An economic method to build a puffing instrument for drug application in vitro

Background: In in vitro electrophysiological studies, a quick application of picoliters of drug within milliseconds is required to avoid the desensitization of membrane receptors. However, conventional gravity-fed drug delivery devices sometime fail to achieve this. Moreover, the high financial cost of the advanced drug delivery system often limits the application of commercial instruments in academic research. New method: Taking advantage of the availability of data acquisition system and software in almost every electrophysiology laboratory, a simple puffing device was designed and assembled using low-cost commercially off-the-shelf components to inject picoliter amounts of drugs. Results: An optimal drug delivery with precise timing and volume was achieved using the custom made puffing device. The glutamate-evoked currents of cortical neurons recorded with patch-clamp technique were maintained for a prolonged period of time. Similarly, puffed inhibitory transmitters including GABA and glycine also produced satisfactory currents. Comparison with existing method(s): Our custom-made puffing system holds the advantage over conventional gravity-fed systems in operating within milliseconds of time. The channel number of the new device can easily be increased by simply adding more identical modules in parallel, and thus offering more flexibility than commercial puffing devices. Conclusions: This custom-made puffing device can be characterized as reliable, modular and inexpensive system for modern drug delivery research and application.