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Depression is one of the most common psychiatric diseases in the population. Agomelatine is a novel antidepressant drug with melatonin receptor agonistic and serotonin 5-HT2C antagonistic properties. Furthermore, being a melatonergic drug, agomelatine has the potential of being used in therapeutic applications like melatonin as an antioxidant, anti-inflammatory and antiapoptotic drug. The action mechanism of agomelatine on the membrane structure has not been clarified yet. In the present study, we aimed to investigate the interaction of agomelatine with model membranes of dipalmitoylphosphatidylcholine (DPPC) and dipalmitoylphosphatidylgylcerol (DPPG) by Fourier transform infrared (FTIR) spectroscopy and differential scanning calorimetry (DSC). We found that agomelatine interacts with the head group in such a manner that it destabilizes the membrane architecture to a large extent. Thus, agomelatine causes alterations in the order, packing and dynamics of the DPPC and DPPG model membranes. Our results suggest that agomelatine strongly interacts with zwitterionic and charged membrane phospholipids. Because lipid structure and dynamics may have influence on the structure of membrane bound proteins and affect the signal transduction systems of membranes, these effects of agomelatine may be important in its action mechanism.

Humans can be exposed to ionizing radiation, due to various reasons, whose structural effects on biological membranes are not well defined. The current study aims to understand the ionizing radiation-induced structural and functional alterations in biomolecules of brain membranes using Fourier transform infrared (FT-IR) spectroscopy using rat animal models. For this purpose, 1000 cGy of ionizing radiation was specifically directed to the head of Sprague Dawley rats. The rats were decapitated after 24 h. The results revealed that the lipid-to-protein ratio decreased and that irradiation caused lipid peroxidation and increases in the amounts of olefinic =CH, carbonyl, and methylene groups of lipids. In addition, ionizing radiation induced a decrease in membrane fluidity, disordering of membrane lipids, strengthening of the hydrogen bonding of the phosphate groups of lipid head-groups, and weakening in the hydrogen bonding of the interfacial carbonyl groups of lipids. Radiation further caused significant decrements in the α-helix and turns, and significant increments in the β-sheet and random coil contents in the protein structure. Hierarchical cluster analyses, performed in the whole region (3030-1000 cm(-1)), lipid (3030-2800 cm(-1)), and protein (1700-1600 cm(-1)) regions separately, successfully differentiated the control and irradiated groups of rat brain membranes and showed that proteins in the membranes are affected more than lipids from the damages induced with ionizing radiation. As a result, the current study showed that FT-IR spectroscopy can be used successfully as a novel method to monitor radiation-induced alterations on biological membranes.

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The interaction of single-pulse Nd:YAG laser, operating at 1064 nm wavelength and 6 ns pulse duration, with AISI 316L stainless steel target surface was investigated experimentally and theoretically. Surface modication of stainless steel using laser irradiation was studied by observing the eects of varying incident laser pulse intensities on surface morphology. Surface structure of laser treated stainless steel was determined by optical microscopy and prolometry analyses. Numerical calculation by heat transfer equation was performed for single laser pulse irradiation. The results, obtained by theoretical and experimental processes, of the interaction between single-pulse Nd:YAG laser irradiation and AISI 316L stainless steel target surface are reported.