Vertico spatially modulated illumination

3D dual colour super resolution microscopy with Her2 and Her3 in breast cancer cells, standard dyes: Alexa 488, Alexa 568 - LIMON (SPDM +SMI

A particularity of this technology compared with focusing techniques such as 4Pi microscopy, is the wide field exposures which allow entire cells to be depicted at the nano scale. Such a 3D exposure of a whole cell with a typical object size of 20 µm × 20 µm require only 2 minutes. Wide field exposures signify that the entire object is illuminated and detected simultaneously.

The structural resolution achievable using SPDM can be expressed in terms of the smallest measurable distance between two in their spatial position determined punctiform particle of different spectral characteristics ("topological resolution"). Modeling has shown that under suitable conditions regarding the precision of localization, particle density etc., the "topological resolution" corresponds to a "space frequency" which in terms of the classical definition is equivalent to a much improved optical resolution.

Dual color localization microscopy SPDMphymod/super resolution microscopy with GFP & RFP fusion proteins

Only in the past two years have molecules been used in nanoscopic studies which emit the same spectral light frequency (but with different spectral signatures based on the flashing characteristics) but which can be switched on and off by means of light as is necessary for spectral precision distance microscopy. By combining many thousands of images of the same cell, it was possible using laser optical precision measurements to record localization images with significantly improved optical resolution. The application of these novel nanoscopy processes appeared until recently very difficult because it was assumed that only specially manufactured molecules could be switched on and off in a suitable manner by using light.

Standard fluorescent dyes already successfully used with the SPDMphymod technology: GFP, RFP, YFP, Alexa 488, Alexa 568, Alexa 647, Cy2, Cy3, Atto 488 and fluorescein.

LIMON (Light MicrOscopical nanosizing microscopy) was invented in 2001 at the University of Heidelberg and combines localization microscopy and spatially modulated illumination to the 3D super resolution microscopy.

The 3D images using Vertico-SMI are made possible by the combination of SMI and SPDM, whereby first the SMI and then the SPDM process is applied. The SMI process determines the center of particles and their spread in the direction of the microscope axis. While the center of particles/molecules can be determined with a 1-2 nm precision, the spread around this point can be determined down to an axial diameter of approx. 30-40 nm.

Despite its use in biomedical labs, super resolution technologies could serve as important tools in pharmaceutical research. They could be especially helpful in the identification and valuation of targets. For example, biomolecular machines (BMM) are highly complex nanostructures consisting of several large molecules and which are responsible for basic functions in the body cells. Depending on their functional status, they have a defined 3D structure. Examples of biomolecular machines are nucleosomes which enable the DNA, a two meter long carrier of genetic information, to fold in the body cells in a space of a few millionth of a millimeter in diameter only. Therefore, the DNA can serve as an information and control center.