Hydrazine-catalyzed ultrasensitive detection of DNA and proteins.
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, approximately 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 microM and 10 fg/mL to 10 ng/mL, were observed, along with the detection limits of 450 aM (2700 DNA molecules in a 10-microL 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, <4.3% for n = 10), and low detection limit of the method offer a good promise for practical DNA and protein analyses.
Department of Chemistry, Pusan National University, Busan, South Korea.
Muhammad J A
MJ
Shiddiky
Md Aminur
MA
Rahman
Yoon-Bo
YB
Shim
D002384:Catalysis; D004247:DNA / Q000032:analysis* / Q000737:chemistry*; D004563:Electrochemistry; D006834:Hydrazines / Q000737:chemistry*; D015394:Molecular Structure; D011506:Proteins / Q000032:analysis* / Q000737:chemistry*
D006834:Hydrazines; D011506:Proteins; C029424:hydrazine; D004247:DNA