Suppressive actions of eicosapentaenoic acid on lipid droplet formation in 3T3-L1 adipocytes

Background : Lipid droplet (LD) formation and size regulation reflects both lipid influx and efflux, and is central in the regulation of adipocyte metabolism, including adipokine secretion. The length and degree of dietary fatty acid (FA) unsaturation is implicated in LD formation and regulation in adipocytes. The aims of this study were to establish the impact of eicosapentaenoic acid (EPA; C20:5n-3) in comparison to SFA (STA; stearic acid, C18:0) and MUFA (OLA; oleic acid, C18:1n-9) on 3T3-L1 adipocyte LD formation, regulation of genes central to LD function and adipokine responsiveness. Cells were supplemented with 100 μM FA during 7-day differentiation.

Results : EPA markedly reduced LD size and total lipid accumulation, suppressing PPARγ, Cidea and D9D/SCD1 genes, distinct from other treatments. These changes were independent of alterations of lipolytic genes, as both EPA and STA similarly elevated LPL and HSL gene expressions. In response to acute lipopolysaccharide exposure, EPA-differentiated adipocytes had distinct improvement in inflammatory response shown by reduction in monocyte chemoattractant protein-1 and interleukin-6 and elevation in adiponectin and leptin gene expressions.

Conclusions : This study demonstrates that EPA differentially modulates adipogenesis and lipid accumulation to suppress LD formation and size. This may be due to suppressed gene expression of key proteins closely associated with LD function. Further analysis is required to determine if EPA exerts a similar influence on LD formation and regulation in-vivo.

Magnetic liquid marbles : Toward “Lab in a Droplet“

Liquid marbles exhibit great potential for use as miniature labs for small-scale laboratory operations, such as experiment and measurement. While important progress has been made recently in exploring their applications as microreactions, “on-line“ measurement of the components inside the liquid still remains a challenge. Herein, it is demonstrated that “on-line“ detection can be realized on magnetic liquid marbles by taking advantage of their unique magnetic opening feature. By partially opening the particle shell, electrochemical measurement is carried out with a miniaturized three-electrode probe and the application of this technique for quantitative measurement of dopamine is demonstrated. Fully opened magnetic liquid marble makes it feasible to detect the optical absorbance of the liquid in a transmission mode. With this optical method, a glucose assay is demonstrated. Moreover, when magnetic particle shell contains low melting point material, e.g., wax, the liquid marble shows a unique encapsulation ability to form a rigid shell after heating, which facilitates the storage of the non-volatile ingredients. These unique features, together with the versatile use as microreactors, enable magnetic liquid marbles to function as a miniature lab (or called “lab in a droplet“), which may find applications in clinical diagnostics, biotechnology, chemical synthesis, and analytical chemistry.

Fluid mixing in droplet-based microfluidics with a serpentine microchannel

The hydrodynamics and mixing process within droplets travelling along a three dimensional serpentine microchannel are studied using a computational fluid dynamics simulation based on the volume-of-fluid approach. The fluid mixing within the droplet follows symmetric circulations in the straight section, which generates axial mixing. In the winding section, the asymmetric circulations lead to the reorientation of the fluids within the droplet, thus enhancing the mixing efficiency. The mixing performance is controlled by the spatial distribution of the mixing components and the circulation period within the droplet. The best mixing occurs when the droplet size is comparable with the channel width. When the droplet size is less than two times the channel width, the asymmetric circulations make it easy for the fluid to distribute in the axial direction, which leads to a fast mixing process. For larger droplets, the long circulation period becomes more significant, which causes lower mixing efficiency.