In situ dynamics in the liquid state
Ocean Application Fields
Cell & Cancer Biology
Biochemistry & Nanobiotechnology
Aggregation mechanisms for chemical and biomolecular sensing
20 nm Au nanoparticles were preloaded and real-time aggregation dynamics was observed in STEM mode as a function of pH. H. Su MSc & J. Xu TU Delft, The Netherlands Youku video
Aggregation & fusion mechanisms of polystyrene nanoparticles
Using unstained polystyrene particles suspended in water, imaging of the core-shell structure was recorded showing fusing of the particles from the ebeam interaction. Dr. N. Jose & Dr. C. Ducati Cambridge University, United Kingdom
Easy Sample Preparation
Directly deposit your sample onto the Nano-Cell
A pipette can be used for easy and fast loading of the sample onto the bottom chip of the Nano-Cell. For biological sample preparation, the bottom chip can be placed into a multi-well for cell culturing directly onto the chip.
Creating the liquid environment
within the microscope
The Ocean Nano-Cells are ultra-clean consumable sample carriers, which have electron transparent windows in the centre of the top and bottom chip (forming the Nano-Cell). A range of spacer sizes is available for any experiment and the low mechanical stress of high-quality SiNx makes each Nano-Cell robust.
Modular Sample Holder
Ensure a clean experiment
with a removable tip & tubing
Once the Nano-Cell is placed into self-aligning precision slot within the Sample Holder tip, the O-rings and lid are sealed and the system is ready for vacuum testing. As the tip is removable, the internal liquid tubing can be replaced at any time to avoid clogging / cross-contamination and can be cleaned. For STEM, the tip can be turned 180° to ensure that the sample is on the electron transparent window of the top chip.
The Complete Solution
Including Liquid syringe pump & Vacuum test station
Included in the Ocean system is the syringe pump which allows for a maximum flow rate of 10 ul/min and minimum flow rate of 25 nl/min through the Nano-Cell. Additionally, the vacuum test station ensures that, once the Sample Holder is leak tight, it is ready for inserting into the microscope.
Frequently Asked Questions
How much time does the preparation for an experiment take?
- 5 minutes to load the sample on the Nano-Cell
- 5 minutes to assemble the tip: placing the Nano-Cell and closing off the lid
- 10 minutes to do the leak test
NOTE: This time does not include the sample preparation, which varies from sample to sample. Replacing the inner tubing would normally take around 15 minutes
Which liquids can be used?
Is it necessary to use the syringe pump?
Is it possible to record images of live eukaryotic cells with liquid STEM?
How can you maintain the cell viable in the electron beam and avoid considerable radiation damage?
Can I improve the resolution if I reduce the liquid layer?
What are the advantages of liquid (S)TEM over current ultrahigh-resolution optical methods (i.e. STED, PALM, STORM)?
Is it possible to do correlative microscopy between liquid STEM and other techniques such as fluorescent microscopy?
Correlative fluorescence microcopy and Liquid STEM is possible when using labels containing a fluorescent quantum dot instead of a gold nanoparticle. The quantum dots can also be detected within the background signal produced by the low-Z elements (i.e. water, biological tissue). The concept of labelling is similar to fluorescence microscopy, except for the much higher resolution of the liquid (S)TEM (it can even reach a factor of 50 better resolution).
How to reduce the charging effects caused by the secondary electrons during STEM imaging of biosamples?
When working with a biological sample, the latter can be placed in a solution of H2O and salt (i.e. 100mM NaCl). The salt provides electrical conductance in the liquid to reduce the charging effects. Alternatively, the user can use PBS solution (phosphate-buffered saline) which is a water-based salt solution. PBS has many uses in bio research cause is isotonic (same level of ion concentrations as in the human body) and non-toxic for most cells.
How can one mitigate the effect of thermal gradients and charging on non-conductive liquids?
The flow of liquid (i.e. flows below 1uL/min) can help mitigate the creation of charge and/or temperature gradients that might accumulate while imaging with an electron beam. Similarly, these flows can help minimize the bubble formation. The continuous flow is useful during imaging to remove excess heat, water radiolysis products such as free electrons, hydrogen gas, and radicals from the imaged region.
How to prevent the sample from flowing away from the field of view?
There are some occasions where it is desirable to prevent as much movement of the sample as possible. In order to promote i.e. cell adherence, the silicon nitride of the window can be functionalized with poly-L-lysine. The cells have been experimentally shown to properly adhere to the SiN membrane and without moving in the liquid flow. Additional molecules can be used to functionalize the surface and create chemical bindings that would constrain the sample movement. Furthermore, it has been reported that Brownian motion of the samples in liquid does not hinder the achievement of nanoscale resolution. It has been also reported that the movements of floating NPs in close proximity to a SiN membrane were measured to be nearly three orders of magnitude smaller than what would be expected for NPs floating in a bulk liquid.
Is it possible to tilt the holder?
We do not guarantee any specific tilt with the Ocean S3 system. However, any alpha tilt would depend on the pole piece gap and the position of the objective aperture.
Is it possible to heat or bias the liquid?
At this point, the Ocean Nano-Cell is static and does not contain electrical contacts to allow for heating or biasing. However, stay tuned for more! In some experiments, it’s possible to pre-heat the liquid before introducing to the system.
Download the Ocean brochure
For more information on workflow, applications and specifications.
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