Surface functionalization with dendrimer molecules for optical waveguide lightmode spectroscopy

We developed a new surface modification method, which uses a hydrophilic dendrimer, Superfect (TM), originally a transfection reagent, to modify the sensor waveguide for label-free detection of Optical Waveguide Lightmode Spectroscopy (OWLS). The modified 3-dimensional surface can absorb the antibody through electrostatic force. Here we used the insulin-anti-insulin antibody (IAA) as an example of peptide-protein interaction to investigate the parameters of this method. 2 mu IU/ml (approximately 71 pg/ml) insulin in the solution can be detected by the Superfect-IAA surface using direct Ag-Ab binding protocol, monitoring with OWLS technique. It was proved that the antigen can be detected sensitively and quantitatively in real-time. It is also easy to regenerate the sensor chip without losing sensing performance, compared with the chemical modifications.