Changes in Membrane Lipid Order of Cells by Optimized Microplasma Irradiation for High-Molecule Drug Absorption

Abstract

Microplasma-based drug delivery, particularly transdermal drug delivery, has emerged as a promising alternatives to conventional methods due to its unique advantages. In this system, plasma components interact not only with the stratum corneum but also with the cells beneath it. Cell membranes mainly comprise lipids which are highly susceptible to plasma components, including reactive oxygen and nitrogen species. However, the effects of microplasma irradiation on cell membrane lipids are largely unexplored. In this context, the current study investigated an important physical property of cell membranes, membrane lipid order, in small intestinal epithelial cells after microplasma irradiation. First, the microplasma irradiation condition was optimized for the intracellular delivery of high molecular weight molecules, namely fluorescein isothiocyanate-dextran (FD-150 and FD-2000). Air microplasma discharge was applied at varying voltages (i.e., 3.5, 4.0, and 4.5 kV), and the efficiency of drug absorption was evaluated using a microplate reader and a fluorescence microscope. The cell viability was calculated using an automated cell counter. The most favorable outcomes in terms of both drug absorption and cell viability were achieved at 4 kV. Next, the membrane lipid order of cells was investigated using a solvatochromic dye after microplasma irradiation at 4 kV. Interestingly, non-irradiated cells exclusively manifested the liquid-ordered phase, whereas irradiated cells displayed a dual-phased composition comprising both liquid-ordered and liquid-disordered phases. In addition, live-cell imaging unveiled that alterations in membrane lipid order commenced as early as 4 min post-irradiation. This evidence points to a significant reduction in lipid packing and membrane thickness induced by microplasma irradiation. The findings shed light on the intricate mechanism underlying cellular drug absorption facilitated by microplasma irradiation. The insights gained into the impact on membrane lipid properties will contribute to developing safe and efficient drug delivery systems while minimizing side effects.

Lipidomics of Microplasma-Irradiated Cells at Optimized Discharge Conditions for the Absorption of High-Molecule Drug

“…In our previous study, we observed a significant reduction in cell viability following microplasma irradiation at 4.5 kV, with an additional 1 h incubation period. Also, we did not find any differences in the drug absorption into cells between the control cells and those irradiated with microplasma at 4.5 kV [12]. In this current study, we investigated the changes in lipids at this specific irradiation condition.…”

“…We performed untargeted lipidomics of microplasma-irradiated cells in order to investigate the effects of microplasma irradiation on cellular lipids, particularly cell membrane lipids. The microplasma irradiation conditions employed in this study were based on our previous research, wherein a voltage of 4.0 kV was identified as optimal for facilitating the absorption of larger molecules into cells [12].…”

“…Further, we investigated a crucial physical characteristic of cell membranes, the membrane lipid order, after microplasma treatment at the optimized conditions. While the untreated cells exhibited an exclusive liquid-ordered phase, the microplasma-irradiated cells displayed both liquid-ordered and liquid-disordered phases [12]. The study suggested that the altered membrane lipid order facilitates the transport of molecules through the cell membrane by modulating the fluidity and permeability of the membrane.…”

“…The applied microplasma irradiation conditions were based on our published literature [12]. IEC6 cells cultured in dishes (60 mm × 15 mm) were irradiated with microplasma discharge for a duration of 2 min.…”

“…Drug permeation through the intercellular pathway of the skin is limited to 500 Da, while intestinal tissue allows permeability of molecules with molecular weights of 70 kDa without any enhancers [9,10]. Recently, we showed the capability of microplasma irradiation to deliver high-weight molecules with molecular weights of up to 2000 kDa into rat intestinal epithelial cells [11,12].…”