Study on conditions of DNA immobilization by surface plasmon resonance imaging

Abstract

Surface plasmon resonance (SPR) is an optical label-free sensing technique with high sensitivity and has been widely used in biological and chemical studies. Recently, there are many reports about sensing DNA microarrays with two-dimensional surface plasmon resonance imaging (SPRi) technique. However, the relations between the SPR refractive index response and the conditions of DNA immobilization are still not well known. This impedes the development of SPR bio-sensing. In this paper, we use a SPR imaging technique which we have previously reported-parallel scan spectral SPR imaging-to study the equivalent refractive index of the DNA probes (Bacterial 16S rDNA universal primer) immobilized on gold surface of the SPR sensing module. We change the immobilization conditions including types of the buffer solution, the incubation time and the concentrations of probe, obtain the equivalent refractive index of these biochemical molecules on the gold surface. From the relations of the equivalent refractive index and these conditions, we finally conclude with the optimal conditions of the DNA immobilization. These results are useful for further DNA microarray studies base on SPR.