A New Strategy Of DNA Detection Based On Nano-Enzyme

A new reagent named nano-enzyme was developed for DNA hybridization detection. 15nm Gold nanoparticles (Au NPs) were employed to assemble multiple molecules of horse radish peroxidase (HRP) and thiolated DNA detection probes to form a "DNA-NP-HRP" nano-structure, which had functions of DNA detection and signal amplification. In our detection experiment, target DNAs were caught by capture probes labeled on Magnetic microparticles (MMPs), magnetically collected, and hybridized with the nano-enzyme. After washing away unspecific adsorptions, substrates were added to the mixture to take the enzyme catalyzed oxidation reactions, and gave out optic signals corresponding to the DNA hybridization. Two different substrates were used in our experiments. ABTS (2, 2'-Azino - bis ( 3 - Ethylbenzthiazoline - 6 - Sulfonic Acid)) was for absorbance detection, and HPPA (3-(4-Hydroxyphenyl)propionic acid) was for fluorescence detection. Because one gold nanoparticle can carry multiple molecules of HRP, the signals were well amplified compared to the method in which only one HRP molecule was labeled on a detection probe. This simple and inexpensive strategy exhibited good sensitivity and reproducibility. The absorbance-based detection method using ABTS had a detection limit of about 30 pM with a detection range of 100pM～3nM, while the fluorescent method using HPPA had a detection limit as low as 3 pM with a broader detection range of...