Reagentless electrochemical biosensor for single nucleotide polymorphism detection

Overview

This technology is a reagentless, hand-held electrochemical biosensor designed to detect single nucleotide polymorphisms (SNPs) and quantify nucleic acids with high sensitivity and single-nucleotide resolution. By eliminating the need for labeling strategies, specialist operators, costly reagents, and benchtop laboratory instruments, the platform addresses two major limitations of conventional electrochemical biosensors. The system is well suited for applications in agricultural genomics (such as detecting genetic variations in crops like corn), clinical diagnostics, and any field setting where rapid, decentralized genetic analysis is needed.

Technical specifications

• Probe design: A peptide nucleic acid (PNA) capture strand is immobilized on a gold electrode and functionalized with a Ruthenium (Ru) redox reporter.
• Detection mechanism: When a complementary oligonucleotide target is present, it displaces the bound strand from the PNA probe. This displacement changes the local solvent environment around the Ruthenium center, altering the reorganization energy (λ) and shifting the electron transfer rate (k) and reduction potential.
• Signal generation: The change in reduction potential is measured electrochemically, providing a quantifiable, label-free signal tied directly to target binding.
• Performance targets: Single-nucleotide resolution, high sensitivity, and operation without sample purification or added reagents.
• Form factor: Designed as a portable, hand-held device rather than a benchtop instrument, with a planned multiplexed sensor prototype for simultaneous detection of multiple targets.

Technology readiness level

The underlying science has been validated through prior work showing that reduction potentials of redox agents can be modulated by controlling solvent access to the metal center, with shifts from approximately 330 mV to approximately 200 mV observed. Established literature supports the use of PNA-oligomer duplexes as sensitive capture probes for SNPs, and the strong electrostatic interaction between Ruthenium complexes and nucleic acid phosphate backbones is well characterized. The project plan calls for adapting a previously developed PNA probe, fabricating biosensors at the Northwestern University cleanroom, validating them in the laboratory using common corn genetic variations, and then building a multiplexed prototype for field validation. Estimated development time for a working prototype is 9 to 12 months.