The Detection of UV‐induced Membrane Damages by a Combination of Two Biosensor Techniques

Abstract

Ketoprofen is an important anti-inflammatory drug, but its dermal application is limited because of the photosensitizing properties causing phototoxic reactions of the skin when exposed to UV light. We have recently investigated the peroxide formation of ketoprofen in solutions of linoleic acid during UV irradiation. To continue these studies and focus on UV-induced changes in membrane integrity and barrier function we established an in vitro model using two biosensor techniques simultaneously. Support-fixed bilayers were irradiated with different doses of UV-B up to damaging intensities with or without ketoprofen. Cyclic voltammetry was carried out to detect alterations in membrane permeability; quartz crystal microbalance (QCM) measurements were helpful in analyzing whether a permeability increase was caused by depletion of membrane components. In absence of ketoprofen, increasing UV-B doses induce membrane permeabilities of both unsaturated and saturated bilayers. QCM measurements could not reveal a significant loss of membrane components as a reason for the permeability. In contrast, 0.3 mM ketoprofen induced a dose-dependent increase in membrane permeability. QCM results indicated a mass loss. Although this model does not explain all molecular mechanisms of membrane damage by ketoprofen, the combined application of both QCM and CV is a novel and powerful tool to investigate functional mechanisms of UV-induced membrane damages.

Structural Variations of the Cell Wall Precursor Lipid II and Their Influence on Binding and Activity of the Lipoglycopeptide Antibiotic Oritavancin

“…To further validate the data obtained from the in vitro assays, the binding parameters of oritavancin and vancomycin to selected lipid II variants (lipid II, lipid II-Gly 5 , amidated lipid II, amidated lipid II-Gly 5 , lipid II-D-Lac, and amidated lipid II-D-Lac) were determined using a quartz crystal microbalance (QCM) technique (48)(49)(50).…”

“…Changes in the oscillation frequency of quartz sensors, representing binding events at the sensor surface equipped in a flow chamber, were followed in real time and used to calculate binding kinetic constants with appropriate software. The quartz sensors were cleaned and prepared with the covalent immobilization of a hexadecanthiol monolayer as described previously (48). The supported bilayers were completed by transferring a monolayer consisting of 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC)-0.1 mol% lipid intermediate onto a covalently fixed C 16 H 33 SH monolayer by the LangmuirBlodgett technique.…”

Model membrane approaches to determine the role of calcium for the antimicrobial activity of friulimicin

“…Cleaning and preparation procedures of the quartz sensors for QCM have been described previously [8]. Preparation of microscope glass slides for AFM were described [9].…”

Analysis of membrane interactions of antibiotic peptides using ITC and biosensor measurements

“…The modification of the quartz crystals has already been described [24,25]. A DOPC or DOPG ± 0.1 mol% lipid II layer was transformed by Langmuir-Blodgett technique onto a 1-hexadecanethiol covered quartz crystal.…”