β-Cyclodextrin Polymer-Based Host-Guest Interaction and Fluorescence Enhancement of Pyrene for Sensitive Isocarbophos Detection

Research progress of fluorescent composites based on cyclodextrins: Preparation strategies, fluorescence properties and applications in sensing and bioimaging

Fluorescence analysis has been regarded as one of the commonly used analytical methods because of its advantages of simple operation, fast response, low cost and high sensitivity. So far, various fluorescent probes, with noble metal nanoclusters, quantum dots, organic dyes and metal organic frameworks as representatives, have been widely reported. However, single fluorescent probe often suffers from some deficiencies, such as low quantum yield, poor chemical stability, low water solubility and toxicity. To overcome these disadvantages, the introduction of cyclodextrins into fluorescent probes has become a fascinating approach. This review (with 218 references) systematically covers the research progress of fluorescent composites based on cyclodextrins in recent years. Preparation strategies, fluorescence properties, response mechanisms and applications in sensing (ions, organic pollutants, bio-related molecules, temperature, pH) and bioimaging of fluorescent composites based on cyclodextrins are summarized in detail. Finally, the current challenges and future perspectives of these composites in relative research fields are discussed.

β-Cyclodextrin Polymer-Based Fluorescence Enhancement Strategy via Host-Guest Interaction for Sensitive Assay of SARS-CoV-2

Nucleocapsid protein (N protein) is an appropriate target for early determination of viral antigen-based severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). We have found that β-cyclodextrin polymer (β-CDP) has shown a significant fluorescence enhancement effect for fluorophore pyrene via host-guest interaction. Herein, we developed a sensitive and selective N protein-sensing method that combined the host-guest interaction fluorescence enhancement strategy with high recognition of aptamer. The DNA aptamer of N protein modified with pyrene at its 3' terminal was designed as the sensing probe. The added exonuclease I (Exo I) could digest the probe, and the obtained free pyrene as a guest could easily enter into the hydrophobic cavity of host β-CDP, thus inducing outstanding luminescent enhancement. While in the presence of N protein, the probe could combine with it to form a complex owing to the high affinity between the aptamer and the target, which prevented the digestion of Exo I. The steric hindrance of the complex prevented pyrene from entering the cavity of β-CDP, resulting in a tiny fluorescence change. N protein has been selectively analyzed with a low detection limit (11.27 nM) through the detection of the fluorescence intensity. Moreover, the sensing of spiked N protein from human serum and throat swabs samples of three volunteers has been achieved. These results indicated that our proposed method has broad application prospects for early diagnosis of coronavirus disease 2019.