Detection of HLA-B*27 gene using a spectral plasmon resonance imaging system

Detection of HLA-B*27 gene is clinically important due to its strong association with diseases, such as ankylosing spondylitis. Nucleic acid-based biosensors represent a promising clinical tool for gene diagnosis. Surface plasmon resonance (SPR) can be used to monitor DNA-DNA hybridization in real-time and without any prior labeling step. Here, a self-built HLA-B*27 positive PCR products spectral SPR imaging system was used for multichannel direct-detection of a specific sequence of the HLA-B*27 gene. Thiol-labeled single-stranded oligonucleotide probes, which were proved to be superior to amine-labeled probes in immobilization, were immobilized onto the surfaces of the gold spots on the sensor chip to target the specific sequence in the HLA-B*27 gene in blood. SPR measurements were performed with different concentrations of synthetic target DNA sequence. The calibration curve of synthetic target sequence showed a good linear relationship between the concentration of the synthetic target sequence and the shift of the SPR wavelength from 10 nM to 500 nM with a detection limit of 5 nM. The HLA-B*27 gene was isolated from human whole blood and amplified using polymerase chain reaction (PCR). PCR products were measured using the SPR imaging system. HLA-B*27 positive PCR products showed significant SPR wavelength shift, while synthetic non-complementary sequence and negative PCR products showed no significant SPR wavelength shift. The method is high-specific, high-throughput and label-free.