@misc{9236549,
  abstract     = {{Degradable dextran microspheres (DDMs) are promising materials with potential applications in drug delivery and medical devices due to their biocompatibility, biodegradability and versatile properties. DDMs are produced through a water-in-oil emulsion in which an aqueous dextran solution is dispersed in an organic solvent containing an emulsifier. Addition of a crosslinker, such as epichlorohydrin (ECH), crosslinks the dextran chains within the droplets and microspheres are formed. Since the relationship between process parameters and microsphere properties are complex, a deeper understanding of the process is required in order to achieve robust and reproducible production while enabling control of microsphere properties.

The aim of this project was to investigate how key process parameters influence the formation and properties of DDMs, by employing a design of experiments (DoE) approach. A full factorial experimental design was performed using the software MODDE to study the effects of dextran concentration, reaction temperature and ECH concentration on microsphere formation, particle size distribution (PSD), PSD span and swollen volume. An additional DoE was performed to investigate a region of the design space that produced elongated, non-spherical particles, focusing on the effects of temperature and stirring rate.

The results demonstrated that the DDM process is complex and contains several regions in which microspheres are not produced. Although none of the investigated factors or interaction terms were statistically significant according to the coefficient plot for the first DoE, experimental observations and contour plots still suggested that temperature and ECH concentration influenced microsphere properties. Increasing temperature generally increased particle size and swollen volume, while increasing ECH concentration decreased these responses. Possible interaction effects between temperature and ECH concentration were observed for PSD span and swollen volume. The experimental results also indicated that dextran concentration influences microsphere formation, where higher concentrations promoted microsphere formation and resulted in larger spheres.

Particle elongation and sphericity were strongly influenced by both temperature and stirring rate. Increasing the temperature generally reduced particle size and promoted the formation of smaller and more spherical particles. Similarly, increasing the stirring rate reduced particle size and resulted in more spherical particles. The results demonstrate that there is no distinct transition from elongated to spherical particles, the particle morphology can be tuned gradually by balancing temperature and stirring rate. In addition, the swollen volume was influenced by both factors, indicating a complex interaction between temperature and stirring rate depending on the region of the chemical space.}},
  author       = {{Nordberg, Estelle}},
  language     = {{eng}},
  note         = {{Student Paper}},
  title        = {{Decoding the Chemical Space of Degradable Dextran Microspheres}},
  year         = {{2026}},
}