Augmenting long range SPR sensitivity with quantum dots-AgNP-PVA layer for methylene blue detection

This study introduces an innovative Long-Range Surface Plasmon Resonance (LRSPR) technique, incorporating the silver nanoparticle-amine functionalized carbon quantum dot-polyvinyl alcohol (AgNP-NCQD-PVA) layer as both a dielectric buffer layer and a sensing material. This integration substantially enhances the sensitivity of LRSPR for methylene blue detection, marking a significant advancement in photonic technology. The AgNP-NCQD-PVA LRSPR demonstrates exceptional sensitivity with two distinct slopes: 4.2473 nm/ppm for the range of 0.5–5 ppm (R²=0.9231) and 0.5279 nm/ppm for the range of 5–50 ppm (R²=0.9629). These results indicate improved accuracy and reliability over bare Au LRSPR, which offers a more limited detection range of 0.5–5 ppm. The AgNP-NCQD-PVA LRSPR has a higher resolution than bare Au-LRSPR, as indicated by its FOM values of 0.0332 ppm⁻¹. The higher binding affinity (1.642 × 10⁴ M⁻¹) of the AgNP-NCQD-PVA LRSPR further enhances its performance, making it a more effective sensor for detecting minute changes in analyte concentration. These innovations set new standards in sensor performance, promising significant advancements in high-precision photonic sensing applications.