Novel Rapid Protein Coating Technique for Silicon Photonic Biosensor to Improve Surface Morphology and Increase Bioreceptor Density

Silicon photonic devices with either silicon or nitride waveguides have increasingly been used in many applications besides communications, especially as sensors label-free biosensing, where guided light signals are affected by biorecognition molecules immobilized on the surface. The coating of protein (i.e., bioreceptors) biochemical process waveguide surface is a crucial step creating functionalized device that can be for biosensing. As conventional method uses 3-aminopropryltriethoxysilane (APTES) and glutaraldehyde (GA), APTES-GA has limitation using GA crosslink, which two functional groups bind to nonspecific proteins, causing irregular binding. In this study, we proposed new technique avoid such problem applying APTES silanization 1-ethyl-3-(3-dimethyl aminopropyl)-carbodiimide (EDC)-N-hydroxysuccinimide (NHS) denoted APTES-(EDC/NHS) method. EDC/NHS reaction was shown able immobilize ordered orientation due consistent arrangement between carboxylic group an amine covalent-linked By silanization, circumvented use hazardous cleaning agent technique. Several characterization techniques were carried out assess compare biocoating techniques, including scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), spectroscopic ellipsometry (SE), atomic force (AFM). On silicon, results antihuman TNF-alpha antibody showed better repeatability terms less roughness coated at 1.5 nm compared 6.3 nm, molecules. device, exhibits dense immobilization SEM images stable amide bond formation via crosslink mechanism. specificity antibodies confirmed enzyme-linked immunosorbent assays (ELISA), average optical density 450 0.175 ± 0.01 0.064 0.009 negative control. also reduced overall time since proteins crosslinked silanized single step.