Injections Of Propidium Iodide Into Hela Culture Cells Using A Nanoinjection Lance Array

Nanoinjection lance arrays have been used to inject propidium iodide, a dye, into living cells. The lance arrays consist of approximately four million needle-like structures on a 2 x 2 cm silicon chip, fabricated using standard methods for silicon wafers. A culture of He La cancer cells, commonly used in genetic research, has been employed for testing the nanoinjection process. Propidium iodide at several concentrations has been used as the dye for cell injection. The dye binds to nucleic acids after injection, and does not fluoresce when not bound, allowing accurate flow cytometry measurement of successful injections. Over 200 wells were tested to gather reliable testing data, consisting of negative controls (no treatment), positive controls (dye added with no injection), and samples (dye added and injection performed). Tests were performed for dye concentrations of 20, 40, 60, and 80 mu L per 1 mL of cell media solution, for two different lance array geometries. The multi-cell nanoinjection process presented in this paper has proven to produce positive dye uptake results in injected cells while maintaining high cell viability, with an average uptake rate of about 52% for cells injected with the highest concentration of dye. Reviewing all data, the average sample success rate is 8 times higher than the rate of dye uptake in the positive controls. Cell viability in these tests is on average 96.2%. The process may be used in a variety of research areas.