Zhi-Wei Liu,Zhong Han,Xin-An Zeng,Da-Wen Sun,Rana Muhammad Aadil
In this study, the effects of pulsed electric field (PEF) treatments on the electro-permeability of vesicles made from dipalmitoyl-sn-glycero-3-phosphocholine (DPPC), dioleoyl-sn-glycero-3-phosphocholine (DOPC), Soya phosphatidylcholine (soya PC), cholesterol and a binary mixture of them encapsulated 5(6)-Carboxyfluorescein (5(6)-CF) were investigated, based on the electric field strength of 0–40 kV/cm and treatment time of 0–4.8 ms. Results indicated that the electro-permeability of lipid membrane was directly related to the composition of lipid bilayers membrane of vesicles. As compared to DPPC vesicles, DOPC vesicles were much more sensitive to PEF treatment. For the DOPC vesicles, the 5(6)-CF release percentage (R) was 9.24%, 20.12%, and 30.62% after PEF treatment at 20, 30, and 40 kV/cm for 4.8 ms treatment time, respectively. However, for the DPPC vesicles, it was only 1.84%, 4.02%, and 6.51%, respectively. On the other hand, the electro-permeability of DOPC vesicles was greatly affected by the addition of DPPC. The electro-permeability of DOPC vesicles was decreased sharply with the increase of DPPC molar ratio. Under the PEF treatment with 40 kV/cm and 1.2 ms, it was observed that the R of DOPC vesicles decreased markedly from 27.56% to 9.80% with the molar ratio of DPPC increased from 0 to 40%.For the soya PC vesicles, the R was dropped sharply from 48.13% to 24.11% with the molar ratio of cholesterol increased from 0 to 50%. Raman spectroscopy analysis revealed that the decrease of electro-permeability of soya PC vesicles with the addition of cholesterol was responsible for the incorporating of cholesterol into hydrocarbon partition of lipid bilayers, leading to the order arrangement of hydrocarbon chain of phospholipids , which was resulted an increase in the thickness of bilayers membrane and decrease in the fluidity of bilayers membrane. However, for the mixture of DOPC and DPPC (DOPC/DPPC) vesicles, there has no effect on the conformation of hydrocarbon chain of phospholipids and the fluidity of bilayer membrane of DOPC/DPPC vesicles with the addition of DPPC.
Mengyao Guan,Zhiliang Han,Na Liu,Zhou Zhou,Xiangyang Qu,Tao Zhang,Shiyan Chen,Huaping Wang
Hydrogel based electrodes have been applied in the field of bioelectronics, which is of great significance for constructing a robust human-computer interface. However, achieving both reliable conductivity and tissue matching mechanical properties remains challenging. Here, we report a synergistic strategy for constructing a hydrogel electrode for bioelectronic interface with tissue modulus and high conductivity by bacterial cellulose (BC) template induced growth polypyrrole (PPy) electrical percolation network combining a polymethacryloyloxyethyl trimethyl ammonium chloride (PDMC) hydrophilic network. This strategy balances the modulus and conductivity of the bioelectrode, makes up for the adverse effect of the conductive filler on the mechanical properties of the hydrogel, and constructs an effective conductive pathway. The electrical percolation of the hydrogel can be achieved at a low permeability threshold, and the flexibility ( E = 288 kPa) of the hydrogel electrode with high conductivity (135.75 S/m) can be obtained. Moreover, the hydrogel electrode has low interface impedance and superior charge storage and injection capability, which allows higher signal-to-noise ratio of recording epidermal electrophysiological signals than that of commercial electrodes. The conductive, flexible and biocompatible hydrogel prepared here provides a new way to construct reliable bioelectronic devices.
SiC-MoSi 2 composites with low electrical resistivity and high infrared emissivity were fabricated via pressureless sintering. The relationship between microstructure evolution and electrical behaviors along with infrared emission properties of the resulting composites is investigated at various sintering temperatures . The electrical resistivity undergoes two significant drops with increasing sintering temperature. Pore elimination bears responsible for the initial decrease in electrical resistivity. Transmission electron microscopy (TEM) observation manifests that the thinned amorphous layers at SiC/MoSi 2 interface decrease grain boundary resistivity and allow for electrical percolation to occur when sintering temperature further rises. Additionally, increasing sintering temperature leads to a higher infrared emissivity owing to the formation of Mo 4.8 Si 3 C 0.6 and the decreased boundaries. The lowest electrical resistivity of 7.2 Ω cm and the highest infrared emissivity of 0.721 are recorded for composite sintered at 2000 ℃. Overall, SiC-MoSi 2 composites exhibit a promising prospect as infrared source elements that must endure harsh environments.
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