Engineering a two-dimensional metal-carbon nanozyme-based portable paper-based colorimetric chip for onsite and visual analysis of pyrophosphate.

Sensitive and accurate analysis of pyrophosphate (PPi) is of great importance for preventing health hazard in environment. Nevertheless, most of sensors focus on sensitivity and selectivity, but practicality is also a significant quota. How to reconciling sensitivity, selectivity and practicability in one single sensor is desirable but remains challenging. Here, we created a novel metal-carbon nanozyme V ₂ O ₅ @C with two-dimensional (2D) morphology and high yet exclusive peroxidase (POD)-like activity via a glucose and NH ₄ NO ₄ -co-directed avenue, and further showed its application in constructing a portable and disposable paper-based analytical chip (PA-chip) for rapid, visual and onsite analysis of PPi. PPi etched V ₂ O ₅ to prevent the decomposition of H ₂ O ₂ into ·OH, resulting in weakened POD-like activity. In comparison with PPi deficiency, colorless TMB couldn't be oxidized into oxidized TMB with a dropped absorption at 652 nm. Therefore, obviously shallowed blue color on PA-chip surface was recorded, and demonstrated a negative relationship with PPi dosage, enabling rapid and visual detection of PPi with a limit of detection of 2.6 nM. This study demonstrated the burgeoning applications of nanozymes with POD-like activity in construction of PA-chips for PPi and will quicken the advancement of practical sensors, guaranteeing environmental safety.
Competing Interests: Declaration of competing interest The authors declare no competing financial interest.
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