Biosensing based on optimized asymmetric optofluidic nanochannel gratings

Abstract Interferometric biosensing offers the potential of label-free detection with very high sensitivities. In our optofluidic grating detector the accumulation of biological target molecules on the surface of functionalized nanochannels can be detected due to the change in refractive index. Based on an analytical model, the sensitivity of the optofluidic grating detector was improved by a factor of 3.5 to 8.45 RIU−1 (refractive index unit) by adapting the grating geometries. The grating consists of nanochannels, through which the sample flows. This allows transport without diffusion-limitations inside the sensing area, as it is of particular importance when molecule concentration in the sample decreases. The nanochannels were functionalized by silanization and covalent bonding of antibodies. Finally, the binding of Mycobacterium ulcerans specific antigen MUL2232 was detected label-free.