Tandem β-mercaptoethanol and 2-(3-trichlorosilylpropyloxy)-ethyltrifluoroacetate Coating on Flat Gold Surfaces to Significantly Prevent Non-Specific Adsorption

Gold surface-based acoustic (bio)sensors often face non-specific adsorption issues, creating specificity and sensitivity issues which negatively affect the sensor’s performance. This can be prevented by antifouling coatings, such as 2-(3-trichlorosilylpropyloxy)-ethyltrifluoroacetate (Si-MG-TFA), which is used for silica quartz surfaces used in electromagnetic piezoelectric acoustic devices. Previous research provides evidence that this coating can reduce fouling by a factor of ten, but this could not be successfully replicated on gold surfaces. However, we have found a novel method of successfully applying the Si-MG-TFA coating on gold, with comparable antifouling performance, by using β-mercaptoethanol as an intermediate linker between the gold surface and the Si-MG-TFA. By using the self-assembled monolayer approach to coat gold with β-mercaptoethanol, the gold’s surface becomes hydroxylated, allowing for a proper Si-MG-TFA coating via covalent ether bonds, as seen in silica quartz surfaces. Serum tests using a thickness shear mode acoustic sensor and atomic force microscopy for surface characterization provide evidence of comparable antifouling performance and successful coating of Si-MG-TFA, respectively, on sufficiently flat gold surfaces. Overall, our work shows a potential method of significantly preventing non-specific adsorption for any method involving gold surface-based (bio)sensing.