Detection of C-reactive protein based on measurement of Brownian motion by micro-particle-tracking-velocimetry

A novel bio-sensing technique based on Brownian motion change with use of a micro-particle-tracking-velocimetry (micro-PT V) has been successfully developed to measure the antigen-antibody interactions. The rapid interaction between antigen, C-reactive protein (CRP), and the nanobeads conjugated with antibody, anti-CRP, enabled the real-time detection of CRP to be easily carried out. During the binding process of nanobeads to CRP, the mean value of the beads diameter increased so that the Brownian velocity decreased with increasing time. Moreover, higher CRP concentration led to lower Brownian velocity of the nanobead at equilibrium state. Furthermore, the sensitivity was raised when the smaller nanobeads were used.