Interfacing Cells with Vertical Nanoscale Devices: Applications and Characterization

Abstract

Measurements of the intracellular state of mammalian cells often require probes or molecules to breach the tightly regulated cell membrane. Mammalian cells have been shown to grow well on vertical nanoscale structures in vitro, going out of their way to reach and tightly wrap the structures. A great deal of research has taken advantage of this interaction to bring probes close to the interface or deliver molecules with increased efficiency or ease. In turn, techniques have been developed to characterize this interface. Here, we endeavor to survey this research with an emphasis on the interface as driven by cellular mechanisms.

Keywords: biointerface; electron microscopy; electrophysiology; molecular delivery; vertical structures.

Figure 1.

Overview of fabrication methods for vertical structures. A) Deposition of material through a resist aperture via electrodeposition (Weidlich et al. 2017). B) Nanoimprinting utilizes a mold-based pressing process(Miyauchi et al. 2016). C) Polymerization via focused gallium ion beam (De Angelis et al. 2013). D) Etching process through particle templating (Rey et al. 2016).

Figure 2.

Vertical structures for electrophysiology. A) Doped silicon nanoelectrodes record intracellular action potentials from primary and stem cell-derived neurons. Scale bar: 4 um. (R. Liu et al. 2017) B) Nanotube channels increase field effect transistor performance. Left: germanium branch on silicon nanowire. Inset gold nanodot on nanowire. Middle: structure after coating with aluminum oxide. Right: Hollow nanotube forms the transistor channel after etching of germanium core. Scale bars: 200 nm for all but left inset (100 nm). (Duan et al. 2011)

Figure 3.

A) General circuit model of the cell-electrode interface. B) Drug test using nanoelectrodes and human embryonic stem cell-derived cardiomyocytes. C) Nanoelectrodes enable measurement of arrhythmia in patient-derived cardiomyocyte culture. (Lin et al. 2017) D) Parallel recordings of rat ventricular cardiomyocytes before (left) and after (right) administration of a Na+ ion channel blocker. E) The ability to record with high spatial resolution across a tissue-scale area allows for conclusions about regional arrhythmia in response to drugs. 54 pixels recorded by the CMOS array labeled

Figure 4.

Strategies for enhanced molecular delivery. A) Nanostraw device schematic. B) Azidosugar delivery schematic. (Xu et al. 2017) C) Electron micrograph and cross section of HeLa cells on porous silicon nanoneedles. Scale bars: left, 5 um, right, 2 um. (C. Chiappini et al. 2015)

Figure 5.

Cellular assays. A) Schematic of nanostraw sampling of intracellular molecular contents. (Cao et al. 2017) B) SEM of alumina nanostraws. (Cao et al. 2017) C) Confocal z-stack of images depicting nanopillar-induced nuclear deformation. The nuclear envelope is labeled with GFP-Sun2. Scale bars 3 um. (Hanson et al. 2015) D) Schematic of Nanopillar-induced curvature for studies of endocytosis. E) Collocalized immunostaining for clathrin and dynamin2 allows correlation between degree of curvature and protein accumulation. (Zhao et al. 2017)

Figure 6:

Fluorescence microscopy of cells and vertical structures. A) SNAP labelled cell membrane tightly wraps around nanowires. (Berthing et al. 2012) B) NAP for molecular detection of cells and nanostructures. (Frederiksen et al. 2016)

Figure 7.

SEM of cells vertical structures. A) Cardiomyocytes on quartz nanopillars with protrusions approach the pillar surface. (Santoro et al. 2017) B) Comparison of fibroblast on vertical structures vs. flat surface. (S. Lee et al. 2015)(Lee, et al. 2015) C) cells spreading on vertical structures at different densities. (Persson et al. 2015)

Figure 8.

Various interface preparation protocols. A) Traditional resin embedding method. (Wierzbicki et al., 2013) B) Critical point drying (Van Meerbergen et al., 2008) C) Ultra-thin resin plasticization. (Santoro et al., 2017)