Metal Organic Framework-Modified Carbon Fiber Microelectrodes for Enhanced Neurochemical Detection

Neurochemical detection with fast scan cyclic voltammetry (FSCV) and carbon fiber microelectrodes (CFMEs) often lacks sufficient sensitivity and selectivity for measuring low dopamine levels found in the brain. In this study, carbon fiber microelectrodes (CFMEs) were modified with the iron-based metal organic framework (MIL-88B(Fe)) to alter the electrode surface and improve dopamine detection performance. When tested with a triangle waveform (scanning from -0.4 to +1.3 V, 400 V s^-1, 10 Hz), MIL-88B(Fe)-modified CFMEs showed a higher oxidative peak current for dopamine, increasing from 57.0 ± 5 nA on bare CFMEs to 100.5 ± 5 nA dopamine (n = 7, p < 0.0001), corresponding to an enhancement of approximately 76%. These modified electrodes exhibited a linear response in the nanomolar dopamine range (10-100 nM), with sensitivity increasing from 30 ± 2 nA nA/μM for bare CFMEs to 49 ± 3 nA/μM for MIL-88B(Fe)-modified CFMEs, and a limit of detection of 53 nM (3.3 σ/S) with a limit of quantification of 162 nM. The electrodes simultaneously detected dopamine, tyrosine, and hydrogen peroxide, with distinct oxidation peaks and a high recovery rate (~97%) in biological fluid. Together, these results indicate improved dopamine sensitivity relative to bare CFMEs and demonstrate the ability to distinguish dopamine from co-detected species with FSCV.