• Shiddiky, Muhammad J. A.
• Shim, Yoon Bo
• Rahman, Md Aminur

Abstract

<p>A sensitive electrochemical assay of DNA and proteins employing electrocatalytic reduction of hydrogen peroxide by labeled hydrazine on the probe immobilized surfaces was developed. The method utilizes a conducting polymer, poly-5,2′:5′, 2″-terthiophene-3′-carboxylic acid (pTTCA), covalently linked to the dendrimer (DEN) and hydrazine. The detection signal was amplified by the pTTCA/DEN assembly loaded with Au nanoparticles (particle size, ∼3.5 nm) onto which huge target DNA- or proteins-linked hydrazine labels (avidin-hydrazine) were adsorbed. The linear dynamic ranges for the electrocatalytic detection of DNA and proteins, extending from 1.0 fM to 10 μM and 10 fg/mL to 10 ng/mL, were observed, along with the detection limits of 450 aM (2700 DNA molecules in a 10-μL sample) and 4.0 fg/mL, respectively. The method eliminates the use of enzymes for DNA and protein detection and opens a way for DNA-free detection of proteins. The simplicity, good reproducibility (RSD, &lt;4.3% for n = 10), and low detection limit of the method offer a good promise for practical DNA and protein analyses.</p>

Topics

• nanoparticle
• surface
• polymer
• Hydrogen
• additive manufacturing
• dendrimer
• carboxylic acid