D-shaped optical fibre-based LSPR sensing probes for detection of Tomato Leaf Curl New Delhi Virus

The D-shaped fibre optic-based probe has been developed for evanescent wave absorption-mediated Begomovirus DNA detection. This probe was subjected to functionalization through amine functional groups using a conventional amine silanization process. Subsequently, the localized surface plasmon resonance (LSPR) based plasmonic surface has been developed following the gold nanoparticle immobilization technique. The refractive index response of this probe was determined using sucrose solutions. Observed a linear correlation between LSPR absorbance and refractive index that was capable of detecting 0.118 ± 0.047 × 10^− 3 unit change in refractive index with the sensitivity of 1.025 ΔA/Δn. This LSPR probe was modified for the development of biosensing probes by incubating cross-linker mediated complementary DNA (cDNA). The characteristic LSPR peak absorption dynamics of gold nanoparticles were monitored at 540 nm wavelength to confirm the specific conjugation between cDNA and viral ssDNA. The biosensing response of this cDNA probe was tested by incubating single-stranded viral DNA (ssDNA) as the target specific sample which was extracted from the Tomato Leaf Curl New Delhi virus infected tomato leaves where the limit of detection was 85 ± 5ng/µL. From these viral ssDNA binding results, a portable optical sensor has been conceptualized using digital electronic logic states. This D-shaped fibre optic sensor has enormous commercial value for real-time monitoring of plant viruses from the genus of Begomovirus.