Micro- and Nanoscale Technologies for Delivery into Adherent Cells

Abstract

Several recent micro- and nanotechnologies have provided novel methods for biological studies of adherent cells because the small features of these new biotools provide unique capabilities for accessing cells without the need for suspension or lysis. These novel approaches have enabled gentle but effective delivery of molecules into specific adhered target cells, with unprecedented spatial resolution. We review here recent progress in the development of these technologies with an emphasis on in vitro delivery into adherent cells utilizing mechanical penetration or electroporation. We discuss the major advantages and limitations of these approaches and propose possible strategies for improvements. Finally, we discuss the impact of these technologies on biological research concerning cell-specific temporal studies, for example non-destructive sampling and analysis of intracellular molecules.

Keywords: adherent cells; cell specificity; electroporation; nanobiotechnology.; non-destructive analysis; single-cell access.

Figure 1

Mechanical penetration. For delivery of molecules into cells, the membrane of a target cell can be mechanically pierced using a needle-like structure with a sharp tip including (counterclockwise) nanopipettes [5], one-dimensional nanowires [4], or cantilevers with either 1D nanoscale tips [8] or embedded microchannels [15, 19]. These figures are reproduced with permission of Macmillan Publishers Ltd, American Chemical Society, Elsevier, and American Chemical Society, respectively.

Figure 2

Electroporation. When a cell is subjected to a sufficiently large electric field, transient nanopores are formed in the cell membrane through which molecules can be delivered into the cell. Electroporation has been used in both lab-on-a-chip (left column) and nanoprobe (right column) configurations including (counterclockwise) localized electroporation device (LEPD), and microwell-, nanopipette-, and nanofountain-electroporation (Microwell-E, Nanopipette-E, and NFP-E), respectively. These figures are reproduced from [3] and [26], [78], and [18] with permission of The Royal Society of Chemistry, The Japan Society of Applied Physics, and American Chemical Society, respectively.

Figure 3

Example of envisioned integrated micro/nanofluidic platform for transfection, sampling, biomolecular detection, sorting, and on-chip cell culture [, , , , , –97]. Through temporal analysis, intracellular processes leading to mechanistic understanding through systems biology is possible [82, 83]. (Reproduced from [88] and [91], [35] and [97], [96], and [83] with permission of The Royal Society of Chemistry, American Chemical Society, The American Association for the Advancement of Science, and the National Academy of Sciences, respectively)