Characterization of cellular optoporation with distance

We have developed and characterized cellular optoporation with visible wavelengths of light using standard uncoated glass cover slips as the absorptive media. A frequency-doubled Nd:YAG laser pulse was focused at the interface of the glass surface and aqueous buffer, creating a stress wave and transiently permeabilizing nearby cells. Following optoporation of adherent cells, three spatial zones were present which were distinguished by the viability of the cells and the loading efficiency (or number of extracellular molecules loaded). The loading efficiency also depended on the concentration of the extracellular molecules and the molecular weight of the molecules. In the zone farthest from the laser beam (> 60 microns under these conditions), nearly all cells were both successfully loaded and viable. To illustrate the wider applicability of this optoporation method, cells were loaded with a substrate for protein kinase C and the cellular contents then analyzed by capillary electrophoresis. In contrast to peptides loaded by microinjection, optoporated peptide showed little proteolytic degradation, suggesting that the cells were minimally perturbed. Also demonstrating the potential for future work, cells were optoporated and loaded with a fluorophore in the enclosed channels of microfluidic devices.