Neuraminidase-Activatable NIR Fluorescent Probe for Influenza Virus Ratiometric Imaging in Living Cells and Colorimetric Detection on Cotton Swabs

Influenza, as one of the most serious communicable respiratory infectious diseases, is caused by influenza viruses. Neuraminidase (NA), also referred to as sialidase, is an important protein on the influenza virus surface. Because of its enzymatic function, NA has been selected as a promising target to develop influenza virus diagnosis reagents or drugs. Herein, a neuraminidase-responsive, light-up, near-infrared (NIR) fluorescence probe (SA-DCM) was reported that possesses both ratiometric and colormetric properties for different applications. Benefitting from the ratiometric properties, SA-DCM showed an increased anti-interference capacity for environmental fluctuation and enhanced detection accuracy with a large Stokes shift (>150 nm) and outstanding sensitivity and selectivity. Due to its colorimetric property, a color shift of the product HO-DCM from yellow to purple occurs when the pH value is adjusted. Therefore, a colorimetric approach through direct color conversion on a cotton swab to detect NA was established, and the result could be directly read by the naked eye with simplicity and practicality.