I am excited that the Sample Assistant autosampler for the NanoSight NS300 was recently launched as we are get increasing numbers of requests for automated NTA analyses. The full launch webinar is available showing the system in operation and the user interfaces.
Having worked with several of the beta test sites, I can see how valuable this accessory will be in the field. Many of our users are testing increasing numbers of samples, some to the point where a person is essentially full time testing samples on the NanoSight system. On one hand, it is encouraging to see how critical NTA data has become in different fields. On the other, I understand the desire to find something more engaging than full days in front of an instrument.
The greatest value is freeing researchers from a tedious day on the bench and allowing them to turn their attention to more valuable endeavors. A 96-well plate only requires approximately 30 minutes interfacing with the software after samples are prepped and loaded in the tray. After clicking Run, walk away until it is time to review the data. I wish we could quote some of the enthusiastic responses we have received on this so far.
A further benefit of automatic measurements is improved reproducibility since operator-dependent variability is reduced to essentially zero. Once the experiment conditions are determined, all tests will be completed in exactly the same way. We have seen some significant improvements in data quality without changing any testing parameters, just substituting the Sample Assistant for manual operation.
As with any new system, new users should test the system with their particular samples to see if any adjustments to procedures need to be made. Even with sample cooling, samples do sit in the plates for several hours so long-term stability should be tested. In some cases, we have seen different plates affect stability but this might be solved with a quick wash with a solution that treated the plate surfaces in some way. Malvern’s technical team are available to advise on this process as always.
Anybody looking for higher throughput or to improve data quality on even smaller sample numbers should consider the Sample Assistant. Have a look at the webinar and please contact us with any further questions.
Thank you for your participation!
Following are a few of the questions from the recent webinar, reproduced here for some additional information:
Q: How long does typical analysis take per sample? How many replicates/duration is used?
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.
Q: Would 96 exosome samples will be stable in solution for the duration of analysis?
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.
Q: Is it possible to use more than one wash buffer?
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.
Q: What is the format/extension of the result excel file ? .xls ? .csv ?
The data can be exported in the same formats as standard NanoSight analyses. This includes .pdf reports with graphs and .csv spreadsheet files.
Q: Is it possible to include a mixing protocol in the SOP in order to ensure homogeneity and avoid aggregation in the bottom of the well?
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.
Q: 10 minutes including wash cycles? how long it takes to flush between samples?
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.
Q: Can the sample temperature be controlled in the autosampler?
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.
Q: While autofocus is working well with beads or other material with a high refractive index, it can be more tricky with complex matrices like diluted biofluids to detect the smallest particles. What is the strategy there? Do you use manual focusing?
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.
Q: Is camera level pre-set before the analysis? For biological samples the settings are quite different from standards and significant noise from larger particles may cause small ones to be poorly tracked.
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.
Q: On the slide for liposomes at high dilution. There is like an increase of size as a function of well plate number for buffer 2. Did you have an explanation for that?
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.
Q: Does this work with v3.2 software or is there a different s/w platform?
The Sample Assistant uses a specific version of NTA software, with NTA 3.3 being the initial release.
Q: How is the risk of air bubble introduction managed?
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.
Q: Is it compatible with NS500/LM10?
The sample assistant is designed to work with the automated NS300 and NS500 models only.
Q: Is this compatible with older instruments such as the Nano-ZS?
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.
Previous blogs and related content:
Basic Principles of Nanoparticle Tracking Analysis – Q&A
- Lessons learned from NTA interlaboratory comparison
- NanoSight unique contributions to today’s hottest research fields
- Adeno-Associated Virus titer and aggregation characterization
- Measuring Exosome Stability with Nanoparticle Tracking Analysis
- Use of NanoSight Sample Assistant to increase throughput and reproducibility in the physical characterization of exosomes