An UiO-66/P-L-histidine composite film fabricated by electropolymerization and electrodeposition for sensing biomarker 4-nitroquinoline N-oxide

Abstract A sensitive and selective electrochemical sensor for sensing 4-nitroquinoline N-oxide (4-NQO) by differential pulse voltammetry was designed. Poly L-histidine (P-L-his) composite and metal-organic framework UiO-66 (Zr) modified electrode was used as the working electrode which had large specific surface area, mesoporous structure and excellent conductivity. Unlike most modification methods, UiO-66 was electrodeposited in this study. Compared with drop coating, electrodeposition proceeds efficiently under mild conditions and often requires shorter time. FTIR, EDX, TEM, SEM and electrochemical assay were used to characterize the prepared materials and modified electrodes. After that, some experimental conditions like electro-polymerization time, deposition time, pH and scan rate were also improved and optimized separately. At the UiO-66/P-L-his-modified glassy carbon electrode, a good linear relationship between 4-NQO concentration and its peak current was obtained under the best conditions in a wide range from 0.2 to 50.0 μM, and the limit of detection (S/N = 3) was 66.7 nM. Moreover, multiple experiments elucidated that the as-synthesized sensor could be applied to detect 4-NQO in actual samples, and the recoveries results obtained were satisfactory.