Amplified detection of femtomolar DNA based on a one-to-few recognition reaction between DNA-Au conjugate and target DNA.
A sensitive electrochemical DNA biosensor based on the amplification of Au nanoparticles (AuNPs) has been developed. The AuNPs were modified with two types of signaling reporter DNAs, i.e. a methylene blue probe (MB-probe 2-SH) and T10 with a methylene blue signaling molecule (MB-T10-SH), forming DNA-AuNP conjugates. The MB-probe 2-SH is complementary to the target DNA, while MB-T10-SH is not. The presence of MB-T10-SH reduces the cross-reaction between target DNA and MB-probe 2-SH on the AuNPs, resulting in increased sensitivity of the biosensor. In our assay, the DNA sensor is fabricated by immobilizing a capture probe on the surface of the Au electrode, which then hybridizes with the corresponding target DNA, and further hybridizes with a DNA-Au conjugate. The signal of MB is measured by differential pulse voltammetry, while the DNA-Au conjugate enables the detection of target DNA in the linear range of 10(-13) to 10(-8) M with the detection limit as low as 50 fM.
School of Materials Science and Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798, Singapore. HZhang@ntu.edu.sg hzhang166@yahoo.com.
Zhijuan
Z
Wang
Juan
J
Zhang
Changfeng
C
Zhu
Shixin
S
Wu
Daniel
D
Mandler
Robert S
RS
Marks
Hua
H
Zhang
D015374:Biosensing Techniques; D004247:DNA / Q000032:analysis*; D055664:Electrochemical Techniques; D004566:Electrodes; D006046:Gold / Q000737:chemistry*; D053768:Metal Nanoparticles / Q000737:chemistry; D008751:Methylene Blue / Q000737:chemistry; D009693:Nucleic Acid Hybridization; D013438:Sulfhydryl Compounds / Q000737:chemistry
D013438:Sulfhydryl Compounds; D006046:Gold; D004247:DNA; D008751:Methylene Blue