Black Phosphorus-Based Reusable Biosensor Platforms for the Ultrasensitive Detection of Cortisol in Saliva

A black phosphorus (BP)-based reusable biosensor platform is developed for the repeated and real-time detection of cortisol using antibody-conjugated magnetic particle (MP) structures as a refreshable receptor. Here, we took advantage of the low-noise characteristics of a mechanically exfoliated BP-based field-effect transistor (FET) and hybridized it with anti-cortisol antibody-functionalized MPs to build a highly sensitive cortisol sensor. This strategy allowed us to detect cortisol down to 1 aM in real time and discriminate cortisol from other hormones. In this case, we could easily remove MPs with used antibodies from the surface of a BP-FET and reuse the chip for up to eight repeated sensing operations. Moreover, since our platform could be fabricated using conventional photolithography techniques and the sensor can be reused multiple times, one should be able to significantly reduc…