A Programmable Optical Fiber SPR Biosensor Sensitized with Self-assembling Polypeptides and Gold Nanoparticles

Two important issues in the surface plasmon resonance (SPR) biosensing field are improving sensor performance and expanding detectable target species. To address these challenges, this paper proposes an SPR biosensor modified with self-assembling polypeptides and gold nanoparticles (AuNPs). Peptide sequences are widely used in optical fiber SPR sensing due to their editable properties, self-assembly capability, and low toxicity. Here, engineered peptides self-assemble into nanofibers, increasing the sensor’s specific surface area and providing customizable active sites. AuNPs further enhance refractive index sensitivity. The biosensor allows programmable peptide sequences and hybridization schemes to adapt to various sensitivity-enhancing strategies and detection requirements. We tested the sensor for rabbit IgG detection, achieving a biosensitivity of 0.0365 \(\:nm/(ng/mL)\) and a detection limit (LOD) of 2.74 \(\:ng/mL\) . Compared to SPR sensors modified with single nanoparticles, our design demonstrates superior sensitivity and lower LOD. Beyond enhancing detection capabilities, this methodology establishes a universal framework for target-specific sensor customization. The economically optimized design protocol demonstrates strong translational potential to facilitate market adoption of optical fiber SPR biosensing platforms.