Dual-channel non-enzymatic sensor for comprehensive purine profiling: synergizing anodically pretreated boron-doped...

The comprehensive profiling of purine metabolites-uric acid (UA), xanthine (XT), hypoxanthine (HX), and inosine (INO)-is vital for diagnosing metabolic disorders, yet remains analytically challenging due to severe overlap in oxidation potentials and the electrochemical inactivity of INO on conventional carbon surfaces. This work describes a label-free, dual-channel electrochemical platform utilizing disposable screen-printed graphene electrodes (SPGEs) to overcome these limitations. The architecture employs two spatially decoupled sensing modalities: (1) an anodically pretreated boron-doped nanodiamond (BDND) channel to resolve the UA-XT-HX kinetically triad, and (2) a Pd²⁺- functionalized coordination channel that enables selective INO oxidation. Under optimized conditions, the platform achieved simultaneous quantification of UA, XT, and HX with a limit of detection (LOD) of 1 µM, while INO was detected at 60 µM. Notably, this reagentless design exhibits exceptional long-term stability, retaining > 95% activity after 20 weeks of storage-a significant advancement over fragile enzymatic sensors. Validated in human urine, the sensor yielded recoveries of 95-105% with minimal matrix interference. This dual-channel approach offers a robust and scalable strategy for comprehensive purine profiling while bypassing the logistical and stability constraints inherent in bio-reagents. The key novelty of this platform lies in its spatially decoupled, dual-channel architecture, which circumvents cross-interference and enables the simultaneous, non-enzymatic point-of-care detection of four structurally related purine metabolites.