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Dennis Huang

Dennis Huang




University of Pennsylvania


Jamianne Wilcox

Faculty Sponsor(s): 

Megan Valentine

Faculty Sponsor's Department(s): 

Mechanical Engineering

Project Title: 

Measuring Surfactant Surface Coverage of Biomimetic Cargos from Interfacial Tension

Project Description: 

Kinesin motor proteins play an important role in intracellular transport by moving different types of cargo such as

vesicles and filaments along microtubule tracks in living cells. The principles behind single kinesin intracellular

transport are well known; however, little is known about collective kinesin behavior. In particular, we predict that

kinesin motor proteins will behave differently when attached to cargo with a rigid vs. a fluid membrane. To better

understand kinesin behavior when interacting with fluid membranes, biomimetic sunflower oil droplets were created

with two surfactant types (ceramide-PEG(2000) and biotinylated DSPE-PEG(2000)). The ratio of the two

surfactants determines how many kinesins can bind to the droplets through a biotin-streptavidin-biotin linkage.

Equilibrium interfacial tension was measured using an optical tensiometer for different concentrations and different

ratios of the two surfactants. The kinesin surface coverage was calculated from the equilibrium interfacial tension

and the ratio of biotinylated surfactants. Based on the calculated surface coverage of kinesin motor proteins, we can

control the number of kinesins present on each biomimetic sunflower oil droplet by manipulating the concentrations

and ratio of the two different surfactants. Once the biomimetic sunflower oil droplets are optimized to attach the

desired number of kinesins, tests can be performed using an optical trap to determine the kinesin behavior when

pulling the fluid membrane droplets.