A low-cost surface plasmon resonance instrument based on detection of resonance excitation wavelength

A laboratory-made surface plasmon resonance (SPR) instrument based on the detection of resonance excitation wavelength has been successfully fabricated. The performance and workability of the SPR instrument was demonstrated as a DNA biosensor. Biotinylated single-stranded oligonucleotides (ssDNA) were chemically immobilized on a gold-film surface of the SPR instrument as a DNA probe for the detection of its fully complementary, half-complementary and non-complementary ssDNA. The immobilization of the ssDNA probe was done by avidin-biotin linkage. The ssDNA used were 12-mer oligonucleotides. The sensing mechanism was based on the shift in resonance wavelength of an excitation light beam as the target ssDNA hybridized with the ssDNA on the gold-film surface. The linear dynamic ranges of the DNA biosensor for fully complementary and half-complementary ssDNA are 0.04-1.2 pM and 0.08-1.1 pM, respectively. The DNA biosensor showed higher sensitivity to fully complementary ssDNA than to half-complementary ssDNA. But no shift of resonance wavelength to the non-complementary ssDNA was observed.