New trends in single-molecule bioanalytical detection

Eleonora Macchia,Cincia Di Franco,Gaetano Scamarcio,Kyriaki Manoli,Luisa Torsi

doi:10.1007/s00216-020-02540-9

Abstract

Single-molecule sensing is becoming a major driver in biomarker assays as it is foreseen to enable precision medicine to enter into everyday clinical practice. However, among the single-molecule detection methods proposed so far, only a few are fully exploitable for the ultrasensitive label-free assay of biofluids. Firstly introduced single-molecule sensing platforms encompass low-background-noise fluorescent microscopy as well as plasmonic and electrical nanotransducers; these are generally able to sense at the nanomolar concentration level or higher. Label-based single-molecule technologies relying on optical transduction and microbeads that can scavenge and detect a few biomarkers in the bulk of real biofluids, reaching ultralow detection limits, have been recently commercialized. These assays, thanks to the extremely high sensitivity and convenient handling, are new trends in the field as they are paving the way to a revolution in early diagnostics. Very recently, another new trend is the label-free, organic bioelectronic electrolyte-gated large transistors that can potentially be produced by means of large-area low-cost technologies and have been proven capable to detect a protein at the physical limit in real bovine serum. This article offers a bird’s-eye view on some of the more significant single-molecule bioanalytical technologies and highlights their sensing principles and figures-of-merit such as limit of detection, need for a labelling step, and possibility to operate, also as an array, directly in real biofluids. We also discuss the new trend towards single-molecule proof-of-principle extremely sensitive technologies that can detect a protein at the zeptomolar concentration level involving label-free devices that potentially offer low-cost production and easy scalability.

Highlights

To have the chance to collide into each other and eventually react in a reasonably short time period, two reacting species, Published in the topical collection Euroanalysis XX with guest editor Sibel A
Wide-field sensing [8] involves the assay of an analyte at the attomolar or even zeptomolar limit of detection with a wide interface hosting a large number of recognition elements (1011–1012 cm−2)
While investigations into collective effects enabling the signal amplification needed to enable EGOFET bioelectronic sensors to detect 1–103 binding events with a wide surface comprising billions to trillions of recognition elements are in progress, a reasonable explanation involving a combination of capacitive coupled field-effect transistor (FET) transduction and hydrogen-bonding network in self-assembled monolayers has been proposed

Summary

Introduction

To have the chance to collide into each other and eventually react in a reasonably short time period, two reacting species, Published in the topical collection Euroanalysis XX with guest editor Sibel A. This is generally referred to as the label-based far-field approach to single-molecule detection.

Results

Conclusion