Construction of an Ultrasensitive Molecularly Imprinted Virus Sensor Based on an “Explosive” Secondary Amplification Strategy for the Visual Detection of Viruses

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.