Modular conductive MOF-gated field-effect biosensor for sensitive discrimination on the small molecular scale

Abstract

Field-effect transistors (FETs) are a promising transducer for biosensors owing to their drastic signal amplifi-cation, showing a high sensitivity enough to detect ultra-low concentrations of small-molecular biomarkers in biofluids. However, the discrimination of small molecules from their structural analogues in biofluids using a FET is challenging; because of the 1) Debye screening in high-ionic-strength conditions, 2) few or no charges of the analytes, and 3) lack of target-specific receptors for small molecules. To overcome these limitations, we report a modular conductive MOF (c-MOF)-gated FET biosensor array that discriminates small-molecular neurotrans-mitters in biofluids. Adsorption and oxidation of analytes inside the pore of catalytic c-MOF films allow the sensitive detection of small molecules close to the clinically relevant concentration, regardless of the ionic strength of the media. The hierarchical screening ability of c-MOF attributed to their tunable pore size, surface charge, and host-guest interactions induces differentiated adsorption of small molecules. The cross-reaction intended by c-MOF design of our biosensor could provide discriminatory information of each neurotransmitter corresponding to the differences of one functional group in the molecule. Using our system, we also demonstrate discrimination capability under the interference of biologically relevant substances and artificial cerebrospinal fluid.