Tuning phospholipid bilayer permeability by flavonoid apigenin: Electrochemical and atomic force microscopy study

The effects of the esterified Quercetin with omega3 and omega6 fatty acids on viability, nanomechanical properties, and BAX/BCL-2 gene expression in MCF-7 cells

Quercetin is one of the major flavonoids and it appears to have cytotoxic effects on various cancer cells through regulating the apoptosis pathway genes such as BAX and BCL2. Combination of Quercetin (Q) with other compounds can increase its effectiveness. In the present study, the effects of the Quercetin and its esterified derivatives on viability, nanomechanical properties of cells, and BAX/BCL-2 gene expression were investigated. Using the MTT and flow cytometry assays, the cytotoxic potential, apoptosis, and necrosis were investigated. The AFM assay was performed to find the nanomechanical properties of cells as the elastic modulus value and cellular adhesion forces. The BAX/BCL2 gene expression was investigated through the Real-Time PCR. The results showed that the esterification of Quercetin with linoleic acid (Q-LA) and α-linolenic acid (Q-ALA) increased the cytotoxic potential of Q. The elastic modulus value and cellular adhesion forces were increased using the esterified derivatives and the highest ratio of BAX/BCL2 gene expression was observed in Q-LA. Esterified Quercetin derivatives have a higher cytotoxic effect than the un-esterified form in a dose-dependent manner. Esterified derivatives caused the nanomechanical changes and pores formation on the cytoplasmic membrane. One of the internal apoptosis pathway regulation mechanisms of these compounds is increasing the BAX/BCL2 gene expression ratio.

Biomembranes in bioelectronic sensing

Cell membranes are integral to the functioning of the cell and are therefore key to drive fundamental understanding of biological processes for downstream applications. Here, we review the current state-of-the-art with respect to biomembrane systems and electronic substrates, with a view of how the field has evolved towards creating biomimetic conditions and improving detection sensitivity. Of particular interest are conducting polymers, a class of electroactive polymers, which have the potential to create the next step-change for bioelectronics devices. Lastly, we discuss the impact these types of devices could have for biomedical applications.

Impact of Electric Fields on the Nanoscale Behavior of Lipid Monolayers at the Surface of Graphite in Solution

The nanoscale organization and dynamics of lipid molecules in self-assembled membranes is central to the biological function of cells and in the technological development of synthetic lipid structures as well as in devices such as biosensors. Here, we explore the nanoscale molecular arrangement and dynamics of lipids assembled in monolayers at the surface of highly ordered pyrolytic graphite (HOPG), in different ionic solutions, and under electrical potentials. Using a combination of atomic force microscopy and fluorescence recovery after photobleaching, we show that HOPG is able to support fully formed and fluid lipid membranes, but mesoscale order and corrugations can be observed depending on the type of the lipid considered (1,2-dioleoyl- sn-glycero-3-phosphocholine, 1,2-dioleoyl- sn-glycero-3-phospho-l-serine (DOPS), and 1,2-dioleoyl-3-trimethylammoniumpropane) and the ion present (Na⁺, Ca²⁺, Cl^-). Interfacial solvation forces and ion-specific effects dominate over the electrostatic changes induced by moderate electric fields (±1.0 V vs Ag/AgCl reference electrode) with particularly marked effects in the presence of calcium, and for DOPS. Our results provide insights into the interplay between the molecular, ionic, and electrostatic interactions and the formation of dynamical ordered structures in fluid lipid membranes.