An angle-scanning surface plasmon resonance imaging device for detection of mismatched bases in caspase-3 DNA

Abstract

A laboratory-made angle-scanning surface plasmon resonance (SPR) imaging device using a high-precision piezoceramic motor has been fabricated. A rhombic structure was exploited to convert the linear motion of the piezoceramic motor into the angular motion of the laser and CCD arrays. The SPR imaging system was used to detect the mismatched bases in the caspase-3 DNA with the advantage of high-throughput. DNAs containing different numbers of mismatches were studied directly using the SPR imager. One strand of the DNA was modified with an amino-group and then spotted on the chemically modified sensing surface via amino–carboxyl reaction. The uniformity of the probe spots was measured, and the standard deviation of the resonance angle was less than 0.03°. According to the results of the DNA hybridization, the SPR signal generated by the single strand DNA (ssDNA) with less than 3 mutated bases was comparable to that generated by the complementary ssDNA. These results showed that the SPR sensor could carry out comparison and differentiation between the caspase-3 DNA sequences. A single mismatch in DNA could be distinguished. The detection limit was 25 pmol L⁻¹. This SPR imaging method for detection of the mismatched bases in the caspase-3 is fast, label-free, visual and sensitive.