colfosceril-palmitate and dipalmitoylphosphatidylserine

Topics: 1,2-Dipalmitoylphosphatidylcholine; Alanine; Amino Acid Sequence; Amino Acid Substitution; Antineoplastic Agents; Cell Line, Tumor; Cell Membrane; Cell Survival; Cholesterol; HEK293 Cells; HeLa Cells; Humans; Isoleucine; L-Lactate Dehydrogenase; Leucine; Liposomes; Peptides; Phosphatidylserines; Protein Engineering; Protein Structure, Secondary; Static Electricity; Structure-Activity Relationship

Cadmium selenide (CdSe) magic-sized quantum dots (MSQDs) are semiconductor nanocrystals with stable luminescence that are feasible for biomedical applications, especially for in vivo and in vitro imaging of tumor cells. In this work, we investigated the specific interaction of CdSe MSQDs with tumorigenic and non-tumorigenic cells using Langmuir monolayers and Langmuir-Blodgett (LB) films of lipids as membrane models for diagnosis of cancerous cells. Surface pressure-area isotherms and polarization modulation reflection-absorption spectroscopy (PM-IRRAS) showed an intrinsic interaction between the quantum dots, inserted in the aqueous subphase, and Langmuir monolayers constituted either of selected lipids or of tumorigenic and non-tumorigenic cell extracts. The films were transferred to solid supports to obtain microscopic images, providing information on their morphology. Similarity between films with different compositions representing cell membranes, with or without the quantum dots, was evaluated by atomic force microscopy (AFM) and confocal microscopy. This study demonstrates that the affinity of quantum dots for models representing cancer cells permits the use of these systems as devices for cancer diagnosis.

Topics: 1,2-Dipalmitoylphosphatidylcholine; Air; Animals; Cadmium Compounds; Cell Extracts; Cell Line; Cell Line, Transformed; Endothelial Cells; Gene Expression; Microscopy, Atomic Force; Oncogene Proteins; Phosphatidylserines; Quantum Dots; Rabbits; Selenium Compounds; Surface Properties; Transgenes; Unilamellar Liposomes; Water

Investigating the role of drugs whose pharmaceutical activity is associated with cell membranes is fundamental to comprehending the biochemical processes that occur on membrane surfaces. In this work, we examined the action of 1,4-naphthoquinone in lipid Langmuir monolayers at the air-water interface, which served as a model for half of a membrane, and investigated the molecular interactions involved with tensiometry and vibrational spectroscopy. The surface pressure-area isotherms exhibited a noticeable shift to a lower area in relation to 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) and 1,2-dihexadecanoyl-sn-glycero-3-phospho-l-serine (DPPS) lipid monolayers, which indicated a disruption of the monolayer structure and solubilisation of the lipids towards the aqueous subphase. To better correlate to the action of this drug in biological membrane events, cell cultures that represented tumorigenic and non-tumorigenic cells were spread onto the air-water interface, and 1,4-naphthoquinone was then incorporated. While only slight changes were observed in the non-tumorigenic cells upon drug incorporation, significant changes were observed in the tumorigenic cells, on which the organisation of the Langmuir monolayers was disrupted as evidenced by tensiometry and vibrational spectroscopy. This work then shows that this drug interacts preferentially for specific surfaces. In simplified models, it has a higher effect for the negative charged DPPS rather than the zwitterionic DPPC; and for complex cell cultures, 1,4-naphthoquinone presents a more significant effect for that representing tumorigenic cells.

Topics: 1,2-Dipalmitoylphosphatidylcholine; Animals; Cell Line, Transformed; Cell Membrane; Membranes, Artificial; Models, Chemical; Naphthoquinones; Phosphatidylserines; Rabbits; Surface Tension