Spotlight – Drug Delivery Efficacy and Free Radical Processes in Skin

photograph of martina menke

Prof. Dr. rer. nat. Martina Meinke
Charité – Universitätsmedizin Berlin
Department of Dermatology, Venerology and Allergology
Center of Experimental and Applied Cutaneous Physiology
Berlin, Germany
Tel: +030 450 518 244

The Medical Physics Group focuses on utilizing electron paramagnetic resonance (EPR) spectroscopy to study skin and skin cells. The group, headed by Prof. Dr. Martina Meinke, has three main research areas: 1) the research on drug delivery with spin labelled drugs using the shape of the EPR spectra to get information about polarity and viscosity of the microenvironment of the drug combined with spin quantification calculating the drug penetration efficiency; 2) measurement of formed radicals due to oxidative stress and radical scavenging activity of the skin and skin cells using spin probes; and 3) the determination of the formed radicals using spin traps.

The group is part of the Center of Experimental and Applied Cutaneous Physiology (CCP), headed by Prof. Dr. Jürgen Lademann. In combination with available optical systems of the CCP, such as in vivo multiphoton and laser scanning microscopic as well as in vivo Raman spectroscopic and microspectroscopic imaging, intercellular and follicular penetration of topically applied substances can be investigated, including those loaded into nanocarriers. We use EPR to monitor the release of drugs loaded into the nanoparticles as well as changes in the microenvironment of the drug, such as polarity and rotational correlation time. For these investigations multifrequency EPR investigations are necessary, and are realized by a cooperation we have with the Physics Department of Freie Universität Berlin. The combination of spectroscopic and microscopic methods provides us with deep insight into the penetration behavior of substances/drugs and also of the carrier system itself. Thus, penetration mechanisms can be elucidated in more detail, which helps improve the application of therapies for skin diseases.

We also use EPR for the measurement of oxidative stress along with possible biological and clinical consequences. Specifically, these techniques involve the use of spin probes to quantify and characterize formed radicals. Our resonant Raman spectroscopy capabilities help us determine, non-invasively, the level of cutaneous carotenoids as a markers of nutrition, lifestyle, and stress. These methods—combined with in vivo analysis of the collagen and elastin index in human skin by two photon microscopy, and a general analysis of the skin surface structure—provide good insight into different anti-aging strategies, like topical application of antiaging creams, sunscreens, or the oral intake of supplements rich in antioxidants.

In order to grasp the complexity of the skin, in vivo investigations are complemented by studies on skin biopsies (ex vivo) of different species (murine, porcine, and human skin). To understand the interaction between skin parameters and signaling pathways and cascades, secondary (HaCaT cells) or primary keratinocytes (isolated from fresh tissue) are used. The group of Prof. Meinke is located at the Department of Dermatology of the Charité – Universitätsmedizin Berlin and the developed methods are transferred from basic research to the application on volunteers and patients.