Electrochemical impedance-based DNA sensor using pyrrolidinyl peptide nucleic acids for tuberculosis detection

Area of Science:

• Analytical Chemistry
• Biosensors
• Molecular Diagnostics

Background:

• Development of sensitive and selective DNA detection methods is crucial for disease diagnostics.
• Existing electrochemical DNA sensors often require complex fabrication or lack regeneration capabilities.
• Paper-based analytical devices (PADs) offer a low-cost and portable platform for diagnostics.

Purpose of the Study:

• To develop a label-free electrochemical DNA sensor based on immobilized pyrrolidinyl peptide nucleic acid (acpcPNA) on a paper-based analytical device (PAD).
• To enable simple regeneration of the sensor by PAD replacement.
• To demonstrate the sensor's application for detecting Mycobacterium tuberculosis (MTB) DNA.

Main Methods:

• Covalent immobilization of acpcPNA onto partially oxidized cellulose paper.
• Electrochemical Impedance Spectroscopy (EIS) to measure charge transfer resistance changes upon DNA hybridization.
• Cyclic Voltammetry (CV) for verification of immobilization and hybridization steps.
• Testing with synthetic MTB oligonucleotides and PCR-amplified DNA from clinical samples.

Main Results:

• The sensor successfully distinguished hybridization events by measuring changes in charge transfer resistance (Rct).
• Optimal conditions yielded a linear calibration curve from 2-200 nM with a limit of detection of 1.24 nM.
• The acpcPNA probe demonstrated high selectivity against mismatched and non-complementary DNA sequences.
• The sensor platform was successfully applied to detect MTB DNA in clinical samples.

Conclusions:

• A novel paper-based electrochemical DNA sensor (ePAD) using acpcPNA was successfully developed.
• The sensor is label-free, regenerable, sensitive, selective, and suitable for detecting MTB DNA.
• This technology presents a promising alternative for low-cost, point-of-care DNA diagnostics.