Lasers in live cell microscopy
Herbert Schneckenburger
Aalen University, Germany
: Res J Opt Photonics
Abstract
Due to their unique properties-coherent radiation, diffraction limited focusing, low spectral bandwidth and in many cases short light pulses-lasers play an increasing role in live cell microscopy [1]. Lasers are indispensable tools in 3D microscopy, e.g. confocal laser scanning (CLSM) or light sheet microscopy (LSFM), when images are recorded plane by plane, and resulting 3D plots are calculated subsequently. Here, a miniaturized module for LSFM of 3-dimensional cell cultures is presented, which is easily adapted to any inverted microscope, and which is a versatile and low-cost alternative to commercial light sheet microscopes [2]. Different types of sample holders for LSFM have been developed, including rotatable micro-capillaries [3] or micro-wells on object slides after additive manufacturing [4]. Laser-assisted imaging techniques also include super-resolution microscopy with a resolution below the Abbe-criterion using e.g. structured illumination (SIM) techniques. Thus, by a combination of Total Internal Reflection Fluorescence Microscopy (TIRFM) and SIM, we attained axial and lateral resolutions below 100 nm and applied them to detect membrane proximal fluorophores with very high precision [5]. Additional information on cellular location of metabolites as well as on molecular interactions is obtained from spectral or fluorescence lifetime imaging (FLIM) techniques. In particular, Förster Resonance Energy Transfer (FRET) in the nanometer range from a donor to an acceptor molecule appears important to probe intra- as well as intermolecular interactions [6]. Fluorescence spectra and lifetimes (in the nanosecond range) have proven to be important parameters in 2D as well as in 3D cell systems. Furthermore, axial tomography permits to observe 3D samples from variable sides and to attain a combination of angular views with isotropic resolution [3]. In addition to live cell imaging, lasers can be used for micromanipulation, e.g. for optical tweezers or laser-assisted optoporation [7].
Biography
Herbert Schneckenburger is a professor of Physics and Biomedical Optics at Aalen University and a private lecturer of the Medical Faculty of the University of Ulm. He received his PhD in Physics from the University of Stuttgart in 1979 and his habilitation in Biomedical Technology from the University of Ulm in 1992. His research is focused on cell biology, optical microscopy and time-resolved laser spectroscopy, where he published almost 300 scientific articles, received 6 patents, managed and pursued 36 projects with third-party funding. As a Senior Professor since 2019 he is still an active researcher and international expert in his field.
