A Förster resonance energy transfer (FRET)-based biosensor using Cu nanoclusters (NCs) as energy donors and signal magnifiers and MnO 2 nanospheres as both energy acceptors and target recognizers for selective detection of glutathione (GSH) was developed. MnO 2 nanospheres, synthesized through an ultrasonication assisted top down method, can quench the photoluminescence (PL) of Cu NCs through FRET, after forming complex through electrostatic interactions. GSH can recover PL of Cu NCs by triggering the decomposition of complex through digesting MnO 2 nanospheres into Mn 2+ . Additionally, the PL can be further magnified through the host-guest interactions between GSH and Cu NCs, with around 25 times higher than the original intensity and 3 times higher than the initial PL intensity of Cu NCs. Under the optimum conditions, the FRET based sensor can detect GSH in the concentration range from 0 to 140 μM, with a detection limit of 17 μM. Moreover, the proposed method shows a strong anti-interference ability, achieving the sensitive directly detection of GSH in human whole blood samples. Our results provide insights in designing FRET based sensors. Moreover, all the components are nontoxic and biodegradable, demonstrating their potential applications in other fields such as nanomedicine and environmental science.
Siying Xie,Cheng Qin,Furong Zhao,Zhaoyang Shang,Pei Wang,Muhammad Sohail,Xing Zhang,Bingzhi Li
CRISPR-driven biosensing is developing rapidly, but current studies mostly adopt dye-labeled ssDNA as the signal reporter, which is costly and unstable. Herein, we developed a label-free and low-background reporter for CRISPR/Cas12a signaling by integrating DNA-templated copper nanoclusters (DNA–CuNCs) and exonuclease I (EXO I). The template of the DNA–CuNCs was rationally designed as a ds-/ss-DNA hybrid, ensuring that after a quick and nonpersistent cut of Cas12a, a majority of the template can be digested by EXO I. Based on this novel reporter, a biosensor termed CRISPR-CNS (cost-effective, nimble, and sensitive copper nanocluster sensor integrating CRISPR) was developed. Due to the high signal-to-background ratio of our proposed reporter, CRISPR-CNS shows excellent performances for nucleic acid detection, yielding a detection limit of 20 copies for SARS-CoV-2 RNA. Considering its facile synthesis, robust fluorescence, effective cost, and good sensitivity, this combination shall serve as a highly potential output for CRISPR-based point-of-care testing.
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