1：Experimental Design and Method Selection:

The study employs a surface plasmon resonance (SPR) transduction mechanism combined with molecular imprinting technology (MIP) for high sensitivity and selectivity. A fiber optic substrate is used for miniaturization and in vivo applications. The sensing layer involves a nanocomposite of multiwalled carbon nanotubes (MWCNTs) wrapped with dopamine-imprinted polypyrrole (PPy) and coated with a nafion membrane.

2：Sample Selection and Data Sources:

Artificial cerebrospinal fluid (aCSF) samples are prepared with dopamine concentrations ranging from 0 to 10^-5 M, using phosphate buffer and specific salts to mimic physiological conditions.

3：List of Experimental Equipment and Materials:

Equipment includes a scanning electron microscope (SEM) (Zeiss EVO 50), transmission electron microscope (TEM) (JEOL JEM-1400), UV-Vis spectrometer (Perkin Elmer Lambda 1050), tungsten halogen lamp (Avalight-HAL), spectrometer (Avaspec-3648), thermal evaporation coating unit, dip coater, and flow cell. Materials include plastic clad silica fiber (core diameter 600 μm, numerical aperture

4：4, from Fiberguide industries), silver wire, pyrrole, MWCNTs, hydrogen peroxide, iron(II) chloride, dopamine hydrochloride, uric acid, ascorbic acid, epinephrine, serotonin, nafion, SDS, CTAB, various salts for aCSF, and chemicals like ethanol and acids. Experimental Procedures and Operational Workflow:

The procedure involves functionalizing MWCNTs with carboxylic acid, polymerizing PPy around MWCNTs in the presence of dopamine to create imprinted sites, eluting dopamine to form cavities, coating with nafion, dip-coating the nanocomposite onto a silver-coated optical fiber probe, and recording SPR spectra for different dopamine concentrations in a flow cell setup with light from a halogen lamp coupled to a spectrometer.

5：Data Analysis Methods:

SPR spectra are analyzed to determine resonance wavelength shifts, sensitivity is calculated as the derivative of the calibration curve, limit of detection (LOD) is computed as three times the standard deviation divided by sensitivity near zero concentration, and selectivity, stability, and response time are assessed through control experiments and repeat measurements.