Development of a piezoelectric biosensor based on PVDF films

• Author(s): Marques, Ana Raquel Correia Gonçalves
• Date: 2011
• Persistent ID: http://hdl.handle.net/10362/6575
• Origin: Repositório Institucional da UNL
• Subject(s): Biosensor; PVDF; Piezoelectricity; PVDF membranes; Surface modification
• Document Type: Master thesis
• Language: English
• Advisor(s): Roque, Ana; Gomes, Pedro
• Contributor(s): RUN

Description

Dissertação para obtenção do Grau de Mestre em Engenharia Química e Bioquímica

The core of this work is a piezoelectric biosensor in which acoustic waves are launched in very thin PVDF polymer films to produce an oscillatory resonant device. The essence of the device consists in a polymer film system made of a piezoelectric polymer, PVDF, responsible for the film oscillation and a porous membrane, Immobilon, a special type of porous PVDF with protein binding capacity which can act as a biosensitive area. The possibility of using a film system composed only by PVDF was studied. Due to its strong hydrophobic nature, surface modification was aimed to be performed by coating a functional layer on the membrane surface, in order to improve the hydrophilicity and biocompatibility of PVDF. An immersion method was preformed and applied to porous and non-porous PVDF membranes. Three distinct coating solutions were studied, namely, polyethylene glycol (PEG), 3,4-Dihydroxy-DL-phenylalanine (DL-DOPA) and Gum Arabic solutions. Hydrophilicity improvements of the membranes were characterized by water contact angle measurements and its elemental composition was studied by elemental microanalysis. BSA protein marked with FITC fluorescein was used to perform quantitative and qualitative assays in order to study its adsorption to coated and uncoated PVDF membranes. Globally, the best results were obtained when a solution of PEG was utilized with 0.2 μm microporous membrane. The sensor response was tested with polyethylene glycol (PEG) and bovine serum albumin (BSA), using a film system composed by PVDF/0.2 μm Immobilon/PVDF, which was able to respond to the presence of both compounds in liquid medium.