Figure 2.

(a) Representative microscopic images illustrate successful molecular delivery into trapped cells using μSEA. The white dashed lines outline the cell trapping chambers. HEK 293 cells, pre-stained with Hoechst 33342, were isolated and maintained in the cell trapping orbits in each chamber. Successful delivery of a membrane-impermeable fluorescent molecule Propidium Iodide (PI) into orbiting cells via electroporation was confirmed by detecting fluorescent signals emitted from trapped cells. The results were obtained by electroporating cells with AC square wave pulses with V = 15 V, f = 20 kHz, τ = 1 ms, and Δt = 1 s, followed by 30 s incubation in the PI solution. Scale bar represents 200 μm. (b–e) Optimization of electroporation parameters for various cell lines. Viability and electroporation efficiency of collected cells for (b) HEK293, (c) MDA-MB-231, (d) HeLa, and (e) MCF7 cells. The electroporation parameters that were kept consistent to obtain these results were AC square wave pulses with f = 20 kHz, τ = 1 ms, and Δt = 1 s. Error bars represent standard errors from experiments in triplicates. (n ≥ 280 cells per experiments). (f) Histograms of the intensity profile for the HEK293 cells after GFP delivery for delivery dosage control. The delivered amount of GFP increased with increasing incubation durations from 30 s to 120 s. 20 pulses were applied for all three conditions. Green lines overlaid on the histogram represent the Gaussian distribution (n ≥ 18 cells per experiment).