Single cell dose-response studied by quantitative optical injection

G.V. Orsinger, J.D. Williams, M. Romanowski
University of Arizona, US

Keywords: liposome, gold, optical injection, optical trap

Summary:

We present a nanotechnology technique that uses gold-coated liposomes propelled by an optical trap to deliver zeptomole quantities of molecules for activating cellular responses in a single cell. We have previously presented liposome-based plasmon resonant nanocapsules designed for applications in delivering therapeutic and diagnostic compounds selectively to cancerous or diseased tissues and cells and more recently we have demonstrated the application of plasmon resonant gold-coated liposomes for selectively delivering fluorescent molecules to specific cellular components by optical manipulation. The high polarizability of the liposome’s unique gold shell provides stable optical trapping. Optical injection, whereby gold-coated liposomes are forced into a cell by an optical trapping laser, enables delivery of a quantifiable dose of bioactive molecules with high precision. We encapsulated inositol trisphosphate (IP3), a ubiquitous intracellular secondary messenger, within 100 nm gold-coated liposomes and apply a modified optical trap to inject the liposomes and their contents into the cytosol of a single cell to target IP3R, binding to which leads to an increase in cytosolic calcium concentration. This unique in vitro technique will enable a better understanding of the often heterogeneous cellular response to drugs and will inevitably lead to the development of sophisticated therapies for treating disease.