Enhanced microdialysis based on hydrophobic deep eutectic solvents for sampling of eugenol in Glyptocidaris...

Microdialysis is an in vivo technique for dynamically analyzing biochemical components in tissues and fluids. Traditional microdialysis systems are primarily designed for low molecular weight polar compounds, resulting in lower recoveries for hydrophobic compounds. This study aimed to develop a greener, cost-effective, and enhanced microdialysis method for recovering eugenol, isoeugenol, and methyl isoeugenol, utilizing hydrophobic deep eutectic solvents as the perfusate, with the method's feasibility verified through in vivo experiments.

Among the 19 types of deep eutectic solvents evaluated, thymol-levulinic acid was identified as the most suitable for eugenol compounds based on liquid-liquid microextraction and microdialysis experiments, showing an in vitro microdialysis recovery approximately 100 times higher than that of water. The optimization of microdialysis parameters was conducted, including molar ratio of HBA:HBD, temperature, flow rate, and semi-permeable membrane length. In the in vivo microdialysis experiments, the temporal concentration of eugenol, which was used as an anesthetic in Glyptocidaris crenularis, was detected by GC-MS/MS and calibrated using ex vivo recovery. When the concentration of eugenol in artificial seawater was maintained at 100 μg mL^-1, the eugenol levels in the coelomic fluid of Glyptocidaris crenularis rose from 0 to 6.89 ± 0.38 μg mL^-1 within 60 min, then stabilized in next 80 min.

The findings demonstrate that deep eutectic solvents enhanced microdialysis provides high recoveries and enables real-time monitoring of drug concentration changes in biological systems, making this method a valuable tool for pharmacokinetic studies and environmental monitoring.