Alginate microspheres have recently become increasingly popular in the realm of drug delivery for their biocompatibility, nontoxicity, inexpensiveness, among other factors. Recent strict regulations on microsphere size have drastically increased manufacturing cost and waste, even though the effect of size variance on drug delivery and subsequent performance is unclear. If sphere size variance does not significantly affect drug release profiles, it is possible that future ordinances may loosen tolerances in manufacturing to limit waste produced and expenditures. We use a mathematical model developed by Nickel et al. [12], to theoretically predict drug delivery profiles based on sphere size, and correlate the expected release with experimental data. This model considers diffusion as the key component for drug delivery, which is defined by Fick’s Laws of Diffusion. Alginate, chosen for its simple fabrication method and biocompatibility, was formed into microspheres with a modified extrusion technique and characterized by size. Size variance was introduced in batches and delivery patterns were compared to control groups of identical size. Release patterns for brilliant blue dye, the mock drug chosen, were examined for both groups via UV spectrometry. The absorbance values were then converted to concentration value using a calibration curve done prior to experimentation. The concentration values were then converted to mass values. These values then produced curves representing the mass of the drug released over time. Although the control and experimental values were statistically significantly different, the curves were rather similar to each other. However, when compared to the predicted release pattern, the curves were not the same. Unexpected degradation caused this dissimilarity between the curves. The predictive model was then adjusted to account for degradation by changing the diffusion coefficient in the code to a reciprocal first order exponent. The similarity between the control and experimental curves can insinuate the notion that size tolerances for microsphere production can be somewhat lenient, as a batch containing fifteen beads of the same size and one with three different sizes yields similar release patterns.

Type 1 diabetes is a metabolic disorder in which the pancreas produces little to no insulin due to the cells being destroyed by a person’s own body. A potential treatment for this disorder is the allogeneic transplantation of pancreatic beta cells. Unfortunately, this potential solution requires the use of immunosuppressants. For my project with the Weaver Lab, I will be assessing pseudoislet survival in macroencapsulation via injection molding. I will be analyzing survival and metabolic assays of the pseudoislets in the mold process. Pseudoislets in hydrogels usually undergo hypoxia-included cell death due to the diffusion distances oxygen has to travel. We will test the impact of macroencapsulation device geometry on hypoxia within encapsulated cells. I will be culturing pancreatic cells and encapsulating them in hydrogels. Macroencapsulation devices will be utilized to shield islets from the immune system and eliminate the need for immunosuppressants. In order to analyze the cells’ structure and to ensure their viability, confocal microscopy will be used. Staining for live cells will be done using calcein AM which produces green fluorescence and indicates live cells. Staining for dead cells on the other hand will be done using an ethidium homodimer which produces red fluorescence and indicates dead cells. To determine if the cells are metabolically active the Alamar Blue assay will be used.