Single-molecule electronic biosensor array for RNA detection and identification

Overview

This technology offers a novel approach to molecular diagnostics by detecting specific RNA and DNA sequences through direct electrical readout at the single-molecule level. Unlike conventional electronic biosensors that rely on indirect changes in conductance from surface binding events, this platform uses the target oligonucleotide itself as the conduction pathway. When a complementary target binds, it completes the circuit and produces a dramatic, thousand-fold change in electrical conductance that can be measured directly.

The approach eliminates the need for enzymatic amplification steps such as PCR, simplifying sample processing and reducing the time, cost, and equipment required for detection. The team has also developed a reliable method for integrating these single-molecule sensors with conventional on-chip electronics, opening a path toward compact, portable diagnostic devices suitable for point-of-care and field deployment.

Technical specifications

Core sensing principle:

• Direct measurement of electrical current through individual RNA or DNA duplexes
• Sequence-specific conductance signatures, sensitive even to single-nucleotide differences
• Conductance changes on the order of 1000x upon target binding
• Amplification-free detection, removing the need for PCR or enzymatic processing

Integration and platform features:

• Single-molecule electronic devices fabricated and integrated with conventional chip-based electronics
• Reproducible on-chip device integration demonstrated across multiple measurements
• Approximately 10 distinct oligonucleotide sequences measured to date, including SARS-CoV-2-related targets
• Previous single-molecule break junction (SMBJ) experiments demonstrated reliable discrimination of E. coli Shiga toxin RNA sequences and single base-pair mismatches
• Planned development of a conductance reference library covering 10 E. coli-related sequences and relevant interfering sequences

Sample processing roadmap:

• Initial validation in buffered solutions to establish baseline conductance values
• Testing in complex matrices such as E. coli lysates spiked with target sequences
• Optimization of fragmentation and separation protocols to minimize processing steps and enable field use

Technology readiness level

The platform is at an early-to-mid stage of development. On-chip integration of single-molecule devices with conventional electronics has been demonstrated reproducibly, and proof-of-concept detection has been achieved for SARS-CoV-2-related oligonucleotide targets and for E. coli Shiga toxin RNA sequences using the SMBJ technique. The remaining work focuses on translating these results to the integrated chip-based platform, building a comprehensive conductance library for E. coli serotype discrimination, validating performance in complex biological samples, and simplifying sample processing for field-capable operation. The full validation program is estimated at approximately two years.