Laser scanning microscope (renewal)

• Subject Area: Basic Research in Biology and Medicine
• Term: since 2026
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 584856522

A multifunctional laser scanning microscope is being upgraded for use in investigating the interaction of nanoparticles with biological matter in the form of proteins and cells. To upgrade the microscope, a request is made to replace three lasers, a control computer, and a scanner. The imaging technique of the laser scanning microscope is used to optically examine samples with dyes or luminescent nanoparticles. For example, processes in cells and their environment are examined over time, particularly the uptake, intracellular distribution, and excretion of nanoparticles, together with the staining of important cellular organelles. Scanning the sample with multiple lasers enables visual representations of complex processes, even within the marked cells. For this purpose, the laser wavelengths are specifically tuned to the markers, such as dyes and semiconductor quantum dots. The device has a permanently installed Ar laser (with lines at 458 nm, 488 nm, and 514 nm), a 633 nm HeNe laser, a 405 nm diode laser, and a 561 nm diode-pumped solid-state laser. Nanoparticles can be functionalized for use in cells with a protein corona. In particular, CdSe quantum dots (488 nm excitation wavelength of the Ar laser), and the dyes fluorescein isothiocyanate (FITC, 488 nm excitation wavelength of the Ar laser), calcein (488 nm excitation wavelength of the Ar laser), Alexa Fluor 594 (561 nm excitation wavelength of the solid-state laser), Nile Red (nominal excitation wavelength 550 nm, 561 nm of the solid-state laser), Rhodamine B (561 nm excitation wavelength of the solid-state laser) and Alexa Fluor 633 (633 nm excitation wavelength of the HeNe laser) are used as markers. Furthermore, fluorescence correlation spectroscopy (FCS) is used to determine, for example, the size of the particles moving through the volume excited by the laser from the temporal course of the fluorescence intensity in a defined sample volume. This is used in particular to investigate the increase in size of nanoparticles due to the formation of a protein corona. The 405 nm line of the diode laser and the 458 nm line of the Ar laser are often used for this purpose. FCS measurements make it possible to characterize the protein corona. To do this, FCS measurements are used to compare different proteins and investigate the influence of their environment. As mentioned, the behavior of the dissociation constants of proteins when the pH value varies is of particular interest. Based on the hydrodynamic reduction diameter, protein degradation by proteases can be investigated using FCS measurements.

• DFG Programme: Major Research Instrumentation
• Major Instrumentation: Laser-Scanning Mikroskop (Erneuerung)
• Instrumentation Group: 5090 Spezialmikroskope
• Applicant Institution: Universität Hamburg
• Leader: Professor Dr. Wolfgang Parak