The Spectradyne nCS1 employs a novel implementation of the resistive pulse sensing method to count and size nanoparticles quickly and with high resolution. Sizing precision of ±3% is typically achieved, with measurement rates up to 10,000 particles/s. Because particles are measured individually in the nCS1, accurate size distributions of samples with a wide range of diameters can be obtained.
Spectradyne has used these capabilities to measure the particle size distribution in commercial samples of nanoparticles (NPs) for targeted drug delivery. The concentration and size distribution of drug-carrying nanoparticles give critical information about bioavailability of the drug, and the immunogenicity and stability of the formulation. The nCS1 has been used to characterize diverse particle types, including organic and inorganic NPs. The results inform the customer's manufacturing process and provide analysis that cannot be obtained using other methods.
In one example (plot on right, below), biocomposite nanoparticles for the delivery of high-potency cancer drugs to the site of a tumor were combined with 150 nm polystyrene control beads. The NIST-traceable polystyrene beads provide a size control, and can improve the measurement precision. The mean diameter of the nanoparticle drug carriers was determined to be 61 nm (CV ~ 25%), with total concentration 3.5 × 1013 particles/mL.
In a second example (plot on right, below) a lipid nanoparticle drug formulation is analyzed. The sample was prepared as described above, with 150 nm polystyrene control nanoparticles added to yield a final concentration of 5 × 109 particles/mL. The mean diameter of the lipid nanoparticles was measured to be 62 nm (CV ~ 19 %), and the concentration of the 62 nm particle population was measured to be 2.6 × 1010 particles/mL.