Amperometric Monitoring of Dissolution of pH-Responsive EUDRAGIT® Polymer Film Coatings.

Electrochemical sensors are powerful tools for the detection and real-time monitoring of a wide variety of analytes. However, the long-term operation of Faradaic sensors in complex media is challenging due to fouling. The protection of the electrode surface during in vivo operation is a key element for improving the monitoring of analytes. Here, we study different EUDRAGIT® controlled release acrylate copolymers for protecting electrode surfaces. The dissolution of these polymers-namely EUDRAGIT® L 30 D-55 and EUDRAGIT® FS 30 D-is triggered by a change in pH of the environment, and it is electrochemically monitored by detecting electrode access by means of a redox probe. The full dissolution of the polymer is achieved within 30 min and the electrode response indicates a complete recovery of the original electrochemical performance. We demonstrate that amperometric sensing is a practical and straightforward technique for real-time and in situ sensing of EUDRAGIT® dissolution profiles. It will find future applications in determining the protection of polymer electrode coating in real matrices and in vivo applications.

High-throughput analysis of the steroid profile in placental cell cultures to evaluate endocrine disrupting effects of contaminant exposure.

Human placental JEG-3 cells conserve a high P450 aromatase activity and are therefore suitable to evaluate how contaminants may interfere with the routes involved in estrogen synthesis during pregnancy. This has been traditionally assessed by measuring aromatase activity through the amount of tritiated water (3H2O) formed during the aromatization of 1ß-3H-androst-4-ene-3,17-dione (3H-AD). This work presents a greener and safer analytical approach for this purpose, which consists of the determination of the trace amounts of the steroids (estradiol, estrone, testosterone, and androstenedione) present in the culture medium. Turbulent flow chromatography coupled to liquid chromatography-tandem mass spectrometry (TFC-HPLC-MS/MS) delivered the high selectivity and sensitivity (limits of detection between 2 and 5 pg/mL) required for these measurements. Moreover, its automation allows high-throughput of samples with minimum sample handling and achieves high precision in the analysis (relative standard deviation values <6%). As a proof of concept, the method was applied to evaluate the effect of monohaloacetic acid exposure on the steroid profile of JEG-3 cells. Iodoacetic acid showed an estrogenic effect (statistically significant increase of estradiol levels compared to unexposed cells) at the highest concentration level tested (0.5 µM) that deserves further evaluation.