Nanoparticles as a tool in capillary electrochromatography

• Autor(a) principal: Chaves, Susana Isabel Ribeiro
• Data de Publicação: 2009
• Tipo de documento: Dissertação
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10400.6/1341
• topic: Electrocromatografia capilar; Nanopartículas - Propranolol; Nanopartículas - Lisozima; Nanopartículas - Proteínas; Miniaturização; Domínio/Área Científica::Engenharia e Tecnologia::Engenharia Química

Two different types of molecularly imprinted nanoparticles against (R)-propranolol were used to separate the enantiomers of propranolol in capillary electrochromatography mode, methacrylic acid based nanoparticles and core-shell molecularly imprinted polymer nanoparticles. Partial filling technique was used to avoid interference of molecularly imprinted polymer nanoparticles in UV detection. With methacrylic acid based nanoparticles it was not possible to obtain enantiomer separation. Strong unspecific interactions between the molecular imprinted polymer nanoparticles and propranolol disturbed enantiomer separation. Since large content of acetonitrile had to be used in order to obtain stable suspensions of molecularly imprinted polymer nanoparticles, the electrostatic interactions were favored which contributed to the unspecific interactions occurring. Core-shell molecularly imprinted polymer nanoparticles present suspension stability at low content of acetonitrile due to the poly(acrylamide) shell that makes them more hydrophilic. Enantiomer separation of propranolol was achieved with 40% of acetonitrile. Reproducibility was problematic due to the unspecific interactions occurring. With time several factors can occur contributing to the decreased reproducibility of results such as, interactions between the molecularly imprinted polymer nanoparticles and the capillary wall or evaporation of the organic solvent due to the design of vials used in capillary electrochromatography system. The core-shell molecularly imprinted polymer nanoparticles are more suitable for propranolol enantiomer separation in comparison to methacrylic acid based nanoparticles. More stable suspensions give a greater range of conditions that can be tested. Silanized gadolinium oxide nanoparticles were tested as pseudostationary phase in capillary electrochromatography for protein separation. The lack of interference with UV detection and the large surface area of these nanoparticles make them a promising tool in capillary electrochromatography for protein separation. These nanoparticles interact with the proteins that are analyzed. Increased injection times of the nanoparticles give retained peaks of human growth hormone showing that strong interactions between the protein and nanoparticles are occurring. Lysozyme that was not recovered using conventional capillary electrophoresis could be detected when nanoparticles were used as pseudostationary phase. The nanoparticles can act as a coating in the capillary wall or due to their large surface area they can prevent adsorption of the lysozyme to the capillary.