A Polyoxometalate—Carbon Nanotube Enhanced Electrochemical Sensor for Aptamer‐Based Diagnostics

A novel inorganic–organic nanocomposite material composed of multi‐walled carbon nanotubes (MWCNTs), polyoxometalates (POMs), and aptamers is presented for the electrochemical detection of target molecules in aqueous environments. The responsive POM–aptamer units are synthesized via a strain‐promoted azide–alkyne cycloaddition (SPAAC) reaction, covalently linking a single‐stranded DNA (ssDNA) aptamer to the Lindqvist‐type hexavanadate [V 6 O 13 ((OCH 2 ) 3 CCH 2 N 3 ) 2 ] 2− (V 6 ‐N 3 ) through a triazole bridge. These conjugates are immobilized onto amine‐functionalized MWCNTs and drop‐casted onto a platinum microelectrode surface to form a “Pt//MWCNT/POM– aptamer ” heterostructure. The sensor is evaluated using diclofenac, a pharmaceutical pollutant, as a model analyte. By combining the molecular recognition capabilities of aptamers with the redox properties of POMs and the excellent electrical conductivity of MWCNTs, the hybrid sensor demonstrates significantly enhanced electrochemical sensitivity. This sensing platform shows great potential for application in decentralized medical devices for rapid ex‐vivo diagnostics of complex biological matrices such as blood.