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NPL to Evaluate NanoSight's Nanoparticle Tracking Analysis

Published on March 12, 2009 at 6:14 AM

The UK's national metrology institute, the National Physical Laboratory (NPL), is commencing a one-year evaluation program of NanoSight's nanoparticle characterization technology, Nanoparticle Tracking Analysis (NTA).

The program takes the form of a Joint Industry Project, funded in part by government. The initial objective is a validation of NTA and comparison with existing nanoparticle sizing techniques and standards.

Dr Alex Cuenat, NPL’s Nanomaterials Group Leader, reports: “What differentiates NanoSight from existing light scattering techniques is that it provides a direct view of the sample under analysis and rapid quantitative estimation of the sample size, size distribution and concentration.

“No method is truly universal. Most ensemble measurements are made using dynamic light scattering (DLS) or photon correlation spectroscopy (PCS). These methods are very fast with thousands of particles analysed in a single second but they cannot accurately analyze multi-modal (more than one size) dispersions or follow changes during analysis.

“NanoSight’s Nanoparticle Tracking Analysis (NTA) differs in that it measures particle speed compared to DLS which is measuring intensity of light scattered. This unique real-time capability to follow the Brownian motion of individual nano-particles, leads to advantages over DLS. These include avoidance of a bias towards larger particles, which is driven by the latter’s dependence on scatter intensity; an estimate of concentration which NanoSight provides; and a unique image validating the results and providing additional insight.

“We first saw a NanoSight prototype in 2005 and recognised how, with development, the technique had potential to fill gaps in characterization methodologies of sub-micron dispersions. Since then, we have seen this technique develop well, so, although we do not know yet how this will result, we are enthusiastic about running an in-depth validation. This investigation will look at precision and accuracy and assess the validity of the algorithms used in NTA in some depth.”

Dr Patrick Hole, Development Manager at NanoSight comments: “During the past four years, we have seen nanoparticle size and size distribution at the top of the list of characterization requirements for those assessing the toxicology of engineered nanoparticles. We are already working with a number of researchers in this field. Before accepting NTA, they will usually compare NanoSight to DLS/PCS or electron microscopy to see what additional information can be obtained on their own samples.

“With more than 150 users worldwide, we have seen many successful comparative tests, but in this project with NPL, we have third party scrutiny from an internationally respected expert group. Consequently, this project is a significant step towards gaining technical acceptance, as well as a chance for us to improve NTA with expert input from Dr Cuenat’s team.”

One such advocate of the technique is Professor Kenneth Dawson, at UCD in Ireland who states: “We have evaluated NanoSight for evaluating nanoparticle dispersions for nanosafety and find it uniquely useful in assessing dispersion quality. The rigorous approach taken by NPL in verification of this will be very welcome.”

Another NanoSight user, Dr Rob Aitken, Director of SAFENANO says: “Improved characterization in the field of nanotoxicology is a critical requirement, and NanoSight has demonstrated significant potential in filling the gaps not covered by other techniques”.

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