In this work, Hemin@MOF was prepared by doping hemin into Cu-MOF-199 and applied in the electrochemical sensing of H2O2 and DNA. The Hemin@MOF modified electrode (Hemin@MOF/GCE) exhibited an excellent electrocatalytic activity toward H2O2 and the detection limit of H2O2 was as low as 0.07 μmol·L−1 with the range of 0.1 to 2200 μmol·L−1. Based on the eminent electrochemical performance, Hemin@MOF was further employed as an electrochemical signal indicator to construct a novel electrochemical DNA biosensor. Here, via amidation reaction, the stem-loop-structure probe DNA (pDNA) carrying 3'-amino and 5'-biotin was anchored on the carboxyl functionalized graphene. Then the pDNA was unfolded by the hybridization of the matched target DNA (tDNA). The following recognition between streptavidin (SA) on the Hemin@MOF-SA and biotin at the pDNA led the Hemin@MOF-SA to access the electrode surface. In this way, the electrode modified with Hemin@MOF-SA and matched tDNA could display remarkable catalytic activity toward the reaction of H2O2. The proposed electrochemical DNA biosensor showed an excellent performance with 9 orders of magnitude in the range from 1.0 × 10−15 to 1.0 × 10−6 mol·L−1, the low detection limit of 6.9 × 10−16 mol·L−1 and the one-base mismatch differentiation ability. In addition, the two as-prepared electrochemical sensors also exhibited good stability, showing a potential application in the practical analysis.
Liyan Zhang,Chuan Fan,Min Liu,Fengjuan Liu,Shanshan Bian,Shuyue Du,Shuyun Zhu,Hua Wang
Catalytic hemin was first remolded with biomineralized gold to form Hemin-Au core and further encapsulated into the Tb metal organic framework (MOF) matrix. The so obtained Hemin-Au@MOF composites could possess high environmental stability and especially double catalysis activities of enhanced peroxidase-like and gold catalysis. Steady state kinetics studies indicate that Hemin-Au@MOF could present much higher intrinsic catalysis and substrate affinity (lower Michaelis constants) than native hemin and even natural peroxidase . Furthermore, the catalytic composites were employed for labeling antibodies towards the sandwiched immunoassays for alpha-fetoprotein (AFP) as a model biomarker of cancers. The results indicate that the Hemin-Au@MOF-based immunoassays could be conducted by two signal amplification ways of hemin-catalyzed chromogenic reaction and gold-catalyzed silver staining, enabling the detection of AFP in blood with the level down to 0.020 ng mL −1 . Importantly, the proposed fabrication protocol combining the gold biomineralization and MOF encapsulation routes may be extended for the fabrication of a variety of enzymes or enzymatic mimics with the improved environmental stability and multiple catalysis activities for the wide catalysis applications.
危险品化学品经营许可证（带存储）