AVS 49th International Symposium
    Biomaterials Tuesday Sessions
       Session BI-TuP

Paper BI-TuP18
Realisation of Biosensor Interfaces by Surface Reactions on Silanised Tantalum Pentoxide

Tuesday, November 5, 2002, 5:30 pm, Room Exhibit Hall B2

Session: Biointerfaces and Surfaces I
Presenter: W. Laureyn, IMEC, Belgium
Authors: W. Laureyn, IMEC, Belgium
R. De Palma, IMEC, Belgium
F. Frederix, IMEC, Belgium
K. Bonroy, IMEC, Belgium
J.-M. Friedt, IMEC, Belgium
K.-H. Choi, IMEC, Belgium
A. Campitelli, IMEC, Belgium
G. Maes, KULeuven, Belgium
Correspondent: Click to Email
Affinity biosensors allow the detection of affinity based interactions between bio-molecules, e.g. in antibody-antigen recognition. The presence of antigens in an analyte can be verified by their binding to complementary antibodies, immobilised onto a biosensor surface. Tantalum pentoxide (Ta@sub 2@O@sub 5@) is regarded as a promising material for the realisation of affinity biosensors, especially for impedimetric biosensing, because of its high dielectric constant and chemical stability. To date, the main method for the immobilisation of proteins to oxide surfaces has involved reactions with short-chain trialkoxysilanes, leading to heterogeneous and less effective biosensor interfaces. Alkyltrichlorosilanes, on the contrary, generate well-structured Self-Assembled Monolayers (SAMs), when produced under the proper conditions. Unfortunately, most polar functional groups ideal for protein immobilisation (COOH and NH@sub 2@) have to be generated from non-polar precursor alkyltrichlorosilanes, after SAM-formation of the latter. In this contribution, several approaches for the introduction of polar functional groups on Ta@sub 2@O@sub 5@ , silanised with alkyltrichlorosilanes, will be presented. A novel surface reaction for the introduction of COOH and NH@sub 2@ groups on SAMs of bromoalkyltrichlorosilane is evaluated and compared to the oxidation of allylalkyltrichlorosilane and the reduction of cyanoalkyltrichlorosilane respectively. The proposed surface reaction consists in a nucleophilic substitution of the bromine termination with functional thiol compounds. The silanisation of Ta@sub 2@O@sub 5@ and the subsequent surface reactions are characterised by means of contact angle measurements, XPS, infrared spectroscopy and cyclic voltammetry. Finally, the immobilisation of IgG, on the generated functional Ta@sub 2@O@sub 5@ surfaces, and the subsequent binding of anti-IgG are monitored by means of Quartz Crystal Microbalance and Atomic Force Micrososcopy.