Production of molecular vehicles based porous on silica nanostructures for transportation of hydrophobic molecules

Author(s)

Amauri Jardim de Paula

• Document type: Doctoral Thesis
• Press: Campinas, SP.
• Institution: Universidade Estadual de Campinas (UNICAMP). Instituto de Química
• Defense date: 2012-08-16

Examining board members

Oswaldo Luiz Alves; Adley Forti Rubira; Flavio Maron Vichi; Maria do Carmo Gonçalves; Edvaldo Sabadini

• Advisor: Oswaldo Luiz Alves

Abstract

Based on the Stöber method, an elegant and efficient process for synthesizing SiO2 colloidal nanoparticles, modifications were done in order to produce porous nanoparticles (50-80 nm) with high surface area (~1000 mg), volume of pores (~1,5 m g) and high colloidal stability. The nanostructures are made of hierarchically functionalized colloidal silica nanoparticles, with internal pores with disordered structure and diameters ranging from 1.8 to 10 nanometers, functionalized with phenyl groups; and external surface covered with ionizable propylmethylphosphonate groups. The hierarchical and chemically antagonistic functionalization (hydrophobic = internal pores; hydrophilic = external surface) allows hydrophobic molecules (low solubility in water) to be easily incorporated in the hydrophobic porous cavities, whereas particles maintain stably dispersed in water for months. Hydrophobic molecules were incorporated by the porous SiO2 nanoparticles in concentrations up to 3% (w/w) simply by mixing colloidal aqueous suspensions of these nanomaterials and insoluble molecules (powders). The uptake capacity for a specific hydrophobic molecule (camptothecin) was significantly higher than in other porous systems of SiO2 that have been currently used. The efficiency of the molecular vehicles was evidenced through the transportation of camptothecin, a potent antitumoral agent which led to the growth inhibition of human leukemic cells. Besides, the synthetic approach used in this thesis also made possible the functionalization of the external surface of nanoparticles with other hydrophilic and reactive organic groups, such as propylamine. Consequently, the characteristics of these SiO2 nanoparticles here shown fulfill several current scientific demands: necessity of porous silica nanostructures with a wide distribution of pore sizes, homogeneous morphology, narrow size distribution and real dispersibility in water (colloidal). Thereby, this set of properties opens up perspectives involving the use of this system as a technological platform susceptible to several applications, acting as a vehicle for the dispersion and liberation of hydrophobic molecules in aqueous media (AU)

• FAPESP's process: 09/10056-8 - PRODUCTION OF SILICA MESOPOROUS NANOSTRUCTURES TO TRANSPORT HYDROPHOBIC ANTITUMOR AGENTS
• Grantee: Amauri Jardim de Paula
• Support Opportunities: Scholarships in Brazil - Doctorate