Advancing diagnostics with BODIPY-bismuthene DNA biosensors

In this work, an electrochemical biosensor is prepared based on few-layer bismuthene hexagons (FLBHs) and a water-soluble BODIPY (BDP) derivative (BDP-NaSO₃) for early infection diagnosis. In particular, the detection in advance of a virus sequence in nasopharyngeal swab samples was developed. The combination of the FLBHs and BDP-NaSO₃ facilitates the direct, sensitive, and specific detection of gene viruses without the need for any prior amplification step. This work demonstrates that the FLBHs provide an improved electrochemical platform for immobilizing thiolated DNA capture probes that increase the sensitivity of the biosensor, while BDP-NaSO₃ serves as a newly powerful electrochemical indicator of the hybridization event. As a proof of concept, SARS-CoV-2 was selected as the model virus. The developed biosensor demonstrated selective, rapid, and straightforward detection of the specific sequence RNA-dependent RNA-polymerase (RdRp) of SARS-CoV-2 with a detection limit of 4.97 fM and a linear range from 16.6 fM to 100 fM. Furthermore, this platform successfully detects the virus directly in nasopharyngeal swab samples with a viral load of at least 19 Cts without being subjected to any prior amplification stage. Finally, the high stability of the biosensor response, which has been working under ambient conditions for over one month, the selectivity and rapidity for specific virus detection, and the requirement of low-volume samples for the determination are remarkable characteristics that make it ideal for its potential application in clinical diagnosis in point-of-care settings.