Benzoate group attachment to TEMPO provides enhanced discrimination of liposomes fabricated using human lung normal and carcinoma cells

Abstract

It is widely accepted that the lipid compositions of the plasma membranes of healthy and cancer cells significantly differ from each other. During the cancer progression, cancer cells change the lipid constituent of the membranes resulting in the loss of lipid asymmetry between the membrane leaflets. Consequently, physicochemical properties of the cell membranes are also changed in response to altered lipid organization. Partitioning of the spin probe 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) into the membranes of the cells has broadly been applied to characterize membrane properties of various cells in health and disease conditions. In this work, we used liposomes fabricated using lipids extracted from normal and carcinoma cells. This system permits the determination of the properties of the healthy and cancer cell membranes provided exclusively by its lipid components. Application of TEMPO-benzoate, in which the benzoate group is attached to the TEMPO, indicates significantly enhanced discrimination of liposomes between cancer and normal cells. Partitioning experiments with TEMPO-benzoate revealed relatively enhanced incorporation efficiency for liposomes of cancer cells. On the contrary, TEMPO incorporation efficiency in the same liposomes of cancer cells was not much different compared to healthy cells. Data indicate that TEMPO-benzoate as a probe is more suitable than TEMPO to discriminate cancer cells from healthy cells. Free energy gain observed for TEMPO-benzoate resulted mainly from the hydrophobic effect of the benzoate group.