Single-molecule reliable detections with a large-area electronic interface

BIST Colloquium Series 2022-23

by Dr. Luisa Torsi, Dipartimento di Chimica, Università degli Studi di Bari Aldo Moro, Bari, Italy

Abstract

A large millimeter-wide electronic interface can detect at a singlemolecule/entity limit-of-detection. The technology is called SiMoT – SingleMolecule with a large Transistor.1 So far, antigens (Immunoglobulins, Creactive proteins, spike 1, HIV p-24), antibodies (anti-immunoglobulins, anti-spike1), peptides, viruses (SARS-Cov-2), bacteria (Xylella fastidiosa), and even DNA strands (KRAS, miR-182) have been detected. Selectivity is assured by covering the gate electrode with a large number (1011 – 1012/cm2 ) of recognition elements to affinity binding the target element.

SiMoT detects directly in a droplet (0.1 mL) of a real fluid such as saliva from COVID-19 patients, blood serum, pancreatic cysts juice, and olive saps from infected trees. Relevantly Brownian diffusion enables the entity to statistically hit the millimeter-wide interface in a few minutes.2 Considering the footprint of a molecule on a millimeter-wide interface, it is like spotting a droplet of water falling on the surface of a 1 Km wide lake as depicted in the Figure on the left.

The applications span from a handheld intelligent singlemolecule binary bioelectronic system for fast and reliable immunometric point-of-care testing of COVID19 patients3 and Xylella fastidiosa single bacterium detected in infected plants sap. The phenomenon enabling such outstanding performance level was discovered in 2018. 4 While still under investigation, it is supposed to involve an amplification that starts from the single affinity binding that triggers a propagating collaborative response.

Future actions include the deepening of our understanding of the sensing mechanism and the engagement in a campaign of thousands of clinical trials that will bring SiMoT beyond TRL5.

1. E. Macchia et al. Chemical Review 2022, 122, 4636 DOI: 10.1021/acs.chemrev.1c00290
2. E. Macchia et al. Advanced Science 2022, 2104381 DOI: DOI: 10.1002/advs.2021043811
3. E. Macchia et al., Science Advances 2022, 8 (27) DOI: 10.1126/sciadv.abo0881
4. E. Macchia et al., Nature Communication 2018, DOI: 10.1038/s41467-018-05235-z

Speaker invited by ICN2

The colloquium is part of the BIST Master of Research curriculum but is also open and free for anyone interested in participating.