Revolutionising nanoparticle formulation

Challenge

Nanoparticles are tiny, highly functional materials, that offer great potential in the pharmaceutical and other industries. Nanoparticles can, for instance, be formulated to encapsulate drug molecules to target chosen sites and for delivery at controlled and sustained rates. However, scaling-up production from batch to continuous processes was hindered by timeconsuming methods for ensuring particle sizes are maintained within tightly controlled limits.

Typically, measurements were performed using Transmission Electron Microscopy (TEM) and similar reliable, yet expensive, methods. As only a proportion of each sample can be measured using TEM, other techniques were also needed to verify entire production runs. The whole process could take days, if not weeks.

Developing industrial-scale production processes requires testing formulations produced in many combinations of synthesis reactor conditions, including temperature, time, mixing, reagent ratios and concentrations of nanoparticles. Slow, low-throughput batch measurement techniques, such as TEM, impeded progress.

Dynamic Light Scattering (DLS) is another technique for measuring particle size, derived observing the speeds of particles in motion. However, at best, single angle DLS produces errors in particle size measurements of about a factor of two, and a larger error for particle concentration, so was useful only as a screening tool.

Multi-angle DLS devices were being developed for faster and cheaper nanoparticle characterisation, but, with no suitable good practice guidance or nanoparticle reference materials of known particle concentration, these instruments could not be reliably calibrated.