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Procházková M, Kuchovská E, Killinger M, Klepárník K. Novel Förster Resonance Energy Transfer probe with quantum dot for a long-time imaging of active caspases inside individual cells. Anal Chim Acta 2023; 1267:341334. [PMID: 37257963 DOI: 10.1016/j.aca.2023.341334] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2022] [Revised: 02/28/2023] [Accepted: 05/07/2023] [Indexed: 06/02/2023]
Abstract
With the goal to investigate biological phenomena at a single-cell level, we designed, synthesized and tested a molecular probe based on Förster resonance energy transfer (FRET) between a highly luminescent quantum dot (QD) as a donor and a fluorophore or fluorescence quencher as an acceptor linked by a specific peptide. In principle, QD luminescence, effectively dissipated in the probe, is switched on after the cleavage of the peptide by a protease and the release of the quencher. We proposed a novel synthesis strategy of a probe. A two-step synthesis consists of: (i) Conjugation of CdTe QDs functionalized by -COOH groups of succinic acid on the nanoparticle surface with the designed specific peptide (GTADVEDTSC) using a ligand-exchange approach; (ii) A fast, high-yield reaction of amine-reactive succinimidyl group on the BHQ-2 quencher with N-terminal of the peptide. This way, any crosslinking between individual nanoparticles and any nonspecific conjugation bonds are excluded. The analysis of the product after the first step proved a high reaction yield and nearly no occurrence of unreacted QDs, a prerequisite of the specificity of our luminescent probe. Its parameters evaluated as Michaelis-Menten description of enzymatic kinetics are similar to products published by other groups. Our research is focused on the fluorescence microscopy analyses of biologically active molecules, such as proteolytic active caspases, playing important roles in cell signaling regulations in normal and diseased states. Consequently, they are attractive targets for clinical diagnosis and medical therapy. The ultimate goal of our work was to synthesize a new QD luminescent probe for a long-time quantitative monitoring of active caspase-3/7 distribution in apoptotic osteoblastic MC3T3-E1 cells treated with camptothecin. As a result of comparison, our synthetized luminescent probe provides longer imaging times of caspases than commercial products. The probe proved the stability of the luminescence signal inside cells for more than 14 days.
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Affiliation(s)
- Markéta Procházková
- Department of Bioanalytical Instrumentation, Institute of Analytical Chemistry, v.v.i., Czech Academy of Sciences, Veveří 97, 602 00, Brno, Czech Republic; Department of Chemistry, Faculty of Science, Masaryk University, Kotlářská 267/2, 611 37, Brno, Czech Republic.
| | - Eliška Kuchovská
- Department of Bioanalytical Instrumentation, Institute of Analytical Chemistry, v.v.i., Czech Academy of Sciences, Veveří 97, 602 00, Brno, Czech Republic.
| | - Michael Killinger
- Department of Bioanalytical Instrumentation, Institute of Analytical Chemistry, v.v.i., Czech Academy of Sciences, Veveří 97, 602 00, Brno, Czech Republic; Department of Chemistry, Faculty of Science, Masaryk University, Kotlářská 267/2, 611 37, Brno, Czech Republic.
| | - Karel Klepárník
- Department of Bioanalytical Instrumentation, Institute of Analytical Chemistry, v.v.i., Czech Academy of Sciences, Veveří 97, 602 00, Brno, Czech Republic.
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Han Z, Vaidya RM, Arogundade OH, Ma L, Zahid MU, Sarkar S, Kuo CW, Selvin PR, Smith AM. Structural Design of Multidentate Copolymers as Compact Quantum Dot Coatings for Live-Cell Single-Particle Imaging. CHEMISTRY OF MATERIALS : A PUBLICATION OF THE AMERICAN CHEMICAL SOCIETY 2022; 34:4621-4632. [PMID: 36968145 PMCID: PMC10038122 DOI: 10.1021/acs.chemmater.2c00498] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Quantum dots (QDs) are a class of semiconductor nanocrystal used broadly as fluorescent emitters for analytical studies in the life sciences. These nanomaterials are particularly valuable for single-particle imaging and tracking applications in cells and tissues. An ongoing technological goal is to reduce the hydrodynamic size of QDs to enhance access to sterically hindered biological targets. Multidentate polymer coatings are a focus of these efforts and have resulted in compact and stable QDs with hydrodynamic diameters near 10 nm. New developments are needed to reach smaller sizes to further enhance transport through pores in cells and tissues. Here, we describe how structural characteristics of linear multidentate copolymers determine hydrodynamic size, colloidal stability, and biomolecular interactions of coated QDs. We tune copolymer composition, degree of polymerization, and hydrophilic group length, and coat polymers on CdSe and (core)shell (HgCdSe)CdZnS QDs. We find that a broad range of polymer structures and compositions yield stable colloidal dispersions; however, hydrodynamic size minimization and nonspecific binding resistance can only be simultaneously achieved within a narrow range of properties, requiring short polymers, balanced compositions, and small nanocrystals. In quantitative single-molecule imaging assays in synapses of live neurons, size reduction progressively increases labeling specificity of neurotransmitter receptors. Our findings provide a design roadmap to next-generation QDs with sizes approaching fluorescent protein labels that are the standard of many live-cell biomolecular studies.
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Affiliation(s)
- Zhiyuan Han
- Department of Materials Science and Engineering and Holonyak Micro and Nanotechnology Laboratory, University of Illinois Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Rohit M Vaidya
- Center for Biophysics and Quantitative Biology, University of Illinois Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Opeyemi H Arogundade
- Holonyak Micro and Nanotechnology Laboratory and Department of Bioengineering, University of Illinois Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Liang Ma
- Department of Materials Science and Engineering and Holonyak Micro and Nanotechnology Laboratory, University of Illinois Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Mohammad U Zahid
- Holonyak Micro and Nanotechnology Laboratory and Department of Bioengineering, University of Illinois Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Suresh Sarkar
- Holonyak Micro and Nanotechnology Laboratory and Department of Bioengineering, University of Illinois Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Chia-Wei Kuo
- Department of Bioengineering, University of Illinois Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Paul R Selvin
- Center for Biophysics and Quantitative Biology, Center for the Physics of Living Cells, and Department of Physics, University of Illinois Urbana-Champaign, Urbana, Illinois 61801, United States-8163
| | - Andrew M Smith
- Department of Materials Science and Engineering, Holonyak Micro and Nanotechnology Laboratory, Department of Bioengineering, Cancer Center at Illinois, and Carl R. Woese Institute for Genomic Biology, University of Illinois Urbana-Champaign, Urbana, Illinois 61801, United States
- Carle Illinois College of Medicine, Urbana, Illinois 61801, United States
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Single molecule tracking of bacterial cell surface cytochromes reveals dynamics that impact long-distance electron transport. Proc Natl Acad Sci U S A 2022; 119:e2119964119. [PMID: 35503913 PMCID: PMC9171617 DOI: 10.1073/pnas.2119964119] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Multiheme cytochromes in Shewanella oneidensis MR-1 transport electrons across the cell wall, in a process called extracellular electron transfer. These electron conduits can also enable electron transport along and between cells. While the underlying mechanism is thought to involve a combination of electron hopping and lateral diffusion of cytochromes along membranes, these diffusive dynamics have never been observed in vivo. Here, we observe the mobility of quantum dot-labeled cytochromes on living cell surfaces and membrane nanowires, quantify their diffusion with single-particle tracking techniques, and simulate the contribution of these dynamics to electron transport. This work reveals the impact of redox molecule dynamics on bacterial electron transport, with implications for understanding and harnessing this process in the environment and bioelectronics. Using a series of multiheme cytochromes, the metal-reducing bacterium Shewanella oneidensis MR-1 can perform extracellular electron transfer (EET) to respire redox-active surfaces, including minerals and electrodes outside the cell. While the role of multiheme cytochromes in transporting electrons across the cell wall is well established, these cytochromes were also recently found to facilitate long-distance (micrometer-scale) redox conduction along outer membranes and across multiple cells bridging electrodes. Recent studies proposed that long-distance conduction arises from the interplay of electron hopping and cytochrome diffusion, which allows collisions and electron exchange between cytochromes along membranes. However, the diffusive dynamics of the multiheme cytochromes have never been observed or quantified in vivo, making it difficult to assess their hypothesized contribution to the collision-exchange mechanism. Here, we use quantum dot labeling, total internal reflection fluorescence microscopy, and single-particle tracking to quantify the lateral diffusive dynamics of the outer membrane-associated decaheme cytochromes MtrC and OmcA, two key components of EET in S. oneidensis. We observe confined diffusion behavior for both quantum dot-labeled MtrC and OmcA along cell surfaces (diffusion coefficients DMtrC = 0.0192 ± 0.0018 µm2/s, DOmcA = 0.0125 ± 0.0024 µm2/s) and the membrane extensions thought to function as bacterial nanowires. We find that these dynamics can trace a path for electron transport via overlap of cytochrome trajectories, consistent with the long-distance conduction mechanism. The measured dynamics inform kinetic Monte Carlo simulations that combine direct electron hopping and redox molecule diffusion, revealing significant electron transport rates along cells and membrane nanowires.
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Bradsher CE, Ontko CD, Koziel AC, McBride JR, Rosenthal SJ. Fluorescent Colloidal Ferroelectric Nanocrystals. J Am Chem Soc 2022; 144:1509-1512. [DOI: 10.1021/jacs.1c09821] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Affiliation(s)
- Cara E. Bradsher
- Department of Chemistry, Vanderbilt University, VU Station B Box 351822, Nashville, Tennessee 37235, United States
| | - Cayla D. Ontko
- Department of Chemistry, Vanderbilt University, VU Station B Box 351822, Nashville, Tennessee 37235, United States
| | - Alexandra C. Koziel
- Department of Chemistry, Vanderbilt University, VU Station B Box 351822, Nashville, Tennessee 37235, United States
| | - James R. McBride
- Department of Chemistry, Vanderbilt University, VU Station B Box 351822, Nashville, Tennessee 37235, United States
- Vanderbilt Institute for Nanoscale Science and Engineering, Vanderbilt University, VU Station B Box 351822, Nashville, Tennessee 37235, United States
- Department of Interdisciplinary Materials Science, Vanderbilt University, VU Station B Box 351822, Nashville, Tennessee 37235, United States
| | - Sandra J. Rosenthal
- Department of Chemistry, Vanderbilt University, VU Station B Box 351822, Nashville, Tennessee 37235, United States
- Vanderbilt Institute for Nanoscale Science and Engineering, Vanderbilt University, VU Station B Box 351822, Nashville, Tennessee 37235, United States
- Department of Interdisciplinary Materials Science, Vanderbilt University, VU Station B Box 351822, Nashville, Tennessee 37235, United States
- Department of Pharmacology, Vanderbilt University, VU Station B Box 351822, Nashville, Tennessee 37235, United States
- Department of Physics and Astronomy, Vanderbilt University, VU Station B Box 351822, Nashville, Tennessee 37235, United States
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Tomlinson ID, Kovtun O, Torres R, Bellocchio LG, Josephs T, Rosenthal SJ. A Novel Biotinylated Homotryptamine Derivative for Quantum Dot Imaging of Serotonin Transporter in Live Cells. Front Cell Neurosci 2021; 15:667044. [PMID: 34867196 PMCID: PMC8637195 DOI: 10.3389/fncel.2021.667044] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2021] [Accepted: 10/19/2021] [Indexed: 11/21/2022] Open
Abstract
The serotonin transporter (SERT) is the primary target for selective serotonin reuptake inhibitor (SSRI) antidepressants that are thought to exert their therapeutic effects by increasing the synaptic concentration of serotonin. Consequently, probes that can be utilized to study cellular trafficking of SERT are valuable research tools. We have developed a novel ligand (IDT785) that is composed of a SERT antagonist (a tetrahydro pyridyl indole derivative) conjugated to a biotinylated poly ethylene glycol (PEG) via a phenethyl linker. This compound was determined to be biologically active and inhibited SERT-mediated reuptake of IDT307 with the half-maximal inhibitory concentration of 7.2 ± 0.3 μM. We demonstrated that IDT785 enabled quantum dot (QD) labeling of membrane SERT in transfected HEK-293 cultures that could be blocked using the high affinity serotonin reuptake inhibitor paroxetine. Molecular docking studies suggested that IDT785 might be binding to the extracellular vestibule binding site rather than the orthosteric substrate binding site, which could be attributable to the hydrophilicity of the PEG chain and the increased loss of degrees of freedom that would be required to penetrate into the orthosteric binding site. Using IDT785, we were able to study the membrane localization and membrane dynamics of YFP-SERT heterologously expressed in HEK-293 cells and demonstrated that SERT expression was enriched in the membrane edge and in thin cellular protrusions.
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Affiliation(s)
- Ian D. Tomlinson
- Department of Chemistry, Vanderbilt University, Nashville, TN, United States
| | - Oleg Kovtun
- Department of Chemistry, Vanderbilt University, Nashville, TN, United States
| | - Ruben Torres
- Department of Chemistry, Vanderbilt University, Nashville, TN, United States
- Vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, TN, United States
| | | | - Travis Josephs
- Neuroscience Program, Vanderbilt University, Nashville, TN, United States
| | - Sandra J. Rosenthal
- Department of Chemistry, Vanderbilt University, Nashville, TN, United States
- Vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, TN, United States
- Department of Pharmacology, Vanderbilt University, Nashville, TN, United States
- Department of Chemical and Biomolecular Engineering, Vanderbilt University, Nashville, TN, United States
- Department of Physics and Astronomy, Vanderbilt University, Nashville, TN, United States
- Vanderbilt Institute of Nanoscale Science and Engineering, Vanderbilt University, Nashville, TN, United States
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Kovtun O, Torres R, Bellocchio LG, Rosenthal SJ. Membrane Nanoscopic Organization of D2L Dopamine Receptor Probed by Quantum Dot Tracking. MEMBRANES 2021; 11:578. [PMID: 34436341 PMCID: PMC8401772 DOI: 10.3390/membranes11080578] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Revised: 07/26/2021] [Accepted: 07/26/2021] [Indexed: 01/11/2023]
Abstract
The role of lateral mobility and nanodomain organization of G protein-coupled receptors in modulating subcellular signaling has been under increasing scrutiny. Investigation of D2 dopamine receptor diffusion dynamics is of particular interest, as these receptors have been linked to altered neurotransmission in affective disorders and represent the primary target for commonly prescribed antipsychotics. Here, we applied our single quantum dot tracking approach to decipher intrinsic diffusion patterns of the wild-type long isoform of the D2 dopamine receptor and its genetic variants previously identified in several cohorts of schizophrenia patients. We identified a subtle decrease in the diffusion rate of the Val96Ala mutant that parallels its previously reported reduced affinity for potent neuroleptics clozapine and chlorpromazine. Slower Val96Ala variant diffusion was not accompanied by a change in receptor-receptor transient interactions as defined by the diffraction-limited quantum dot colocalization events. In addition, we implemented a Voronoї tessellation-based algorithm to compare nanoclustering of the D2 dopamine receptor to the dominant anionic phospholipid phosphatidylinositol 4,5-bisphosphate in the plasma membrane of live cells.
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Affiliation(s)
- Oleg Kovtun
- Department of Chemistry, Vanderbilt University, Nashville, TN 37235, USA; (R.T.); (L.G.B.)
| | - Ruben Torres
- Department of Chemistry, Vanderbilt University, Nashville, TN 37235, USA; (R.T.); (L.G.B.)
- Vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, TN 37235, USA
| | - Laurel G. Bellocchio
- Department of Chemistry, Vanderbilt University, Nashville, TN 37235, USA; (R.T.); (L.G.B.)
| | - Sandra Jean Rosenthal
- Department of Chemistry, Vanderbilt University, Nashville, TN 37235, USA; (R.T.); (L.G.B.)
- Vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, TN 37235, USA
- Department of Pharmacology, Vanderbilt University, Nashville, TN 37235, USA
- Department of Chemical and Biomolecular Engineering, Vanderbilt University, Nashville, TN 37235, USA
- Vanderbilt Institute of Nanoscale Science and Engineering, Vanderbilt University, Nashville, TN 37235, USA
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Kovtun O, Torres R, Ferguson RS, Josephs T, Rosenthal SJ. Single Quantum Dot Tracking Unravels Agonist Effects on the Dopamine Receptor Dynamics. Biochemistry 2021; 60:1031-1043. [PMID: 32584548 DOI: 10.1021/acs.biochem.0c00360] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
D2 dopamine receptors (DRD2s) belong to a family of G protein-coupled receptors that modulate synaptic dopaminergic tone via regulation of dopamine synthesis, storage, and synaptic release. DRD2s are the primary target for traditional antipsychotic medications; dysfunctional DRD2 signaling has been linked to major depressive disorder, attention-deficit hyperactivity disorder, addiction, Parkinson's, and schizophrenia. DRD2 lateral diffusion appears to be an important post-translational regulatory mechanism; however, the dynamic response of DRD2s to ligand-induced activation is poorly understood. Dynamic imaging of the long isoform of DRD2 (D2L) fused to an N-terminal antihemagglutinin (HA) epitope and transiently expressed in HEK-293 cells was achieved through a combination of a high-affinity biotinylated anti-HA antigen-binding fragment (Fab) and streptavidin-conjugated quantum dots (QD). Significant reduction (∼40%) in the rate of lateral diffusion of QD-tagged D2L proteins was observed under agonist (quinpirole; QN)-stimulated conditions compared to basal conditions. QN-induced diffusional slowing was accompanied by an increase in frequency, lifetime, and confinement of temporary arrest of lateral diffusion (TALL), an intrinsic property of single receptor lateral motion. The role of the actin cytoskeleton in QN-induced diffusional slowing of D2L was also explored. The observed dynamic changes appear to be a sensitive indicator of the receptor activity status and might also spatially and temporally shape the receptor-mediated downstream signaling. This dynamic information could potentially be useful in informing drug discovery efforts based on single-molecule pharmacology.
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Affiliation(s)
- Oleg Kovtun
- Department of Chemistry, Vanderbilt University, Nashville, Tennessee 37240, United States
| | - Ruben Torres
- Department of Chemistry, Vanderbilt University, Nashville, Tennessee 37240, United States
- Vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, Tennessee 37240, United States
| | - Riley S Ferguson
- Department of Chemistry, Vanderbilt University, Nashville, Tennessee 37240, United States
| | - Travis Josephs
- Neuroscience Program, Vanderbilt University, Nashville, Tennessee 37240, United States
| | - Sandra J Rosenthal
- Department of Chemistry, Vanderbilt University, Nashville, Tennessee 37240, United States
- Department of Pharmacology, Vanderbilt University, Nashville, Tennessee 37240, United States
- Department of Physics and Astronomy, Vanderbilt University, Nashville, Tennessee 37240, United States
- Department of Chemical and Biomolecular Engineering, Vanderbilt University, Nashville, Tennessee 37240, United States
- Vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, Tennessee 37240, United States
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Peckys DB, Quint C, Jonge ND. Determining the Efficiency of Single Molecule Quantum Dot Labeling of HER2 in Breast Cancer Cells. NANO LETTERS 2020; 20:7948-7955. [PMID: 33034459 DOI: 10.1021/acs.nanolett.0c02644] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Quantum dots exhibit unique properties compared to other fluorophores, such as bright fluorescence and lack of photobleaching, resulting in their widespread utilization as fluorescent protein labels in the life sciences. However, their application is restricted to relative quantifications due to lacking knowledge about the labeling efficiency. We here present a strategy for determining the labeling efficiency of quantum dot labeling of HER2 in overexpressing breast cancer cells. Correlative light- and liquid-phase electron microscopy of whole cells was used to convert fluorescence intensities into the underlying molecular densities of the quantum dots. The labeling procedure with small affinity proteins was optimized yielding a maximal labeling efficiency of 83%, which was applicable to the high amount of ∼1.5 × 106 HER2 per cell. With the labeling efficiency known, it is now possible to derive the absolute protein expression levels in the plasma membrane and its variation within a cell and between cells.
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Affiliation(s)
- Diana B Peckys
- Molecular Biophysics, Center for Integrative Physiology and Molecular Medicine, Saarland University, 66421 Homburg, Germany
| | - Cedric Quint
- Department of Physics, Saarland University, 66123 Saarbrücken, Germany
| | - Niels de Jonge
- Department of Physics, Saarland University, 66123 Saarbrücken, Germany
- INM - Leibniz Institute for New Materials, 66123 Saarbrücken, Germany
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Rosenthal SJ, Josephs T, Kovtun O, McCarty R. Seasonal effects on bipolar disorder: A closer look. Neurosci Biobehav Rev 2020; 115:199-219. [DOI: 10.1016/j.neubiorev.2020.05.017] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2020] [Revised: 05/22/2020] [Accepted: 05/25/2020] [Indexed: 11/15/2022]
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Freymeyer NJ, Click SM, Reid KR, Chisholm MF, Bradsher CE, McBride JR, Rosenthal SJ. Effect of indium alloying on the charge carrier dynamics of thick-shell InP/ZnSe quantum dots. J Chem Phys 2020; 152:161104. [PMID: 32357779 DOI: 10.1063/1.5145189] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Thick-shell InP/ZnSe III-V/II-VI quantum dots (QDs) were synthesized with two distinct interfaces between the InP core and ZnSe shell: alloy and core/shell. Despite sharing similar optical properties in the spectral domain, these two QD systems have differing amounts of indium incorporation in the shell as determined by high-resolution energy-dispersive x-ray spectroscopy scanning transmission electron microscopy. Ultrafast fluorescence upconversion spectroscopy was used to probe the charge carrier dynamics of these two systems and shows substantial charge carrier trapping in both systems that prevents radiative recombination and reduces the photoluminescence quantum yield. The alloy and core/shell QDs show slight differences in the extent of charge carrier localization with more extensive trapping observed in the alloy nanocrystals. Despite the ability to grow a thick shell, structural defects caused by III-V/II-VI charge carrier imbalances still need to be mitigated to further improve InP QDs.
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Affiliation(s)
| | - Sophia M Click
- Department of Chemistry, Vanderbilt University, Nashville, Tennessee 37235, USA
| | - Kemar R Reid
- Vanderbilt Institute of Nanoscale Science and Engineering, Vanderbilt University, Nashville, Tennessee 37235, USA
| | - Matthew F Chisholm
- Material Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830, USA
| | - Cara E Bradsher
- Department of Chemistry, Vanderbilt University, Nashville, Tennessee 37235, USA
| | - James R McBride
- Department of Chemistry, Vanderbilt University, Nashville, Tennessee 37235, USA
| | - Sandra J Rosenthal
- Department of Chemistry, Vanderbilt University, Nashville, Tennessee 37235, USA
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Quantitative Analysis of Single Quantum Dot Trajectories. Methods Mol Biol 2020. [PMID: 32246331 DOI: 10.1007/978-1-0716-0463-2_6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
Abstract
Single quantum dot tracking (SQDT) is a powerful technique for interrogating biomolecular dynamics in living cells and tissue. SQDT has particularly excelled in driving discovery at the single-molecule level in the fields of neuronal communication, plasma membrane organization, viral infection, and immune system response. Here, we briefly characterize various elements of the SQDT analytical framework and provide the reader with a detailed set of executable commands to implement commonly used algorithms for SQDT data processing.
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Sarkar S, Le P, Geng J, Liu Y, Han Z, Zahid MU, Nall D, Youn Y, Selvin PR, Smith AM. Short-Wave Infrared Quantum Dots with Compact Sizes as Molecular Probes for Fluorescence Microscopy. J Am Chem Soc 2020; 142:3449-3462. [PMID: 31964143 PMCID: PMC7335634 DOI: 10.1021/jacs.9b11567] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Materials with short-wave infrared (SWIR) emission are promising contrast agents for in vivo animal imaging, providing high-contrast and high-resolution images of blood vessels in deep tissues. However, SWIR emitters have not been developed as molecular labels for microscopy applications in the life sciences, which require optimized probes that are bright, stable, and small. Here, we design and synthesize semiconductor quantum dots (QDs) with SWIR emission based on HgxCd1-xSe alloy cores red shifted to the SWIR by epitaxial deposition of thin HgxCd1-xS shells with a small band gap. By tuning alloy composition alone, the emission can be shifted across the visible-to-SWIR (VIR) spectra while maintaining a small and equal size, allowing direct comparisons of molecular labeling performance across a broad range of wavelength. After coating with click-functional multidentate polymers, the VIR-QD spectral series has high quantum yield in the SWIR (14-33%), compact size (13 nm hydrodynamic diameter), and long-term stability in aqueous media during continuous excitation. We show that these properties enable diverse applications of SWIR molecular probes for fluorescence microscopy using conjugates of antibodies, growth factors, and nucleic acids. A broadly useful outcome is a 10-55-fold enhancement of the signal-to-background ratio at both the single-molecule level and the ensemble level in the SWIR relative to visible wavelengths, primarily due to drastically reduced autofluorescence. We anticipate that VIR-QDs with SWIR emission will enable ultrasensitive molecular imaging of low-copy number analytes in biospecimens with high autofluorescence.
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Affiliation(s)
- Suresh Sarkar
- Department of Bioengineering , University of Illinois at Urbana-Champaign , Urbana , Illinois 61801 , United States
- Micro and Nanotechnology Laboratory , University of Illinois at Urbana-Champaign , Urbana , Illinois 61801 , United States
| | - Phuong Le
- Department of Bioengineering , University of Illinois at Urbana-Champaign , Urbana , Illinois 61801 , United States
- Micro and Nanotechnology Laboratory , University of Illinois at Urbana-Champaign , Urbana , Illinois 61801 , United States
| | - Junlong Geng
- Micro and Nanotechnology Laboratory , University of Illinois at Urbana-Champaign , Urbana , Illinois 61801 , United States
- Beckman Institute for Advanced Science and Technology , University of Illinois at Urbana-Champaign , Urbana , Illinois 61801 , United States
| | - Yang Liu
- Department of Bioengineering , University of Illinois at Urbana-Champaign , Urbana , Illinois 61801 , United States
- Micro and Nanotechnology Laboratory , University of Illinois at Urbana-Champaign , Urbana , Illinois 61801 , United States
| | - Zhiyuan Han
- Micro and Nanotechnology Laboratory , University of Illinois at Urbana-Champaign , Urbana , Illinois 61801 , United States
- Department of Materials Science and Engineering , University of Illinois at Urbana-Champaign , Urbana , Illinois 61801 , United States
| | - Mohammad U Zahid
- Department of Bioengineering , University of Illinois at Urbana-Champaign , Urbana , Illinois 61801 , United States
- Micro and Nanotechnology Laboratory , University of Illinois at Urbana-Champaign , Urbana , Illinois 61801 , United States
| | - Duncan Nall
- Department of Physics , University of Illinois at Urbana-Champaign , Urbana , Illinois 61801 , United States
- Center for the Physics of Living Cells , University of Illinois at Urbana-Champaign , Urbana , Illinois 61801 , United States
| | - Yeoan Youn
- Center for the Physics of Living Cells , University of Illinois at Urbana-Champaign , Urbana , Illinois 61801 , United States
- Center for Biophysics and Quantitative Biology , University of Illinois at Urbana-Champaign , Urbana , Illinois 61801 , United States
| | - Paul R Selvin
- Department of Physics , University of Illinois at Urbana-Champaign , Urbana , Illinois 61801 , United States
- Center for the Physics of Living Cells , University of Illinois at Urbana-Champaign , Urbana , Illinois 61801 , United States
- Center for Biophysics and Quantitative Biology , University of Illinois at Urbana-Champaign , Urbana , Illinois 61801 , United States
| | - Andrew M Smith
- Department of Bioengineering , University of Illinois at Urbana-Champaign , Urbana , Illinois 61801 , United States
- Micro and Nanotechnology Laboratory , University of Illinois at Urbana-Champaign , Urbana , Illinois 61801 , United States
- Department of Materials Science and Engineering , University of Illinois at Urbana-Champaign , Urbana , Illinois 61801 , United States
- Carl R. Woese Institute for Genomic Biology , University of Illinois at Urbana-Champaign , Urbana , Illinois 61801 , United States
- Carle Illinois College of Medicine , Urbana , Illinois 61801 , United States
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Thal LB, Mann VR, Sprinzen D, McBride JR, Reid KR, Tomlinson ID, McMahon DG, Cohen BE, Rosenthal SJ. Ligand-conjugated quantum dots for fast sub-diffraction protein tracking in acute brain slices. Biomater Sci 2020; 8:837-845. [PMID: 31790090 PMCID: PMC7002256 DOI: 10.1039/c9bm01629e] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Semiconductor quantum dots (QDs) have demonstrated utility in long-term single particle tracking of membrane proteins in live cells in culture. To extend the superior optical properties of QDs to more physiologically relevant cell platforms, such as acute brain slices, we examine the photophysics of compact ligand-conjugated CdSe/CdS QDs using both ensemble and single particle analysis in brain tissue media. We find that symmetric core passivation is critical for both photostability in oxygenated media and for prolonged single particle imaging in brain slices. We then demonstrate the utility of these QDs by imaging single dopamine transporters in acute brain slices, achieving 20 nm localization precision at 10 Hz frame rates. These findings detail design requirements needed for new QD probes in complex living environments, and open the door to physiologically relevant studies that capture the utility of QD probes in acute brain slices.
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Affiliation(s)
- Lucas B Thal
- Department of Chemistry, Vanderbilt University, Nashville, TN 37235, USA.
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Thal LB, Kovtun O, Rosenthal SJ. Labeling Neuronal Proteins with Quantum Dots for Single-Molecule Imaging. Methods Mol Biol 2020; 2135:169-177. [PMID: 32246334 DOI: 10.1007/978-1-0716-0463-2_9] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Single-molecule imaging has illuminated dynamics and kinetics of neuronal proteins in their native membranes helping us understand their effective roles in the brain. Here, we describe how nanometer-sized fluorescent semiconductors called quantum dots (QD) can be used to label neuronal proteins in a single QD imaging format. We detail two generalizable protocols accompanied by experimental considerations giving the user options in approach tailored to the materials and equipment available. These protocols can be modified for experiments to verify target specificity, as well as single molecule analysis such as single particle tracking and protein clustering.
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Affiliation(s)
- Lucas B Thal
- Department of Chemistry, Vanderbilt University, Nashville, TN, USA
- Vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, TN, USA
| | - Oleg Kovtun
- Department of Chemistry, Vanderbilt University, Nashville, TN, USA
| | - Sandra J Rosenthal
- Department of Chemistry, Vanderbilt University, Nashville, TN, USA.
- Vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, TN, USA.
- Department of Pharmacology, Vanderbilt University, Nashville, TN, USA.
- Department of Physics and Astronomy, Vanderbilt University, Nashville, TN, USA.
- Department of Chemical and Biomolecular Engineering, Vanderbilt University, Nashville, TN, USA.
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Kovtun O, Tomlinson ID, Ferguson RS, Rosenthal SJ. Quantum dots reveal heterogeneous membrane diffusivity and dynamic surface density polarization of dopamine transporter. PLoS One 2019; 14:e0225339. [PMID: 31751387 PMCID: PMC6872175 DOI: 10.1371/journal.pone.0225339] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2019] [Accepted: 11/01/2019] [Indexed: 12/11/2022] Open
Abstract
The presynaptic dopamine transporter mediates rapid reuptake of synaptic dopamine. Although cell surface DAT trafficking recently emerged as an important component of DAT regulation, it has not been systematically investigated. Here, we apply our single quantum dot (Qdot) tracking approach to monitor DAT plasma membrane dynamics in several heterologous expression cell hosts with nanometer localization accuracy. We demonstrate that Qdot-tagged DAT proteins exhibited highly heterogeneous membrane diffusivity dependent on the local membrane topography. We also show that Qdot-tagged DATs were localized away from the flat membrane regions and were dynamically retained in the membrane protrusions and cell edges for the duration of imaging. Single quantum dot tracking of wildtype DAT and its conformation-defective coding variants (R60A and W63A) revealed a significantly accelerated rate of dysfunctional DAT membrane diffusion. We believe our results warrant an in-depth investigation as to whether compromised membrane dynamics is a common feature of brain disorder-derived DAT mutants.
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Affiliation(s)
- Oleg Kovtun
- Department of Chemistry, Vanderbilt University, Nashville, Tennessee, United States of America
- Vanderbilt Institute of Nanoscale Science and Engineering, Vanderbilt University, Nashville, Tennessee, United States of America
| | - Ian D. Tomlinson
- Department of Chemistry, Vanderbilt University, Nashville, Tennessee, United States of America
- Vanderbilt Institute of Nanoscale Science and Engineering, Vanderbilt University, Nashville, Tennessee, United States of America
| | - Riley S. Ferguson
- Department of Chemistry, Vanderbilt University, Nashville, Tennessee, United States of America
| | - Sandra J. Rosenthal
- Department of Chemistry, Vanderbilt University, Nashville, Tennessee, United States of America
- Vanderbilt Institute of Nanoscale Science and Engineering, Vanderbilt University, Nashville, Tennessee, United States of America
- Department of Pharmacology, Vanderbilt University, Nashville, Tennessee, United States of America
- Department of Chemical and Biomolecular Engineering, Vanderbilt University, Nashville, Tennessee, United States of America
- Department of Physics and Astronomy, Vanderbilt University, Nashville, Tennessee, United States of America
- Vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, Tennessee, United States of America
- * E-mail:
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Tomlinson ID, Kovtun O, Crescentini TM, Rosenthal SJ. Biotinylated-spiperone ligands for quantum dot labeling of the dopamine D2 receptor in live cell cultures. Bioorg Med Chem Lett 2019; 29:959-964. [DOI: 10.1016/j.bmcl.2019.02.024] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2018] [Revised: 02/19/2019] [Accepted: 02/21/2019] [Indexed: 12/26/2022]
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Abstract
Quantum dots are nanometer-sized semiconductors that have size-tunable, narrow emission bands, high quantum yields, and are resistant to photobleaching. Ligand-conjugated quantum dots enable the real time visualization of membrane proteins and have revealed that membrane diffusion dynamics are intrinsic to protein regulation, are susceptible to the level of membrane cholesterol, and are altered in genetic variants linked to disease, suggesting a mise en place approach to neuropsychopharmacology.
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Affiliation(s)
- Sandra J. Rosenthal
- Department of Chemistry, Department of Physics and Astronomy, Department of Pharmacology, and the Department of Chemical and Biomolecular Engineering, and Vanderbilt Institute of Nanoscale Science and Engineering Vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, Tennessee 37235, United States
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Thal LB, Tomlinson ID, Quinlan MA, Kovtun O, Blakely RD, Rosenthal SJ. Single Quantum Dot Imaging Reveals PKCβ-Dependent Alterations in Membrane Diffusion and Clustering of an Attention-Deficit Hyperactivity Disorder/Autism/Bipolar Disorder-Associated Dopamine Transporter Variant. ACS Chem Neurosci 2019; 10:460-471. [PMID: 30153408 PMCID: PMC6411462 DOI: 10.1021/acschemneuro.8b00350] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The dopamine transporter (DAT) is a transmembrane protein that terminates dopamine signaling in the brain by driving rapid dopamine reuptake into presynaptic nerve terminals. Several lines of evidence indicate that DAT dysfunction is linked to neuropsychiatric disorders such as attention-deficit/hyperactivity disorder (ADHD), bipolar disorder (BPD), and autism spectrum disorder (ASD). Indeed, individuals with these disorders have been found to express the rare, functional DAT coding variant Val559, which confers anomalous dopamine efflux (ADE) in vitro and in vivo. To elucidate the impact of the DAT Val559 variant on membrane diffusion dynamics, we implemented our antagonist-conjugated quantum dot (QD) labeling approach to monitor the lateral mobility of single particle-labeled transporters in transfected HEK-293 and SK-N-MC cells. Our results demonstrate significantly higher diffusion coefficients of DAT Val559 compared to those of DAT Ala559, effects likely determined by elevated N-terminal transporter phosphorylation. We also provide pharmacological evidence that PKCβ-mediated signaling supports enhanced DAT Val559 membrane diffusion rates. Additionally, our results are complimented with diffusion rates of phosphomimicked and phosphorylation-occluded DAT variants. Furthermore, we show DAT Val559 has a lower propensity for membrane clustering, which may be caused by a mutation-derived shift out of membrane microdomains leading to faster lateral membrane diffusion rates. These findings further demonstrate a functional impact of DAT Val559 and suggest that changes in transporter localization and lateral mobility may sustain ADE and contribute to alterations in dopamine signaling underlying multiple neuropsychiatric disorders.
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