Attachment of astroglial cells to microfabricated pillar arrays of different geometries

Abstract

We studied the attachment of astroglial cells on smooth silicon and arrays of silicon pillars and wells with various widths and separations. Standard semiconductor industry photolithographic techniques were used to fabricate pillar arrays and wells in single-crystal silicon. The resulting pillars varied in width from 0. 5 to 2.0 micrometer, had interpillar gaps of 1.0-5.0 micrometer, and were 1.0 micrometer in height. Arrays also contained 1.0-micromter-deep wells that were 0.5 micrometer in diameter and separated by 0.5-2.0 micrometer. Fluorescence, reflectance, and confocal light microscopies as well as scanning electron microscopy were used to quantify cell attachment, describe cell morphologies, and study the distribution of cytoskeletal proteins actin and vinculin on surfaces with pillars, wells, and smooth silicon. Seventy percent of LRM55 astroglial cells displayed a preference for pillars over smooth silicon, whereas only 40% preferred the wells to the smooth surfaces. Analysis of variance statistics performed on the data sets yielded values of p > approximately.5 for the comparison between pillar data sets and < approximately.0003 in the comparison between pillar and well data sets. Actin and vinculin distributions were highly polarized in cells found on pillar arrays. Scanning electron microscopy clearly demonstrated that cells made contact with the tops of the pillars and did not reach down into the spaces between pillars even when the interpillar gap was 5.0 microm. These experiments support the use of surface topography to direct the attachment, growth, and morphology of cells. These surfaces can be used to study fundamental cell properties such as cell attachment, proliferation, and gene expression. Such topography might also be used to modify implantable medical devices such as neural implants and lead to future developments in tissue engineering.

Vertical silicon nanowires as a universal platform for delivering biomolecules into living cells

“…Building on the previous observation that vertically grown NWs can support cell culture (15)(16)(17)(18)(19), we show that vertical NW substrates can serve as a universal, scalable, and highly efficient modality for introducing DNAs, RNAs, peptides, proteins, and small molecules into both immortalized and primary cell types, without chemical modification or viral packaging. This simplicity and generality, which stem from the direct physical access to the cell's interior afforded by NW penetration (15)(16)(17)(18)(19), make NW-based delivery distinct from chemical and viral methods that are widely employed (1)(2)(3)(4)(5)(6). Furthermore, this NW-based system is fully compatible with standard microarray printing techniques, allowing large collections of biomolecules to be delivered, or even codelivered, into live cells in a parallel and miniaturized fashion.…”

“…Vertical nanowire (NW) substrates can satisfy these stringent requirements because the NWs enable direct physical access to the cells' interiors (15)(16)(17)(18)(19). Here, we report an experimental platform based on vertical silicon (Si) NWs that can deliver virtually any type of molecule into a wide variety of cells in a format compatible with microarray technology and live-cell imaging.…”

Directional Alignment of MG63 Cells on Polymer Surfaces Containing Point Microstructures

“…This preference could be explained in terms of the geometry of the patterned structures. Measuring the angle produced between consecutive posts, between post (0,0) and (0,1), (1,1), (2,1), (3,1), and so on, (Figure 8 a), reveals that the most common angles seen in Figures 6 and 7 are reproduced ( Table 2). As the angle decreases, so the distance between posts in direct alignment increases (with the exception of 08).…”

“…[1][2][3][4][5][6][7][8][9][10][11][12] This has led to the discovery that micro-and nanotopology causes cells to elongate, [9] align to the direction of the surface pattern, [9,[13][14] to rearrange the extracellular matrix in contact with the surface, [11,15] and to internally re-organize cellular components. [9,12] It is also possible that the topography can illicit varying cellular responses.…”

Vertical nanopillars for highly localized fluorescence imaging

“…Recently, Shalek et al reported the use of vertical silicon nanowires to deliver biomolecules such as proteins and DNA plasmids into living cells that grew attached to the nanowires (9). Together with other works that show vertical nanowires can support cell culture (10)(11)(12)(13)(14), these observations suggest a new and exciting possibility of using vertical nanowires as a universal platform to probe intracellular molecular events.…”