Part 1 Differences in workingprinciple and accuracybetween dynamic light scattering particle sizer mainly based on Malvern particle sizer and nCS1 microfluidic nano-particle sizer (microfluidic resistance pulse particle sizer).

Like other light scattering techniques, during the secondary conversion of collected light scattering signals and collected data by DLS, the magnitude of the signal is proportional to the sixth power of the particle diameter: In other words, the calculated data from the light scattering signal of a particle with a diameter of 500 nanometers is 10 to the 12th power of a particle with a diameter of 5 nanometers. If large and small particles are mixed together in the sample cell to be tested, small particles will be "blocked" by large particles, and the light scattering data of large particles will be stronger, which will cause the tested fitting curve data to deviate from the existence of actual sample particles. Optical techniques such as DLS and optical tracking significantly amplify the relative number of large particles, and in the case of a uniform distribution with close particle sizes, actually show peaks that do not even exist on the large size.

The nCS1 microfluidic nanoparticle particle size analyzer adopts non-optical microfluidic + resistive pulse technology. The introduction of nano-level microfluidic chip technology allows particles to pass through the pore area of the microfluidic chip one by one, and the voltage pulse signal generated by the particles is only proportional to the particle volume and has nothing to do with the particle material, light absorption, light scattering signal strength, etc. The working principle of the nCS1 microfluidic nanoparticle is shown in Figure 1. Particles pass through the pore area of the nanoscale microfluidic chip one by one, and corresponding resistive pulse signals will be generated.

Figure 1 Working principle of the nCS1 microfluidic nanometer particle size analyzer

By measuring the size of the voltage pulse signal generated by each particle and the statistics of the number of particles, nCS1 can give particle size and number analysis results that are more consistent with reality with higher accuracy. Microanalysis of complex polydisperse samples provides unprecedented capabilities. In addition, since particles are measured electrically rather than optically in nCS1, particles of all materials are measured equally well, including some biological particles with refractive indices similar to those of media (such as water or ethanol)(samples with refractive indices similar to those of media cannot give accurate scattering signals when measured optically, and particle sizers cannot distinguish particles from media well).

Polydisperse samples were measured with different equipment:

Nist certified nanoparticle suspensions with known average diameters of 52, 94, 122 and 150 nm were mixed together, and the final concentration of each sample was 5×109 particles/mL. Samples are sent to the corresponding equipment platform, and the results of the three technologies are displayed side by side as shown in Figure 2. The gray dotted line in each case represents the expected distribution of the four particles. Only nCS1 clearly distinguished the four components of the mixture and obtained concentration measurements for each subpopulation within the range recognized by the particle manufacturer. The secondary conversion fitting results of optical tracking NTA and dynamic light scattering DLS failed to measure the true components.

Figure 2 Measurement results of DLS nCS1 NTA technology on samples with known particle sizes. The dotted

line shows the theoretical distribution of the four particles after mixing.

Figure 3  The measurement results of DLS nCS1NTA technology on four samples with known particle sizes are shown in the same box.

These results show that typical DLS or optical tracking instruments have obvious difficulties in finely resolving particle diameters, and also severely amplifies the relative number of large particles compared to small particles. For samples with a very uniform distribution or multiple particles present, in theory, an approximately trapezoidal result should be produced. A peak will usually occur in DLS measurements, even if the mixed sample does not have such a particle population, while the nCS1 microfluidic nano-particle size analyzer did not show such a peak, but could show a more polydisperse distribution.

Part 2 Performance of the nCS1 Microfluidic Nanoparticle Size Analyzer in the Determination of LNP Lipid Nanoparticles and Liposomes

Figure 4 Appearance of the nCS1 microfluidic nanoparticle and microfluidic chip sample cell.

The nCS1 microfluidic nanoparticle occupies a small desktop area, approximately 1.5 square feet (left). Using a disposable microfluidic chip sample cell (right) for analysis, only 3 μL of samples is needed, which also prevents contamination between measurements and eliminates cleaning requirements.

图 5 使用nCS1和DLS测量的两个LNP样品。(The DLS results only label the average particle size results here, as shown by the dotted line in the figure.)

The DLS measurements showed no differences between the two samples (except for PDI), while the nCS1 results showed key differences in the average size, distribution and concentration of the two samples.

图 6 脂质体挤出膜大小对脂质体尺寸的影响。

The same formulation was extruded through a small hole and a large hole. The nCS1 results showed significant differences in the particle size distribution. DLS gave an approximate peak shape, and small differences could not be distinguished.

The 150-nm standard particles added to the sample during nCS1 measurement also verified the measurement results.

For more details, please contact:

Manager Wang Tel: 13020218906 Email: biotech@willnano.com Website: www.willnano.com Suzhou Microfluidic Nanobiotechnology Co., Ltd.

微流纳米Vic