Nanozyme-integrated paper chip based on high peroxidase-like activity of Zn-doped reduced graphene oxide for glucose sensing

초록

The discovery of nanozymes exhibiting peroxidase-like activity is becoming increasingly important and urgent for biological and medical applications. In current research, the successful synthesis of Zn, N-doped Reduced Graphene Oxide (Zn-NrGO) nanozyme has been reported. The peroxidase-like activity of the Zn-NrGO was revealed through a Michaelis-Menten slow-steady kinetic study. The estimated Michaelis constant (Km) to be 6.356 mM and 0.115 mM, indicating the nanozyme has high affinity towards both H2O2 and TMB substrates, respectively. In addition, the relatively catalytic performance (kcat/Km) for H2O2 substrate is 3.57 x 104 mM(-1) s(-1), implying the peroxidase-like activity of the Zn-NrGO nanozyme is 700-fold higher than that of the pristine rGO. Notably, Zn-NrGO was incorporated into a paper substrate to form a nanozyme-based glucose paper chip, which showed a high selectivity in the presence of various interferences and was capable of detecting glucose markers in human serum within a linear range of 1-30 mM at a limit of detection (LOD) of 0.78 mM. The fabricated paper chip also showed high reliability with relative standard deviation (RSD) <= 10 % and recovery of 98.0-108.7 %. This study will contribute to the development of the nanozyme-based glucose paper chip serving as a diabetic point-of-care testing service.

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