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Yang J, Zhu B, Ran C. The Application of Bio-orthogonality for In Vivo Animal Imaging. Chem Biomed Eng 2023; 1:434-447. [PMID: 37655167 PMCID: PMC10466453 DOI: 10.1021/cbmi.3c00033] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/15/2023] [Revised: 06/06/2023] [Accepted: 06/08/2023] [Indexed: 09/02/2023]
Abstract
The application of bio-orthogonality has greatly facilitated numerous aspects of biological studies in recent years. In particular, bio-orthogonal chemistry has transformed biological research, including in vitro conjugate chemistry, target identification, and biomedical imaging. In this review, we highlighted examples of bio-orthogonal in vivo imaging published in recent years. We grouped the references into two major categories: bio-orthogonal chemistry-related imaging and in vivo imaging with bio-orthogonal nonconjugated pairing. Lastly, we discussed the challenges and opportunities of bio-orthogonality for in vivo imaging.
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Affiliation(s)
- Jun Yang
- Athinoula
A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital/Harvard Medical School, Room 2301, Building 149, Charlestown, Boston, Massachusetts 02129, United States
| | - Biyue Zhu
- Athinoula
A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital/Harvard Medical School, Room 2301, Building 149, Charlestown, Boston, Massachusetts 02129, United States
| | - Chongzhao Ran
- Athinoula
A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital/Harvard Medical School, Room 2301, Building 149, Charlestown, Boston, Massachusetts 02129, United States
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2
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Tian M, Zhu Y, Guan W, Lu C. Quantitative Measurement of Drug Release Dynamics within Targeted Organelles Using Förster Resonance Energy Transfer. Small 2023:e2206866. [PMID: 37026420 DOI: 10.1002/smll.202206866] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/07/2022] [Revised: 03/01/2023] [Indexed: 06/19/2023]
Abstract
Measuring the release dynamics of drug molecules after their delivery to the target organelle is critical to improve therapeutic efficacy and reduce side effects. However, it remains challenging to quantitatively monitor subcellular drug release in real time. To address the knowledge gap, a novel gemini fluorescent surfactant capable of forming mitochondria-targeted and redox-responsive nanocarriers is designed. A quantitative Förster resonance energy transfer (FRET) platform is fabricated using this mitochondria-anchored fluorescent nanocarrier as a FRET donor and fluorescent drugs as a FRET acceptor. The FRET platform enables real-time measurement of drug release from organelle-targeted nanocarriers. Moreover, the obtained drug release dynamics can evaluate the duration of drug release at the subcellular level, which established a new quantitative method for organelle-targeted drug release. This quantitative FRET platform can compensate for the absent assessment of the targeted release performances of nanocarriers, offering in-depth understanding of the drug release behaviors at the subcellular targets.
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Affiliation(s)
- Mingce Tian
- State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing, 100029, China
| | - Yaping Zhu
- State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing, 100029, China
| | - Weijiang Guan
- State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing, 100029, China
| | - Chao Lu
- State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing, 100029, China
- Green Catalysis Center, College of Chemistry, Zhengzhou University, Zhengzhou, 450001, China
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3
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Tan M, Li X, Zhang H, Zheng M, Xiong J, Cao Y, Cao G, Wang Z, Ran H. Förster Resonance Energy Transfer Nanobullet for Photoacoustic Imaging and Amplified Photothermal-Photodynamic Therapy of Cancer. Adv Healthc Mater 2023:e2202943. [PMID: 36773308 DOI: 10.1002/adhm.202202943] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2022] [Revised: 02/05/2023] [Indexed: 02/12/2023]
Abstract
Synergistic photodynamic and photothermal therapy (PDT-PTT) has emerged as an appealing effective antitumor approach. However, clinical utilization of PDT-PTT is plagued by aggregation-caused photobleaching, sequential double irradiations, unsatisfying balance between single oxygen (1 O2 ) quantum yield and photothermal conversion efficiency. Here, an anchored tumor-homing cell-penetrating peptide (PEGA-pVEC) and PANI-ES/HMME loaded FRET nanobullet (AHP-P) are reported. Within nanobullet, HMME (donor) and PANI-ES (acceptor) spontaneously form a förster resonance energy transfer (FRET) pair. Upon 660 nm laser irradiation, HMME convert near-infrared fluorescence (NIRF) to PANI, thus produce FRET-amplified photoacoustic imaging guided PTT. In addition, AHP-P with pH-sensitivity can gradually release HMME within acidic tumor environment, boosts the 1 O2 regeneration alongside with highly efficient photothermal conversion for photoinduced cancer PTT-PDT. Furthermore, the AHP-P nanobullet can home in on the tumor site and penetrate into cytoplasm through PEGA-pVEC, inducing remarkable tumor regression with an ≈80% tumor volume reduction and decreased skin phototoxicity in vivo during FRET-amplified PTT-PDT.
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Affiliation(s)
- Mixiao Tan
- The Second Affiliated Hospital of Chongqing Medical University & Chongqing Key Laboratory of Ultrasound Molecular Imaging, Chongqing, 400010, China
| | - Xuemei Li
- The Second Affiliated Hospital of Chongqing Medical University & Chongqing Key Laboratory of Ultrasound Molecular Imaging, Chongqing, 400010, China.,Dianjiang People's Hospital of Chongqing, Chongqing, 408300, China
| | - Hua Zhang
- The Second Affiliated Hospital of Chongqing Medical University & Chongqing Key Laboratory of Ultrasound Molecular Imaging, Chongqing, 400010, China
| | - Min Zheng
- The Second Affiliated Hospital of Chongqing Medical University & Chongqing Key Laboratory of Ultrasound Molecular Imaging, Chongqing, 400010, China
| | - Jie Xiong
- The Second Affiliated Hospital of Chongqing Medical University & Chongqing Key Laboratory of Ultrasound Molecular Imaging, Chongqing, 400010, China
| | - Yang Cao
- The Second Affiliated Hospital of Chongqing Medical University & Chongqing Key Laboratory of Ultrasound Molecular Imaging, Chongqing, 400010, China
| | - Guoliang Cao
- CAS Key Laboratory for Biomedical Effects of Nanomaterials & Nanosafety, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Beijing, 100190, China
| | - Zhigang Wang
- The Second Affiliated Hospital of Chongqing Medical University & Chongqing Key Laboratory of Ultrasound Molecular Imaging, Chongqing, 400010, China
| | - Haitao Ran
- The Second Affiliated Hospital of Chongqing Medical University & Chongqing Key Laboratory of Ultrasound Molecular Imaging, Chongqing, 400010, China
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Kaeokhamloed N, Roger E, Béjaud J, Lautram N, Manero F, Perrot R, Abbara C, Briet M, Legeay S. New In Vitro Coculture Model for Evaluating Intestinal Absorption of Different Lipid Nanocapsules. Pharmaceutics 2021; 13:595. [PMID: 33919334 DOI: 10.3390/pharmaceutics13050595] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2021] [Revised: 04/19/2021] [Accepted: 04/20/2021] [Indexed: 11/16/2022] Open
Abstract
Standard models used for evaluating the absorption of nanoparticles like Caco-2 ignore the presence of vascular endothelium, which is a part of the intestinal multi-layered barrier structure. Therefore, a coculture between the Caco-2 epithelium and HMEC-1 (Human Microvascular Endothelial Cell type 1) on a Transwell® insert has been developed. The model has been validated for (a) membrane morphology by transmission electron microscope (TEM); (b) ZO-1 and β-catenin expression by immunoassay; (c) membrane integrity by trans-epithelial electrical resistance (TEER) measurement; and (d) apparent permeability of drugs from different biopharmaceutical classification system (BCS) classes. Lipid nanocapsules (LNCs) were formulated with different sizes (55 and 85 nm) and surface modifications (DSPE-mPEG (2000) and stearylamine). Nanocapsule integrity and particle concentration were monitored using the Förster resonance energy transfer (FRET) technique. The result showed that surface modification by DSPE-mPEG (2000) increased the absorption of 55-nm LNCs in the coculture model but not in the Caco-2. Summarily, the coculture model was validated as a tool for evaluating the intestinal absorption of drugs and nanoparticles. The new coculture model has a different LNCs absorption mechanism suggesting the importance of intestinal endothelium and reveals that the surface modification of LNCs can modify the in vitro oral absorption.
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Denay G, Schultz P, Hänsch S, Weidtkamp‐Peters S, Simon R. Over the rainbow: A practical guide for fluorescent protein selection in plant FRET experiments. Plant Direct 2019; 3:e00189. [PMID: 31844834 PMCID: PMC6898725 DOI: 10.1002/pld3.189] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/16/2019] [Revised: 11/07/2019] [Accepted: 11/08/2019] [Indexed: 05/29/2023]
Abstract
Receptor-like kinases (RLK) and receptor-like proteins (RLP) often interact in a combinatorial manner depending on tissue identity, membrane domains, or endo- and exogenous cues, and the same RLKs or RLPs can generate different signaling outputs depending on the composition of the receptor complexes they are involved in. Investigation of their interaction partners in a spatial and dynamic way is therefore of prime interest to understand their functions. This is, however, limited by the technical complexity of assessing it in endogenous conditions. A solution to close this gap is to determine protein interaction directly in the relevant tissues at endogenous expression levels using Förster resonance energy transfer (FRET). The ideal fluorophore pair for FRET must, however, fulfil specific requirements: (a) The emission and excitation spectra of the donor and acceptor, respectively, must overlap; (b) they should not interfere with proper folding, activity, or localization of the fusion proteins; (c) they should be sufficiently photostable in plant cells. Furthermore, the donor must yield sufficient photon counts at near-endogenous protein expression levels. Although many fluorescent proteins were reported to be suitable for FRET experiments, only a handful were already described for applications in plants. Herein, we compare a range of fluorophores, assess their usability to study RLK interactions by FRET-based fluorescence lifetime imaging (FLIM) and explore their differences in FRET efficiency. Our analysis will help to select the optimal fluorophore pair for diverse FRET applications.
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Affiliation(s)
- Grégoire Denay
- Institute for Developmental GeneticsHeinrich Heine University DüsseldorfDüsseldorfGermany
| | - Patrick Schultz
- Institute for Developmental GeneticsHeinrich Heine University DüsseldorfDüsseldorfGermany
| | - Sebastian Hänsch
- Center for Advanced ImagingHeinrich Heine University DüsseldorfDüsseldorfGermany
| | | | - Rüdiger Simon
- Institute for Developmental GeneticsHeinrich Heine University DüsseldorfDüsseldorfGermany
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6
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Abstract
T-cells are remarkably specific and effective when recognizing antigens in the form of peptides embedded in MHC molecules (pMHC) on the surface of Antigen Presenting Cells (APCs). This is despite T-cell antigen receptors (TCRs) exerting usually a moderate affinity (µM range) to antigen when binding is measured in vitro(1). In view of the molecular and cellular parameters contributing to T-cell antigen sensitivity, a microscopy-based methodology has been developed as a means to monitor TCR-pMHC binding in situ, as it occurs within the synapse of a live T-cell and an artificial and functionalized glass-supported planar lipid bilayer (SLB), which mimics the cell membrane of an Antigen presenting Cell (APC) (2). Measurements are based on Förster Resonance Energy Transfer (FRET) between a blue- and red-shifted fluorescent dye attached to the TCR and the pMHC. Because the efficiency of FRET is inversely proportional to the sixth power of the inter-dye distance, one can employ FRET signals to visualize synaptic TCR-pMHC binding. The sensitive of the microscopy approach supports detection of single molecule FRET events. This allows to determine the affinity and off-rate of synaptic TCR-pMHC interactions and in turn to interpolate the on-rate of binding. Analogous assays could be applied to measure other receptor-ligand interactions in their native environment.
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Affiliation(s)
- Markus Axmann
- Institute for Applied Physics - Biophysics, Vienna University of Technology
| | - Gerhard J Schütz
- Institute for Applied Physics - Biophysics, Vienna University of Technology
| | - Johannes B Huppa
- Institute for Hygiene and Applied Immunology, Medical University of Vienna;
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7
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Omer T, Zhao L, Intes X, Hahn J. Reduced temporal sampling effect on accuracy of time-domain fluorescence lifetime Förster resonance energy transfer. J Biomed Opt 2014; 19:086023. [PMID: 25166472 PMCID: PMC4147194 DOI: 10.1117/1.jbo.19.8.086023] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/10/2014] [Accepted: 07/30/2014] [Indexed: 05/04/2023]
Abstract
Fluorescence lifetime imaging (FLIM) aims at quantifying the exponential decay rate of fluorophores to yield lifetime maps over the imaged sample. When combined with Förster resonance energy transfer (FRET), the technique can be used to indirectly sense interactions at the nanoscale such as protein–protein interactions, protein–DNA interactions, and protein conformational changes. In the case of FLIM-FRET, the fluorescence intensity decays are fitted to a biexponential model in order to estimate the lifetime and fractional amplitude coefficients of each component of the population of the donor fluorophore (quenched and nonquenched). Numerous time data points, also called temporal or time gates, are typically employed for accurately estimating the model parameters, leading to lengthy acquisition times and significant computational demands. This work investigates the effect of the number and location of time gates on model parameter estimation accuracy. A detailed model of a FLIM-FRET imaging system is used for the investigation, and the simulation outcomes are validated with in vitro and in vivo experimental data. In all cases investigated, it is found that 10 equally spaced time gates allow robust estimation of model-based parameters with accuracy similar to that of full temporal datasets (90 gates).
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Affiliation(s)
- Travis Omer
- Rensselaer Polytechnic Institute, Department of Biomedical Engineering, 110 8th Street, Troy, New York 12180, United States
| | - Lingling Zhao
- Rensselaer Polytechnic Institute, Department of Biomedical Engineering, 110 8th Street, Troy, New York 12180, United States
| | - Xavier Intes
- Rensselaer Polytechnic Institute, Department of Biomedical Engineering, 110 8th Street, Troy, New York 12180, United States
| | - Juergen Hahn
- Rensselaer Polytechnic Institute, Departments of Biomedical Engineering and Chemical & Biological Engineering, 110 8th Street, Troy, New York 12180, United States
- Address all correspondence to: Juergen Hahn, E-mail:
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Saremi B, Wei MY, Liu Y, Cheng B, Yuan B. Re-evaluation of biotin-streptavidin conjugation in Förster resonance energy transfer applications. J Biomed Opt 2014; 19:085008. [PMID: 25162908 PMCID: PMC4145247 DOI: 10.1117/1.jbo.19.8.085008] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/30/2014] [Revised: 07/29/2014] [Accepted: 08/06/2014] [Indexed: 06/03/2023]
Abstract
Bioaffinity conjugation between streptavidin (SA) and biotin has been widely used to link donors and acceptors for investigating the distance-dependent Förster resonance energy transfer (FRET). When studying a commonly used FRET system of (QD-SA)-(biotin-DNA-dye) [donor: quantum dot (QD); acceptor: small organic fluorescent dye; and linker: deoxyribose nucleic acid (DNA) molecule via SA-biotin conjugation], however, a contradictory finding was recently reported in the literature. It was found that the FRET lost its dependence on the number of DNA base pairs when using a phosphate-buffered saline (PBS) solution. We found that the conflicted results were caused by the ionic strength of the adopted buffer solutions. Our results suggest that the dependent FRET on the number of DNA bases is favorable in a low-ionic-strength buffer, whereas in relatively high-ionic-strength buffers, the FRET loses the DNA length dependence. We propose that the independence is mainly caused by the conformational change of DNA molecules from a stretched to a coiled mode when the cations in the high-ionic-strength buffer neutralize the negatively charged backbone of DNA molecules, thereby bringing the acceptors close to the donors.
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Affiliation(s)
- Bahar Saremi
- University of Texas at Arlington, Department of Bioengineering, Ultrasound and Optical Imaging Laboratory, Arlington, 500 UTA Boulevard, Texas 76010, United States
- University of Texas at Arlington and University of Texas Southwestern Medical Center at Dallas, Joint Biomedical Engineering Program, Texas 75390, United States
| | - Ming-Yuan Wei
- University of Texas at Arlington, Department of Bioengineering, Ultrasound and Optical Imaging Laboratory, Arlington, 500 UTA Boulevard, Texas 76010, United States
- University of Texas at Arlington and University of Texas Southwestern Medical Center at Dallas, Joint Biomedical Engineering Program, Texas 75390, United States
| | - Yuan Liu
- University of Texas at Arlington, Department of Bioengineering, Ultrasound and Optical Imaging Laboratory, Arlington, 500 UTA Boulevard, Texas 76010, United States
- University of Texas at Arlington and University of Texas Southwestern Medical Center at Dallas, Joint Biomedical Engineering Program, Texas 75390, United States
| | - Bingbing Cheng
- University of Texas at Arlington, Department of Bioengineering, Ultrasound and Optical Imaging Laboratory, Arlington, 500 UTA Boulevard, Texas 76010, United States
- University of Texas at Arlington and University of Texas Southwestern Medical Center at Dallas, Joint Biomedical Engineering Program, Texas 75390, United States
| | - Baohong Yuan
- University of Texas at Arlington, Department of Bioengineering, Ultrasound and Optical Imaging Laboratory, Arlington, 500 UTA Boulevard, Texas 76010, United States
- University of Texas at Arlington and University of Texas Southwestern Medical Center at Dallas, Joint Biomedical Engineering Program, Texas 75390, United States
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9
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Borrenberghs D, Thys W, Rocha S, Demeulemeester J, Weydert C, Dedecker P, Hofkens J, Debyser Z, Hendrix J. HIV virions as nanoscopic test tubes for probing oligomerization of the integrase enzyme. ACS Nano 2014; 8:3531-45. [PMID: 24654558 PMCID: PMC4004294 DOI: 10.1021/nn406615v] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
Employing viruses as nanoscopic lipid-enveloped test tubes allows the miniaturization of protein-protein interaction (PPI) assays while preserving the physiological environment necessary for particular biological processes. Applied to the study of the human immunodeficiency virus type 1 (HIV-1), viral biology and pathology can also be investigated in novel ways, both in vitro as well as in infected cells. In this work we report on an experimental strategy that makes use of engineered HIV-1 viral particles, to allow for probing PPIs of the HIV-1 integrase (IN) inside viruses with single-molecule Förster resonance energy transfer (FRET) using fluorescent proteins (FP). We show that infectious fluorescently labeled viruses can be obtained and that the quantity of labels can be accurately measured and controlled inside individual viral particles. We demonstrate, with proper control experiments, the formation of IN oligomers in single viral particles and inside viral complexes in infected cells. Finally, we show a clear effect on IN oligomerization of small molecule inhibitors of interactions of IN with its natural human cofactor LEDGF/p75, corroborating that IN oligomer enhancing drugs are active already at the level of the virus and strongly suggesting the presence of a dynamic, enhanceable equilibrium between the IN dimer and tetramer in viral particles. Although applied to the HIV-1 IN enzyme, our methodology for utilizing HIV virions as nanoscopic test tubes for probing PPIs is generic, i.e., other PPIs targeted into the HIV-1, or PPIs targeted into other viruses, can potentially be studied with a similar strategy.
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Affiliation(s)
- Doortje Borrenberghs
- Laboratory for Photochemistry and Spectroscopy, Department of Chemistry, KU Leuven, Celestijnenlaan 200F, 3001 Heverlee, Flanders, Belgium
| | - Wannes Thys
- Laboratory for Molecular Virology and Gene Therapy, Department of Pharmaceutical and Pharmacological Sciences, KU Leuven, Kapucijnenvoer 33, 3000 Leuven, Flanders, Belgium
| | - Susana Rocha
- Laboratory for Photochemistry and Spectroscopy, Department of Chemistry, KU Leuven, Celestijnenlaan 200F, 3001 Heverlee, Flanders, Belgium
| | - Jonas Demeulemeester
- Laboratory for Molecular Virology and Gene Therapy, Department of Pharmaceutical and Pharmacological Sciences, KU Leuven, Kapucijnenvoer 33, 3000 Leuven, Flanders, Belgium
| | - Caroline Weydert
- Laboratory for Molecular Virology and Gene Therapy, Department of Pharmaceutical and Pharmacological Sciences, KU Leuven, Kapucijnenvoer 33, 3000 Leuven, Flanders, Belgium
| | - Peter Dedecker
- Laboratory for Photochemistry and Spectroscopy, Department of Chemistry, KU Leuven, Celestijnenlaan 200F, 3001 Heverlee, Flanders, Belgium
| | - Johan Hofkens
- Laboratory for Photochemistry and Spectroscopy, Department of Chemistry, KU Leuven, Celestijnenlaan 200F, 3001 Heverlee, Flanders, Belgium
- Nano-Science Center, Department of Chemistry, University of Copenhagen, Universitetsparken 5, 2100 Copenhagen, Denmark
| | - Zeger Debyser
- Laboratory for Molecular Virology and Gene Therapy, Department of Pharmaceutical and Pharmacological Sciences, KU Leuven, Kapucijnenvoer 33, 3000 Leuven, Flanders, Belgium
| | - Jelle Hendrix
- Laboratory for Photochemistry and Spectroscopy, Department of Chemistry, KU Leuven, Celestijnenlaan 200F, 3001 Heverlee, Flanders, Belgium
- Address correspondence to
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Zhao Y, Schapotschnikow P, Skajaa T, Vlugt TJH, Mulder WJM, de Mello Donegá C, Meijerink A. Probing lipid coating dynamics of quantum dot core micelles via Förster resonance energy transfer. Small 2014; 10:1163-1170. [PMID: 24343988 DOI: 10.1002/smll.201301962] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/26/2013] [Revised: 10/07/2013] [Indexed: 06/03/2023]
Abstract
Lipid coated nanocrystal assemblies are among the most extensively investigated nanoparticle platforms for biomedical imaging and therapeutic purposes. However, very few efforts have been addressed to the lipid coating exchange dynamics in such systems, which is key to our understanding of the nanoparticles' coating stability and their interactions with the environment. Here, we apply the Förster resonance energy transfer (FRET) from quantum dot (QD) core to Cy5.5 dye labeled lipids at the surface to monitor the lipid exchange dynamics in situ and to study its dependence on concentration, temperature and solvent. A kinetic model is developed to describe the experimental data, allowing the rate constants and the activation energy for lipid exchange to be determined. The activation energy for lipid exchange on QD micelles is 155 kJ/mol in saline environment and 130 kJ/mol in pure water. The findings presented here provide basic knowledge on these self-assembled structures and contribute to understanding their performance and to further design of nanomedicine.
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Affiliation(s)
- Yiming Zhao
- Condensed Matter and Interfaces, Debye Institute, Utrecht University, Princetonplein 5, Utrecht, 3584 CC, The Netherlands; Translational and Molecular Imaging Institute, Ichan School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY, 10029, USA
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11
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Abstract
Single-molecule spectroscopy has developed into a widely used method for probing the structure, dynamics, and mechanisms of biomolecular systems, especially in combination with Förster resonance energy transfer (FRET). In this introductory tutorial, essential concepts and methods will be outlined, from the FRET process and the basic considerations for sample preparation and instrumentation to some key elements of data analysis and photon statistics. Different approaches for obtaining dynamic information over a wide range of timescales will be explained and illustrated with examples, including the quantitative analysis of FRET efficiency histograms, correlation spectroscopy, fluorescence trajectories, and microfluidic mixing.
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Affiliation(s)
- Benjamin Schuler
- Department of Biochemistry, University of Zurich, Winterthurerstrasse 190, 8057
Zurich, Switzerland
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12
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Zhao Y, van Rooy I, Hak S, Fay F, Tang J, de Lange Davies C, Skobe M, Fisher EA, Radu A, Fayad ZA, de Mello Donegá C, Meijerink A, Mulder WJM. Near-infrared fluorescence energy transfer imaging of nanoparticle accumulation and dissociation kinetics in tumor-bearing mice. ACS Nano 2013; 7:10362-70. [PMID: 24134041 PMCID: PMC3947574 DOI: 10.1021/nn404782p] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
In the current study we show the dissociation and tumor accumulation dynamics of dual-labeled near-infrared quantum dot core self-assembled lipidic nanoparticles (SALNPs) in a mouse model upon intravenous administration. Using advanced in vivo fluorescence energy transfer imaging techniques, we observed swift exchange with plasma protein components in the blood and progressive SALNP dissociation and subsequent trafficking of individual SALNP components following tumor accumulation. Our results suggest that upon intravenous administration SALNPs quickly transform, which may affect their functionality. The presented technology provides a modular in vivo tool to visualize SALNP behavior in real time and may contribute to improving the therapeutic outcome or molecular imaging signature of SALNPs.
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Affiliation(s)
- Yiming Zhao
- Condensed Matter and Interfaces, Debye Institute for Nanomaterials Science, Utrecht University, Princetonplein 5, 3584 CC Utrecht, The Netherlands
- Translational and Molecular Imaging Institute, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY 10029, USA
| | - Inge van Rooy
- Translational and Molecular Imaging Institute, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY 10029, USA
- Developmental and Regenerative Biology, Icahn School of Medicine at Mount Sinai
| | - Sjoerd Hak
- MI Lab and Department of Circulation and Medical Imaging, The Norwegian University of Science and Technology, Trondheim, Norway
| | - Francois Fay
- Translational and Molecular Imaging Institute, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY 10029, USA
| | - Jun Tang
- Translational and Molecular Imaging Institute, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY 10029, USA
- Graduate School of Biological Sciences, Icahn School of Medicine at Mount Sinai
| | | | - Mihaela Skobe
- Derald H. Ruttenberg Cancer Center, Icahn School of Medicine at Mount Sinai
| | | | - Aurelian Radu
- Developmental and Regenerative Biology, Icahn School of Medicine at Mount Sinai
| | - Zahi. A. Fayad
- Translational and Molecular Imaging Institute, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY 10029, USA
| | - Celso de Mello Donegá
- Condensed Matter and Interfaces, Debye Institute for Nanomaterials Science, Utrecht University, Princetonplein 5, 3584 CC Utrecht, The Netherlands
| | - Andries Meijerink
- Condensed Matter and Interfaces, Debye Institute for Nanomaterials Science, Utrecht University, Princetonplein 5, 3584 CC Utrecht, The Netherlands
| | - Willem J. M. Mulder
- Translational and Molecular Imaging Institute, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY 10029, USA
- Department of Vascular Medicine, Academic Medical Center, Amsterdam, The Netherlands
- Corresponding author information: Willem Mulder, Ph.D., , Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, Box 1234, New York, NY 10029, Ph. 212-824-8910
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13
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Wang Y, Xia J, Wang LV. Deep-tissue photoacoustic tomography of Förster resonance energy transfer. J Biomed Opt 2013; 18:101316. [PMID: 23884608 PMCID: PMC3719951 DOI: 10.1117/1.jbo.18.10.101316] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/25/2013] [Revised: 07/01/2013] [Accepted: 07/03/2013] [Indexed: 05/20/2023]
Abstract
Förster resonance energy transfer (FRET) is a distance-dependent process that transfers excited state energy from a donor molecule to an acceptor molecule without the emission of a photon. The FRET rate is determined by the proximity between the donor and the acceptor molecules; it becomes significant only when the proximity is within several nanometers. Therefore, FRET has been applied to visualize interactions and conformational changes of biomolecules, such as proteins, lipids, and nucleic acids that cannot be resolved by optical microscopy. Here, we report photoacoustic tomography of FRET efficiency at a 1-cm depth in chicken breast tissue, whereas conventional high-resolution fluorescence imaging is limited to <0.1 cm. Photoacoustic tomography is expected to facilitate the examination of FRET phenomena in living organisms.
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Affiliation(s)
- Yu Wang
- Washington University in St. Louis, Department of Biomedical Engineering, Optical Imaging Laboratory, 1 Brookings Dr., St. Louis, Missouri 63130
| | - Jun Xia
- Washington University in St. Louis, Department of Biomedical Engineering, Optical Imaging Laboratory, 1 Brookings Dr., St. Louis, Missouri 63130
| | - Lihong V. Wang
- Washington University in St. Louis, Department of Biomedical Engineering, Optical Imaging Laboratory, 1 Brookings Dr., St. Louis, Missouri 63130
- Address all correspondence to: Lihong V. Wang, Washington University in St. Louis, Department of Biomedical Engineering, Optical Imaging Laboratory, 1 Brookings Dr., St. Louis, Missouri 63130. Tel: (314) 935-6152; Fax: (314) 935-7448; E-mail:
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14
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Jyothikumar V, Sun Y, Periasamy A. Investigation of tryptophan-NADH interactions in live human cells using three-photon fluorescence lifetime imaging and Förster resonance energy transfer microscopy. J Biomed Opt 2013; 18:060501. [PMID: 23748699 PMCID: PMC3675329 DOI: 10.1117/1.jbo.18.6.060501] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/30/2012] [Revised: 04/23/2013] [Accepted: 05/02/2013] [Indexed: 05/29/2023]
Abstract
A method to investigate the metabolic activity of intracellular tryptophan (TRP) and coenzyme-NADH using three-photon (3P) fluorescence lifetime imaging (FLIM) and Förster resonance energy transfer (FRET) is presented. Through systematic analysis of FLIM data from tumorigenic and nontumorigenic cells, a statistically significant decrease in the fluorescence lifetime of TRP was observed in response to the increase in protein-bound NADH as cells were treated with glucose. The results demonstrate the potential use of 3P-FLIM-FRET as a tool for label-free screening of the change in metabolic flux occurring in human diseases or other clinical conditions.
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Affiliation(s)
- Vinod Jyothikumar
- University of Virginia, W. M. Keck Center for Cellular Imaging, Department of Biology, Physical and Life Sciences Building, Charlottesville, Virginia 22904
| | - Yuansheng Sun
- University of Virginia, W. M. Keck Center for Cellular Imaging, Department of Biology, Physical and Life Sciences Building, Charlottesville, Virginia 22904
| | - Ammasi Periasamy
- University of Virginia, W. M. Keck Center for Cellular Imaging, Department of Biology, Physical and Life Sciences Building, Charlottesville, Virginia 22904
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15
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Choi S, Jin H, Bang J, Kim S. Layer-by-Layer Quantum Dot Assemblies for the Enhanced Energy Transfers and Their Applications toward Efficient Solar Cells. J Phys Chem Lett 2012; 3:3442-3447. [PMID: 26290970 DOI: 10.1021/jz301579x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Two different quantum dots (QDs) with an identical optical band gap were prepared: one without the inorganic shell and short surface ligands (BQD) and the other with thick inorganic shells and long surface ligands (OQD). They were surface-derivatized to be positively or negatively charged and were used for layer-by-layer assemblies on TiO2. By sandwiching BQD between OQD and TiO2, OQD photoluminescence showed seven times faster decay, which is attributed to the combined effect of the efficient energy transfer from OQD to BQD with the FRET efficiency of 86% and fast electron transfer from BQD to TiO2 with the rate of 1.2 × 10(9) s(-1). The QD bilayer configuration was further applied to solar cells, and showed 3.6 times larger photocurrent and 3.8 times larger photoconversion efficiency than those of the device with the OQD being sandwiched by BQD and TiO2. This showcases the importance of sophisticated control of QD layer assembly for the design of efficient QD solar cells.
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Affiliation(s)
- Sukyung Choi
- Department of Chemistry, Pohang University of Science and Technology, Pohang, 790-784, South Korea
| | - Ho Jin
- Department of Chemistry, Pohang University of Science and Technology, Pohang, 790-784, South Korea
| | - Jiwon Bang
- Department of Chemistry, Pohang University of Science and Technology, Pohang, 790-784, South Korea
| | - Sungjee Kim
- Department of Chemistry, Pohang University of Science and Technology, Pohang, 790-784, South Korea
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16
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Chen NT, Cheng SH, Liu CP, Souris JS, Chen CT, Mou CY, Lo LW. Recent advances in nanoparticle-based Förster resonance energy transfer for biosensing, molecular imaging and drug release profiling. Int J Mol Sci 2012; 13:16598-623. [PMID: 23443121 PMCID: PMC3546710 DOI: 10.3390/ijms131216598] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2012] [Revised: 11/15/2012] [Accepted: 11/16/2012] [Indexed: 01/10/2023] Open
Abstract
Förster resonance energy transfer (FRET) may be regarded as a "smart" technology in the design of fluorescence probes for biological sensing and imaging. Recently, a variety of nanoparticles that include quantum dots, gold nanoparticles, polymer, mesoporous silica nanoparticles and upconversion nanoparticles have been employed to modulate FRET. Researchers have developed a number of "visible" and "activatable" FRET probes sensitive to specific changes in the biological environment that are especially attractive from the biomedical point of view. This article reviews recent progress in bringing these nanoparticle-modulated energy transfer schemes to fruition for applications in biosensing, molecular imaging and drug delivery.
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Affiliation(s)
- Nai-Tzu Chen
- Division of Medical Engineering Research, National Health Research Institutes, Zhunan 35053, Miaoli County, Taiwan; E-Mails: (N.-T.C.); (S.-H.C.); (C.-P.L.)
- Department of Chemistry, National Taiwan University, Taipei 10617, Taiwan; E-Mail:
| | - Shih-Hsun Cheng
- Division of Medical Engineering Research, National Health Research Institutes, Zhunan 35053, Miaoli County, Taiwan; E-Mails: (N.-T.C.); (S.-H.C.); (C.-P.L.)
- Department of Radiology, The University of Chicago, Chicago, IL 60637, USA; E-Mails: (J.S.S.); (C.-T.C.)
| | - Ching-Ping Liu
- Division of Medical Engineering Research, National Health Research Institutes, Zhunan 35053, Miaoli County, Taiwan; E-Mails: (N.-T.C.); (S.-H.C.); (C.-P.L.)
| | - Jeffrey S. Souris
- Department of Radiology, The University of Chicago, Chicago, IL 60637, USA; E-Mails: (J.S.S.); (C.-T.C.)
| | - Chen-Tu Chen
- Department of Radiology, The University of Chicago, Chicago, IL 60637, USA; E-Mails: (J.S.S.); (C.-T.C.)
| | - Chung-Yuan Mou
- Department of Chemistry, National Taiwan University, Taipei 10617, Taiwan; E-Mail:
| | - Leu-Wei Lo
- Division of Medical Engineering Research, National Health Research Institutes, Zhunan 35053, Miaoli County, Taiwan; E-Mails: (N.-T.C.); (S.-H.C.); (C.-P.L.)
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17
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Adbul Rahim NA, Pelet S, Kamm RD, So PTC. Methodological considerations for global analysis of cellular FLIM/FRET measurements. J Biomed Opt 2012; 17:026013. [PMID: 22463045 PMCID: PMC3382354 DOI: 10.1117/1.jbo.17.2.026013] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/17/2011] [Revised: 12/18/2011] [Accepted: 12/27/2011] [Indexed: 05/29/2023]
Abstract
Global algorithms can improve the analysis of fluorescence energy transfer (FRET) measurement based on fluorescence lifetime microscopy. However, global analysis of FRET data is also susceptible to experimental artifacts. This work examines several common artifacts and suggests remedial experimental protocols. Specifically, we examined the accuracy of different methods for instrument response extraction and propose an adaptive method based on the mean lifetime of fluorescent proteins. We further examined the effects of image segmentation and a priori constraints on the accuracy of lifetime extraction. Methods to test the applicability of global analysis on cellular data are proposed and demonstrated. The accuracy of global fitting degrades with lower photon count. By systematically tracking the effect of the minimum photon count on lifetime and FRET prefactors when carrying out global analysis, we demonstrate a correction procedure to recover the correct FRET parameters, allowing us to obtain protein interaction information even in dim cellular regions with photon counts as low as 100 per decay curve.
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Affiliation(s)
- Nur Aida Adbul Rahim
- Massachusetts Institute of Technology, Department of Mechanical Engineering, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139
| | - Serge Pelet
- Massachusetts Institute of Technology, Department of Biological Engineering, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139
| | - Roger D. Kamm
- Massachusetts Institute of Technology, Department of Mechanical Engineering, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139
- Massachusetts Institute of Technology, Department of Biological Engineering, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139
| | - Peter T. C. So
- Massachusetts Institute of Technology, Department of Mechanical Engineering, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139
- Massachusetts Institute of Technology, Department of Biological Engineering, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139
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18
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Kraft LJ, Kenworthy AK. Imaging protein complex formation in the autophagy pathway: analysis of the interaction of LC3 and Atg4B(C74A) in live cells using Förster resonance energy transfer and fluorescence recovery after photobleaching. J Biomed Opt 2012; 17:011008. [PMID: 22352642 PMCID: PMC3380812 DOI: 10.1117/1.jbo.17.1.011008] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/10/2011] [Revised: 09/28/2011] [Accepted: 09/29/2011] [Indexed: 05/31/2023]
Abstract
The protein microtubule-associated protein 1, light chain 3 (LC3) functions in autophagosome formation and plays a central role in the autophagy pathway. Previously, we found LC3 diffuses more slowly in cells than is expected for a freely diffusing monomer, suggesting it may constitutively associate with a macromolecular complex containing other protein components of the pathway. In the current study, we used Förster resonance energy transfer (FRET) microscopy and fluorescence recovery after photobleaching (FRAP) to investigate the interactions of LC3 with Atg4B(C74A), a catalytically inactive mutant of the cysteine protease involved in lipidation and de-lipidation of LC3, as a model system to probe protein complex formation in the autophagy pathway. We show Atg4B(C74A) is in FRET proximity with LC3 in both the cytoplasm and nucleus of living cells, consistent with previous biochemical evidence that suggests these proteins directly interact. In addition, overexpressed Atg4B(C74A) diffuses significantly more slowly than predicted based on its molecular weight, and its translational diffusion coefficient is significantly slowed upon coexpression with LC3 to match that of LC3 itself. Taken together, these results suggest Atg4B(C74A) and LC3 are contained within the same multiprotein complex and that this complex exists in both the cytoplasm and nucleoplasm of living cells.
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Affiliation(s)
- Lewis J. Kraft
- Vanderbilt University School of Medicine, Chemical and Physical Biology Program, Nashville, Tennessee 37232
| | - Anne K. Kenworthy
- Vanderbilt University School of Medicine, Chemical and Physical Biology Program, Nashville, Tennessee 37232
- Vanderbilt University School of Medicine, Department of Molecular Physiology and Biophysics, Nashville, Tennessee 37232
- Vanderbilt University School of Medicine, Department of Cell and Developmental Biology, Nashville, Tennessee 37232
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19
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Achermann M, Jeong S, Balet L, Montano GA, Hollingsworth JA. Efficient quantum dot-quantum dot and quantum dot-dye energy transfer in biotemplated assemblies. ACS Nano 2011; 5:1761-8. [PMID: 21314178 PMCID: PMC3062676 DOI: 10.1021/nn102365v] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
CdSe semiconductor nanocrystal quantum dots are assembled into nanowire-like arrays employing microtubule fibers as nanoscale molecular "scaffolds." Spectrally and time-resolved energy-transfer analysis is used to assess the assembly of the nanoparticles into the hybrid inorganic biomolecular structure. Specifically, we demonstrate that a comprehensive study of energy transfer between quantum dot pairs on the biotemplate and, alternatively, between quantum dots and molecular dyes embedded in the microtubule scaffold comprises a powerful spectroscopic tool for evaluating the assembly process. In addition to revealing the extent to which assembly has occurred, the approach allows determination of particle-to-particle (and particle-to-dye) distances within the biomediated array. Significantly, the characterization is realized in situ, without need for further sample workup or risk of disturbing the solution-phase constructs. Furthermore, we find that the assemblies prepared in this way exhibit efficient quantum dot-quantum dot and quantum dot-dye energy transfer that affords faster energy-transfer rates compared to densely packed quantum dot arrays on planar substrates and to small-molecule-mediated quantum dot-dye couples, respectively.
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20
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Claridge SA, Schwartz JJ, Weiss PS. Electrons, photons, and force: quantitative single-molecule measurements from physics to biology. ACS Nano 2011; 5:693-729. [PMID: 21338175 PMCID: PMC3043607 DOI: 10.1021/nn103298x] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/02/2010] [Accepted: 01/10/2011] [Indexed: 05/19/2023]
Abstract
Single-molecule measurement techniques have illuminated unprecedented details of chemical behavior, including observations of the motion of a single molecule on a surface, and even the vibration of a single bond within a molecule. Such measurements are critical to our understanding of entities ranging from single atoms to the most complex protein assemblies. We provide an overview of the strikingly diverse classes of measurements that can be used to quantify single-molecule properties, including those of single macromolecules and single molecular assemblies, and discuss the quantitative insights they provide. Examples are drawn from across the single-molecule literature, ranging from ultrahigh vacuum scanning tunneling microscopy studies of adsorbate diffusion on surfaces to fluorescence studies of protein conformational changes in solution.
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Affiliation(s)
| | | | - Paul S. Weiss
- California NanoSystems Institute
- Department of Chemistry and Biochemistry
- Department of Materials Science and Engineering
- Address correspondence to
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21
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Boeneman K, Deschamps JR, Buckhout-White S, Prasuhn DE, Blanco-Canosa JB, Dawson PE, Stewart MH, Susumu K, Goldman ER, Ancona M, Medintz IL. Quantum dot DNA bioconjugates: attachment chemistry strongly influences the resulting composite architecture. ACS Nano 2010; 4:7253-66. [PMID: 21082822 PMCID: PMC4383186 DOI: 10.1021/nn1021346] [Citation(s) in RCA: 81] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
The unique properties provided by hybrid semiconductor quantum dot (QD) bioconjugates continue to stimulate interest for many applications ranging from biosensing to energy harvesting. Understanding both the structure and function of these composite materials is an important component in their development. Here, we compare the architecture that results from using two common self-assembly chemistries to attach DNA to QDs. DNA modified to display either a terminal biotin or an oligohistidine peptidyl sequence was assembled to streptavidin/amphiphilic polymer- or PEG-functionalized QDs, respectively. A series of complementary acceptor dye-labeled DNA were hybridized to different positions on the DNA in each QD configuration and the separation distances between the QD donor and each dye-acceptor probed with Förster resonance energy transfer (FRET). The polyhistidine self-assembly yielded QD-DNA bioconjugates where predicted and experimental separation distances matched reasonably well. Although displaying efficient FRET, data from QD-DNA bioconjugates assembled using biotin-streptavidin chemistry did not match any predicted separation distances. Modeling based upon known QD and DNA structures along with the linkage chemistry and FRET-derived distances was used to simulate each QD-DNA structure and provide insight into the underlying architecture. Although displaying some rotational freedom, the DNA modified with the polyhistidine assembles to the QD with its structure extended out from the QD-PEG surface as predicted. In contrast, the random orientation of streptavidin on the QD surface resulted in DNA with a wide variety of possible orientations relative to the QD which cannot be controlled during assembly. These results suggest that if a particular QD biocomposite structure is desired, for example, random versus oriented, the type of bioconjugation chemistry utilized will be a key influencing factor.
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Affiliation(s)
- Kelly Boeneman
- Center for Bio/Molecular Science and Engineering, Code 6900, U.S. Naval Research Laboratory, Washington D.C. 20375, USA
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22
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Hovan SC, Howell S, Park PSH. Förster resonance energy transfer as a tool to study photoreceptor biology. J Biomed Opt 2010; 15:067001. [PMID: 21198205 PMCID: PMC3014226 DOI: 10.1117/1.3505023] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/15/2010] [Revised: 08/17/2010] [Accepted: 09/13/2010] [Indexed: 05/30/2023]
Abstract
Vision is initiated in photoreceptor cells of the retina by a set of biochemical events called phototransduction. These events occur via coordinated dynamic processes that include changes in secondary messenger concentrations, conformational changes and post-translational modifications of signaling proteins, and protein-protein interactions between signaling partners. A complete description of the orchestration of these dynamic processes is still unavailable. Described in this work is the first step in the development of tools combining fluorescent protein technology, Förster resonance energy transfer (FRET), and transgenic animals that have the potential to reveal important molecular insights about the dynamic processes occurring in photoreceptor cells. We characterize the fluorescent proteins SCFP3A and SYFP2 for use as a donor-acceptor pair in FRET assays, which will facilitate the visualization of dynamic processes in living cells. We also demonstrate the targeted expression of these fluorescent proteins to the rod photoreceptor cells of Xenopus laevis, and describe a general method for detecting FRET in these cells. The general approaches described here can address numerous types of questions related to phototransduction and photoreceptor biology by providing a platform to visualize dynamic processes in molecular detail within a native context.
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Affiliation(s)
- Stephanie C Hovan
- Case Western Reserve University, Department of Ophthalmology and Visual Sciences, Cleveland, OH 44106, USA
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23
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Kofoed EM, Guerbadot M, Schaufele F. Dimerization between aequorea fluorescent proteins does not affect interaction between tagged estrogen receptors in living cells. J Biomed Opt 2008; 13:031207. [PMID: 18601531 PMCID: PMC2581880 DOI: 10.1117/1.2940366] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Forster resonance energy transfer (FRET) detection of protein interaction in living cells is commonly measured following the expression of interacting proteins genetically fused to the cyan (CFP) and yellow (YFP) derivatives of the Aequorea victoria fluorescent protein (FP). These FPs can dimerize at mM concentrations, which may introduce artifacts into the measurement of interaction between proteins that are fused with the FPs. Here, FRET analysis of the interaction between estrogen receptors (alpha isoform, ERalpha) labeled with "wild-type" CFP and YFP is compared with that of ERalpha labeled with "monomeric" A206K mutants of CFP and YFP. The intracellular equilibrium dissociation constant for the hormone-induced ERalpha-ERalpha interaction is similar for ERalpha labeled with wild-type or monomeric FPs. However, the measurement of energy transfer measured for ERalpha-ERalpha interaction in each cell is less consistent with the monomeric FPs. Thus, dimerization of the FPs does not affect the kinetics of ERalpha-ERalpha interaction but, when brought close together via ERalpha-ERalpha interaction, FP dimerization modestly improves FRET measurement.
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Affiliation(s)
- Eric M Kofoed
- University of California, San Francisco, Diabetes Center and Department of Medicine, S-1230, 513 Parnassus, San Francisco, California 94143-0540, USA
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24
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Doose S, Neuweiler H, Barsch H, Sauer M. Probing polyproline structure and dynamics by photoinduced electron transfer provides evidence for deviations from a regular polyproline type II helix. Proc Natl Acad Sci U S A 2007; 104:17400-5. [PMID: 17956989 PMCID: PMC2077268 DOI: 10.1073/pnas.0705605104] [Citation(s) in RCA: 109] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2007] [Indexed: 11/18/2022] Open
Abstract
Polyprolines are well known for adopting a regular polyproline type II helix in aqueous solution, rendering them a popular standard as molecular ruler in structural molecular biology. However, single-molecule spectroscopy studies based on Förster resonance energy transfer (FRET) have revealed deviations of experimentally observed end-to-end distances of polyprolines from theoretical predictions, and it was proposed that the discrepancy resulted from dynamic flexibility of the polyproline helix. Here, we probe end-to-end distances and conformational dynamics of poly-l-prolines with 1-10 residues using fluorescence quenching by photoinduced-electron transfer (PET). A single fluorophore and a tryptophan residue, introduced at the termini of polyproline peptides, serve as sensitive probes for distance changes on the subnanometer length scale. Using a combination of ensemble fluorescence and fluorescence correlation spectroscopy, we demonstrate that polyproline samples exhibit static structural heterogeneity with subpopulations of distinct end-to-end distances that do not interconvert on time scales from nano- to milliseconds. By observing prolyl isomerization through changes in PET quenching interactions, we provide experimental evidence that the observed heterogeneity can be explained by interspersed cis isomers. Computer simulations elucidate the influence of trans/cis isomerization on polyproline structures in terms of end-to-end distance and provide a structural justification for the experimentally observed effects. Our results demonstrate that structural heterogeneity inherent in polyprolines, which to date are commonly applied as a molecular ruler, disqualifies them as appropriate tool for an accurate determination of absolute distances at a molecular scale.
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Affiliation(s)
- Sören Doose
- Applied Laser Physics and Laser Spectroscopy, University of Bielefeld, Universitätsstrasse 25, 33615 Bielefeld, Germany
| | - Hannes Neuweiler
- Applied Laser Physics and Laser Spectroscopy, University of Bielefeld, Universitätsstrasse 25, 33615 Bielefeld, Germany
| | - Hannes Barsch
- Applied Laser Physics and Laser Spectroscopy, University of Bielefeld, Universitätsstrasse 25, 33615 Bielefeld, Germany
| | - Markus Sauer
- Applied Laser Physics and Laser Spectroscopy, University of Bielefeld, Universitätsstrasse 25, 33615 Bielefeld, Germany
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25
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Schuler B, Lipman EA, Steinbach PJ, Kumke M, Eaton WA. Polyproline and the "spectroscopic ruler" revisited with single-molecule fluorescence. Proc Natl Acad Sci U S A 2005; 102:2754-9. [PMID: 15699337 PMCID: PMC549440 DOI: 10.1073/pnas.0408164102] [Citation(s) in RCA: 357] [Impact Index Per Article: 18.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2004] [Indexed: 11/18/2022] Open
Abstract
To determine whether Forster resonance energy transfer (FRET) measurements can provide quantitative distance information in single-molecule fluorescence experiments on polypeptides, we measured FRET efficiency distributions for donor and acceptor dyes attached to the ends of freely diffusing polyproline molecules of various lengths. The observed mean FRET efficiencies agree with those determined from ensemble lifetime measurements but differ considerably from the values expected from Forster theory, with polyproline treated as a rigid rod. At donor-acceptor distances much less than the Forster radius R(0), the observed efficiencies are lower than predicted, whereas at distances comparable to and greater than R(0), they are much higher. Two possible contributions to the former are incomplete orientational averaging during the donor lifetime and, because of the large size of the dyes, breakdown of the point-dipole approximation assumed in Forster theory. End-to-end distance distributions and correlation times obtained from Langevin molecular dynamics simulations suggest that the differences for the longer polyproline peptides can be explained by chain bending, which considerably shortens the donor-acceptor distances.
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Affiliation(s)
- Benjamin Schuler
- Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, Building 5, Room 104, National Institutes of Health, Bethesda, MD 20892, USA.
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