Confocal Microscope

SLU is performing many live imaging experiments where there is a need to image deep into plants, which has been a big challenge. Multi-photon imaging is not a solution as pigments such as chlorophyll absorbs the light around 880-940 nm needed for excitation, causing overheating and eventually the plant cells bursts. The absorption of light by pigments also leads to a lack of light needed for excitation and hence a worse image compared to normal confocal microscopy.

Therefore, SLU have the intention to buy 2 confocal microscopes from Zeiss, model 1: LSM 880 with Airyscan mounted on an inverted microscope and model 2: LSM 800 with Airyscan mounted on an upright microscope and through this advertisement, SLU is asking the market if other supplier can offer similar features as the Zeiss model LSM 880 with Airyscan and Zeiss model LSM 800 with Airyscan.

SLU intends to buy 2 confocal microscope from Zeiss:

1) Zeiss LSM 880 with Airyscan (incl. fast module) and PicoQuant FLIM/FCS module mounted on an inverted microscope;

2) Zeiss LSM 800 with Airyscan mounted on an upright microscope.

SLU announces its intention and takes into account a standstill period of 10 days from the date of publication.

Förklaring:

The main reason for this choice in confocal is to solve the issue of depth penetration in plants, which is something SLU cannot do with current systems. The reason why SLU want to look deeper into live plants is to study wood formation which is the innermost plant tissue, how fungi (mycorrhiza) colonize plant roots in depth, how young plants exposed to light open their apical hook, how pavement cells of leaves get their puzzle-like shape and other dynamic processes in both Arabidopsis and the tree hybrid Aspen, processes which so far SLU cannot analyze in real-time in live material. Most of these studies needs an inverted microscope as the mounting otherwise become extremely complicated, however the study of leaves needs to be done in an upright microscope to mimic live conditions and avoid steric hindrances during imaging. Taken together SLU hence needs an upright and an inverted confocal microscope system that allows imaging deep into thick samples as Airyscan does. As Zeiss has a patent on Airyscan, no other company (known for SLU) can provide SLU with this so vital function for imaging at SLU. See more information under V I.3 "Additional Information"

Upon practical testing, SLU realized that Zeiss LSM 880 and LSM 800 both with Airyscan makes it possible to do deep imaging into plant tissues. This is due to the unique design of the Airyscan unit where the Airy pattern of light from the sample is projected onto a concentrically-arranged hexagonal detector array with 32 single detector elements as opposed to standard confocal where only one detector is used for imaging then losing the airy pattern information. The ability to readout an extended part of the Airy pattern makes the method of imaging more sensitive and also allows deeper imaging with enough signal intensity to see something. In a standard confocal microscope almost all light is lost during the travelling through the thick sample.

In addition, SLU has a need to do long-time imaging both from the top with an upright confocal microscope and from the bottom with an inverted microscope, in both cases SLU has problems with depth penetration.

SLU tested the hexagonally shaped concentrically-arranged 32 channel GaAsP detection system from Zeiss called Airyscan, which is part of the Zeiss LSM880 system. Airyscan is supposed to increase sensitivity by taking more orders of light from the Airy pattern into account by the 32 separate detectors in contrast to standard confocal that only use one detector for each Airy pattern. What SLU did not know prior to testing was however the improvement in depth imaging that Airyscan provides. SLU could image deeper into plant material with improved contrast and resolution, this most likely due to the features of Airyscan in picking up and separating light from more than the 0th order of light in the point spread function. This improved imaging in the deep tissues was also possible at areas where chlorophyll is present (shoot parts of the plant) with minimal effects of bleaching of the fluorophores or damage to the plants in contrast to multi-photon that killed the plant cells. Hence, Airyscan is the solution to our challenge in reaching further into the plant tissues with confocal imaging techniques needed for live imaging.

The other big part SLU plan to include in the confocal package is PicoQuant fluorescence lifetime imaging and fluorescence correlation spectroscopy microscopy. Several companies can offer FLIM and FCS comparable to the system Zeiss can offer or even better, however, not in the same system as the unique Airyscan detector.

Visma notice: https://opic.com/id/afdibkkwec