A molecularly imprinted electrochemical sensor based on a novel AuNPs/MQDs/NGR ternary composite for sensitive and selective adenine determination

Reliable electrochemical determination of adenine (Ade) in biological samples remains challenging due to interference from structurally similar nucleobases, nonspecific adsorption, and instability of conventional sensing interfaces, which compromise selectivity and signal reproducibility. Here, we report an interface engineered electrochemical molecularly imprinted sensor based on disposable screen-printed electrodes (SPEs). The sensing platform integrates a poly( o -phenylenediamine) molecularly imprinted recognition layer with Au nanoparticles/MXene quantum dots/nitrogen-doped graphene (AuNPs/MQDs/NGR) nanocomposite transduction interface. MXene quantum dots (MQDs) provide abundant edge and terminal sites that promote uniform AuNPs nucleation and anchoring on NGR, forming a conductive and structurally stable sensing layer with reduced charge-transfer resistance. This engineered interface enables stable electropolymerization of the imprinted film and improves signal stability and electrode-to-electrode reproducibility. The sensor exhibited a linear response for Ade from 0.25 to 80.0 μM (R 2  = 0.992) with a detection limit of 0.094 μM and recoveries of 96.40–103.84% in human serum sample. This strategy provides a reproducible and selective electrochemical platform that addresses key limitations of current adenine sensors for analysis in complex biological matrices.