Self-service multimodal detection of subtype influenza A virus H5N1 by visual portable molecular imprinting sensor

At present, the ability to identify subtypes of influenza A virus (IAV) with high similarity in morphology, size, and surface structure is suffered from significant challenges. In this study, we report on the development of a portable, multi-color, colorimetric molecular imprinting polymer (MIP)-based sensor that can specifically identify H5N1. To construct this sensor, using H5N1 as a template, the MIPs was obtained on the Fe3O4@ quantum dots (QDs) prepared in advance. Then, the Fe3+@PDA∼ Apt probe, which was designed for specificity for H5N1, was prepared by modifying the H5N1 ∼ Apt on the surface of the pre-prepared Fe3+-embedded dopamine nanoparticles. A sandwich structure would be formed via the specific combination of MIPs, H5N1 and Fe3+@PDA ∼ Apt. During detection, the fluorescence of QDs quenched, achieving the first detection mode of viruses through the change of fluorescence intensity. Subsequently, Fe3+ in the solution was released, K4[Fe(CN)6] and K3[Fe(CN)6] were added to achieve a multi-color colorimetric detection sensor visible to the naked eyes. The third detection mode can be achieved by detecting the absorbance of the solution by ultraviolet–visible. The sensor was capable of differentiating the target H5N1 virus from other IAV subtypes with high specificity and sensitivity (LOD = 11.6 fM), and the detection of the virus could be enabled by fluorescence spectroscopy, UV–vis spectrophotometry, and colorimetric indication three modes, to provide a reliable point-of-care detection method for ensuring the accurate treatment of patients with H5N1 infection. Importantly, the MIP-based sensor could conveniently achieve the self-service detection at a cost of only RMB in 0.28 yuan.