Laminar flow mediated continuous single-cell analysis on a novel poly(dimethylsiloxane) microfluidic chip

•Laminar flows were used to align and introduce single cells in the microfluidic chip.•Microcylinders in channel were used to mix laminar flows to rapidly lyse moving cells.•DOX uptake in single cells was continuously detected in flowing streams.•Membrane P-gp in single cells was continuously detected in flowing streams.•The designed microfluidic chip suits to high-throughput single-cell analysis.

A novel microfluidic chip with simple design, easy fabrication and low cost, coupled with high-sensitive laser induced fluorescence detection, was developed to provide continuous single-cell analysis based on dynamic cell manipulation in flowing streams. Making use of laminar flows, which formed in microchannels, single cells were aligned and continuously introduced into the sample channel and then detection channel in the chip. In order to rapidly lyse the moving cells and completely transport cellular contents into the detection channel, the angle of the side-flow channels, the asymmetric design of the channels, and the number, shape and layout of micro-obstacles were optimized for effectively redistributing and mixing the laminar flows of single cells suspension, cell lysing reagent and detection buffer. The optimized microfluidic chip was an asymmetric structure of three microchannels, with three microcylinders at the proper positions in the intersections of channels. The microchip was evaluated by detection of anticancer drug doxorubicin (DOX) uptake and membrane surface P-glycoprotein (P-gp) expression in single leukemia K562 cells. An average throughput of 6–8 cells min−1 was achieved. The detection results showed the cellular heterogeneity in DOX uptake and surface P-gp expression within K562 cells. Our researches demonstrated the feasibility and simplicity of the newly developed microfluidic chip for chemical single-cell analysis.

Graphical abstractA novel asymmetric microfluidic device was developed for simple, convenient and high-throughput single-cell analysis based on dynamic cell manipulation in flowing streams. Single cells could be continuously introduced and rapidly lysed in microchannels with the mediation of laminar flows.Figure optionsDownload full-size imageDownload as PowerPoint slide