1. Bioengineering Applications for “Smart” Materials. The term “Smart Materials” refers to a class of materials that undergo a large physical change in response to environmental cues. Poly(N-isopropyl acrylamide) (pNIPAM) is one such polymer that undergoes a change in surface hydrophobicity as a response to temperature drop around physiological temperatures (~32 °C). This change is transmitted to adhered cells (see Project 2) and opens up the use of pNIPAM-treated surfaces for a variety of bioengineering applications, including cell-based sensors (Project 3) and engineered tissues. One method of treating surfaces with pNIPAM is via plasma polymerization (photo at left), which is a one-step, solvent-free method for the deposition of a film that is sterile and pinhole-free, with excellent surface coverage.

2. Investigation of the ECM after Non-destructive Cell Removal. Under normal conditions, it requires harsh methods (e.g., enzymatic digestion) to remove adhered cells from surfaces. Using pNIPAM, it is possible to non-destructively harvest the cell sheets to study the extracellular matrix (ECM) proteins using biological and surface science techniques (in collaboration with NESAC/Bio at the University of Washington). This research represents the first opportunity to study the spatial location of proteins still adhered to cells (i.e., at the apical or basal surface of cells).

3. Development of a Cell-based Biological Sensor using a “Smart” Polymer Microfluidic Chip. Cell-based sensors—once the vision of science fiction—are now becoming a reality in the fields of homeland security, the food service industry, and basic research. Using plasma polymerization, one can take advantage of the wide variety of polymers available for surface modification, thereby tailoring the sensor’s surface to unique applications. The overall objective of this project is to develop a polymeric substrate based on pNIPAM (See Project 1) inside microfluidic channels for use as a sensor/actuator system for the detection of cytotoxins of interest.

4. “Smart” Surfaces for Research in Cancer Cell Biology. Transmembrane proteins regulate cell growth and migration, and are often upregulated in cancer cells. Therefore, cells expressing high levels of these receptors are used as in vitro model systems for monitoring the efficacy of new cancer therapeutics. The expression levels of membrane receptors in soluble cells may be rapidly quantified by flow cytometry, which requires their release into suspension. Traditional cell removal techniques may alter the cell surface expression levels of integral membrane receptors like EGFR. In collaboration with Gabriel López and Angela Wandinger-Ness, we seek to develop pNIPAM-treated substrates for the gentle release of cells into suspension for cancer cell biology studies.