ENHANCING SENSITIVITY AND SELECTIVITY THROUGH AFFINITY RECEPTOR-DECORATED CHITOSAN-COATED GOLD NANOPARTICLES IN SURFACE PLASMON RESONANCE FOR SORTILIN BIOSENSING

The present work reports a highly sensitive and selective surface plasmon resonance (SPR) biosensor for Sortilin (SORT), an important biomarker of coronary artery disease (CAD). In brief, chitosan (CH)-coated gold nanoparticles (Au-NPs) were fabricated through a layer-by-layer (LBL) nanoassembly on green-synthesized Au-NPs, followed by immobilization of anti-SORT antibodies using carbodiimide coupling. The CH coating provided abundant amine groups for efficient antibody attachment. Simultaneously, boron-doped graphene oxide (B-GO) nanosheets were deposited onto an amine-functionalized gold sensor chip to provide a large surface area and abundant active sites for anchoring the anti-SORT-decorated CH-coated Au-NP nanoassembly. The developed SPR biosensor exhibited a wide linear detection range from 400 to 0.1 ng/mL and a low detection limit of 6.09 pg/mL. Furthermore, the sensor demonstrated excellent stability, reproducibility, and real-time analytical capability, offering a label-free, eco-friendly, and minimally invasive platform for sensitive SORT detection.