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Abstract
Electrochemical biosensors are of enormous interests in a variety fields including clinical diagnosis and food analysis. However, in biological media the nonspecific adsorption of proteins, referred to as
biofouling, interferes with the performance of such devices in terms of reducing sensitivity and selectivity. Hence, antifouling coatings are needed for electrochemical sensors to deliver on their potential when it comes to biologically derived samples. The common effective solutions to the critical issue of biofouling involves using poly(ethyleneglycol) (PEG) or oligo(ethyleneglycol) (OEG)-alkanethiol layers. This is because a highly compressed hydration layer can be formed with these monolayers which is believed to be the reason this chemistry can effectively preventing nonspecific adsorption of protein. However, the use of such long chain self-assembled monolayers (SAMs) or polymeric layers on electrodes is not desirable because such polymers form a high impedance layer on the electrode, effectively passivating the electrode. Surface modifying layers that do not passivate the electrodes typically are also not effective at providing protection against biofouling. In this concern, we have developed an aryldiazonium salt based mixed layer platform. Phenyl phosphorylcholine (PPC) and phenyl butyric acid (PBA) are used for antifouling and bio-recognition component linkage, respectively. Such surface chemistry was demonstrated to be a versatile platform with good antifouling, low impedance and controllable surface composition properties, and was successfully applied to the development of an immunosensor for detecting tumor necrosis factor α in whole blood.