Bioconjugation of zirconium uridine monophosphate: Application to myoglobin direct electrochemistry

Porous nano-granule of zirconium uridine monophosphate, Zr(UMP)2·H2O is, for the first time, synthesized under mild experimental conditions and applied to the bioconjugation of myoglobin (Mb) to realize its direct electron transfer. UV–vis and resonance Raman spectroscopies prove that Mb in the Zr(UMP)2·H2O film maintains its secondary structure similar to the native state. The conjugation film of the Mb–Zr(UMP)2·H2O on the glassy carbon (GC) electrode gives a well-defined and quasi-reversible cyclic voltammogram, which reflects the direct electron transfer of the heme FeIII/FeII couple of Mb. On the basis of the satisfying bioelectrocatalysis of the nano-conjugation of Mb and genetic substrate, a kind of mediator-free biosensor for H2O2 is developed. The linear range for H2O2 detection is estimated to be 3.92–180.14 μM. The apparent Michaelis–Menten constant (Km) and the detection limit based on the signal-to-noise ratio of 3 are found to be 196.1 μM and 1.52 μM, respectively. Both the apparent Michaelis–Menten constant and the detection limit herein are much lower than currently reported values from other Mb films. This kind of sensor possesses excellent stability, long-term life (more than 20 days) and good reproducibility.