Engineering of All Solution/Substrate Processable Biosensors for the Detection of Epinephrine as Low as Pm with Rapid Readout

Designing next-generation affordable compact point-of-care (POC) epinephrine biosensors is a significant and challenging issue at the moment. In this context, all solution/substrate processable sensing material is developed by a simple one-step molecular engineering of 2D-reduced graphene oxide (rGO). As a proof-of-concept, a flexible POC device is fabricated which demonstrates a distinct and selective response to epinephrine down to 13/20 pM in the buffer/real sample solution in a wide linear range of 10 -10 -10 -4 M with rapid readout (2.2 s). Systematic experimental and density functional theoretical (DFT) studies are conducted to uncover the underlying reason for the sensor's remarkable performance. It is found that the precise link between the immobilized molecule [ p -aminobenzoic acid (PAB)] and the 2D-rGO basal plane results in a beneficial change in the 2D-topological feature, charge mobility and interlayer chemistry. Besides, the sensing material functions as biomolecule selector, capturer and transducer via strong H-bond interaction and π-π electron coupling/resonance effect, which leads to enhanced sensitivity and specificity. The achievement of this simple yet efficient molecular engineering technique, which can successfully alter the electronic and chemical arrangement of the 2D matrix, opens up a new avenue for the development of various types of flexible and tunable biosensors