Efficient Electrochemical Self-Catalytic Platform Based on l-Cys-hemin/G-quadruplex and Its Application for Bioassay

Area of Science:

• Biochemistry
• Nanotechnology
• Analytical Chemistry

Background:

• Artificial enzyme catalysis is often limited by low substrate binding affinity.
• Improving binding affinity is crucial for enhancing catalytic efficiency in artificial enzyme systems.

Purpose of the Study:

• To develop a novel self-catalytic complex with enhanced binding affinity for improved artificial enzyme activity.
• To construct a sensitive electrochemical aptasensor for thrombin detection using the developed self-catalytic system.

Main Methods:

• Synthesized an l-Cysteine-hemin/G-quadruplex complex to improve binding affinity.
• Investigated substrate binding affinity using Michaelis-Menten kinetics, comparing the new complex with hemin/G-quadruplex.
• Assembled an l-Cysteine bilayer onto the complex to concentrate the substrate near the active site.
• Constructed an electrochemical aptasensor based on the self-catalytic platform for thrombin detection.

Main Results:

• The l-Cysteine-hemin/G-quadruplex exhibited a significantly lower K_m (2.615 μM) for l-Cysteine compared to hemin/G-quadruplex (8.640 μM), indicating enhanced binding affinity.
• Substrate concentration around the active center was increased via bilayer assembly, boosting catalytic efficiency.
• The aptasensor demonstrated high sensitivity for thrombin detection, with a linear range from 0.1 pM to 80 nM and a detection limit of 0.032 pM.

Conclusions:

• The developed self-catalytic strategy effectively enhances artificial enzymatic catalytic efficiency by improving substrate binding affinity.
• The novel l-Cysteine-hemin/G-quadruplex complex provides a robust platform for developing highly sensitive biosensors.
• This approach offers a promising avenue for advancing artificial enzyme applications and electrochemical sensing technologies.