A major focus of the cell biological work concerns the interaction of cells with light. Here, research is mainly focused on photochemical processes, such as the mode of action of photosensitizers for photodynamic therapy (PDT) (1) (2), as well as photomechanical processes, such as the manipulation of cells by pulsed lasers. In addition, the ILM's biology working group is also dealing with the establishment and validation of test systems for different issues that are dealt with in publicly funded projects or as research contracts with industry (3). Of particular interest here is the provision of cell models for the evaluation of drugs and of nanocarriers for precision therapy. Current work focuses on the optimization of nanocarriers for tissue replacement (4) and cancer medicine (5). Through a collaboration with the German Cancer Research Center, access to genetically engineered tumor cells with switchable expression of cell surface proteins exists, which can function as potential receptors of surface-functionalized nanocarriers  (6) (7). The institute has access to modern imaging methods (e.g. confocal laser scanning microscopy, confocal Raman microscopy, scattered light microscopy) as well as the possibility of developing tailor-made analysis concepts within the framework of interdisciplinary funding projects.

For high-throughput analyses, a microplate reader is available for measuring absorbance, fluorescence and luminescence as well as the possibility of reagent injection.  The reader can be used in continuous measurement procedures and endpoint measurements and is currently mainly used for biochemical (e.g. enzyme kinetics) and cell biological assays (3).

Flow cytometry is a method for the rapid and quantitative optical analysis of cell suspensions, e.g. with regard to their vitality, the expression of selected proteins, or the uptake of photosensitizers. The ILM has a state-of-the-art cytometer with 3 lasers and 8 optical parameters as well as well-founded expertise and protocols for the comprehensive characterisation of cell populations from cell cultures (2D, 3D) and CAM transplants.

The chorioallantoic membrane (CAM) of the fertilized chicken egg provides an extraembryonic, vascularized and immunodeficient test environment for the characterization of transplants with respect to their ability to initiate invasive growth or the formation of new blood vessels. The ILM has long-standing expertise in the use of CAM for issues relating to PDT, the evaluation of drug carriers and drugs, and functional genomics (8) (7) (5). The processing and analysis of transplants is carried out using histological / (immune) histochemical methods, ex vivo microscopy or flow cytometry.

Histology is used for the analysis of tissue samples, e.g. to evaluate changes caused by laser radiation, or to characterize grafts in the CAM animal experiment replacement model. The spectrum of established techniques includes different staining (H&E, azan etc.) in soft tissue histology (paraffin and frozen sections) and hard tissue histology (thin sections).

Immunostaining for the characterization of tissue sections and cell cultures in situ is used e.g. for the semi-quantitative analysis of tissue samples from the CAM animal experiment replacement model, or for multicolor fluorescence microscopy in the context of cell biological questions.

The ILM has equipment and expertise for the application of standard molecular biological techniques for the characterisation of cell cultures and tissues on the DNA, RNA and protein level. In addition, common cloning techniques and methods for the production of recombinant mammalian cell lines have been established (6).

Protocols for the cultivation of different model organisms exist for microbiological investigations. In addition to gram-negative Escherichia coli (K12), which are also used for genetic engineering, these are gram-positive Staphylococcus warneri and the likewise gram-positive spore formers Bacillus subtilits.