This technology enables modification of a cell’s surface properties while preserving most of its native behavior by attaching a polyelectrolyte multilayer (PEM) patch to the cell. A PEM is first assembled on a planar substrate through an aqueous-based layer-by-layer (LbL) process which takes place in the absence of living cells. This allows the use of a wide range of assembly conditions including cytotoxic chemistries. This PEM is then patterned into a number of discontiguous patches using photolithography-based techniques like "lift-off" and plasma etching or polymer-on-polymer stamping (POPS).
The PEM patches used in this technology generally consists of a labile releasable layer dissociable under non-cytotoxic conditions, a functional or payload layer customizable for different applications, and a cytophilic layer with specific affinity for surface ligands of a predetermined cell type. Additional layers may be incorporated to augment substrate adhesion or to improve release properties. Once PEM patch fabrication is complete, target cells are incubated with the substrate-bound patches whereupon they bind to the cytophilic layer of the patch. Finally, relevant environmental conditions, such as pH or the presence of a specific enzyme, are modified to break down the labile layer and release the cell-patch complex from the substrate.
The end result of this process is a viable cell with a functionalized PEM patch covering only part of its surface, leaving the remainder to mediate native cellular interactions.