Solid-phase colorimetric apta-biosensor for thrombin detection

Herein, we developed a solid-phase colorimetric apta-biosensor for thrombin detection. Aggregation of gold nanoparticles (AuNPs) deposited on a 3-aminopropyltriethoxysilane (APTES) substrate was utilized to form the colorimetric sensor. The APTES-coated substrate with primary aptamer (TBA1)-conjugated AuNPs (AuNP-TBA1) was used to construct the solid-phase sensing platform, where an enhancement of the localized surface plasmon resonance due to the AuNPs was observed upon incubation with a target molecule (thrombin). The introduction of secondary aptamer-conjugated AuNPs (AuNP-TBA2) induced plasmonic coupling of the AuNPs, resulting in significantly enhanced spectral signals and peak shifts and visually detectable color changes. This sensing platform not only includes several advantages, such as simplicity and rapid detection, but also allows naked-eye detection sensitivity at 3 mu g/mL with no analytical equipment and a limit of detection of 1.33 mu g/mL using UV-vis.