Optimizing the Degree of Methacrylation for Polyelectrolyte Complex Microcapsules

Osteoarthritis is a chronic degenerative joint disease that affects millions of adult Americans. The effects of this disease go beyond pain causing lifestyle changes and impacting economic well-being. Current leading treatments are not permeant solutions for patients and still hold a multitude of potential risks. One challenge of these treatments is cell growth and integration. An emerging solution to aid in the growth, handleability, and integration of chondrocytes is using polyelectrolyte complex microcapsules to house the cells. To optimize microcapsules for successful future use, this research investigated the effects of the degree of methacrylation on the capsule membrane for a range of methacrylic acid methacrylated hyaluronic acid (HA-MA) ratios. This range included 1:0.1 HA-MA, 1:0.25 HA-MA, 1:0.5 HA-MA, 1:1 HA-MA, 1:2 HA-MA, and 1:3.5 HA-MA ratio. Nuclear Magnetic Resonance (NMR) was used to verify reaction completion and calculate degree of methacrylation. It was seen that as the ratio of methacrylic acid to hyaluronic acid increased so did the degree of methacrylation until a peak of 68% degree of methacrylation for the 1:2 HA-MA ratio was reached. Encapsulation was performed via the air droplet method in which 1 weight percent of the HA-MA ratio was mixed with 4 weight percent of Chondroitin Sulfate A for stability purposes (CSA). Microcapsule membranes and interiors were characterized using Scanning Electron Microscopy (SEM). Photos exhibited thickening of the capsule membrane for higher 1:1 and 1:2 HA-MA ratios. This research set ups future experiments in determining how degree of methacrylation effects capsule compression strength. Moreover, having this data for all the tested ratios helps to narrow down the parameter choices for other future experiments, besides the above-mentioned strength testing, that further optimize the polyelectrolyte complex microcapsules to enhance cell growth, handleability, and integration.