November 27, 2019 -- New research published in Nature Communications on November 27th demonstrates a new chemical technique that provides researchers enhanced control over the size and shape of nanoparticles used in drug delivery systems.
Mimicking human biological organization has long been of interest to scientists and engineers. Anisotropic structures (directionally dependent) are ubiquitous in biology, and thus a target for nanoparticle drug delivery systems. DNA nanotechnology has allowed these structures to be built with a high degree of precision, although there are still concerns over scalability and cost-effectiveness.
In the current study, researchers from the University of Birmingham and the University of Bath report a distinct method for the production of controlled three-dimensional anisotropic polymer nanoparticles, termed morphological transformation (MORPH) using isotropic nanoparticles and transforming and growing them through supramolecular bonds and the addition of polymer.
"If you change the shape of a nanoparticle from, for example, a spherical to a cylindrical shape, others have shown that this can have a dramatic effect on how it interacts with cells in the body, and how it is distributed through the body. By being able to control the size and shape, we can start to design and test nanoparticles that are exactly suited to an intended function," explains Tom Wilks from the University of Birmingham's School of Chemistry.
The technique begins with a base nanoparticle, made of a polymer, and a second polymer is added in solution. The polymers are designed so they want to bond to each other, so the second polymer is driven into the core of the nanoparticle, forcing it to expand. The exact size and shape of the nanoparticle is then determined simply by how much of the second polymer is added. The unique features of this technique are complementary copolymer addition in length and width, and induced anisotrophy which allows isotropic particles to be used as seeds for growth.
"The precise way that these polymers were designed and the control we have over how much of the second polymer is added means we can accurately predict the shape of the nanoparticle, and have a high degree of control over its size," explains Wilks.
The researchers believe that this self-assembly technique could be used to create precise aspect ratio of nanoparticles with a variety of applications ranging from photonics to fuel cells and drug delivery systems. "This is an important first step in being able to effectively harness nanoparticles for a whole host of applications, but there are a lot of questions still to answer," says Wilks. "For example, in the field of drug delivery, we need to know much more about what would happen once drug molecules are introduced to our nanoparticles, as well as how the sizes and shapes of the nanoparticles can be optimized for different uses."
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