Simple internal reflection microscopy system designed to meet budget limitations without compromising sensitivity or image quality, with optical sectioning performance of around 100nm
Many of the key events in the cell occur in close proximity to membrane surfaces or at the surface of the cell.
Any optical technique that can visualise these events without interference from the underlying regions within the cell or cellular structure will increase the amount and quality of information collected. With the launch of Sirf (simple internal reflection fluorescence), Zeiss is offering individual scientists a total reflection microscope based exclusively on standard HBO/XBO light sources rather than lasers.
Designed specially to meet budget limitations without compromising sensitivity or image quality, the system boasts optical sectioning performance of the order of 100nm.
Because there are no interfering fluorescence signals from other layers of the specimen, the Sirf image is very rich in contrast.
Applications include the selective visualisation of cell/substrate contact regions, tracking secretion in living cells, measuring the binding rates of cell surface receptors, the examination of submicroscopic morphology, and single molecule experiments on molecular motors.
By selectively exciting cellular fluorophores adsorbed, adhered, or bound to the surface and combining it with conventional epi-fluorescence, researchers can relate surface effects to internal cellular structures. "Sirf is a revolutionary development that dramatically simplifies the microscope set-up required to undertake cell surface and membrane studies," says Aubrey Lambert, marketing manager at Carl Zeiss UK.
"This will significantly increase the number of scientists and laboratories able to take advantage of total reflection microscopy and continues our strategy of providing complete systems for microscopists of all levels.
"What's more, the Sirf slider is retrofittable to existing Axioplan 2 imaging and Axiovert 200 microscopes and has a free aperture for conventional fluorescence illumination. "Changing between Sirf and normal epi-florescence is as simple as moving the slider".
In total reflection microscopy, also called evanescent wave microscopy, a beam of light set at the critical angle illuminates the sample.
At this angle, the excitation light is not transmitted by the specimen but totally reflected by the interface between the cover slip and the aqueous medium.
For Sirf microscopy, a Sirf slider is simply inserted into the microscope and adjusted so that only a ring-shaped area of the exit pupil of the alpha Plan Fluar 100x/1.45 oil objective is illuminated.
This ensures that the light leaving the objective strikes the specimen at the critical angle of total reflection.
Zeiss already has a Tirf microscopy system that is also based on the highly successful 'slider' approach pioneered by the award winning ApoTome contrast enhancement system.
In adopting the same principle, the Sirf slider guarantees reproducible alignment, compatibility with existing options and modules, and successful observations.
The Sirf system comprises an Axioplan 2 imaging or Axiovert 200 with epi-fluorescence, the Sirf slider and an alpha Plan Fluar 100x/1.45 oil immersion objective.
