The Experts below are selected from a list of 924 Experts worldwide ranked by ideXlab platform
Zian Lin - One of the best experts on this subject based on the ideXlab platform.
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an enzyme inorganic hybrid Nanoflower based immobilized enzyme reactor with enhanced enzymatic activity
2015Co-Authors: Yuqing Yin, Zian Lin, Yun Xiao, Guo Lin, Qi Xiao, Zongwei CaiAbstract:A facile approach for the synthesis of enzyme–inorganic hybrid Nanoflowers and their application as an immobilized α-chymotrypsin (ChT) reactor (IMER) for highly efficient protein digestion was described. The hybrid Nanoflowers were room-temperature synthesized in aqueous solution using calcium phosphate (Ca3(PO4)2) as the inorganic component and ChT as the organic component. The effects of reaction parameters on the formation of the enzyme-embedded hybrid Nanoflowers and their growth mechanism were investigated systematically. By monitoring the reaction of N-benzoyl-L-tyrosine ethyl ester (BTEE), the enzymatic activity of the immobilized ChT was calculated and the results showed 266% enhancement in enzymatic activity. The performance of such a nanoreactor was further demonstrated by digesting bovine serum albumin (BSA) and human serum albumin (HSA), with a stringent threshold for unambiguous identification of these digests, the yielding sequence coverages for Nanoflower-based digestion were 48% and 34%, higher than those obtained with the free enzyme. The digestion time of BSA and HSA in the former case was less than 2 min, about 1/360 of that performed in the latter case (12 h). Furthermore, the residual activity of the Nanoflowers decreased slightly even after eight repeated use, demonstrating promising stability. In addition, the hybrid Nanoflower-based IMER was applicable to the digestion of a complex human sample, showing great promise for proteome analysis.
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facile synthesis of enzyme inorganic hybrid Nanoflowers and its application as a colorimetric platform for visual detection of hydrogen peroxide and phenol
2014Co-Authors: Zian Lin, Yun Xiao, Yuqing Yin, Wei Liu, Huanghao YangAbstract:This study reports a facile approach for the synthesis of horseradish peroxidise (HRP)-inorganic hybrid Nanoflowers by self-assembly of HRP and copper phosphate (Cu3(PO4)2·3H2O) in aqueous solution. Several reaction parameters that affect the formation of the hybrid Nanoflowers were investigated and a hierarchical flowerlike spherical structure with hundreds of nanopetals was obtained under the optimum synthetic conditions. The enzymatic activity of HRP embedded in hybrid naonflowers was evaluated based on the principle of HRP catalyzing the oxidation of o-phenylenediamine (OPD) in the presence of hydrogen peroxide (H2O2). The results showed that 506% enhancement of enzymatic activity in the hybrid Nanoflowers could be achieved compared with the free HRP in solution. Taking advantages of the structural feature with catalytic property, a Nanoflower-based colorimetric platform was newly designed and applied for fast and sensitive visual detection of H2O2 and phenol. The limits of detection (LODs) for H2O2 a...
Richard N Zare - One of the best experts on this subject based on the ideXlab platform.
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rapid detection of phenol using a membrane containing laccase Nanoflowers
2013Co-Authors: Lin Zhu, Lu Gong, Yifei Zhang, Rui Wang, Zheng Liu, Richard N ZareAbstract:With the rapid development of nanoscience and nanotechnology, nanostructured biocatalysts that take the advantage of nanomaterials in terms of both functional and structural availability have offered new opportunities for improving biological functions of enzymes and expanding applications in areas such as biosensors, bioanalytical devices, and industrial biocatalysis. Recently, we reported a method of preparing protein–inorganic hybrid nanostructures with flower-like shapes, which have shown much greater activities than free enzymes and most of the reported immobilized enzymes. To bring this appealing catalyst into practical use, however, an effective accommodation of these high-performance enzyme catalysts is required. One way is to weakly attach these enzyme Nanoflowers to porous materials by physical adsorption. Recently, Krieg et al. reported the fabrication of a supramolecular membrane by noncovalent modification of a commercial membrane, which suggests the possibility of fabricating functional filtration membranes by a simple post-modification procedure, thus enabling many new and interesting applications. It thus came to our mind to fabricate a membrane incorporating enzyme Nanoflowers for the rapid detection of hazardous compounds through visualization of the catalyzed product. Owing to their high toxicity even at a low concentration, phenols are listed as major toxic pollutants by the Environmental Protection Agency of the USA and other countries. Sensitive detection of phenolic compounds has been well established using instrumental analysis such as liquid chromatography. However, these methods usually require sophisticated instrumentation and a multistep procedure, making them less convenient for rapid and on-site detection. The present study started by the fabrication of an enzyme Nanoflower incorporated into a membrane. As shown in Figure 1, a suspension of laccase–inorganic hybrid Nanoflowers, which have a high activity (ca. 200% that of free laccase) for phenol oxidization, as we observed previously, was injected into a commercial disposable syringe filter equipped with a cellulose acetate membrane (pore size 0.2 mm). This procedure thus deposited enzyme Nanoflowers with an average size of 4 mm onto the membrane. Then the aqueous sample containing phenol was mixed with an aqueous solution of 4-aminoantipyrine and was passed through the membrane with incorporated laccase Nanoflowers, causing oxidative coupling of phenol with 4-aminoantipyrine to form an antipyrine dye that has an absorption maximum at 495 nm. This procedure allowed rapid analysis by a UV/ Vis spectrophotometer or by the naked eye. Finally, pure water was injected into the filter to remove unreacted reagents and the reaction products, followed by drying the membrane in air for the next use. For the preparation of laccase–copper phosphate Nanoflowers, typically, 0.8 mm aqueous CuSO4 was added to phosphate buffered saline (PBS) containing 0.1 mgmL 1 laccase at pH 7.4 and 25 8C. After three days, the precipitate of laccase Nanoflowers appeared with porous, flower-like structures. Scanning electron microscopy (SEM) images of the Nanoflowers are presented in Figure 2a,b, from which the average diameter of the laccase Nanoflowers was determined [a] L. Zhu, L. Gong, Y. Zhang, R. Wang, Prof. J. Ge, Prof. Z. Liu Department of Chemical Engineering, Tsinghua University Beijing 100084 (China) E-mail : junge@mail.tsinghua.edu.cn liuzheng@mail.tsinghua.edu.cn [b] Prof. R. N. Zare Department of Chemistry, Stanford University Stanford, CA 94305-5080 (USA) E-mail : zare@stanford.edu [] These authors contributed equally to this work. Figure 1. Fabrication, use, washing, and reuse of the membrane with incorporated laccase Nanoflowers. Phenol and ortho-, meta-, and para-substituted phenols carrying carboxy, halogen, methoxy, or sulfonic acid groups react with 4-aminoantipyrine to form colored compounds, which can then be readily detected.
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Protein-inorganic hybrid Nanoflowers
2012Co-Authors: Jun Ge, Jiandu Lei, Richard N ZareAbstract:Flower-shaped inorganic nanocrystals have been used for applications in catalysis and analytical science, but so far there have been no reports of 'Nanoflowers' made of organic components. Here, we report a method for creating hybrid organic-inorganic Nanoflowers using copper (II) ions as the inorganic component and various proteins as the organic component. The protein molecules form complexes with the copper ions, and these complexes become nucleation sites for primary crystals of copper phosphate. Interaction between the protein and copper ions then leads to the growth of micrometre-sized particles that have nanoscale features and that are shaped like flower petals. When an enzyme is used as the protein component of the hybrid Nanoflower, it exhibits enhanced enzymatic activity and stability compared with the free enzyme. This is attributed to the high surface area and confinement of the enzymes in the Nanoflowers.
Jinsong Ren - One of the best experts on this subject based on the ideXlab platform.
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biomimetic Nanoflowers by self assembly of nanozymes to induce intracellular oxidative damage against hypoxic tumors
2018Co-Authors: Zhenzhen Wang, Yan Zhang, Zhen Liu, Fangfang Cao, Zhaowei Chen, Jinsong RenAbstract:Reactive oxygen species (ROS)-induced apoptosis is a promising treatment strategy for malignant neoplasms. However, current systems are highly dependent on oxygen status and/or external stimuli to generate ROS, which greatly limit their therapeutic efficacy particularly in hypoxic tumors. Herein, we develop a biomimetic Nanoflower based on self-assembly of nanozymes that can catalyze a cascade of intracellular biochemical reactions to produce ROS in both normoxic and hypoxic conditions without any external stimuli. In our formulation, PtCo nanoparticles are firstly synthesized and used to direct the growth of MnO2. By adjusting the ratio of reactants, highly-ordered MnO2@PtCo Nanoflowers with excellent catalytic efficiency are obtained, where PtCo behaves as oxidase mimic and MnO2 functions as catalase mimic. In this way, the well-defined MnO2@PtCo Nanoflowers not only can relieve hypoxic condition but also induce cell apoptosis significantly through ROS-mediated mechanism, thereby resulting in remarkable and specific inhibition of tumor growth.
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self assembly of an organic inorganic hybrid Nanoflower as an efficient biomimetic catalyst for self activated tandem reactions
2015Co-Authors: Yanyan Huang, Xiang Ran, Youhui Lin, Jinsong RenAbstract:The BSA–Cu3(PO4)2·3H2O hybrid Nanoflower was used as a biomimetic catalyst with excellent catalytic activity, durability and stability. When GOx was used as the protein component, this composite could realize self-activated cascade catalysis. Our Nanoflower system could also be used to decompose organic pollutants with high efficiency.
Yuqing Yin - One of the best experts on this subject based on the ideXlab platform.
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an enzyme inorganic hybrid Nanoflower based immobilized enzyme reactor with enhanced enzymatic activity
2015Co-Authors: Yuqing Yin, Zian Lin, Yun Xiao, Guo Lin, Qi Xiao, Zongwei CaiAbstract:A facile approach for the synthesis of enzyme–inorganic hybrid Nanoflowers and their application as an immobilized α-chymotrypsin (ChT) reactor (IMER) for highly efficient protein digestion was described. The hybrid Nanoflowers were room-temperature synthesized in aqueous solution using calcium phosphate (Ca3(PO4)2) as the inorganic component and ChT as the organic component. The effects of reaction parameters on the formation of the enzyme-embedded hybrid Nanoflowers and their growth mechanism were investigated systematically. By monitoring the reaction of N-benzoyl-L-tyrosine ethyl ester (BTEE), the enzymatic activity of the immobilized ChT was calculated and the results showed 266% enhancement in enzymatic activity. The performance of such a nanoreactor was further demonstrated by digesting bovine serum albumin (BSA) and human serum albumin (HSA), with a stringent threshold for unambiguous identification of these digests, the yielding sequence coverages for Nanoflower-based digestion were 48% and 34%, higher than those obtained with the free enzyme. The digestion time of BSA and HSA in the former case was less than 2 min, about 1/360 of that performed in the latter case (12 h). Furthermore, the residual activity of the Nanoflowers decreased slightly even after eight repeated use, demonstrating promising stability. In addition, the hybrid Nanoflower-based IMER was applicable to the digestion of a complex human sample, showing great promise for proteome analysis.
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facile synthesis of enzyme inorganic hybrid Nanoflowers and its application as a colorimetric platform for visual detection of hydrogen peroxide and phenol
2014Co-Authors: Zian Lin, Yun Xiao, Yuqing Yin, Wei Liu, Huanghao YangAbstract:This study reports a facile approach for the synthesis of horseradish peroxidise (HRP)-inorganic hybrid Nanoflowers by self-assembly of HRP and copper phosphate (Cu3(PO4)2·3H2O) in aqueous solution. Several reaction parameters that affect the formation of the hybrid Nanoflowers were investigated and a hierarchical flowerlike spherical structure with hundreds of nanopetals was obtained under the optimum synthetic conditions. The enzymatic activity of HRP embedded in hybrid naonflowers was evaluated based on the principle of HRP catalyzing the oxidation of o-phenylenediamine (OPD) in the presence of hydrogen peroxide (H2O2). The results showed that 506% enhancement of enzymatic activity in the hybrid Nanoflowers could be achieved compared with the free HRP in solution. Taking advantages of the structural feature with catalytic property, a Nanoflower-based colorimetric platform was newly designed and applied for fast and sensitive visual detection of H2O2 and phenol. The limits of detection (LODs) for H2O2 a...
Zongwei Cai - One of the best experts on this subject based on the ideXlab platform.
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an enzyme inorganic hybrid Nanoflower based immobilized enzyme reactor with enhanced enzymatic activity
2015Co-Authors: Yuqing Yin, Zian Lin, Yun Xiao, Guo Lin, Qi Xiao, Zongwei CaiAbstract:A facile approach for the synthesis of enzyme–inorganic hybrid Nanoflowers and their application as an immobilized α-chymotrypsin (ChT) reactor (IMER) for highly efficient protein digestion was described. The hybrid Nanoflowers were room-temperature synthesized in aqueous solution using calcium phosphate (Ca3(PO4)2) as the inorganic component and ChT as the organic component. The effects of reaction parameters on the formation of the enzyme-embedded hybrid Nanoflowers and their growth mechanism were investigated systematically. By monitoring the reaction of N-benzoyl-L-tyrosine ethyl ester (BTEE), the enzymatic activity of the immobilized ChT was calculated and the results showed 266% enhancement in enzymatic activity. The performance of such a nanoreactor was further demonstrated by digesting bovine serum albumin (BSA) and human serum albumin (HSA), with a stringent threshold for unambiguous identification of these digests, the yielding sequence coverages for Nanoflower-based digestion were 48% and 34%, higher than those obtained with the free enzyme. The digestion time of BSA and HSA in the former case was less than 2 min, about 1/360 of that performed in the latter case (12 h). Furthermore, the residual activity of the Nanoflowers decreased slightly even after eight repeated use, demonstrating promising stability. In addition, the hybrid Nanoflower-based IMER was applicable to the digestion of a complex human sample, showing great promise for proteome analysis.
