this, the project will count on the antitumoral properties of violacein (hydrophobic molecule produced by bacteria of Negro river), which will be incorporated in the pores of silica. Through the advantages offered by the use of these nanostructures as platforms, one aims generating materials with real perspectives of technological innovation. Results obtained through this project may be extrapolated for several other possible applications, once the hybrid systems can be considered as vehicles for any other type of hydrophobic molecule. Besides, one intends achieving an important step in the understanding of biological interactions occurring between the hybrid systems produced (core-shell nanostructures and composites) and the media involved in the route of application, more specifically the skin and blood plasma.