Phase imaging with tapping mode atomic force microscopy (AFM) and force modulation microscopy were used to probe the mechanical properties of phase-separated lipid monolayers made of a mixture (0.25:0.75) of the surface-active lipopeptide surfactin and of dipalmitoylphosphatidylcholine (DPPC). The pi-A isotherms and the result of a molecular modeling study revealed a loose, 2-D liquid-like organization for the surfactin molecules and a closely packed, 2-D solid-like organization for DPPC molecules. This difference in molecular organization was responsible for a significant contrast in height, tapping mode phase and force modulation amplitude images. Phase imaging at light tapping, i.e., with a ratio of the set-point tapping amplitude with respect to the free amplitude A(sp)/A(0) approximately 0.9, showed larger phase shifts on the solid-like DPPC domains attributed to larger Young's modulus. However, contrast inversion was observed for A(sp)/A(0)<0.7, suggesting that at moderate and hard tapping the image contrast was dominated by the probe-sample contact area. Surprisingly, force modulation amplitude images showed larger stiffness for the liquid-like surfactin domains, suggesting that the contrast was dominated by contact area effects rather than by Young's modulus. These data emphasize the complex nature of the contrast mechanisms of dynamic AFM images recorded on mixed lipid monolayers.
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Int J Nanomedicine
January 2025
Department of Medicine, Surgery and Pharmacy, University of Sassari, Sassari, Italy.
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January 2025
Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan USA.
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View Article and Find Full Text PDFInt J Mol Sci
December 2024
Laboratory of Animal Biology, National Institute for Research and Development for Biology and Animal Nutrition, Calea Bucuresti No. 1, Balotesti, 077015 Ilfov, Romania.
The present study aimed to investigate the ability of an aqueous extract derived from mustard seed meal to counteract the effects of endotoxin lipopolysaccharide (LPS) on the intestinal epithelium. Caco-2 cells were cultured together with HT29-MTX and used as a cellular model to analyze critical intestinal parameters, such as renewal, integrity, innate immunity, and signaling pathway. Byproducts of mustard seed oil extraction are rich in soluble polysaccharides, proteins, allyl isothiocyanates, and phenolic acids, which are known as powerful antioxidants with antimicrobial and antifungal properties.
View Article and Find Full Text PDFMolecules
January 2025
Department of Physics and Biophysics, Faculty of Food Science and Nutrition, Poznan University of Life Sciences, Wojska Polskiego 38/42, 60-637 Poznan, Poland.
This study aimed to evaluate the oxidative stability and surface properties of cold-pressed vegetable oils using the Langmuir monolayer technique. Six oils-milk thistle, evening primrose, flaxseed, camelina sativa, black cumin, and pumpkin seed-were analyzed to investigate their molecular organization and behavior at the air/water interface, particularly after undergoing oxidation. The results showed that oils rich in polyunsaturated fatty acids (PUFAs), such as flaxseed and evening primrose oils, formed monolayers with larger molecular areas and lower stability, which led to faster oxidative degradation, especially under thermal conditions.
View Article and Find Full Text PDFNanoscale
January 2025
School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou, 510006, China.
Methuosis, a non-apoptotic pattern of cell death, triggers the accumulation of macropinosome-derived vacuoles in the cytoplasm. Through this novel mechanism, methuosis inducers possess great potential in fighting apoptosis-resistant cancer cells and offer a promising alternative for cancer treatment. However, the potent methuosis inducer, 3-(5-methoxy, 2-methyl-1-indol-3-yl)-1-(4-pyridinyl)-2-propen-1-one (MOMIPP), faces an intractable issue of insolubility in most solvents, hindering dosing and compromising the validation of its antitumor efficacy.
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