Editable Au NCs@ZIF-8 nanomaterial-modified paper in situ as well as portable smartphone-assisted sensing assay for the highly sensitive Cu (II) detection in Wilson’s disease

High levels of Cu (II) in the human body can cause kidney dysfunction, liver cirrhosis, and many neurological diseases, such as Wilson’s disease (WD). Therefore, rapid and efficient detection of Cu (II) in urine is highly essential. First, by a simple multiple seeded growth method, the gold nanoclusters (Au NCs) embedded metal-organic framework (ZIF-8) is decorated on cellulose paper to generate a fluorescent Au NCs@ZIF-8 paper. Then the Au NCs@ZIF-8 paper is loaded on the fluidic cartridge integrated with the syringe for ultra-sensitive urine copper detection. The fluorescence paper is intercalated in a reusable fluidic cartridge and attached to a syringe, allowing the fluidic cartridge to flow a amount of samples through the paper. The interaction of Cu (II) with in situ growth of Au NCs@ZIF-8 on the paper induced fluorescence quenching, which fluorescence images can be recorded and analyzed by the portable smartphone-assisted device. Furthermore, a large amount of sample solution was flowed through the Au NCs@ZIF-8 paper, enabling more Cu (II) to react with the Au NCs@ZIF-8 paper on the novel paper-based analytical device (nPAD). Cu (II) detection can be completed by nPAD in 20 mins, and the limit of detection was as low as 9.2 nM. We show the value of the paper device for on-site detection of copper (II) and indicate that it has excellent potential for clinical applications and environmental monitoring.