Analytical Chemistry by further controlling the microenvironment, we can gain a greater understanding of the conditions necessary for peptide release to occur. This knowledge increases our ability to apply essential molecules of repair to restore function to a damaged neural network. The ease of fabrication and cell culture, as well as the coupling to MS, make this device readily amenable to many neuronal types. The system demonstrated here can be extended to work with other cell types and culturing platforms to enable the interface of culturing, stimulation, and release characterization. Potential enhancements include the ability to quantify the amount of peptides released such as via the approach for Zhong et al.29 or other direct MS approaches such as the method described by Rubakhin and Sweedler.50 In addition, via appropriate interfacing to CE−laser induced ﬂuorescence (LIF)51−53 and CE−MS,54,55 more complete characterization of the extrac- ellular media can be performed. Finally, as this system is transparent and contains an accessible culturing platform, future eﬀorts can include Ca2+ imaging or electrophysiology to enable a new range of studies on neuronal release dynamics. AUTHOR INFORMATION Corresponding Author *Fax: 217-265-6290. Phone: 217-244-7359. E-mail: jsweedle@ illinois.edu. Notes The authors declare no competing ﬁnancial interest. ■ ACKNOWLEDGMENTS The authors thank Stanislav Rubakhin and Ming Zhong for helpful discussions and Jared Kindt for assistance in generating the ﬁgures. C.C. was supported by the NIH Cellular and Molecular Biology Training Grant T32 GM007283. S.S. and J.J. acknowledge the Thailand Research Fund (TRF) through the Royal Golden Jubilee Ph.D. Program. This material is based on work supported by Award No. P30 DA018310 from the National Institute on Drug Abuse and Award No. R01 NS031609 from the National Institute of Neurological Disorders and Stroke. 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