High-efficiency G4-hemin@peptide biomimetic nanozyme and domain-limited DNA walker for sensitive electrochemical analysis of miRNA-21

G-quadruplex (G4)/hemin DNAzyme is promising horseradish peroxidase (HRP)-mimic candidate in the biological field. However, designing a DNAzyme with satisfactory catalytic activity comparable to protease remains an ongoing challenge. In this work, we developed novel G4-hemin@peptide biomimetic nanozymes via one-pot assembly of peptide containing lysine (Lys), histidine (His) and arginine (Arg) residues and G4-hemin, which possessed superior peroxidase-mimicking activity on account of mimicking the active site and catalytic microenvironment of HRP, simultaneously. Steady-state kinetic analysis demonstrated that the catalytic performance of G4-hemin@peptide was increased 9.3-fold compared with G4-hemin DNAzyme. Additionally, DNA quadrangular prism (QP₄) not only acted as gold nanoparticles (AuNPs)-encapsulated scaffold to integrate with G4-hemin@peptide for high-performance enzyme cascade platform, but also employed as domain-limited orbital for bipedal DNA walker, leading to 2.5-fold enhancement in walking efficiency than that of conventional DNA walker on the stochastic tracks. On this basis, the proposed electrochemical biosensor achieved miRNA-21 sensitive analysis, with a low detection limit of 0.5 fM. This study introduces a novel approach to develop high-efficiency artificial enzyme for the fabrication of nanozyme cascade system.