Yi Yu,QingYi Zhu,Feifan Xiang,Yue Hu,Lijie Zhang,Xiangju Xu,Nannan Liu,Shaoming Huang
AuNPs/SWCNT, a hybrid nanomaterial which is single-walled carbon nanotube (SWCNT) modified with gold nanoparticles (AuNPs), has great application prospects for chemical and biological sensors. For the innate nanogap between tiny AuNPs deposited on sidewall of SWCNT, AuNPs/SWCNT is suitable for the fabrication of simple and effective electrical signal switching devices. Here, we develop a novel strategy of applying AuNPs/SWCNT to fabricate nanogap device for DNA hybridization detection. The detection strategy is based on the target DNA mediating the catalytic activity of the AuNPs by desorbing the probe DNA from AuNPs. The signal transduction depends on the growth of tiny AuNPs which is closely related to the AuNPs catalytic activity. Sensing occurs at the tiny AuNPs growing and connecting into a continuous nanowire along the SWCNT, leading to a conductimetric response. The biosensing device can detect target DNA with the detection limit of 1 pM and the ability to discriminate triple and quintuple base pair mismatches.
Mengli Wang,Lele Ma,Le Kang,Mingsan Miao,Huaixia Yang
Estrogen receptor alpha (ERα) is an important biomarker for breast cancer which is positive in over 75% of breast cancer cases. In this study, an electrochemical biosensor was constructed for sensitive detection of ERα based on the signal amplification of AuNPs-SWCNT nanocomposites and hemin@HKUST-1. AuNPs-SWCNT was served as a conductive substrate, and be used to immobilize the aptamer (Apt) by an Au–S bonding. Then, Apt, ERα and antibody (Ab) formed a sandwich composite structure through specific recognition and immobilized on the electrode. The hemin@HKUST-1 was introduced into the biosensor via an amide bond with Ab and acted as the signal molecule. AuNPs-SWCNT could significantly enhance the conductivity of the electrode and the large specific surface area of HKUST-1 enabled it to load more hemin, and greatly improved the sensitivity of the biosensor. The detection limit (LOD) of the biosensor could reach 27.8 fg·ml−1 after optimization of the conditions, with the current intensity and the logarithm of the ERα concentration exhibited a good linear relationship between 100 fg·ml−1 and 100 ng·ml−1. In addition, the biosensor possessed excellent selectivity, stability, reproducibility and Interference immunity. More importantly, it shows great application potential in practical detection.
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