Covalent Binding vs. Adsorption of Biomolecules on Silicon Nitride Planar Waveguides

Effective immobilization of biomolecules at transducer interfaces plays a crucial role in biosensors development. In this work, we compared several silicon nitride (Si3N4) surface silanization methods in terms of efficient biomolecule immobilization either through physical adsorption or covalent binding. Two silanizing agents, namely 3- aminopropyltriethoxysilane (APTES) and 3-glycidyloxypropyltrimethoxysilane (GOPTS), were employed. It was found that silanization with GOPTS provided slightly higher protein immobilization capacity and homogeneity and lower non-specific binding as compared to APTES modification. Therefore, it could be employed for the effective functionalization of Si3N4 waveguides for biosensing applications.