Lab-In-A-Syringe: A Novel Electrochemical Biosensor for On-Site and Real-Time Monitoring of Dopamine in Freely Behaving Mice

There is a growing demand for real-time analysis and sampling of biofluids on a single low-cost platform in ultralow fluid volumes with robustness. In this study, a microfluidic sensor was developed, manufactured through an additive manufacturing technique, and used for dopamine (DA) measurements. We implemented a biosensing system using pencil graphites (PGEs) integrated into a three-dimensional (3D) printed microfluidic syringe-type device (pSyringe). The amperometry technique was used to monitor the current changes associated with the electrooxidation of DA. The sensing signal was stable and linear in a concentration range of DA between the limit of quantification (0.1 nM) and the upper limit of linearity (500 nM). The pSyringe sensing device is simple, robust, and stable, making it suitable for real-time measurement of DA in cerebrospinal fluid (CSF) from freely moving mice.