NanoSight Sample Assistant – Q&A

The Sample Assistant can analyze up to 96 samples in one experiment. Repeat measures of each of these samples can be done underflow (or static if desired) for durations as long as the limit of the standard software. In practice, 96 samples measured with three 60-second repeats takes 15 hours including data processing and export.

Our application note on the Sample Assistant speaks directly to stability over the course of a plate, including exosome examples. On the question of exosome sample stability, we have an application note on the experiments each user would have to do with their specific samples and buffers. Our beta testers have been running huge numbers of exosome samples after characterizing whether their samples were stable or not. Some did require changes to buffer or washing the plates first. It’s working very well in beta testing.

Only one wash buffer is possible. Adding second diluent/buffer solutions, and the necessary mechanical parts would have increased cost and complication to the project. It is something we would consider for future developments.

The data can be exported in the same formats as standard NanoSight analyses. This includes .pdf reports with graphs and .csv spreadsheet files.

For samples that might sediment or segregate, there is an option to mix the sample before introduction. The transfer pump withdraws and dispenses back into the sample well several times before transferring to the instrument. This has been tested with a range of materials including metal nanoparticles and is very effective.

A single (standard) wash cycle takes approximately two minutes and uses approximately 2ml of system liquid to clean the sample chamber. Additional cycles can be programmed into the method. Data in our application note shows this wash cycle to be completely effective (no carryover) for the test samples.

The Sample Assistant includes temperature control of the sample tray. While it has a broad operating range, for many diluents we can’t keep the samples more than a few degrees below ambient to avoid degassing due to warming in the tubing and instrument. If you need cooler than that, the entire system would need to be placed in a cooled chamber.

The focal plane doesn’t change depending on particle size of the sample, so we prefer to use the 100nm latex particles which are in an ideal range of intensity and diffusion rate. This makes the automatic focusing more reliable and faster. If there was some reason to use other size latex particles or other materials, the autofocus would still work just fine. One could also manually focus before the sample sequence was initiated, which would remain valid unless there was some drift in the ideal focus.

The Camera Level can be set for each experiment or Auto Camera Level can be used for unknown samples. Best practice would be to test samples with conditions that are optimized through an understanding of the best conditions for that sample type.

This was an indication of sample instability. The Sample Assistant is very useful for time studies like this to characterize the sample but this also highlights the studies that need to be done on samples to ensure they are suitable.

The Sample Assistant uses a specific version of NTA software, with NTA 3.3 being the initial release.

The Sample Assistant uses the same sample chamber and flow path as the manual NS300 system so doesn’t clear a bubble any differently. However, bubbles essentially never get in the system because we have eliminated those points at which bubbles can be introduced to the system. A great deal of development and testing has focused on this issue. From using it extensively and working with our beta test sites here, the system is very reliable in this regard.

The sample assistant is designed to work with the automated NS300 and NS500 models only.

Most of Malvern Panalytical’s instruments have automation options. The Nanosampler is suitable for the Zetasizer and is very similar to the Sample Assistant shown in the webinar. There is also the APS instrument which is DLS measurement like the Zetasizer with a 96 well plate sample loader.