FSI and non-FSI studies on a functionally graded temperature-responsive hydrogel bilayer in a micro-channel

Taking into account both fluid-structure interaction (FSI) and non-FSI simulations, the deformation of a bilayer is investigated in this paper. The bilayer, which is utilized in a micro-channel, consists of a Functionally-graded (FG) temperature-responsive hydrogel layer and an incompressible elastomeric one. Allocating two different positions to the elastomeric layer, we make two different bilayers where in one of them, the elastomer layer is located on the left (LSE) and on the right (RSE) in another one. Also, to see the effect of grading, two bilayers with homogenous hydrogel layers with different amounts of cross-linking density are considered. For FG cases in which the hydrogel layer's properties vary through thickness direction, both ascending and descending arrangements are analyzed. Each simulation, whether it is FSI or non-FSI, is conducted utilizing three software. FLUENT for fluid domain examinations, ABAQUS for FEM analysis, and MpCCI to couple two aforementioned simulation domains. By extracting and comparing both simulations results, it is observed that the influence of the fluid flow is very significant and should not be ignored. Moreover, it is discovered that the fluid flow affects more the RSE configuration and also the bilayers with lower amounts of cross-linking density. Finally, we investigate how some parameters, such as inlet pressure, can affect the behavior of the bilayer.

Fluorescence Microscopy of Piezo1 in Droplet Hydrogel Bilayers

Mechanosensitive ion channels are membrane gated pores which are activated by mechanical stimuli. The focus of this study is on Piezo1, a newly discovered, large, mammalian, mechanosensitive ion channel, which has been linked to diseases such as dehydrated hereditary stomatocytosis (Xerocytosis) and lymphatic dysplasia. Here we utilize an established in-vitro artificial bilayer system to interrogate single Piezo1 channel activity. The droplet-hydrogel bilayer (DHB) system uniquely allows the simultaneous recording of electrical activity and fluorescence imaging of labelled protein. We successfully reconstituted fluorescently labelled Piezo1 ion channels in DHBs and verified activity using electrophysiology in the same system. We demonstrate successful insertion and activation of hPiezo1-GFP in bilayers of varying composition. Furthermore, we compare the Piezo1 bilayer reconstitution with measurements of insertion and activation of KcsA channels to reproduce the channel conductances reported in the literature. Together, our results showcase the use of DHBs for future experiments allowing simultaneous measurements of ion channel gating while visualising the channel proteins using fluorescence.

Bioinspired microstructures of chitosan hydrogel provide enhanced wear protection

Hydrogel bilayer structure leads to different tribological behaviors in terms of friction and wear resistance.