An artificial enzyme-based assay: DNA detection using a peroxidase-like copper-creatinine complex.

Area of Science:

• Biochemistry
• Analytical Chemistry
• Nanotechnology

Background:

• Artificial enzymes offer tunable catalytic properties for biosensing.
• Copper-creatinine complexes exhibit peroxidase-like activity.
• Nanoparticle-based assays enable signal amplification for sensitive detection.

Purpose of the Study:

• To develop an artificial enzyme-based DNA assay utilizing a copper-creatinine complex.
• To investigate the catalytic activity of copper complexes with different ligands for TMB oxidation.
• To achieve highly sensitive DNA detection through a double signal amplification strategy.

Main Methods:

• Utilized a peroxidase-like copper (Cu)-creatinine complex as a catalyst for 3,3',5,5'-tetramethylbenzidine (TMB) oxidation.
• Employed double signal amplification involving catalytic growth of Cu on gold (Au) nanoparticle (NP) labels and homogeneous catalysis.
• Investigated the effect of ligands (creatinine, imidazole, poly(l-histidine)) on catalytic activity and reaction kinetics.

Main Results:

• The Cu-creatinine complex demonstrated efficient TMB oxidation with a slow further oxidation rate, crucial for high signal-to-background ratios.
• Fast seed-mediated Cu growth on Au NPs and suppressed Cu autonucleation were achieved under specific buffer conditions.
• The assay achieved a sensitive DNA detection limit of 0.1 pM in a microplate format.

Conclusions:

• An artificial enzyme-based DNA assay using a Cu-creatinine complex was successfully developed.
• The assay's double signal amplification mechanism provides high sensitivity and specificity.
• This approach offers a promising platform for sensitive DNA detection in various applications.