化学
纳米团簇
生物传感器
镊子
荧光
DNA
抗体
适体
生物物理学
检出限
纳米颗粒
纳米技术
费斯特共振能量转移
胶体金
表面等离子共振
核酸
生物分子
光学镊子
作者
Jia-Yang He,Xin Shang,Chunli Yang,Si-Yu Zuo,Ruo Yuan,Wenju Xu
标识
DOI:10.1021/acs.analchem.1c02444
摘要
Exploring the ratiometric fluorescence biosensing of DNA-templated biemissive silver nanoclusters (AgNCs) is significant in bioanalysis, yet the design of a stimuli-responsive DNA device is a challenge. Herein, using the anti-digoxin antibody (anti-Dig) with two identical binding sites as a model, a tweezer-like DNA architecture is assembled to populate fluorescent green- and red-AgNCs (g-AgNCs and r-AgNCs), aiming to produce a ratio signal via specific recognition of anti-Dig with two haptens (DigH). To this end, four DNA probes are programmed, including a reporter strand (RS) dually ended with a g-/r-AgNC template sequence, an enhancer strand (ES) tethering two same G-rich tails (G18), a capture strand (CS) labeled with DigH at two ends, and a help strand (HS). Initially, both g-AgNCs and r-AgNCs wrapped in the intact RS are nonfluorescent, whereas the base pairing between RS, ES, CS, and HS resulted in the construction of DNA mechanical tweezers with two symmetric arms hinged by a rigid fulcrum, in which g-AgNCs are lighted up due to G18 proximity (green-on), and r-AgNCs away from G18 are still dark (red-off). When two DigHs in proximity recognize and bind anti-Dig, the conformation switch of these tweezers resultantly occurs, taking g-AgNCs away from G18 for green-off and bringing r-AgNCs close to G18 for red-on. As such, the ratiometric fluorescence of r-AgNCs versus g-AgNCs is generated in response to anti-Dig, achieving reliable quantization with a limit of detection at the picomolar level. Based on the fast stimulated switch of unique DNA tweezers, our ratiometric strategy of dual-emitting AgNCs would provide a new avenue for a variety of bioassays.
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