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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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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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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    

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NADPH oxidase and reactive oxygen species as signaling molecules in carcinogenesis

Gang WANG

《医学前沿（英文）》 2009年 第3卷 第1期   页码 1-7 doi: 10.1007/s11684-009-0018-5

摘要： Reactive oxygen species (ROS) are small molecule metabolites of oxygen that are prone to participate in redox reactions their high reactivity. Intracellular ROS could be generated in reduced nicotinamide-adenine dinucleotidephosphate (NADPH) oxidase-dependent and/or NADPH oxidase-independent manners. Physiologically, ROS are involved in many signaling cascades that contribute to normal processes. One classical example is that ROS derived from the NADPH oxidase and released in neurotrophils are able to digest invading bacteria. Excessive ROS, however, contribute to pathogenesis of various human diseases including cancer, aging, dimentia and hypertension. As signaling messengers, ROS are able to oxidize many targets such as DNA, proteins and lipids, which may be linked with tumor growth, invasion or metastasis. The present review summarizes recent advances in our comprehensive understanding of ROS-linked signaling pathways in regulation of tumor growth, invasion and metastasis, and focuses on the role of the NADPH oxidase-derived ROS in cancer pathogenesis.

关键词： free radicals     tumor     phox     cell proliferation     cancer therapy    

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Oxidative stress in granulosa cells contributes to poor oocyte quality and IVF-ET outcomes in women with polycystic ovary syndrome

Qiaohong Lai, Wenpei Xiang, Qing Li, Hanwang Zhang, Yufeng Li, Guijin Zhu, Chengliang Xiong, Lei Jin

《医学前沿（英文）》 2018年 第12卷 第5期   页码 518-524 doi: 10.1007/s11684-017-0575-y

摘要：

The increased levels of intracellular reactive oxygen species (ROS) in granulosa cells (GCs) may affect the pregnancy results in women with polycystic ovary syndrome (PCOS). In this study, we compared thein vitro fertilization and embryo transfer (IVF-ET) results of 22 patients with PCOS and 25 patients with tubal factor infertility and detected the ROS levels in the GCs of these two groups. Results showed that the PCOS group had significantly larger follicles on the administration day for human chorionic gonadotropin than the tubal factor group (P<0.05); however, the number of retrieved oocytes was not significantly different between the two groups (P>0.05). PCOS group had slightly lower fertilization, cleavage, grade I/II embryo, clinical pregnancy, and implantation rates and higher miscarriage rate than the tubal factor group (P>0.05). We further found a significantly higher ROS level of GCs in the PCOS group than in the tubal factor group (P<0.05). The increased ROS levels in GCs caused GC apoptosis, whereas NADPH oxidase 2 (NOX2) specific inhibitors (diphenyleneiodonium and apocynin) significantly reduced the ROS production in the PCOS group. In conclusion, the increased ROS expression levels in PCOS GCs greatly induced cell apoptosis, which further affected the oocyte quality and reduced the positive IVF-ET pregnancy results of women with PCOS. NADPH oxidase pathway may be involved in the mechanism of ROS production in GCs of women with PCOS.

关键词： PCOS     ROS     granulosa cell     IVF-ET     NADPH oxidase    

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标题 作者 时间 类型 操作

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

期刊论文

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

期刊论文

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

期刊论文

NADPH oxidase and reactive oxygen species as signaling molecules in carcinogenesis

Gang WANG

期刊论文

Oxidative stress in granulosa cells contributes to poor oocyte quality and IVF-ET outcomes in women with polycystic ovary syndrome

Qiaohong Lai, Wenpei Xiang, Qing Li, Hanwang Zhang, Yufeng Li, Guijin Zhu, Chengliang Xiong, Lei Jin

期刊论文