Real-time monitoring of ssDNA binding using a fiber optic LSPR microfluidic platform

In this paper, we present the development of a localized surface plasmon resonance (LSPR) sensor for the detection of single-stranded DNA (ssDNA). The LSPR chip was fabricated using gold nanoparticles (AuNPs) with a diameter of 80 nm. It was integrated with a microfluidic chamber to ensure stable measurements. We employed data processing techniques to fit the absorbance curve and extract the resonance wavelength, significantly reducing noise and achieving a 100-fold improvement in signal quality. The fabricated LSPR chips demonstrated a bulk refractive index sensitivity of approximately 85–90 nm/RIU. This paper outlines a robust methodology for reliable LSPR measurements based on cheap and readily accessible instruments. We have shown successfully real-time binding between Poly(T₂₀) and Poly(A₂₀), sensitive down to a concentration of 2 nM, while maintaining signal fluctuations 10 times lower than the shift in resonance wavelength without using any complex signal amplification technique. The sensor exhibits a limit of detection (LOD) of 0.75 nM. The proposed method shows potential for high-sensitivity and reliable real-time detection of smaller biomolecules, environmental pollutants, foodborne pathogens, toxins, and disease biomarkers.