The size, charge (zeta-potential) and concentration of nanoparticles is critical as these properties

directly affect their material properties as well as colloidal behaviour and stability. In particular, particle size, charge and concentration is important to developing safe and efficient nanomedicine formulations. Izon Science has developed the qNano, the first commercially available system that can accurately and simultaneously measure the size, surface charge and concentration of nano- and micro- particles.

Izon instruments are based on a high resolution particle-by-particle analysis technique, known as Tunable Resistive Pulse Sensing (TRPS). This technique provides a more detailed sample analysis, which can reveal features hidden by other, lower resolution, techniques such as dynamic light scattering (DLS).

The new analysis capabilities provided by the Izon instruments opens up new possibilities in studying and better understanding nanomaterials and nanomedicines which will improve Scientists ability to develop more effective nano-scale materials, diagnostics, and therapeutics.

Click Here to watch a video of how TRPS works 

TRPS using qNano: a breakthrough technique for particle characterization

Izon’s TRPS technique is unique in that it accurately and simultaneously determines the size, ζ-potential, and concentration (particles/mL) of particles from the resistive pulse signal each particle generates as it passes through a nanopore (See Figure 1).

Figure 1. Particle-by-particle determinaiton of Charge and Size with the qNano system, using the Tunable Resistive Pulse Sensing (TRPS) technique. Each particle generates a transient disruption in current flow as it passes through a nanopore in the qNano instrument (A). Size and charge data for each particle can be determined based on the magnitude and duration of current disruption, respectively (B).

As the properties of hundreds to thousands of individual particles can be easily and rapidly measured an accurate, high resolution, view of the sample is generated. This type of analysis provides a unique and previously unavailable level of detailed information to researchers who seek to understand how these properties affect their particle formulations, or want to characterize changes in their particles or even identify specific particle types within a bulk suspension. The novel ability to measure and use size and charge as means to identify different particles is illustrated in Figures 2 & 3.

This level of particle analysis detail is particularly important to the field of drug delivery where the physical properties of particles (size, charge and concentration) have been shown to affect their circulation time, toxicity, local accumulation, uptake by cells, release of drugs and even therapeutic efficacy of nanomediciens.

An example, of TRPS analysis for nanomedicine is the ability to measure the size and charge profile of PEGylated and unPEGYlated liposomes (Figure 2), which are often used as nano-scale drug delivery vehicles.

Figure 2: Particle size of individual particles along with charge analysis of PEGylated and non-PEGylated sample shown using TRPS technique. The charge of individual liposome and the PEGylated liposome particles are shown in the 2D dot plot.

Figure 3: Simultaneous size and charge measurement of a trimodal analyte sample containing 200, 240 and 350 nm particles, which had corresponding zeta-potentials of -35, -8 and -20 mV. The dot plot shows the properties of the individual nanoparticles and the histograms show their distribution.

Applications of detailed particle analysis with TRPS 

TRPS dramatically improves the way in which scientists measure nanoscale materials. The unique analysis capabilities of Izon’s qNano system can be applied to a wide range of particle systems, as shown in the table below. In general, any synthetic or biological between 50 and 20,000 nm in size can be measured using the Izon qNano.

Table 1. TRPS has a wide range of applications in nanomedicine, haemotology, diagnostics, microbiology and material science.

Summary

TRPS provides a unique high-resolution view of the physical properties of nano- and micro particle samples, with the following advantages:

• High resolution, particle-by-particle detail provides representative information on complex particle systems, not possible with bulk analysis techniques like DLS;
• Size, charge and concentration (particles/mL) of 50nm – 10 micron size particles simultaneously determined;
• Ability to monitor and understand particle aggregation and stability;
• Quantify functionalization reactions during particle production and development;
• Measurement under physiologically-relevant conditions (molarities, pH, etc.);
• Wide range of applications in nanomedicine, extracellular vesicle analysis, virus analysis;
• Real time analysis (thousands of particles), with total set-up and measurement time approximately 10-15 minutes per sample.

About Izon Science

Izon Science, based in Christcurch, New Zealand, designs and manufactures precision instrumentation for nano- and micro-scale particle analysis. Izon originated in New Zealand and now sells its products in 34 countries. It has its European headquarters in Oxford, UK and its US headquarters are in Cambridge, MA. www.izon.com