Karsten König is C4 Full Professor and Head of the Department of Biophotonics and Laser Technologies at the Saarland University, Germany. He is also founder and president of the company JenLab GmbH with facilities in Jena and Saarbruecken.
He gained the PhD degree in physics as well as the habilitation degree in cell biology from the University Jena. Prof. König published about 500 scientific papers (2x Nature) in the field of biophotonics and laser material processing, filed 25 patents, and pioneered fluorescence lifetime imaging, femtosecond laser nanoprocessing, femtosecond laser transfection, and clinical multiphoton tomography.
His work was awarded with the SPIE Prism Award, the Leibinger Innovation Award, the Pascal Rol Award, the Award of the International Society of Skin Pharmacology and Physiology, the Technology for the Human Being Award of the Fraunhofer Society, the Kortum Motivation Prize, the Feulgen Prize, The New Economy Award, and the IAIR Award as European Man of the Year 2014.
His company JenLab sponsors the JenLab Young Investigator Award ($2000) that is presented during the annual Photonics West Conference in San Francisco as well as the Skin Imaging Award ($2000).
Karsten König focuses on biomedical and technical applications of femtosecond laser technology. His current projects include Sub-100nm-Nanomachining with 10 Femtosecond Laser Pulses, Optical Reprogramming by laser transfection, Testing the biosafety of nanoparticles in cosmetic products, and Multiphoton Tomography of astronauts to understand skin ageing effects in space.
He gained the PhD degree in physics as well as the habilitation degree in cell biology from the University Jena. Prof. König published about 500 scientific papers (2x Nature) in the field of biophotonics and laser material processing, filed 25 patents, and pioneered fluorescence lifetime imaging, femtosecond laser nanoprocessing, femtosecond laser transfection, and clinical multiphoton tomography.
His work was awarded with the SPIE Prism Award, the Leibinger Innovation Award, the Pascal Rol Award, the Award of the International Society of Skin Pharmacology and Physiology, the Technology for the Human Being Award of the Fraunhofer Society, the Kortum Motivation Prize, the Feulgen Prize, The New Economy Award, and the IAIR Award as European Man of the Year 2014.
His company JenLab sponsors the JenLab Young Investigator Award ($2000) that is presented during the annual Photonics West Conference in San Francisco as well as the Skin Imaging Award ($2000).
Karsten König focuses on biomedical and technical applications of femtosecond laser technology. His current projects include Sub-100nm-Nanomachining with 10 Femtosecond Laser Pulses, Optical Reprogramming by laser transfection, Testing the biosafety of nanoparticles in cosmetic products, and Multiphoton Tomography of astronauts to understand skin ageing effects in space.
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Here, we report on the use of an ultracompact femtosecond fiber laser for high-resolution tissue imaging. In particular, the development of the PRISM AWARD 2024 winning multimodal multiphoton tomograph based on an ultracompact air-cooled 50/80 MHz fiber laser operating at 780 nm is presented. The 18x9x3.5 cm3 laser head, consisting of a pulse compression unit and a SHG crystal, is positioned inside the 360° imaging head. An optical arm or a fiber delivery for transmitting the ultrashort near-infrared laser beam is no longer required. Interestingly, the femtosecond laser pulses, used for two-photon autofluorescence and SHG imaging, are also employed to realize simultaneous high-resolution (submicron) one-photon confocal microscopy. In addition, optical metabolic imaging (OMI) by time-correlated single photon counting and fluorescence lifetime imaging (FLIM) of autofluorescent coenzymes can be performed. The fifth imaging modality of this multimodal device is white LED far-field imaging for dermoscopy and to define regions of interest for confocal and multiphoton analysis.
The novel “green” 230 W femtosecond fiber laser tomograph can be operated by batteries and charged by sunlight due to the reduced power consumption by 75 % when using the fiber laser system compared to the tunable titanium:sapphire laser. High-resolution confocal and multiphoton imaging with compact fiber lasers in remote areas and on the bedside of the patient becomes a reality.
Flexible solar panels connected via an Anderson power plug have been employed to recharge the system without removing batteries from the medical cart. Applications of this autonomous operating tomograph are high-resolution skin imaging to obtain optical biopsies directly at the patient’s location, including remote areas and on battlefields. Furthermore, on-site in vivo deep tissue multimodal imaging (autofluorescence, SHG, FLIM, confocal reflectance), e.g., on trees, algae, plants, and animals, is possible.
JBO guest editors introduce the Special Section Celebrating Thirty Years of Multiphoton Microscopy in the Biomedical Sciences.
Two-photon microscopes have been successfully translated into clinical imaging tools to obtain high-resolution optical biopsies for
In this study, we investigate ACXL-induced changes to the cornea autofluorescence (AF) using MPT. ACXL was performed in de-epithelialized corneal donor buttons and keratoconus corneas by infusing the samples with 0.1% riboflavin solution followed by UVA irradiation using either an in-house adapted system or a commercial ACXL system. AF lifetime images of the tissue were acquired prior and after treatment using MPT. As a control, corneas without treatment were monitored at the same time points.
Higher AF lifetimes were observed in the stroma of treated corneas than in control samples. The stroma AF lifetime was higher anteriorly, corresponding to the area where ACXL was most effective. First changes were observed as soon as 2 ℎ after treatment. We demonstrate that MPT can be used to follow-up the outcome of ACXL and that ACXL-induced changes can be detected sooner than with conventional methods and non-invasively.
Subsurface photoluminescence lifetime imaging of photovoltaic materials using multiphoton tomography
The reprogramming of somatic cells into induced pluripotent stem (iPS) cells can be evoked through the ectopic expression of defined transcription factors. Conventional approaches utilize retro/lenti-viruses to deliver genes/transcription factors as well as to facilitate the integration of transcription factors into that of the host genome. However, the use of viruses may result in insertional mutations caused by the random integration of genes and as a result, this may limit the use within clinical applications due to the risk of the formation of cancer. In this study, a new approach is demonstrated in realizing non-viral reprogramming through the use of ultrashort laser pulses, to introduce transcription factors into the cell so as to generate iPS cells.
Samples were imaged using a laser-scanning microscope, consisting of a broadband sub-15 femtosecond (fs) near-infrared laser. Signal detection was performed using a 16-channel photomultiplier tube (PMT) detector (PML-16PMT). Therefore, spectral analysis of the fluorescence lifetime data was possible. To ensure a correct spectral analysis of the autofluorescence lifetime data, the spectra of the individual endogenous fluorophores were acquired with the 16-channel PMT and with a spectrometer. All experiments were performed within 12h of the porcine eye enucleation.
We were able to image the cornea, crystalline lens, and retina at multiple depths. Discrimination of each structure based on their autofluorescence intensity and lifetimes was possible. Furthermore, discrimination between different layers of the same structure was also possible. To the best of our knowledge, this was the first time that 2PE-FLIM was used for porcine lens imaging and layer discrimination. With this study we further demonstrated the feasibility of 2PE-FLIM to image and differentiate three of the main components of the eye and its potential as an ophthalmologic technique.
Measurements on the hydration, the transepidermal water loss, the surface structure, elasticity and the tissue density by ultrasound are conducted. Furthermore, high-resolution in vivo histology is performed by multiphoton tomography with 300 nm spatial and 200 ps temporal resolution. The mobile certified medical tomograph with a flexible 360° scan head attached to a mechano-optical arm is employed to measure two-photon autofluorescence and SHG in the volar forearm of the astronauts. Modification of the tissue architecture and of the fluorescent biomolecules NAD(P)H, keratin, melanin and elastin are detected as well as of SHG-active collagen. Thinning of the vital epidermis, a decrease of the autofluoresence intensity, an increase in the long fluorescence lifetime, and a reduced skin ageing index SAAID based on an increased collagen level in the upper dermis have been found. Current studies focus on recovery effects.
Femtosecond laser-induced cell death is beneficial due to the reduced collateral side effects and therefore can be used to selectively destroy target cells within monolayers, as well as within 3D tissues, all the while preserving cells of interest. This is an important characteristic for the application in stem cell research and cancer treatment. Non-precise damage compromises the viability of neighboring cells by inducing side effects such as stress to the cells surrounding the target due to the changes in the microenvironment, resulting from both the laser and laser-exposed cells.
In this study, optimum laser parameters for optical cleaning by isolating single cells and cell colonies are exploited through the use of automated software control. Physiological equilibrium and cellular responses to the laser induced damages are also investigated. Cell death dependence on laser focus, determination and selectivity of intensity/dosage, controllable damage and cell recovery mechanisms are discussed.
Fluorescence correlation spectroscopy on dielectric surfaces in total internal reflection geometries
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Multiphoton Tomography based on two-photon fluorescence and second harmonic generation is a novel non-invasive method to obtain label-free optical tissue biopsies within seconds and with submicron resolution. The course provides deep insight into the basic mechanisms and performance of multiphoton tomographs as medical instruments. Expansion with CARS, FLIM, and OCT modules as well as applications in the field of cancer and stem cell detection, small animal imaging, and intratissue drug tracing (e.g. sunscreen nanoparticles) will also be discussed.
Hands-on tissue studies will be demonstrated with a multiphoton tomograph.
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