Sandwich-type Surface Stress Biosensor Based on Self-Assembled Gold Nanoparticles in PDMS Film for BSA Detection

Poly(dimethylsiloxane) (PDMS) films composed of gold nanomaterials have drawn increasing interest for their application in biosensors. However, gold and PDMS exhibit poor compatibility, limiting their sensitivity in biosensing. Herein, we reported a surface stress biosensor based on a gold nanoparticle-PDMS (AuNP-PDMS) composite film to detect bovine serum albumin (BSA). The AuNP-PDMS film was fabricated by in situ reduction of PDMS and further reduction of glucose. The compatibility between gold and PDMS was improved via a two-step reduction of AuNPs. The surface stress biosensor can specifically detect BSA molecules within the 0-50 μg/mL concentration range using the direct assay and the sandwich assay. The sandwich assay amplified the surface stress and reduced the limit of detection to 0.035 μg/mL, which is lower than that achieved by the direct assay. The sandwich-type biosensor also exhibits stability, repeatability, and specificity. This study is expected to drive the development of new methods for biomolecule detection.