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Viral outbreaks have caused great disruptions to the economy and public health in recent years. The accurate detection of viruses is a key factor in controlling and overcoming epidemics. In this study, an ultrasensitive molecularly imprinted virus sensor was developed based on an “explosive” secondary amplification strategy. Magnetic particles coated with carbon quantum dots (Fe3O4@CDs) were used as carriers and fluorescent probes, while aptamers were introduced into the imprinting layer to enhance the specific recognition of the target virus enterovirus 71 (EV71). When EV71 was captured by the imprinted particles, the fluorescence of the CDs was quenched, especially after binding to the aptamer-modified ZIF-8 loaded with a large amount of phenolphthalein, thereby resulting in signal amplification. Then, when adjusting the pH of the solution to 12, the decomposition of ZIF-8 released phenolphthalein, which turned the solution red, leading to the second “explosive” amplification of the signal. Therefore, the detection of EV71 with ultrasensitivity was achieved, which allows for visual detection by the naked eye in the absence of any instruments. The detection limits for fluorescence and visualization detection were 8.33 fM and 2.08 pM, respectively. In addition, a satisfactory imprinting factor of 5.4 was achieved, and the detection time only needed 20 min. It is expected that this fluorescence-colorimetric dual-mode virus molecularly imprinted sensor will show excellent prospects in epidemic prevention and rapid clinical diagnosis.

The specific identification and detection of a virus are the critical factors to identify and control an epidemic situation. In this study, a novel photonic-magnetic responsive virus-molecularly imprinted photochemical sensor was constructed for recognition of enterovirus 71. As designed, the double-bond-modified magnetic metal organic framework and 4-(4′-acryloyloxyazo) benzoic acid were used as a magnetic carrier and light-responsive functional monomer, respectively. The structure of the recognition site of the virusmolecularly imprinted nanospheres can be photo-switched between two different structures to achieve rapid release and specific binding to the target virus. Additionally, the introduction of a magnetic core enables a rapid separation and recycling of imprinted particles. The device achieves a performance with high-specificity recognition (imprinting factor = 5.1) and an ultrahigh sensitivity with a detection limit of 9.5 × 10 −3 U/mL (3.9 fM). Moreover, it has good reproducibility and can be stored for as long as 6 months. Thus, the approach used in this work opens a new avenue for the construction of multiresponsive virus sensors.

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