Abstract
In this paper, a new strategy is reported for preparing a label-free β-trophin electrochemiluminescent (ECL) immunosensor with good specificity, reproducibility and stability. An aquagel polymer from the hydrolysis of (3-aminopropyl) trimethoxysilane acted as the linker to catch the Au nanoparticles (AuNPs) on the indium-tin oxide (ITO) substrate by a two-step method. The AuNPs play an important role in enhancing ECL and immobilizing the β-trophin antibody. This immunosensor can test for β-trophin using luminol as an ECL probe. The ECL intensity at the resultant sensor, after the direct immuno-interaction, was proportional to the concentration of β-trophin and had a low limit of quantification as 4.2 ng mL(-1). After deep discussions on the ECL mechanism of this immunosensor, we found that its sensitivity is greatly affected by the presence of oxygen and improved under deoxygenation. We believe that this sensor can be used for clinical cases.