Microfluidic Chemical Function Generator for Probing Dynamic Cell Signaling.

Cellular environments are inherently dynamic and generally involve complex, temporally varying signals. Reconstruction of these environments with high spatial and temporal fidelity and simultaneous imaging of intracellular dynamics in live cells remains a major challenge. In this paper, a microfluidic chemical function generator (μCFG) was proposed for probing cell dynamic signaling with high temporal resolution. By combining a hydrodynamic gating module with a chaotic advection mixing module, the μCFG was able to generate a variety of chemical waveforms, such as digital pulsatile chemical waveforms with a frequency higher than 10 Hz and analog chemical waveforms with a frequency higher than 0.2 Hz. The shape, frequency, amplitude, and duty cycle of the waveforms could be also conveniently modulated. To demonstrate the capability of μCFG of probing fast biological processes and elucidate signal transduction pathways in complex signaling networks, a variety of temporal responses of Ca signaling to ATP-induced activation of the PY receptor, a prototypical G-protein coupled receptor (GPCR), were investigated in live cells by precisely and dynamically controlling their microenvironment.