Tunable, Metal-Loaded Polydopamine Nanoparticles Analyzed by Magnetometry

We report the preparation and study of Mn­(III)-, Fe­(III)-, Co­(II)-, Ni­(II)-, Cu­(II)-, Zn­(II)-, and Ga­(III)-loaded polydopamine nanoparticles (PDA-NPs) via autoxidation polymerization of metal–dopamine complexes in the presence of free dopamine. An analysis of the doping range and parameters that influence final particle morphology is presented. In addition, magnetometry provides a probe of the general electronic structure and electronic interactions for Mn­(III)-, Ni­(II)-, and Co­(II)-loaded PDA-NPs. PDA-NPs doped with Mn­(III) are found to have high spin, low anisotropy, and weak magnetic coupling and are therefore predicted to have superior relaxivity behavior compared to previously studied Fe­(III)-loaded PDA-NPs. Comparison of Mn­(III)- and Fe­(III)-loaded PDA-NP relaxivity confirms the predictive ability of the magnetometry measurements

Process Robustness in Lipid Nanoparticle Production: A Comparison of Microfluidic and Turbulent Jet Mixing

The recent clinical and commercial success of lipid nanoparticles (LNPs) for nucleic acid delivery has incentivized the development of new technologies to manufacture LNPs. As new technologies emerge, researchers must determine which technologies to assess and how to perform comparative evaluations. In this article, we use a quality-by-design approach to systematically investigate how the mixer technology used to form LNPs influences LNPstructure. Specifically, a coaxial turbulent jet mixer and a staggered herringbone microfluidic mixer were systematically compared via matched formulation and process conditions. A full-factorial design-of-experiments study with three factors and three levels was executed for each mixer to compare process robustness in the production of antisense oligonucleotide (ASO) LNPs. ASO-LNPs generated with the coaxial turbulent jet mixer were consistently smaller, had a narrower particle size distribution, and had a higher ASO encapsulation as compared to the microfluidic mixer, but had a greater variation in internal structure with less ordered cores. A subset of the study was replicated for mRNA-LNPs with comparable trends in particle size and encapsulation, but more frequent bleb features for LNPs produced by the coaxial turbulent jet mixer. The study design used here provides a road map for how researchers may compare different mixer technologies (or process changes more broadly) and how such studies can inform process robustness and manufacturing control strategies