Microfluidic networks for biomaterial studies In collaboration with Dr. Linda S. Hirst and Prof. Cyrus R. Safinya (Materials Department)

The goal of this research is to geometrically confine and align biomolecules in microfabricated devices in order to define the mechanical and structural properties of self-assembling systems using fluorescence microscopy and x-ray diffraction. This technique allows for the study of fully hydrated samples under biological conditions. In order to align biomolecules, we must take into consideration the persistence length, or flexibility, of the various assemblies. By designing a large array of microfluidic channels with widths on the order or less than the persistence length of the biomolecules, we are able to create passively aligned samples. The structural properties of these large arrays can then be defined using x-ray diffraction. Currently, the microfluidic channel systems are micromachined into bulk titanium thin foils using newly developed microfabrication techniques (Figure 1). Because x-rays must pass through the sample for diffraction studies, the backside of the microfluidic array must be as thin as possible. Therefore, titanium is an excellent substrate for this application due to its relative ductility, which allows for the reduction of x-ray attentuation through backside thinning. Recent studies have incorporated actin filament bundles (Figure 2) and microtubules (Figure 3) into the titanium microfluidic channels. Current work in focusing on complexing and confining these proteins, as well as other biomolecules such as DNA, with cationic phospholipids for structural and mechanical studies.

For additional information, please contact Emily Parker.

Figure 1. (a) Two wells are interconnected via an array of channels. (b) A PDMS cover is used to prevent overflow from one channel to another and to reduce evaporation during subsequent experiments. Scanning electron micrographs of (c) 20 micron wide and (d) 10 micron wide channels.

Figure 2. Fluorescence microscopy images showing actin filament bundles in 20 micron wide titanium microfluidic channels.

Figure 3. Microtubules have also been studied using (a), (b) 5 micron wide and (c) 20 micron wide channels.