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Wednesday 11 Nov 2015[NEST seminar] Thermoresponsive Hydrogels as Self-cleaning Membranes for Implanted Glucose Biosensors

Professor Melissa A Grunlan - Department of Biomedical Engineering, Department of Materials Science and Engineering, Texas A&M University

HAR/170 (3D Visualisation Suite) 13:30-14:30

A membrane that limits biofouling is critical to extend the lifetime and efficacy of implanted glucose biosensors. When cycled above and below its volume phase transition temperature (VPTT, ~33C), poly(N-isopropylacrylamide) (PNIPAAm) hydrogels undergo deswelling and reswelling, respectively. This process is known to effectively remove adhered proteins and cultured cells in vitro. We propose that a PNIPAAm-based hydrogel membrane could control biofouling in vivo via a "self-cleaning" mechanism induced by thermal cycling. This approach is feasible if the membrane can be designed with rapid deswelling/swelling kinetics for efficient cell release, adequate mechanical properties for implantation and also sufficient glucose diffusion. In this work, several parameters were explored to achieve these properties including, incorporation of polysiloxane nanoparticles, a double network hydrogel matrix design and incorporation of an electrostatic comonomer. The impact of these design variables on key membrane properties were assessed, including: deswelling/reswelling behavior (gravimetric and differential scanning calorimetry - DSC), morphology (SEM) and modulus & strength (compression tests). Thermally-driven in vitro cell release and a pre-clinical pilot study demonstrated encouraging results in terms of membrane self-cleaning behavior.

The Speaker

Prof. Melissa Grunlan is currently an Associate Professor of Biomedical Engineering at Texas A&M University. She is also a faculty member of the Department of Materials Science & Engineering and the Center for Remote Health Technologies and Systems. Prof. Grunlan obtained her B.S. in Chemistry and M.S. in Polymers in Coatings from North Dakota State University (Fargo, ND). After spending four years at the H.B. Fuller Company (St. Paul, MN), she received her Ph.D. in Chemistry from the University of Southern California (Los Angeles, CA). Prof. Grunlan joined Texas A&M University as an Assistant Professor in August of 2005 and was promoted to Associate Professor with tenure in September 2011. She is the recipient of the TEES Faculty Fellow Award (2013), the Herbert H. Richardson Faculty Fellow Award (2010-2011), the Association of Former Students Distinguished Achievement Award (2009) and the BP Teaching Excellence Award (2013) from the College of Engineering at TAMU. She was awarded the Royal Academy of Engineering's Distinguished Visiting Fellowship in 2015.

Prof. Grunlan is the director of the "Silicon-Containing Polymeric Biomaterials Group" ( Her research is broadly focused on developing new materials to improve the performance of medical devices. Several specific research areas include self-cleaning membranes for implanted biosensors, anti-fouling coatings for blood-contacting devices and marine applications, and scaffolds for osteochondral and bone tissue healing.

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