By Gail Dutton
A new way to produce protein nanoparticles in a high-throughput environment that are not only numerous but also stable, controllable, and homogeneous has been developed by researchers at the University of Cambridge and Beijing University of Technology.
This new technique uses droplet-microfluidics to generate protein nanoparticles within microdroplets. It relies upon the natural vortices inside the microdroplets to ensure continuous mixing and thus prevent nanoparticle aggregation.
“Two of the main benefits are the high degree of particle uniformity and high throughput,” corresponding author Tuomas P. J. Knowles, professor of physical chemistry and biophysics, University of Cambridge, tells GEN. “We show that our method can be generalized to for nanoparticles from three different proteins.”
Microfluidics enables fine-tuning
In a recent paper, Knowles and colleagues explain how this works. “The internal vortex velocity within microdroplets determines the sizes and ensures the uniformity of the protein nanoparticles. By varying parameters such as protein concentration and flow rates, we are able to finely tune the nanoparticles’ properties and dimensions.”
This technique, he says, “offers a balance between forming nanoparticles rapidly and ensuring they have a uniform size.” In contrast, forming nanoparticles using most microfluidic methods have particles that are polydisperse, while nanofluidics approaches offer high monodispersity but poor throughout that led to low yields. “By running multiple devices in parallel, we can form nanoparticles up to 250 mL per day,” adds Zenon Toprakcioglu, PhD, a research fellow in Cambridge who jointly led the work.
Their work shows the protein nanoparticles fully enter the target cells “with almost all cells containing them.” They were stable for at least 60 days. The researchers created nanoparticles from reconstituted silk fibroin, bovine serum albumin, and beta-lactoglobulin in sizes from 18 to 40 nm.
In droplet-microfluidic devices, oil flows in the external phase, which separates the reaction solution; ethanol in the middle phase, which reduces the solubility of the protein and contributes to protein nucleation; and protein in the internal phase. These devices, unlike usual 2D microfluidic chips, support rapid mixing within the microdroplet reaction vessels.
The researchers currently are studying the kinetic aspects of delivery—how long it takes drugs that were encapsulated within these nanoparticles to be delivered and released inside cells. “This is the key next step to allow our nanoparticles to be used by drug developers,” Knowles says. Therefore, “We believe that this technology has the potential to advance drug delivery generally and can be used for a range of pharmaceutically active molecules.”