Precise surface molecular engineering of 2D-Bi2S3 enables the ultrasensitive simultaneous detection of dopamine, epinephrine, serotonin and uric acid

Multiple biomolecule detection at a single read is an emerging and highly desirable technology in point-of-care diagnostics. Thus, functional nanoscale materials with high precision and stability at an affordable cost are required to fabricate adaptable multiplex biosensing devices with exceptional performance. Herein, an ultrasensitive molecularly engineered 2D-Bi2S3 biosensor is developed via a two-step synthetic approach. Simultaneous detection of dopamine (DA), epinephrine (EP), serotonin (ST), and uric acid (UA) is achieved at the nanomolar level. The surface molecular engineered 2D-Bi2S3 by 4-mercaptobenzoic acid (MBA) exhibits a well crystalline nature and consists of 3–6 stacked layers with creased-paper-like morphology after an MBA molecule has been precisely linked at the basal plane of Bi2S3. Bi2S3-MBA's surface/vibrational spectroscopic and scanning tunneling microscopic studies demonstrate the Bi2S3-MBA electronic nature and the linked molecule present on the Bi2S3 surface with a comparatively large random distribution of MBA molecules at the basal plane than the edge plane. The density functional theory (DFT) calculation verifies the proposed molecular interaction mechanism. The success of this unique surface molecular engineering strategy, which effectively modified the electronic and surface configuration of the 2D-Bi2S3, offers an exciting possibility for building different variants of the versatile biosensor for real-world diagnostic device applications.