This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).

0854462 Grunlan

INTELLECTUAL MERIT

The project investigates temperature controlled activation of micro nano structured nanocomposite hydrogel materials to produce temperature controlled self cleaning surfaces. Cyclical changes in temperature will activate these nanocomposite hydrogel micropillars by switching them back and forth from a water swollen to deswollen state. This activation process will lead to pronounced and rapid changes in surface properties ultimately allowing surfaces to rid themselves of adherent biofouling species such as cells. The proposed microstructured nanocomposite hydrogels may be particularly useful to design self cleaning implanted biosensor membranes or other surfaces whose performance is compromised by biofouling. Enhancing temperature activated self cleaning will be accomplished by a two pronged approach utilizing both material design and micropatterning design components. The investigators will prepare novel nanocomposite hydrogels consisting of poly (N-isopropylacrylamide) (PNIPAAm) hydrogel matrices and variable levels of colloidal polysiloxane nanoparticles. PNIPAAm hydrogels are known to become more hydrophobic when they reversibly switch from a water swollen to a shrunken (deswollen) state at temperatures above the volume phase transition temperature (VPTT) of ~35 °C. Such temperature activated changes in surface hydrophilicity/hydrophobicity have been shown to disrupt the adhesion of adsorbed cells and proteins. In preliminary studies, variable polysiloxane nanoparticle levels were used to tailor the temperature dependent surface properties of PNIPAAm hydrogels. These nanocomposite hydrogels demonstrated superior mechanical strength but did not alter the VPTT (conveniently near body temperature) compared to pure PNIPAAm hydrogels. For each unique composition, nanocomposite hydrogel microstructures (e.g. micropillars) will be prepared and, as a result of their size scale, should produce fast switching surfaces in which changes in hydrophilicity/hydrophobicity are very pronounced compared to their planar (i.e. non micropatterned) analogues. Tailoring nanocomposite hydrogel composition and microstructure topography will ultimately result in surfaces which could quickly and drastically respond to changes in temperature and hence undergo temperature controlled self cleaning.

BROADER IMPACTS

The project on design of robust self cleaning surfaces which combat biofouling has the potential to enhance the performance life time of many commercial devices equipment. Specifically, surfaces designed in this study have the potential to make long term implanted biosensors (e.g. for glucose monitoring) a clinical reality. This research will also reveal the role of polysiloxane nanoparticles and micropillar topography in tailoring the self cleaning properties of PNIPAAm hydrogels. Beyond the advancements in research, this work will effectively train undergraduate and graduate students in a broad, multi disciplinary research program consisting of materials design characterization, microfabrication of soft nanocomposite materials, and its direct application to self cleaning. The multidisciplinary nature of this research will provide a unique training environment for both graduate and undergraduate students from biomedical engineering, electrical engineering, and chemical engineering departments at Texas A&M University. Dr. Melissa Grunlan (PI; Dept. of Biomedical Engineering) will guide the efforts to design and synthesize planar nanocomposite hydrogels and characterize their material properties. Dr. Arum Han (Co-PI; Dept. of Electrical Engineering), an expert in nano microfabrication for bio applications, will focus on the preparation of micropatterned surfaces via various photopolymerization and imprint methods using the materials developed in Dr. Grunlans lab. Dr. Mariah Han (Co-PI; Dept. of Chemical Engineering) will provide expertise in cell release studies. Throughout the duration, feedback will be provided by combined weekly group meetings to explore the best material surface topography combinations for optimal temperature activated self cleaning behavior and efficient microfabrication. This research will strengthen the existing partnership between three departments and effectively utilize resources of the PI, Co-PIs, and university centers. We will actively recruit pre doctoral candidates from under represented groups by their participation in summer Texas A&M University sponsored programs and directed studies throughout the school year. Various aspects of the proposed work will be taught to undergraduate and graduate students enrolled in courses taught by the PI and Co-PI.

Project Start
Project End
Budget Start
2009-09-01
Budget End
2013-08-31
Support Year
Fiscal Year
2008
Total Cost
$300,000
Indirect Cost
Name
Texas Engineering Experiment Station
Department
Type
DUNS #
City
College Station
State
TX
Country
United States
Zip Code
77845