Designing Quantum Capacitive Peptide Interfaces for Electroanalytical Applications

Area of Science:

• Electrochemistry
• Materials Science
• Biotechnology

Background:

• Quantum mechanical rules govern redox-active moieties on metallic interfaces, influencing electron transfer dynamics via quantum capacitance.
• Modifying interfaces with biological receptors enables miniaturized electroanalytical devices with high sensitivity, offering advantages over traditional diagnostic methods.
• Peptide-based redox-active moieties are promising for modifying metallic surfaces, enhancing quantum capacitive signal sensitivity for biosensing applications.

Purpose of the Study:

• To investigate the performance of different ferrocene-tagged peptide structures for biosensing applications.
• To compare the efficiency of self-assembled monolayers (SAMs) formed by various peptide sequences on gold for detecting the Dengue Virus NS1 biomarker.
• To analyze key electrochemical parameters influencing biosensor performance based on peptide chemistry.

Main Methods:

• Fabrication of self-assembled monolayers (SAMs) on gold using ferrocene-tagged peptides (Fc-Glu-XX-Cys-NH2, where XX = Ser, Phe, Gly).
• Electrochemical characterization of interfaces, including formal potential, normalized electronic density of states (DOS), quantum capacitance, and electron transfer rate constants.
• Validation of biosensing capabilities by detecting the NS1 Dengue Virus biomarker.

Main Results:

• The glycine-peptide (Gly-peptide) interface exhibited the highest analytical performance for NS1 detection, showing a sensitivity of 5.6% per decade and the lowest limit of detection (LOD) of 1.4 ng mL⁻¹ and limit of quantitation (LOQ) of 2.6 ng mL⁻¹.
• The phenylalanine-peptide (Phe-peptide) interface showed intermediate performance, while the serine-peptide (Ser-peptide) interface demonstrated the lowest performance.
• Electrochemical parameters varied significantly across the different peptide structures, highlighting the impact of peptide chemistry on interface performance.

Conclusions:

• Ferrocene-tagged peptides can be effectively used to create self-assembled monolayers for advanced biosensor components, particularly for point-of-care diagnostics.
• The overall performance of the biosensing interface is critically dependent on the complete surface chemistry design, not solely on the redox-active group.
• Peptide-based biosensors offer advantages in terms of cost-effectiveness and miniaturization for diagnostic applications.