Six-in-one nanozyme: constructing a triple-mode point-of-care platform for epinephrine detection with exceptional sensitivity and precision

Straightforward strategies for preparing nanozymes with multi-enzyme mimetic activities are highly desirable for various significant fields including biosensing, environmental monitoring, tumor therapy and biocatalysis. While till now, very few of these nanozymes have been designed, particularly for establishing multimode point-of-care testing (POCT) platforms to realize accurate in situ detection without expensive, bulky instruments. Herein, an innovative 3D hierarchical hollow flower-like cobalt–copper coordination polymer decorated with Cu_XO and CuCo₂O₄ nanoparticles (CuCoCPNFs@Cu_XO/CuCo₂O₄) was fabricated via a convenient one-pot approach in the absence of any surfactants and templates. Intriguingly, the resulting CuCoCPNFs@Cu_XO/CuCo₂O₄ shows exceptional ability to mimic the activities of a variety of bioenzymes, such as peroxidase (POD), oxidase (OXD), catalase (CAT), superoxide dismutase (SOD), laccase (LAC), and ascorbic acid oxidase (AAO). On account of the inhibitory effect of epinephrine (EP) on the POD-like activity of CuCoCPNFs@Cu_XO/CuCo₂O₄, a straightforward and label-free triple-mode POCT platform was established for EP determination. This platform provides output signals in the form of color, temperature, and RGB values, which can be monitored using UV-vis absorption spectroscopy, a thermometer, and a smartphone, respectively. The practicability and performance of the proposed EP sensing strategy were further certified in real serum samples. Therefore, the established sensing platform, which integrates multi-enzyme simulated active nanomaterials with a multi-mode POCT approach, provides new inspiration for in situ real-time detection with high sensitivity, selectivity, and accuracy.