Electrochemical quartz crystal microbalance study of the avidin and albumin adsorption under flow injection analysis conditions
|Agnieszka Kochman 1, Wlodzimierz Kutner 1, Giosio Farace 2, Pankaj Vadgama 2|
1. Polish Academy of Sciences, Institute of Physical Chemistry, Kasprzaka 44/52, Warszawa 01-224, Poland
In humans, albumin is responsible, among others, for isolation and removal of foreign intruding solid objects. Thus, implants can be clogged and rejected as well. Therefore, we have undertaken an effort to find conditions, in vitro, under which adsorption of albumin on a solid substrate surface is prevented. Virtually, albumin does not interact with avidin. Therefore, an idea was explored to coat, first, the studied solid surface with avidin in hope that albumin will not adsorb onto it afterwards. For effective adsorption of avidin, we used an avidin-biotin immobilization procedure and monitored this adsorption by using piezoelectric microgravimetry with an electrochemical quartz crystal microbalance (EQCM) under batch conditions. We used a matrix of a conducting polymer film for biotin immobilization by ion exchange. That is, the surface of a gold electrode of the 5 MHz resonant frequency quartz crystal piezoelectric transducer was coated with a polypyrrole film doped with d-botin 4-aminobenzoic acid sodium salt. The film was prepared by electropolymerization under cyclic voltammetry conditions in aqueous solution. Anion of the biotin salt served as counterion for charge compensation of electro-oxidized polypyrrole. Electropolymerization was interrupted at the positive potential limit so, that anions could stay in the polymer. The avidin and albumin adsorption was studied by EQCM under flow injection analysis (FIA) conditions. First, consecutive injections of the avidin solution samples resulted in the negative frequency steps indicating that avidin irreversibly interacted with the biotin sites immobilized in the poly(pyrrole) film. The height of these steps decreased with the injection number as the biotin sites became gradually saturated. Then, adsorption of albumin on the saturated with avidin surface of the polymer film was examined. Morover, adsorption of avidin onto adsorbed layer of albumin was investigated. Results of the FIA experiments indicated that the avidin layer immobilized onto the polypyrrole-biotin film effectively repelled albumin.
Presentation: Poster at SMCBS'2005 Workshop, by Agnieszka Kochman
See On-line Journal of SMCBS'2005 Workshop
Submitted: 2005-10-27 07:56 Revised: 2009-06-07 00:44