Vacuum-assisted fluid flow in microchannels to pattern substrates and cells

Abstract

Substrate and cell patterning are widely used techniques in cell biology to study cell-to-cell and cell-to-substrate interactions. Conventional patterning techniques work well only with simple shapes, small areas and selected bio-materials. This paper describes a method to distribute cell suspensions as well as substrate solutions into complex, long, closed (dead-end) polydimethylsiloxane (PDMS) microchannels using negative pressure. Our method builds upon a previous vacuum-assisted method used for micromolding (Jeon, Choi et al. 1999) and successfully patterned collagen-I, fibronectin and Sal-1 substrates on glass and polystyrene surfaces, filling microchannels with lengths up to 120 mm and covering areas up to 13 × 10 mm2. Vacuum-patterned substrates were subsequently used to culture mammalian PC12 and fibroblast cells and amphibian neurons. Cells were also patterned directly by injecting cell suspensions into microchannels using vacuum. Fibroblast and neuronal cells patterned using vacuum showed normal growth and minimal cell death indicating no adverse effects of vacuum on cells. Our method fills reversibly sealed PDMS microchannels. This enables the user to remove the PDMS microchannel cast and access the patterned biomaterial or cells for further experimental purposes. Overall, this is a straightforward technique that has broad applicability for cell biology.

Microfluidic device‐assisted etching of p‐HEMA for cell or protein patterning

“…We anticipate that this technique may be modified to be utilized for the study of other cell types, such as fibroblasts or neurons. Similar techniques have been used with cells, such as retinal neurons, PC12 cells, and fibroblasts, and thus, it is likely that p‐HEMA patterning is compatible with these and other cell types. Viability of C2C12 myoblasts after patterning was not directly examined in this manuscript; however, the high number of adherent cells after 7 DIV suggests that p‐HEMA patterning does not have adverse effects on cell viability (Figure ).…”

“…This technique can be further modified to pattern proteins in the microfluidic channels. For example, using the vacuum technique, the microchannels can be filled with poly‐ d ‐lysine and laminin to further refine cell and protein patterning since each of these substrates has distinct adherence properties. In the future, additional modification of the p‐HEMA surface will be performed to achieve thicker coating or for use of copolymers of p‐HEMA, such as poly (HPhMA‐co‐HEMA) .…”

“…Scotch tape microfluidic devices were fabricated as previously described . Briefly, glass slides were cleaned with isopropyl alcohol (IPA) and dried with an airgun.…”

“…Inlets and outlets were then punched from the mold using a 1 mm biopsy punch (Tedpella, USA) Scotch tape microfluidic devices were fabricated as previously described. 15 Briefly, glass slides were cleaned with isopropyl alcohol (IPA) and dried with an airgun. Scotch tape was then applied to the surface of the glass slide and rolled with a rubber roller to remove air bubbles.…”

Position along the nasal/temporal plane affects synaptic development by adult photoreceptors, revealed by micropatterning

“…For other cell types however, migration might be a concern; it can be reduced by using BSA, poly(HEMA), Teflon, or other cell-repelling substrates between the patterned stripes. We have successfully applied this approach to fibroblast cultures on a patterned substrate 25 .…”