G. Bidan et al., Electropolymerization as a versatile route for immobilizing biological species onto surfaces - Application to DNA biochips, APPL BIOC B, 89(2-3), 2000, pp. 183-193
Biosensors based on electronic conducting polymers appear particularly well
suited to the requirements of modern biological analysis-multiparametric a
ssays, high information density, and miniaturization. We describe a new met
hodology for the preparation of addressed DNA matrices. The process include
s an electrochemically directed copolymerization of pyrrole and oligonucleo
tides bearing on their 5' end a pyrrole moiety. The resulting poly mer film
deposited on the addressed electrode consists of pyrrole chains bearing co
valently linked oligonucleotides (ODN). An oligonucleotide array was constr
ucted on a silicon device bearing a matrix of 48 addressable 50 x 50 mum go
ld microelectrodes. This technology was successfully applied to the genotyp
ing of hepatitis C virus in blood samples. Fluorescence detection results s
how good sensitivity and a high degree of spatial resolution. In addition,
gravimetric stud ies carried out by the quartz crystal microbalance techniq
ue provide quantitative data on the amount of surface-immobilized species.
In the case of ODN, it allows discrimination between hybridization and nons
pecific adsorption. The need for versatile processes for the immobilization
of biological species on surfaces led us to extend our methodology. A biot
inylated surface was obtained by coelectropolymerization of pyrrole and bio
tin-pyrrole monomers. The efficiency for recognition (and consequently immo
bilization) of R-phycoerythrin-avidin was demonstrated by fluorescence dete
ction. Copolymerization of decreasing ratios of pyrrole-biotin over pyrrole
allowed us to obtain a decreasing scale of fluorescence.