Microfluidic Impedance Biosensor Chips Using Sensing Layers Based on DNA-Based Self-Assembled Monolayers for...

Area of Science:

• Biomedical Engineering
• Analytical Chemistry
• Nanotechnology

Background:

• Cardiac troponin I (cTnI) is a critical biomarker for diagnosing myocardial infarction.
• Current diagnostic methods can be time-consuming or require complex sample preparation.
• Label-free biosensing offers a promising alternative for rapid and sensitive biomarker detection.

Purpose of the Study:

• To develop and validate a microfluidic chip for electrochemical impedance spectroscopy (EIS) based biosensing.
• To achieve label-free detection of cardiac troponin I (cTnI) for potential myocardial infarction diagnosis.
• To optimize electrode surface functionalization for enhanced sensitivity and specificity.

Main Methods:

• Fabrication of a microfluidic chip integrating sputtered electrodes on a glass slide and a polydimethylsiloxane (PDMS) microchannel.
• Development of electrode functionalization protocols using self-assembled monolayers (SAMs) of thiolated oligonucleotides and covalent antibody coupling via carbodiimide chemistry.
• Electrochemical impedance spectroscopy (EIS) measurements for label-free protein detection, including human serum albumin (HSA) as a control and cTnI as the target analyte.

Main Results:

• Oligonucleotide-based SAMs demonstrated superior performance compared to hydrocarbon SAMs for electrode functionalization.
• The microfluidic impedance biosensor successfully detected low concentrations of cardiac troponin I (1 ng/mL) with significant impedance shifts.
• Negligible impedance changes were observed for human serum albumin (1000 ng/mL), indicating high specificity.

Conclusions:

• The developed microfluidic impedance biosensor chip enables rapid, label-free detection of cardiac troponin I.
• The sensor shows promise for clinical applications in diagnosing myocardial infarction by detecting relevant biomarker concentrations.
• Further development could lead to point-of-care diagnostic tools for cardiovascular diseases.