480757 A Microfluidic Method for the Simultaneous Quantification of Hydrogel Erosion and Drug Release

Monday, November 14, 2016
Grand Ballroom B (Hilton San Francisco Union Square)
Christopher M. Serfass1, Roland V. Crystal2, James E. Maneval1, Brandon M. Vogel1 and Erin L. Jablonski1, (1)Chemical Engineering, Bucknell University, Lewisburg, PA, (2)Mechanical Engineering, Bucknell University, Lewisburg, PA

A hydrogel is a jelly-like material consisting of a network of polymer chains capable of absorbing a significant amount of water; enough to make the compound constitute 40-90% of the material’s weight. Hydrogels have many potential uses but those related to the medical industry with controlled drug release formulations being of special interest. In these formulations, drug molecules are loaded into a hydrogel which is placed inside the body. The molecules are then released over a period of days to weeks. A particular variety of hydrogels which show great promise for this application are those which exhibit hydrolytic degradation. In addition to releasing drug molecules over an extended time period, this class of hydrogels will also degrade in the body and eliminate the need for invasive removal later. The degradation rate, however, also has an influence on the rate of drug release. In this work we aim to simultaneously follow drug release and hydrogel erosion.

We have developed a method to create simple microfluidic devices with a channel and walls made from hydrogel. As liquid flows through the device, the hydrogel will degrade as a result of hydrolysis and small molecules (drug or dye molecules can be loaded into the sample) will exit the hydrogel by diffusion and during hydrogel degradation. We use of the differing refractive indices of the hydrogel and air to make the channel visible by periodically injecting air into the channel. This causes a high contrast between the edges of the channel and the surrounding environment and allows degradation to be observed as the edges can be seen to gradually recede with a microscope. Molecule release is accounted for through one of two methods. If the small molecules are dye molecules, the microscope image captures and image analysis are used to qualify diffusion and erosion. If the molecules lack a distinctive color or fluorescence – such as many drug molecules do – molecule release can be measured by analyzing the effluent released from the device.

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