A Dual Approach of an Oil–Membrane Composite and Boron-Doped Diamond Electrode to Mitigate Biofluid Interferences

Electrochemical biosensors promise a simple method to measure analytes for both point-of-care diagnostics and continuous, wearable biomarker monitors. In a liquid environment, detecting the analyte of interest must compete with other solutes that impact the background current, such as redox-active molecules, conductivity changes in the biofluid, water electrolysis, and electrode fouling. Multiple methods exist to overcome a few of these challenges, but not a comprehensive solution. Presented here is a combined boron-doped diamond electrode and oil–membrane protection approach that broadly mitigates the impact of biofluid interferents without a biorecognition element. The oil–membrane blocks the majority of interferents in biofluids that are hydrophilic while permitting passage of important hydrophobic analytes such as hormones and drugs. The boron-doped diamond then suppresses water electrolysis current and maintains peak electrochemical performance due to the foulant-mitigation benefits of the oil–membrane protection. Results show up to a 365-fold reduction in detection limits using the boron-doped diamond electrode material alone compared with traditional gold in the buffer. Combining the boron-doped diamond material with the oil–membrane protection scheme maintained these detection limits while exposed to human serum for 18 h.

Construction of dibutyl phthalate molecularly imprinted electrochemical sensor based on multi-walled carbon nanotubes-modified boron-doped diamond electrode

In order to construct a dibutyl phthalate (DBP) molecularly imprinted electrochemical sensor, the DBP was used as the template molecule, due to the characteristics of multi-walled carbon nanotubes (MWCNTs) loaded with nano-gold to enhance the electrical conductivity of the composite material, a molecularly imprinted film was prepared on the surface of boron-doped diamond electrode (BDD) by potential deposition. The morphology of the composite material MIP/AuNPs/MWCNTs/BDD was analyzed and characterized by scanning electron microscopy (SEM), and the performance of the electrochemical sensor was characterized by cyclic voltammetry (CV), and differential pulse voltammetry (DPV) was used to detect DBP. The electrochemical sensor had a linear range of 1×10-8 ~ 1×10-5 mol/L and a detection limit of 3.3×10 -9 mol/L. The sensor was applied to the detection of DBP in water samples.