Electrochemical nucleic acid detection based on parallel structural dsDNA/recombinant azurin hybrid

Area of Science:

• * Nanotechnology
• * Electrochemistry
• * Molecular Biology

Background:

• * Challenges in nucleic acid biosensor fabrication include surface immobilization, single mismatch detection, and low current response.
• * Existing biosensors often struggle with sensitivity and specificity for detecting subtle genetic variations.

Purpose of the Study:

• * To introduce a novel parallel structural dsDNA/recombinant azurin (PSD/rAzu) hybrid structure for general nucleic acid detection.
• * To overcome limitations of current biosensors by enhancing conductivity, sensitivity, and mismatch detection capabilities.

Main Methods:

• * Design of a parallel structural dsDNA (PSD) with optimized Ag+ ions for enhanced conductivity.
• * Conjugation of PSD with recombinant azurin (rAzu) to create a hybrid platform for electrochemical detection.
• * Utilization of scanning tunneling spectroscopy (STS) and cyclic voltammetry (CV) to analyze DNA electrical conductivity and Ag+ ion reduction.

Main Results:

• * The PSD/rAzu hybrid structure demonstrated high reproducibility and ultra-sensitivity for detecting single base pair mutations.
• * Bifunctional rAzu acted as a selective spacer and electrochemical signal mediator, enabling rapid signal changes upon target binding.
• * A significant electrochemical signal drop was observed due to Ag+ ion intercalation between C-C mismatches in the presence of target strands.

Conclusions:

• * The proposed PSD/rAzu hybrid structure offers a promising platform for sensitive and specific nucleic acid detection, including miRNA and viral DNA.
• * The platform exhibits excellent capability for single mutation recognition and miRNA expression profiling in cancer cells.
• * This novel biosensor design holds potential for advancing nanoscale biosensors and bioelectronic devices.