Herein, an effective pyrene excimer signaled fluorescent biosensor for the determination of tetracycline based on triple-helix aptamer probe (TAP) and supramolecular inclusion of cyclodextrin was reported. The TAP was devised containing an aptamer loop, two DNA segment stems and a triplex-forming oligonucleotide (signal probe) labeled with pyrenes at 5′ and 3′ ends. The presence of target could result in its binding towards aptamer with a mighty affinity, leading to a conformation change of the TAP and whereupon the release of the signal probe. This liberty of signal probe enabled the formation of pyrene excimer, generating fluorescence signals. Further, signal amplification was fulfilled through the addition of γ-cyclodextrin which could interact with pyrene dimer, thus leading to an enhanced “on-state” of the sensing ensemble. In contrast, when the target was absent, the sensing ensemble remained “off-state” because of the long distance between two pyrene molecules. When the conditions were properly optimized, the increasing signal kept a linear dependence on target concentrations ranging from 5.0 nM to 100 nM, and the detection limit reached as low as 1.6 nM. In this way, a newly-constructed, simple, and economically affordable protocol enjoys desirable efficiency, sensitivity, specificity in biosensing. Also, its universality as another attractive behalf in assaying diverse targets was envisioned with only the need of matched aptamer replacement.

在此，报道了一种基于三螺旋适体探针（TAP）和环糊精超分子包合物的有效芘准分子信号荧光生物传感器，用于测定四环素。 TAP 被设计为包含一个适体环、两个 DNA 片段茎和一个在 5' 和 3' 末端用芘标记的三链体形成寡核苷酸（信号探针）。靶标的存在可能导致其以强大的亲和力与适体结合，导致 TAP 构象发生变化，从而释放信号探针。这种自由的信号探针能够形成芘准分子，产生荧光信号。此外，通过添加可与芘二聚体相互作用的γ-环糊精来实现信号放大，从而增强传感整体的“开启状态”。相反，当目标不存在时，由于两个芘分子之间的距离较长，传感整体保持“关闭状态”。当条件适当优化时，增加的信号在 5.0 nM 至 100 nM 范围内与目标浓度保持线性相关，检测限低至 1.6 nM。通过这种方式，一个新构建的、简单的、经济实惠的方案在生物传感中具有理想的效率、灵敏度和特异性。此外，它的普遍性是检测不同靶标的另一个有吸引力的代表，仅需要匹配的适体替换即可。