Enhanced Sensitivity of SPR Sensor Using Au@Bi₂Se₃ Core-Shell Nanoparticles and Lead Ion Detection

Surface plasmon resonance (SPR) sensors are widely used for sensitive and label-free detection in various fields, but their performance is often limited by the low sensitivity and nonspecific targeting of conventional gold film-based sensors. This study proposes a novel SPR sensor incorporating gold nanocubes (AuNCs) and bismuth selenide (Bi2Se<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${}_{{3}}\text {)}$ </tex-math></inline-formula> in a core-shell structure (Au@Bi2Se<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${}_{{3}}\text {)}$ </tex-math></inline-formula> to enhance sensor performance. By using the seed-mediated growth method, Au@Bi2Se3 particles were prepared and integrated with a gold film-based SPR platform for the detection of lead ions (Pb<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${}^{{2}+}\text {)}$ </tex-math></inline-formula>. Experimental results showed that the sensor fabricated with Au@Bi2Se3 particles exhibited a sensitivity of 6522.72 nm/RIU, surpassing the performance of conventional SPR sensors. Additionally, the sensor demonstrated excellent detecting capabilities for lead ion, with a linear relationship observed between the reflectance curve and Pb2+ concentration. This study highlights the potential of the Au@Bi2Se3 core-shell structure to significantly improve SPR biosensor sensitivity and specificity, offering promising applications in environmental monitoring and medical diagnostics.