2024/12/12 by Vivekananda Bal, Moo Sun Hong, Bal, Vivekananda +13
Materials Science · Engineering · #Crystallization and Solubility Studies #Field-Flow Fractionation Techniques
paper · pdf · doi:10.48550/arxiv.2412.09821
Crystallization of proteins, specifically proteins of medical relevance, is\nperformed for various reasons such as to understand the protein structure and\nto design therapies. Obtaining kinetic constants in rate laws for nucleation\nand growth of advanced biotherapeutics such as capsids, an assembly of\nmacromolecules, is challenging and essential to the design of the\ncrystallization processes. In this work, coupled population balance and species\nbalance equations are developed to extract nucleation and growth kinetics for\ncrystallization of recombinant adeno-associated virus (rAAV) capsids. A\ncomparison of model results with that of experimental data for capsid\ncrystallization in hanging-drop vapor diffusion system shows that slow rate of\nvapor diffusion from the droplet controls the initial nucleation and growth\nprocesses, and the capsid nucleation occurs via heterogeneous nucleation in the\nmicrodroplet. Results also show that the capsids, which are of very high\nmolecular weight (~3.6 MDa), have a similar tendency to nucleate as small\norganic molecules such as glycine (75 Da), low-molecular-weight proteins, and\nsmall-molecule active pharmaceutical ingredients due to its ball-shaped outer\nstructure/shape. Capids also show a prolonged nucleation period as for proteins\nand other macromolecules, but has a slow growth rate with a growth rate\npre-factor seven orders of magnitude smaller than that of lysozyme. The capsid\ncrystal growth rate is weakly sensitive to the supersaturation compared to\nlysozyme and is limited by the transport of capsids due to slow Brownian motion\nresulting from the very high molecular weight.\n