Engineering of silicon surfaces at the micro- and nanoscales for cell adhesion and migration control

Abstract

The engineering of surface patterns is a powerful tool for analyzing cellular communication factors involved in the processes of adhesion, migration, and expansion, which can have a notable impact on therapeutic applications including tissue engineering. In this regard, the main objective of this research was to fabricate patterned and textured surfaces at micron- and nanoscale levels, respectively, with very different chemical and topographic characteristics to control cell-substrate interactions. For this task, one-dimensional (1-D) and two-dimensional (2-D) patterns combining silicon and nanostructured porous silicon were engineered by ion beam irradiation and subsequent electrochemical etch. The experimental results show that under the influence of chemical and morphological stimuli, human mesenchymal stem cells polarize and move directionally toward or away from the particular stimulus. Furthermore, a computational model was developed aiming at understanding cell behavior by reproducing the surface distribution and migration of human mesenchymal stem cells observed experimentally.

Keywords: hMSCs; ion-beam patterning; silicon; surface patterns.

Figure 1

Perspective scanning-electron microscopy images from a cross-section performed in micropatterns showing (A) alternating Si and nanostructured porous silicon stripes, (B) and Si/nanostructured porous silicon square grids. (C) Characteristic fluorescence from nanostructured porous silicon areas from a top view of a 2-D square pattern.

Figure 2

(A) Fluorescence microscopy images of hMSCs on 100 μm Si/25 μm nanostructured porous silicon square micropatterns. Actin is stained green and nuclei are stained blue. (B) Detailed image at an intersection, and (C) histogram of hMSC population from image (A) with absolute % and area normalized population (left and right columns respectively).

Figure 3

Adherence vector modulus for cells located on a line perpendicular to the 1-D stripe patterns for (A) 100 μm-wide Si/25 μm-wide nanostructured porous silicon (nanoPS) alternating stripes, (B) 50 μm-wide Si/25 μm-wide nanoPS stripes, (C) 35 μm-wide Si/25 μm-wide nanoPS stripes, and (D) one 2-D grid pattern of 100 μm-wide Si and 25 μm-wide nanoPS stripes. Screen capture of the program developed to perform the simulations and (E) t = 0, and (F) t = 400 seconds.

Figure 3

Adherence vector modulus for cells located on a line perpendicular to the 1-D stripe patterns for (A) 100 μm-wide Si/25 μm-wide nanostructured porous silicon (nanoPS) alternating stripes, (B) 50 μm-wide Si/25 μm-wide nanoPS stripes, (C) 35 μm-wide Si/25 μm-wide nanoPS stripes, and (D) one 2-D grid pattern of 100 μm-wide Si and 25 μm-wide nanoPS stripes. Screen capture of the program developed to perform the simulations and (E) t = 0, and (F) t = 400 seconds.