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DNA-reduced graphene oxide nanocomposites based electrochemical biosensor for highly sensitive detection of cholesterol

《化学科学与工程前沿（英文）》 2021年第15卷第6期页码 1572-1582 doi: 10.1007/s11705-021-2112-4

摘要： High density and uniform distribution of the gold nanoparticles functionalized single-stranded DNA modified reduced graphene oxide nanocomposites were obtained by non-covalent interaction. The positive gold nanoparticles prepared by phase inversion method exhibited good dimensional homogeneity and dispersibility, which could readily combine with single-stranded DNA modified reduced graphene oxide nanocomposites by electrostatic interactions. The modification of single-stranded DNA endowed the reduced graphene oxide with favorable biocompatibility and provided the preferable surface with negative charge for further assembling of gold nanoparticles to obtain gold nanoparticles/single-stranded DNA modified reduced graphene oxide nanocomposites with better conductivity, larger specific surface area, biocompatibility and electrocatalytic characteristics. The as-prepared nanocomposites were applied as substrates for the construction of cholesterol oxidase modified electrode and well realized the direct electron transfer between the enzyme and electrode. The modified gold nanoparticles could further catalyze the products of cholesterol oxidation catalyzed by cholesterol oxidase, which was beneficial to the enzyme-catalyzed reaction. The as-fabricated bioelectrode exhibited excellent electrocatalytic performance for the cholesterol with a linear range of 7.5‒280.5 μmol·L^‒1, a low detection limit of 2.1 μmol·L^‒1, good stability and reproducibility. Moreover, the electrochemical biosensor showed good selectivity and acceptable accuracy for the detection of cholesterol in human serum samples.

关键词： reduced graphene oxide gold nanoparticles electrochemical biosensor cholesterol oxidase cholesterol

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Self-assembly of metal-cholesterol oxidase hybrid nanostructures and application in bioconversion of

Yu Xin, Qiuyue Gao, Yu Gu, Mengyao Hao, Guangming Fan, Liang Zhang

《化学科学与工程前沿（英文）》 2021年第15卷第3期页码 615-629 doi: 10.1007/s11705-020-1989-7

摘要： A cholesterol oxidase (COD) was hybridized with Ca , Zn , Al , Fe and Mn . After precipitation with PO at 4 °C for 72 h, the resulting pellets were freeze-dried. In scanning electron microscopy assays, the metal-COD complexes revealed flower-like or granular structures after hybridization. Fourier transform infrared spectroscopy assay revealed the characteristic peaks of both the enzyme and metal materials. X-ray diffraction analysis indicated that COD was encapsulated in CaHPO ·2H O-, Zn (PO ) ·4H O-, AlPO -, FeP - and Mn (PO ) ·3H O-based nanostructures, respectively. Differential scanning calorimetry assay indicated significant increases in thermo-denaturation temperatures from 60.5 °C to 167.02 °C, 167.02 °C, 137.70 °C, 172.85 °C and 160.99 °C, respectively. Using steroid derivatives as substrates, this enzyme could convert cholesterol, pregnenolone, dehydroepiandrosterone, ergosterol, -sitosterol and stigmasterol to related single products. Hybridization in metal-based nanostructures could significantly enhance the initial conversion ratio and reaction stability of the enzyme. In addition, substrate selectivity could be affected by various metal materials. Briefly, using Ca , Zn , Al , Fe and Mn as hybrid raw materials could help to encapsulate COD in related metal-enzyme nanostructures, and could help to promote the stability and tolerant properties of the enzyme, while also enhancing its catalytic characteristics.

关键词： cholesterol oxidase metal-enzyme hybridization nanostructures sterol derivatives bioconversion

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Insight into the role of cholesterol in modulation of morphology and mechanical properties of CHO-K1

Lei Zhang, Lisha Zhao, Ping-Kai Ouyang, Pu Chen

《化学科学与工程前沿（英文）》 2019年第13卷第1期页码 98-107 doi: 10.1007/s11705-018-1775-y

摘要：

Cholesterol plays a significant role in the organization of lipids and modulation of membrane dynamics in mammalian cells. However, the effect of cholesterol depletion on the eukaryotic cell membranes seems controversial. In this study, the effects of cholesterol on the topography and mechanical behaviors of CHO-K1 cells with manipulated membrane cholesterol contents were investigated by atomic force microscopy (AFM) technique. Here, we found that the depletion of cholesterol in cell membranes could increase the membrane stiffness, reduce the cell height as well as promote cell retraction and detachment from the surface, whereas the cholesterol restoration could reverse the effect of cholesterol depletion on the membrane stiffness. Increased methyl-β-cyclodextrin levels and incubation time could significantly increase Young’s modulus and degree of stiffing on cell membrane and cytoskeleton. This research demonstratede importance of cholesterol in regulating the dynamics of cytoskeleton-mediated processes. AFM technique offers excellent advantages in the dynamic monitoring of the change in membranes mechanical properties and behaviors during the imaging process. This promising technology can be utilized in studying the membrane properties and elucidating the underlying mechanism of distinct cells in the near-native environment.

关键词： cholesterol methyl-β-cyclodextrin atomic force microscopy Young’s modulus CHO-K1 cell