Aptamer-Linked Assay for Thrombin Using Gold Nanoparticle Amplification and Inductively Coupled Plasma−Mass Spectrometry Detection

We describe a sensitive and specific sandwich assay for human α-thrombin. The assay takes advantage of sandwich binding of two affinity aptamers for increased specificity, gold nanoparticles for signal amplification, magnetic beads for fast magnetic separation, and inductively coupled plasma mass spectrometry for ultrasensitive detection. Other proteins, such as immunoglobulin G, serum albumin, transferrin, fibrinogen, and lysozyme did not show interference with the assay for human α-thrombin. The detection limit of human α-thrombin was as low as 0.5 fmol, corresponding to 10 pM thrombin in 50 μL, and the dynamic range covered ∼3 orders of magnitude.