Metallization cross-linking and electronic state engineering of zeolitic imidazole framework: boosting the electroanalytical response of physiological biomolecules

Utilizing the Kirkendall effect to acquire hollow zeolitic imidazole framework (HZIF) allows for the predictable combination of superior guest molecules, which has favorable potential in the field of biomolecular detection. Herein, the ~42 nm hollow nanocages, HZIF(Au), were constructed through the different diffusion rates of Zn2+ and Au3+. By leveraging the Kirkendall effect at different Au3+ levels and over time (0, 5, 30, and 60 min) a composite with iron porphyrin (TCPP(Fe)) (the HZIF(Au4.5)@TCPP(Fe)) was effectively assembled. The selection of various metals within HZIF(Au4.5)@TCPP(Fe)-M (M = Fe, Co, Ni, and Cu) hybrid nanocomposites was then successfully formed via metallization cross-linking engineering. This metallization and the electron-donating properties of TCPP resulted in an electron-rich state for Au while the cross-linking of the carboxyl groups of TCPP with metal ions also significantly improved the electrocatalytic performance. Together, this allowed HZIF(Au4.5)@TCPP(Fe)-Fe to act as an effective electrochemical sensor with dopamine (DA) as the target molecule. In the optimal electrolyte environment, the linear range of 0.006–1500 μmol L−1 and detection limit of 0.002 μmol L−1 (signal-to-noise ratio, S/N = 3) could be realized for the DA response. This study carried out the fine regulation of ZIF nanocrystals through rational design; the unique construction and assembly strategy offered here will open up new routes for the evaluation of disease markers to effectively identify and monitor disease.