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Comparison of ligand migration and binding in heme proteins of the globin family

Chinese Physics B 2015年第12期24卷 109-118页

作者： Karin nienhaus g.ulrich nienhaus Institute of Applied Physics (APH) Karlsruhe Institute of Technology (KIT) Institute of Nanotechnology (INT) and Institute of Toxicology and genetics (ITg) Karlsruhe Institute of Technology (KIT) Department of Physics University of Illinois at Urbana-Champaign

The binding of small diatomic ligands such as carbon monoxide or dioxygen to heme proteins is among the simplest biological processes known. Still, it has taken many decades to understand the mechanistic aspects of this process in full detail. Here, we compare ligand binding in three heme proteins of the globin family, myoglobin, a dimeric hemoglobin, and neuroglobin. The combination of structural, spectroscopic, and kinetic experiments over many years by many laboratories has revealed common properties of globins and a clear mechanistic picture of ligand binding at the molecular level. In addition to the ligand binding site at the heme iron, a primary ligand docking site exists that ensures efficient ligand binding to and release from the heme iron. Additional, secondary docking sites can greatly facilitate ligand escape after its dissociation from the heme. Although there is only indirect evidence at present, a preformed histidine gate appears to exist that allows ligand entry to and exit from the active site. The importance of these features can be assessed by studies involving modified proteins（via site-directed mutagenesis） and comparison with heme proteins not belonging to the globin family.

关键词： flash photolysis ligand binding time-resolved spectroscopy heme protein

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Two-beam phase correlation spectroscopy:a label-free holographic method to quantify particle flow in biofluids

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Photonics Research 2023年第5期11卷 757-764页

作者： LAN YU YU WANg YANg WANg KEQUN ZHUO MIN LIU g.ulrich nienhaus PENg gAO School of Physics Xidian UniversityXi’an 710071China Institute of Applied Physics Karlsruhe Institute of Technology76128 KarlsruheGermany Institute of Nanotechnology Karlsruhe Institute of Technology76344 Eggenstein-LeopoldshafenGermany Institute of Biological and Chemical Systems Karlsruhe Institute of Technology76344 Eggenstein-LeopoldshafenGermany Department of Physics University of Illinois at Urbana-ChampaignUrbanaIllinois 61801USA

We introduce two-beam phase correlation spectroscopy(2B-ΦCS)as a label-free technique to measure the dynamics of flowing particles;e.g.,in vitro or in vivo blood flow.2B-ΦCS combines phase imaging with correlation spectroscopy,using the intrinsic refractive index contrast of particles against the fluid background in correlation *** method starts with the acquisition of a time series of phase images of flowing particles using partially coherent point-diffraction digital holographic ***,phase fluctuations from two selected circular regions in the image series are correlated to determine the concentration and flow velocity of the particles by fitting pair correlation curves with a physical model.2B-ΦCS is a facile procedure when using a microfluidic channel,as shown by the measurements on flowing yeast microparticles,polymethyl methacrylate microparticles,and diluted rat *** the latter experiment,the concentration and average diameter of rat blood cells were determined to be(4.7±1.9)×10^(6)μL^(-1)and 4.6±0.4μm,*** further analyzed the flow of mainly red blood cells in the tail vessels of live zebrafish *** and venous flow velocities were measured as290±110μm s^(-1)and 120±50μm s^(-1),*** envision that our technique will find applications in imaging transparent organisms and other areas of the life sciences and biomedicine.

关键词： flow flow holographic

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Highly Luminescent Positively Charged Quantum Dots Interacting with Proteins and Cells

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Chinese Journal of Chemistry 2022年第22期40卷 2685-2693页

作者： Haixia Wang Karin nienhaus Li Shang gerd ulrich nienhaus Institute of Applied Physics Karlsruhe Institute of Technology(KIT)76131 KarlsruheGermany Institute of Nanotechnology Karlsruhe Institute of Technology(KIT)76344 Eggenstein-LeopoldshafenGermany InstituteofBiologicaland Chemical Systems Karlsruhe Institute of Technology(KIT)76344 Eggenstein-LeopoldshafenGermany Department of Physics University of llinois at Urbana-ChampaignUrbanaIL61801USA Present address:Laboratory of Biomaterials and Translational Medicine Center for NanomedicineThe Third Affiliated HospitalSun Yat-sen UniversityGuangzhou510630China Present address:School of Materials Science and Engineering Northwestern PolytechnicalUniversityXi'an 710072China

We have studied interactions between positively charged MUTAB-stabilized quantum dots(QDs)and model proteins,serum and live cells using fluorescence correlation spectroscopy(FCS),dynamic light scattering(DLS),time-resolved photoluminescence(PL)and live-cell fluorescence *** human serum albumin(HSA)as a model protein,we measured the growth of a protein adsorption layer(“protein corona”)via time-resolved *** formation was characterized by an apparent equilibrium dissociation coefficient,KD≈10μ*** adlayer growth was surprisingly slow(timescale ca.30 min),in stark contrast to many similar measurements with HSA and other proteins and different ***-resolved PL data revealed a characteristic quenching behavior depending on the QD surface coverage with *** together,we found that MUTAB-QDs initially bind HSA molecules weakly(KD≈700μM);however,the affinity is enhanced over time,presumably due to proton injection into the MUTAB layer by HSA triggering ligand *** process was also observed with human blood serum,showing equal kinetics for comparable HSA ***,imaging experiments with cultured human cells(HeLa)revealed that MUTAB-QDs bind to the cell membrane and perforate *** process is reduced upon pre-adsorption of proteins on the MUTAB-QD.

关键词： Quantum dots Nanoparticles Agglomeration Protein adsorption Quantitative fluorescence microscopy

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Self-assembled thermosensitive luminescent nanoparticles with peptide-Au conjugates for cellular imaging and drug delivery

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Chinese Chemical Letters 2020年第3期31卷 859-864页

作者： Xiaoyuan Zhang Wei Liu Haixia Wang Xinne Zhao Zhenfang Zhang gerd ulrich nienhaus Li Shang Zhiqiang Su State Key Laboratory of Chemical Resource Engineering Beijing Key Laboratory of Advanced Functional Polymer CompositesBeijing University of Chemical TechnologyBeijing 100029China Faculty of Physics and Astronomy Friedrich Schiller University JenaJena 07743Germany Institute of Applied Physics Karlsruhe Institute of Technology(KIT)Karlsruhe 76128Germany Institute of Nanotechnology Karlsruhe Institute of Technology(KIT)Eggenstein-Leopoldshafen 76344Germany e Institute of Toxicology and genetics Karlsruhe Institute of Technology(KIT)Eggenstein-Leopoldshafen 76344Germany Department of Physics University of Illinois at Urbana-ChampaignUrbanaIL 6J801 United States State Key Laboratory of Solidification Processing Center for Nano Energy MaterialsSchool of Materials Science and EngineeringNorthwestern Polytechnical UniversityShaanxi Joint Laboratory of Graphene(NPU)Xi'an 710072China

A facile and efficient strategy has been developed to fabricate a multifunctional,theranostic anticancer drug delivery platform featuring active targeting,controlled drug release and fluorescence imaging for real-time control of *** this end,thermo sensitive poly(N-isopropyl acrylamide)(PNIPAM)nanospheres are decorated with peptide-Au cluster conjugates as a smart nanomedicine platform.A sophisticated trifunctional peptide is designed to release the anticancer drug doxorubicin(DOX),target cells and reduce Au^3+ions to form luminescent Au cluste ***,the peptide-Au cluster moieties are attached to the PNIPAM nanospheres via amide bonds rather than noncovalent interactions,significantly improving their stability in biological medium and drug release *** in vitro experiments showed that DOX was released in an efficient and controlled manner under physiological conditions.

关键词： Peptide-Au bioconjugates PNIPAM nanoparticles Fluorescence Drug delivery Cell imaging

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