Die Universiteit Stellenbosch se Sentrale Analitiese Fasiliteit (SAF) het 'n korrelatiewe nanobeeld-platform op die been gebring ‒ 'n eerste vir Afrika, met die verkryging van 'n moderne elektronmikroskoop.
Die nuwe Zeiss MERLIN field emission gun scanning elektonmikroskoop kan eienskappe van so klein as 0,6 nanometer in grootte ontleed, asook die chemiese samestelling van delikate glas-, mineraal- en biologiese monsters bepaal.
Die nuwe mikroskoop is gekorreleer met 'n Zeiss superresolusie-laserskanderingsmikroskoop wat onlangs opgegradeer is om bykomende superresolusie-vermoë te verskaf.
Die korrelasie van hierdie twee voorpunttegnologie-mikroskope het die eerste korrelatiewe nanoresolusie-CLEM-platform in Afrika moontlik gemaak, verduidelik me. Lize Engelbrecht, bestuurder van SAF se Eenheid vir Fluoresserende Mikroskopie. (CLEM is die akroniem vir correlative light (laser) and electron microscopy).
For a detailed technical report, read further:
The Zeiss LSM 780 Confocal Microscope with ELYRA PS1 super-resolution platform has been upgraded in 2015 to include, in addition to the existing Super-resolution Structured Illimunation Microscopy (SR-SIM) module, the Photoactivated localisation microscopy/Stochastic optical reconstruction microscopy (PALM/STORM) module. The upgrade included an additional 405 nm (50 mW) diode laser, as well as a 633 nm (150 mW) diode laser and a new Andor EM-CCD camera IXon DU 885 camera for PALM.
While the limit of resolution is reduced from approximately 200 nm to approximately 100 nm with SR-SIM, PALM/STORM improves the resolution even further down to 30 nm. With confocal microscopy one cannot see the layers of a double membrane, while this is possible with SR-SIM. PALM/STORM then enables the researcher to visualise some structural features of the molecules of these membranes. With this new technology, fluorescent molecules are not excited all at the same time, but over a course of a few minutes. This has an effect referred to in the field as "blinking". With ultra-fast imaging, all these excitation events are recorded and the software reconstructs the image by statistically calculating the exact localisation of each fluorescent molecule.
The Carl Zeiss MERLIN high resolution field emission scanning electron microscope (FE SEM) has nano-scale image and micro- and cryo-EDS analytical capabilities. The MERLIN combines ultra-fast analytics and high resolution imaging and is capable of a wide range of beam flexibility, from a voltage of 20V to 30kV and beam currents of 7pA to 40 nA, as well as resolutions of up to 0.6 nanometres at 30kV and 1.6 nanometres at 1kV.
The system is fitted with a number of detectors for imaging, including: an in-lens and chamber secondary (SE) detectors, an in-column energy selective backscattered (ESB) electron detector, a retractable 5 diode backscattered electron detector (BSD), a cathodoluminescence (CL) detector and a scanning transmission electron microscopy (STEM) detector with a resolution of 0.6nm.
Analytical capability is provided by the Oxford Instruments XMax 150mm2 detector for high resolution spectra and high spatial resolution maps using energy dispersive X-ray spectrometry (EDS). Furthermore, the instrument has a Quorum cryostage for micro-quantitative analysis of beam sensitive samples, as well as a facility for local charge compensation (CC) for the analysis of insulating samples.
The second microscope is a Carl Zeiss Axio Petrographic Light Microscope. It is fully correlated with the MERLIN FE SEM by the Carl Zeiss Shuttle & Find correlative microscopy interface for light- and electron microscopes.
