An Electronic Platform for Rapid Detection of Steroids in Clinical Plasma

The abnormal levels of steroids can lead to various health issues. A concise measurement tool for the steroids in clinical plasma with a wide detection range, ultra-low detection limit, and high detection speed is strongly desired for patients’ clinical diagnosis. Here, we report a highly integrated label-free DNA aptamer-modified electrical biosensor based on graphene field-effect transistors (GFETs) that fulfills all the afore-mentioned requirements. The proposed biosensor is designed for the direct detection of multiple steroid hormones in clinical plasma. It achieves high specificity through the immobilization of highly specific DNA aptamers using cross-linking chemistry on the GFET channel surface. To improve sensitivity, a 10 kDa polyethylene glycol polymer is employed on the graphene surface, increasing the Debye length to approximately 11 nm, which enables the detection of steroid molecules of similar sizes. In clinical plasma, the platform demonstrates a low detection limit of ~1 fM for representative steroid targets, with a wide dynamic range spanning 11 orders of magnitude. In addition, the detection process can complete within 15 minutes, which is 10 times faster than the conventional optical methods. These results offer strong potential for practical clinical usage of electronic biosensor in future point-of-care (POCT) applications.