Novel unlabeled electrochemical sensing platform based on highly electroactive Cu-MOF film for nanoplastic detection in water

An unlabeled electrochemical sensing strategy based on electroactive copper-centered metal–organic framework (Cu-MOF) film coupled with multiwalled carbon nanotubes (MWCNTs) was proposed for the rapid assessment of nanoplastic concentration. The sensing interface was fabricated via the electro-deposition of Cu-MOF on the pre-modified MWCNTs using the cathodic reduction method. The exposed copper active sites in Cu-MOF showed excellent electrochemical activity, which was further enhanced due to rapid electron transfer induced by highly conductive MWCNTs. Through the adsorption functionality of Cu-MOF film towards polystyrene (PS) nanoplastics, the rapid recognition for nanoplastics in aqueous solution was achieved, thereby causing the inhibition of the current response. The results showed a robust dependence of the inhibition rate on the PS mass concentration. The proposed detection method was used for the quantitative determination of PS nanoplastics with the sizes of 100 nm, 500 nm, and 1 μm. The applicability of this electrochemical sensing platform was successfully validated in real-world water sample analysis.