Specific detection of protein in biofluids using graphene transistor biosensors with a 4arm-PEG isolation layer

Specific biomarker detection has become a pervasive diagnosis method across worldwide. Various research has focused on detection in buffer solution thereby resulting in the ignorance of such application in practical scenario. Thus, investigation for specific biomarker measurement in human body fluid is crucial for technology conversion. Graphene, this two-dimensional material with high conductivity and carrier mobility, has caught the researchers' attention in recent years. Herein, we present a graphene field effect transistor (GFET)-based aptameric nanobiosensor for rapid detection in biofluids incorporated with 4arm-PEG, with multiple-branched architecture providing terminal functional groups and maintaining strong hydration capability for effective resistance to nonspecific protein adsorption. CEA, a specific biomarker related to various diseases such as colorectal, gastric and lung cancer, was chosen as a representative tumor biomarker for experimental validation. The results indicate that this 4arm-PEG-modified graphene aptameric nanobiosensor generates a higher signal compared to the traditional rejection element as well as responds to CEA concentration change in a few minutes (3-5 min) with the estimated detection limits of 7.5aM in 1×PBS, 6aM in saliva solution, and 27aM in interstitial fluid solution, respectively. Hence, our sensor holds great potential for accurate monitoring nanomole levels in human body fluid among clinical applications.