Effect of AuNP Size on Detection of PML/RARA Fusion Gene Using Surface Plasmon Resonance Imaging

The surface plasmon resonance (SPR) sensor was used for the detection of the PML/RARA fusion gene, and the sandwich structure as the amplification strategy was constructed with functionalized gold nanoparticles (AuNPs). Three different sizes of AuNPs were selected to investigate the role that size plays in genotypic SPR sensing. To enhance sensor sensitivity and ensure signal reliability, the effects of experimental conditions were examined, such as buffer, flow rate, and probe density, on the sensor performance. Experimental and simulation results demonstrate that buffers with lower dielectric constants exhibit superior sensitivity. While larger AuNPs initially improve the sensor performance, this advantage diminishes as the analyte concentration decreases. Furthermore, varying probe densities influence AuNP enhancement capabilities, with a larger probe spacing effectively regulating the hybridization efficiency. Finally, after considering the nonspecific binding of DNA-AuNPs, the spacer layer of the probe was increased to reduce the background signal. By increasing the spacer layer from polyT 5 to polyT 16, the limit of detection was reduced significantly from 9.03 pM to 5.53 fM, and the coefficient of variation for repeatability improved from 14.89 to 3.40%. Otherwise, the sensor performed exceptionally well in terms of specificity, resistance to fouling, and recovery from complex matrices. The above results establish a surface chemical treatment method for AuNP-enhanced SPR biosensors.