Assembling Surface Linker Chemistry and Minimization of Biosensor Non-Specific Adsorption

The development of a preparation method for biosensing interface on hydroxylated surfaces is presented in this manuscript. This method involves the use of thiosulfonate-based linkers to construct robust and durable SAMs (Self-Assembling Monolayers) onto hydroxylated surfaces. The resulting SAMs have the ability to chemoselectively immobilize thiol-containing molecules under aqueous condition in a single, straightforward, reliable and coupling-free manner. This method is then implemented in the construction of biosensing interfaces for EMPAS (ElectroMagnetic Piezoelectric Acoustic Sensor) dedicated to the detection of avidin. Efforts were devoted to improving the performance of the biosensing interface by reducing/preventing nonspecific adsorption. Improvements were systematically observed with the incorporation of an OEG (Oligo(Ethylene Glycol)) backbone and a diluent (i. e. SAM molecules without a head functional group). The hydroxyl head function and short length of the diluent were crucial in preventing non-specific adsorption. This showed that both enthalpy-driven and entropy-driven mechanisms work in conjunction in order for the surface to achieve high resistance in non-specific adsorption. Expansions of this method to silicon nitride (Si3N 4), aluminium nitride (AlN) and gold (Au) were pursued. Lastly, a previously undocumented EMPAS coil circuit design was reported and discussed.