Supramolecularly Assembled Ratiometric Fluorescent Sensory Nanosystem for “Traffic Light”-Type Lead Ion or pH Sensing

作者：Yuqian Liu, Qingsheng Guo, Xiaojun Qu, Qingjiang Sun · 发表于：ACS Applied Materials & Interfaces · 年份：2018 · DOI：10.1021/acsami.8b10007 · 被引用次数：20 · 研究领域：Advanced biosensing and bioanalysis techniques、Molecular Sensors and Ion Detection、Carbon and Quantum Dots Applications

The combination of functional nucleic acids and nanomaterials enables the continuous development of hybrid nanosystems that have found wide applications including chemo/biosensing. Herein, we report the supramolecular assembly of a “sesame biscuit”-like superstructural nanosystem based on aptamer, quantum dot (QD), and graphene oxide (GO), and its diverse applications in Pb 2+ and pH sensing. The nanosystem was assembled via adsorbing silica-encapsulated green-emitting QD onto the edge of GO by ionic interaction, followed by absorbing aptamer-modified red-emitting QD onto the GO surface via the π-stacking interaction. The nanosystem showed the characteristic of the nonquenched green fluorescence due to silica encapsulation and quenched red fluorescence owing to nanomaterial surface energy transfer. The nanosystem responded to Pb 2+ /pH in ratiometric fluorescence: the red fluorescence varied upon analyte-driven conformational changes of the aptamer, whereas the green one remained constant. Under optimized conditions, the nanosystem was demonstrated to be capable of quantifying Pb 2+ with a detection limit of 11.7 pM, as well as pH with a sensing resolution of 0.1 pH unit. More importantly, the ratiometric nanosystem facilitated visualization of analytes in a distinct “traffic light” manner, which was exemplified by semiquantification of exogenous Pb 2+ in living cells. To demonstrate practicality, fluorescent test strips were fabricated by immobilizing the nanosystem on paper...