Technical Reference #1697

1697.

The Chemistrode: A Droplet-based Microfluidic Device for Stimulation and Recording With High Temporal; Spatial; and Chemical Resolution Delai Chena; Wenbin Dua; Ying Liua; Weishan Liua;; Andrey Kuznetsovb; Felipe E. Mendez; Louis H. Philipson; and Rustem F. Ismagilova;, University of Chicago, PNAS, 105(1697), (2008)
Link To Paper

Abstract:
Microelectrodes enable localized electrical stimulation and recording and they have revolutionized our understanding of the spatiotemporal dynamics of systems that generate or respond to electrical signals. However such comprehensive understanding of systems that rely on molecular signals—e.g. chemical communication in multicellular neural developmental or immune systems— remains elusive because of the inability to deliver capture and interpret complex chemical information. To overcome this challenge we developed the ‘‘chemistrode’’ a plug-based microfluidic device that enables stimulation recording and analysis of molecular signals with high spatial and temporal resolution. Stimulation with and recording of pulses as short as 50 ms was demonstrated. A pair of chemistrodes fabricated by multilayer soft lithography recorded independent signals from 2 locations separated by 15 m. Like an electrode the chemistrode does not need to be built into an experimental system—it is simply brought into contact with a chemical or biological substrate and instead of electrical signals molecular signals are exchanged. Recorded molecular signals can be injected with additional reagents and analyzed off-line by multiple independent techniques in parallel (e.g. fluorescence correlation spectroscopy MALDI-MS and fluorescence microscopy). When recombined these analyses provide a time-resolved chemical record of a system’s response to stimulation. Insulin secretion from a single murine islet of Langerhans was measured at a frequency of 0.67 Hz by using the chemistrode. This article characterizes and tests the physical principles that govern the operation of the chemistrode to enable its application to probing local dynamics of chemically responsive matter in chemistry and biology.

Keywords:
analysis; dispersion; flow; microscale; pulse

Materials & Methods:
Islets were isolated from the pancreas of C57BL/6J wild-type mice (The Jackson Laboratory) 8–12 weeks of age by using collagenase digestion and Ficoll gradients by following procedures described in previously published literature (6). Isolated islets were transferred to glass-bottom culture dishes (Mattek Corporation) and cultured in RPMI medium 1640 supplemented with 10% FBS 2 mM L-glutamine 100 units/mL penicillin and 100 g/mL streptomycin. Islets were maintained in a humidified incubator at 37 °C under an atmosphere of 95% air and 5% CO2 and were used within 3 days of isolation.

Microscopic Technique
Fluorescence Microscopy, Video Microscopy

Cell Type(s)
Hippocampal cells