1
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Singha PK, Kistwal T, Datta A. Single-Particle Dynamics of ZnS Shelling Induced Replenishment of Carrier Diffusion for Individual Emission Centers in CuInS 2 Quantum Dots. J Phys Chem Lett 2023; 14:4289-4296. [PMID: 37126796 DOI: 10.1021/acs.jpclett.3c00467] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Insights into blinking and photoactivation of aqueous copper indium sulfide (CIS) quantum dots have been obtained using fluorescence correlation spectroscopy (FCS) and fluorescence lifetime correlation spectroscopy (FLCS). An unusual excitation wavelength-dependence of photoactivation/photocorrosion is manifested in an increase in the initial correlation amplitude G(0) for λex = 532 nm, but a decrease for λex = 405 nm. This has been rationalized in terms of different contributions from surface-assisted recombination in the two cases. Blinking times obtained from the autocorrelation functions (ACFs) of the 100-200 ns lifetime component (core Cu-mediated recombination) are almost unaffected by shelling, but those from the ACF for the 10-30 ns lifetime (surface states) increase significantly. Absence of cross-correlation between the two recombinative states of bare CIS QDs and the emergence of an anticorrelation with the introduction of the ZnS shell are observed, indicating the diffusive nature of the two states for CIS-ZnS. The diffusion is inhibited in bare CIS QDs due to the preponderance of surface states.
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Affiliation(s)
- Prajit Kumar Singha
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India
| | - Tanuja Kistwal
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India
| | - Anindya Datta
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India
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2
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Das S, Rana G, Ali F, Datta A. Single particle level dynamics of photoactivation and suppression of Auger recombination in aqueous Cu-doped CdS quantum dots. NANOSCALE 2023; 15:4469-4476. [PMID: 36752332 DOI: 10.1039/d2nr06688b] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
Cu-doped CdS quantum dots (QDs) have been synthesized in water using 3-mercaptopropionic acid (3-MPA) as the capping agent. They exhibit intense photoluminescence and excellent color tunability, unlike most of the QDs synthesized/dispersed in water so far. Complete characterization of these aqueous doped CdS QDs has been performed for the first time, along with a single particle level elucidation of their exciton dynamics using fluorescence correlation spectroscopy. Photoactivation via dim/dark to bright particle conversion is observed at higher excitation powers. Dispersive blinking kinetics in undoped QDs reflects the involvement of a broad distribution of trap states. A lesser extent of dispersity is observed for doped QDs, in which hole-capture by Cu-defect states predominates. Excitation fluence dependence of the blinking rate highlights the role of Auger recombination in undoped QDs, which is suppressed significantly upon doping, due to disruption of the electron-hole correlation.
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Affiliation(s)
- Sharmistha Das
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India.
| | - Gourab Rana
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India.
| | - Fariyad Ali
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India.
| | - Anindya Datta
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India.
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3
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Das A, Mishra K, Ghosh S. Revealing Explicit Microsecond Carrier Diffusion from One Emission Center to Another in an All-Inorganic Perovskite Nanocrystal. J Phys Chem Lett 2021; 12:5413-5422. [PMID: 34080871 DOI: 10.1021/acs.jpclett.1c01154] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Blinking of freely diffusing CsPbBr3 nanocrystals (NCs) is studied using fluorescence lifetime correlation spectroscopy (FLCS). Emitted photons from each NCs are assigned to an emission state (exciton or trap) based on their lifetime. Subsequently, an intrastate autocorrelation function (ACF) and an interstate cross-correlation function (CCF) are constructed. Fitting of the AFCs with an analytical model shows that, at low excitation power, the microsecond blinking timescale of the exciton state matches well with that of the trap state. Most interestingly, both of those timescales further correlate with the microsecond growth timescale of the CCF. The strong anti-correlation of the CCF along with the stretched exponential nature of the blinking kinetics confirms the involvement of carrier diffusion and dispersive trap states in NC blinking. At high excitation power, enhanced sample heterogeneity causes a more dispersive blinking. To the best of our knowledge, this is the first report of a NC blinking study using a single-molecule-based FLCS technique.
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Affiliation(s)
- Ayendrila Das
- School of Chemical Sciences, National Institute of Science Education and Research, Homi Bhabha National Institute (HBNI), Khurda 752050, Odisha, India
| | - Krishna Mishra
- School of Chemical Sciences, National Institute of Science Education and Research, Homi Bhabha National Institute (HBNI), Khurda 752050, Odisha, India
| | - Subhadip Ghosh
- School of Chemical Sciences, National Institute of Science Education and Research, Homi Bhabha National Institute (HBNI), Khurda 752050, Odisha, India
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4
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Almeida DB, de Thomaz AA. Measuring the Hydrodynamic Radius of Colloidal Quantum Dots by Fluorescence Correlation Spectroscopy. Methods Mol Biol 2020; 2135:85-93. [PMID: 32246329 DOI: 10.1007/978-1-0716-0463-2_4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Colloidal quantum dots (QDs), due to their versatile optoelectronic properties, have been used in life science applications, especially in fluorescence-based techniques, for over two decades. A great variety of QD syntheses and conjugations are available, and tailoring these for the desired application requires a refined structural characterization. Life science applications rely on the interaction of QDs with biostructures; hence, the knowledge of the QD actual size (i.e., its hydrodynamic radius in the medium the experiment is being carried) and the size of their conjugates is paramount. Fluorescence correlation spectroscopy (FCS) is an optical technique that uses fluorophore light emission to measure its hydrodynamic radius, instead of relying on particle light scattering or crystalline structure, making it ideal for studying bioconjugated QDs in suspension. From the fluorescence intensity autocorrelation, FCS measures the diffusion coefficient of systems in a diluted sample and, by obtaining the diffusion coefficient, it is possible to calculate its hydrodynamic radius. In this chapter we describe the main aspects of the FCS technique and how to use it to calculate the hydrodynamic radius of QDs.
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Affiliation(s)
- Diogo B Almeida
- Quantum Electronics Department, Institute of Physics "Gleb Wataghin", University of Campinas - UNICAMP, Campinas, São Paulo, Brazil
| | - André A de Thomaz
- Quantum Electronics Department, Institute of Physics "Gleb Wataghin", University of Campinas - UNICAMP, Campinas, São Paulo, Brazil.
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5
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Interferometric fluorescence cross correlation spectroscopy. PLoS One 2019; 14:e0225797. [PMID: 31851670 PMCID: PMC6919592 DOI: 10.1371/journal.pone.0225797] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2019] [Accepted: 11/12/2019] [Indexed: 11/20/2022] Open
Abstract
Measuring transport properties like diffusion and directional flow is essential for understanding dynamics within heterogeneous systems including living cells and novel materials. Fluorescent molecules traveling within these inhomogeneous environments under the forces of Brownian motion and flow exhibit fluctuations in their concentration, which are directly linked to the transport properties. We present a method utilizing single photon interference and fluorescence correlation spectroscopy (FCS) to simultaneously measure transport of fluorescent molecules within aqueous samples. Our method, within seconds, measures transport in thousands of homogenous voxels (100 nm)3 and under certain conditions, eliminates photo-physical artifacts associated with blinking of fluorescent molecules. A comprehensive theoretical framework is presented and validated by measuring transport of quantum dots, associated with VSV-G receptor along cellular membranes as well as within viscous gels.
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6
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Sehayek S, Gidi Y, Glembockyte V, Brandão HB, François P, Cosa G, Wiseman PW. A High-Throughput Image Correlation Method for Rapid Analysis of Fluorophore Photoblinking and Photobleaching Rates. ACS NANO 2019; 13:11955-11966. [PMID: 31513377 DOI: 10.1021/acsnano.9b06033] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Super-resolution fluorescence imaging based on localization microscopy requires tuning the photoblinking properties of fluorescent dyes employed. Missing is a rapid way to analyze the blinking rates of the fluorophore probes. Herein we present an ensemble autocorrelation technique for rapidly and simultaneously measuring photoblinking and bleaching rate constants from a microscopy image time series of fluorescent probes that is significantly faster than individual single-molecule trajectory analysis approaches. Our method is accurate for probe densities typically encountered in single-molecule studies as well as for higher density systems which cannot be analyzed by standard single-molecule techniques. We also show that we can resolve characteristic blinking times that are faster than camera detector exposure times, which cannot be accessed by threshold-based single-molecule approaches due to aliasing. We confirm this through computer simulation and single-molecule imaging data of DNA-Cy5 complexes. Finally, we demonstrate that with sufficient sampling our technique can accurately recover rates from stochastic optical reconstruction microscopy super-resolution data.
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Affiliation(s)
- Simon Sehayek
- Department of Physics , McGill University , Montreal , QC , Canada H3A 2T8
| | - Yasser Gidi
- Department of Chemistry , McGill University , Montreal , QC , Canada H3A 0B8
| | | | - Hugo B Brandão
- Department of Physics , McGill University , Montreal , QC , Canada H3A 2T8
| | - Paul François
- Department of Physics , McGill University , Montreal , QC , Canada H3A 2T8
| | - Gonzalo Cosa
- Department of Chemistry , McGill University , Montreal , QC , Canada H3A 0B8
| | - Paul W Wiseman
- Department of Physics , McGill University , Montreal , QC , Canada H3A 2T8
- Department of Chemistry , McGill University , Montreal , QC , Canada H3A 0B8
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7
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Su D, Hou Y, Dong C, Ren J. Fluctuation correlation spectroscopy and its applications in homogeneous analysis. Anal Bioanal Chem 2019; 411:4523-4540. [DOI: 10.1007/s00216-019-01884-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2018] [Revised: 04/12/2019] [Accepted: 04/29/2019] [Indexed: 12/11/2022]
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8
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Alshalfouh A, Oezaslan M, Dosche C, Wittstock G. Electrochemistry of CdSe Quantum Dots Studied by Single Molecule Spectroscopy. ChemElectroChem 2019. [DOI: 10.1002/celc.201801793] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Affiliation(s)
- Abdallatif Alshalfouh
- Institute of ChemistryCarl von Ossietzky University of Oldenburg 26111 Oldenburg Germany
| | - Mehtap Oezaslan
- Institute of ChemistryCarl von Ossietzky University of Oldenburg 26111 Oldenburg Germany
| | - Carsten Dosche
- Institute of ChemistryCarl von Ossietzky University of Oldenburg 26111 Oldenburg Germany
| | - Gunther Wittstock
- Institute of ChemistryCarl von Ossietzky University of Oldenburg 26111 Oldenburg Germany
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9
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Kohle FFE, Hinckley JA, Wiesner UB. Dye Encapsulation in Fluorescent Core-Shell Silica Nanoparticles as Probed by Fluorescence Correlation Spectroscopy. THE JOURNAL OF PHYSICAL CHEMISTRY. C, NANOMATERIALS AND INTERFACES 2019; 123:9813-9823. [PMID: 31819780 PMCID: PMC6901343 DOI: 10.1021/acs.jpcc.9b00297] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Synthetic advances in the formation of ultrasmall (<10 nm) fluorescent poly(ethylene glycol)-coated (PEGylated) core-shell silica nanoparticles (SNPs), enabling improved particle size and surface chemical property control have led to successful clinical translation of SNPs as diagnostic probes in oncology. Despite the success of such probes, details of the dye incorporation and resulting silica architecture are still poorly understood. Here, we employ afterpulse-corrected fluorescence correlation spectroscopy (FCS) to monitor fast fluorescence fluctuations (lag times <10-5 s) of the negatively charged cyanine dye Cy5 as a probe to study such details for dye encapsulation in 5 nm silica cores of PEGylated core-shell SNPs (C dots). Upon deposition of additional silica shells over the silica core we find that the amplitude of photo-induced cis-trans isomerization decreases, suggesting that the Cy5 dyes are located near or on the surface of the original SNP cores. In combination with time correlated fluorescence decay measurements we deduce radiative and non-radiative rates of the Cy5 dye in these particles. Results demonstrate that FCS is a well-suited tool to investigate aspects of the photophysics of fluorescent nanoparticles, and that conformational changes of cyanine dyes like Cy5 are excellent indicators for the local dye environment within ultrasmall SNPs.
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Affiliation(s)
- Ferdinand F. E. Kohle
- Materials Science and Engineering, Cornell University, Ithaca, NY 14853
- Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14853
| | - Joshua A. Hinckley
- Materials Science and Engineering, Cornell University, Ithaca, NY 14853
- Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14853
| | - Ulrich B. Wiesner
- Materials Science and Engineering, Cornell University, Ithaca, NY 14853
- Department of Materials Science and Engineering, Cornell University, 330 Bard Hall, Ithaca, NY 14853. Fax: 607-255-2365
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10
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Yang J, Dong C, Ren J. Chiral ligand‐induced photoluminescence intermittence difference of CdTe quantum dots. LUMINESCENCE 2018; 33:1150-1156. [DOI: 10.1002/bio.3521] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2018] [Revised: 05/31/2018] [Accepted: 06/07/2018] [Indexed: 12/15/2022]
Affiliation(s)
- Jie Yang
- School of Chemistry and Chemical Engineering, State Key Laboratory of Metal Matrix CompositesShanghai Jiao Tong University Shanghai P. R. China
| | - Chaoqing Dong
- School of Chemistry and Chemical Engineering, State Key Laboratory of Metal Matrix CompositesShanghai Jiao Tong University Shanghai P. R. China
| | - Jicun Ren
- School of Chemistry and Chemical Engineering, State Key Laboratory of Metal Matrix CompositesShanghai Jiao Tong University Shanghai P. R. China
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11
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Abbandonato G, Hoffmann K, Resch-Genger U. Determination of quantum yields of semiconductor nanocrystals at the single emitter level via fluorescence correlation spectroscopy. NANOSCALE 2018; 10:7147-7154. [PMID: 29616686 DOI: 10.1039/c7nr09332b] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Comparing the photoluminescence (PL) properties of ensembles of nanocrystals like semiconductor quantum dots (QDs) with single particle studies is of increasing interest for many applications of these materials as reporters in bioimaging studies performed under very dilute conditions or even at the single particle level. Particularly relevant is here the PL quantum yield (ΦF), which determines the signal size together with the reporter's molar extinction coefficient and is a direct measure for nanocrystal quality, especially for the inorganic surface passivation shell and its tightness, which can be correlated also with nanocrystal stability and the possible release of heavy metal ions. Exemplarily for red and green emitting CdTe nanocrystals, we present a method for the determination of ΦF of nanoparticle dispersions at ultralow concentration compared to cuvette measurements using fluorescence correlation spectroscopy (FCS), a single molecule method, and compared to molecular dyes with closely matching spectral properties and known ΦF. Our results underline the potential of this approach, provided that material-inherent limitations like ligand- and QD-specific aggregation affecting particle diffusion and QD drawbacks such as their complex and power-dependent blinking behavior are properly considered as shown here.
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Affiliation(s)
- Gerardo Abbandonato
- Federal Institute for Materials Research and Testing (BAM), Division Biophotonics, Richard-Willstaetter-Str. 11, 12489 Berlin, Germany.
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12
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Liu F, Dong C, Ren J. A study of the diffusion dynamics and concentration distribution of gold nanospheres (GNSs) without fluorescent labeling inside live cells using fluorescence single particle spectroscopy. NANOSCALE 2018; 10:5309-5317. [PMID: 29503992 DOI: 10.1039/c7nr08722e] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Colloidal gold nanospheres (GNSs) have become important nanomaterials in biomedical applications due to their special optical properties, good chemical stability, and biocompatibility. However, measuring the diffusion coefficients or concentration distribution of GNSs within live cells accurately without any extra fluorescent labeling in situ has still not been resolved. In this work, a single particle method is developed to study the concentration distribution of folic acid-modified GNSs (FA-GNSs) internalized via folate receptors, and investigates their diffusion dynamics within live cells using single particle fluorescence correlation spectroscopy (FCS). We optimized the experimental conditions and verified the feasibility of 30 nm GNSs without extra fluorescence labeling being used for single particle detection inside live cells. Then, the FCS characterization strategy was used to measure the concentration and diffusion coefficient distributions of GNSs inside live cells and the obtained results were basically in agreement with those obtained by TEM. The results demonstrate that our strategy is characterized as an in situ, nondestructive, rapid and dynamic method for the assay of live cells, and it may be widely used in the further design of GNP-based drug delivery and therapeutics.
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Affiliation(s)
- Fangchao Liu
- School of Chemistry & Chemical Engineering, State Key Laboratory of Metal Matrix Composites, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai, 200240, P. R. China.
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13
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Sheung JY, Ge P, Lim SJ, Lee SH, Smith AM, Selvin PR. Structural Contributions to Hydrodynamic Diameter for Quantum Dots Optimized for Live-Cell Single-Molecule Tracking. THE JOURNAL OF PHYSICAL CHEMISTRY. C, NANOMATERIALS AND INTERFACES 2018; 122:17406-17412. [PMID: 31656549 PMCID: PMC6814160 DOI: 10.1021/acs.jpcc.8b02516] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
Quantum dots are fluorescent nanoparticles with narrow-band, size-tunable, and long-lasting emission. Typical formulations used for imaging proteins in cells are hydrodynamically much larger than the protein targets, so it is critical to assess the impact of steric effects deriving from hydrodynamic size. This report analyzes a new class of quantum dots that have been engineered for minimized size specifically for imaging receptors in narrow synaptic junctions between neurons. We use fluorescence correlation spectroscopy and transmission electron microscopy to calculate the contributions of the crystalline core, organic coating, and targeting proteins (streptavidin) to the total hydrodynamic diameter of the probe, using a wide range of core materials with emission spanning 545-705 nm. We find the contributing thickness of standard commercial amphiphilic polymers to be ~8 to ~14 nm, whereas coatings based on the compact ligand HS-(CH2)11 - (OCH2CH2)4-OH contribute ~6 to ~9 nm, reducing the diameter by ~2 to ~5 nm, depending on core size. When the number of streptavidins for protein targeting is minimized, the total diameter can be further reduced by ~5 to ~11 nm, yielding a diameter of 13.8-18.4 nm. These findings explain why access to the narrow synapse derive primarily from the protein functionalization of commercial variants, rather than the organic coating layers. They also explain why those quantum dots with size around 14 nm with only a few streptavidins can access narrow cellular structures for neuronal labeling, whereas those >27 nm and a large number of streptavidins, cannot.
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Affiliation(s)
- Janet Y. Sheung
- Department of Physics, University of Illinois at Urbana-Champaign, Champaign, Illinois 61801, United States
- Department of Physics and Astronomy, Vassar College, Poughkeepsie, New York 12604, United States
- Center for the Physics of Living Cells, University of Illinois at Urbana–Champaign, Champaign, Illinois 61801, United States
| | - Pinghua Ge
- Department of Physics, University of Illinois at Urbana-Champaign, Champaign, Illinois 61801, United States
- Center for the Physics of Living Cells, University of Illinois at Urbana–Champaign, Champaign, Illinois 61801, United States
| | - Sung Jun Lim
- Department of Bioengineering, University of Illinois at Urbana–Champaign, Champaign, Illinois 61801, United States
- Micro and Nanotechnology Laboratory, University of Illinois at Urbana–Champaign, Champaign, Illinois 61801, United States
- Intelligent Devices and Systems Research Group, DGIST, 333 Techno Jungang-Daero, Hyeonpung, Daegu 42988, Republic of Korea
| | - Sang Hak Lee
- Department of Physics, University of Illinois at Urbana-Champaign, Champaign, Illinois 61801, United States
- Center for the Physics of Living Cells, University of Illinois at Urbana–Champaign, Champaign, Illinois 61801, United States
| | - Andrew M. Smith
- Department of Bioengineering, University of Illinois at Urbana–Champaign, Champaign, Illinois 61801, United States
- Micro and Nanotechnology Laboratory, University of Illinois at Urbana–Champaign, Champaign, Illinois 61801, United States
- Department of Materials Science and Engineering and University of Illinois at Urbana–Champaign, Champaign, Illinois 61801, United States
| | - Paul R. Selvin
- Department of Physics, University of Illinois at Urbana-Champaign, Champaign, Illinois 61801, United States
- Center for the Physics of Living Cells, University of Illinois at Urbana–Champaign, Champaign, Illinois 61801, United States
- Corresponding Author, P. R. Selvin.
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14
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Oura M, Yamamoto J, Jin T, Kinjo M. Investigation of pH-dependent photophysical properties of quantum nanocrystals by fluorescence correlation spectroscopy. OPTICS EXPRESS 2017; 25:1435-1443. [PMID: 28158025 DOI: 10.1364/oe.25.001435] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Quantum dot (QD) and quantum rod (QR) nanocrystals are widely used non-organic nanocrystals. Their strong fluorescence and photostability make them suitable for biomedical imaging applications. However, their pH-dependence and antibunching properties have not been studied much, especially in aqueous conditions. In this report, we used fluorescence correlation spectroscopy (FCS) with high temporal resolution to demonstrate that the fluorescent blinking and antibunching of QDs/QRs can be changed by varying the pH of their solutions. Furthermore, herein, we reported the relationship between the aggregation and antibunching relaxation time of QDs/QRs for the first time. The findings of this study suggest that FCS can be used to discover novel environmental indicators via observing nanosecond and microsecond phenomena.
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15
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Seth S, Mondal N, Patra S, Samanta A. Fluorescence Blinking and Photoactivation of All-Inorganic Perovskite Nanocrystals CsPbBr3 and CsPbBr2I. J Phys Chem Lett 2016; 7:266-71. [PMID: 26727624 DOI: 10.1021/acs.jpclett.5b02639] [Citation(s) in RCA: 53] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Study of the emission behavior of all-inorganic perovskite nanocrystals CsPbBr3 and CsPbBr2I as a function of the excitation power employing fluorescence correlation spectroscopy and conventional techniques reveals fluorescence blinking in the microsecond time scale and photoinduced emission enhancement. The observation provides insight into the radiative and nonradiative deactivation pathways of these promising substances. Because both blinking and photoactivation processes are intimately linked to the charge separation efficiency and dynamics of the nanocrystals, these key findings are likely to be helpful in realizing the true potential of these substances in photovoltaic and optoelectronic applications.
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Affiliation(s)
- Sudipta Seth
- School of Chemistry, University of Hyderabad , Hyderabad 500046, India
| | - Navendu Mondal
- School of Chemistry, University of Hyderabad , Hyderabad 500046, India
| | - Satyajit Patra
- School of Chemistry, University of Hyderabad , Hyderabad 500046, India
| | - Anunay Samanta
- School of Chemistry, University of Hyderabad , Hyderabad 500046, India
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16
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Early KT, Nesbitt DJ. Ultrafast Laser Studies of Two-Photon Excited Fluorescence Intermittency in Single CdSe/ZnS Quantum Dots. NANO LETTERS 2015; 15:7781-7787. [PMID: 26542640 DOI: 10.1021/acs.nanolett.5b01139] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Two-photon fluorescence microscopy of single quantum dots conditions has been reported by several groups, with contrasting observations regarding the kinetics and dynamics of fluorescence intermittency or "blinking". Here, we investigate the power dependence, kinetics, and statistics of two photon-excited fluorescence intermittency from single CdSe/ZnS quantum dots in a solid PMMA film as a function of sub-bandgap laser intensity at 800 nm. Fluorescence intermittency is observed at all excitation powers and a quadratic (n = 1.97(3)) dependence of the shot noise-limited fluorescence intensity on the incident laser power is verified, confirming essentially zero background contribution from one-photon excitation processes. Such analyses permit two photon absorption cross sections for single quantum dots to be extracted quantitatively from the data, which reveal good agreement with those obtained from previous two-photon FCS measurements. Strictly inverse power law-distributed off-state dwell times are observed for all excitation powers, with a mean power law exponent ⟨m(off)⟩ = 1.65(4) in excellent agreement with the behavior observed under one-photon excitation conditions. Finally, a superquadratic (n = 2.3(2)) rather than quartic (n = 4) power dependence is observed for the on-state blinking dwell times, which we kinetically analyze and interpret in terms of a novel 2 + 1 "hot" exciton ionization/blinking mechanism due to partially saturated 1-photon sub-bandgap excitation out of the two-photon single exciton state. The kinetic results are consistent with quantum dot photoionization quantum yields from "hot" exciton states (4(1) × 10(-6)) comparable with experimental estimates (10(-6)-10(-5)) of Auger ionization efficiencies out of the biexcitonic state.
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Affiliation(s)
- Kevin T Early
- Joint Institute for Lab Astrophysics, National Institute of Standards and Technology and University of Colorado, Boulder, Colorado 80309, United States
- Department of Chemistry and Biochemistry, University of Colorado Boulder, Colorado 80309, United States
| | - David J Nesbitt
- Joint Institute for Lab Astrophysics, National Institute of Standards and Technology and University of Colorado, Boulder, Colorado 80309, United States
- Department of Chemistry and Biochemistry, University of Colorado Boulder, Colorado 80309, United States
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17
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de Thomaz AA, Almeida DB, Pelegati VB, Carvalho HF, Cesar CL. Measurement of the hydrodynamic radius of quantum dots by fluorescence correlation spectroscopy excluding blinking. J Phys Chem B 2015; 119:4294-9. [PMID: 25692215 DOI: 10.1021/jp512214p] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
One of the most important properties of quantum dots (QDs) is their size. Their size will determine optical properties and in a colloidal medium their range of interaction. The most common techniques used to measure QD size are transmission electron microscopy (TEM) and X-ray diffraction. However, these techniques demand the sample to be dried and under a vacuum. This way any hydrodynamic information is excluded and the preparation process may alter even the size of the QDs. Fluorescence correlation spectroscopy (FCS) is an optical technique with single molecule sensitivity capable of extracting the hydrodynamic radius (HR) of the QDs. The main drawback of FCS is the blinking phenomenon that alters the correlation function implicating in a QD apparent size smaller than it really is. In this work, we developed a method to exclude blinking of the FCS and measured the HR of colloidal QDs. We compared our results with TEM images, and the HR obtained by FCS is higher than the radius measured by TEM. We attribute this difference to the cap layer of the QD that cannot be seen in the TEM images.
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Affiliation(s)
- A A de Thomaz
- †Department of Quantum Electronics, Institute of Physics "Gleb Wataghin", State University of Campinas/UNICAMP, 13083-859 Campinas, São Paulo, Brazil
| | - D B Almeida
- †Department of Quantum Electronics, Institute of Physics "Gleb Wataghin", State University of Campinas/UNICAMP, 13083-859 Campinas, São Paulo, Brazil
| | - V B Pelegati
- †Department of Quantum Electronics, Institute of Physics "Gleb Wataghin", State University of Campinas/UNICAMP, 13083-859 Campinas, São Paulo, Brazil
| | - H F Carvalho
- ‡Department of Structural and Functional Biology, Institute of Biology, State University of Campinas/UNICAMP, 13083-865 Campinas, São Paulo, Brazil.,§National Institute of Photonics Applied to Cell Biology (INFABIC), 13083-865 Campinas, São Paulo, Brazil
| | - C L Cesar
- †Department of Quantum Electronics, Institute of Physics "Gleb Wataghin", State University of Campinas/UNICAMP, 13083-859 Campinas, São Paulo, Brazil.,§National Institute of Photonics Applied to Cell Biology (INFABIC), 13083-865 Campinas, São Paulo, Brazil
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Trofymchuk K, Reisch A, Shulov I, Mély Y, Klymchenko AS. Tuning the color and photostability of perylene diimides inside polymer nanoparticles: towards biodegradable substitutes of quantum dots. NANOSCALE 2014; 6:12934-42. [PMID: 25233438 DOI: 10.1039/c4nr03718a] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
Fluorescent organic nanoparticles (NPs) are attractive alternatives to quantum dots due to their potential biodegradability. However, preparation of fluorescent organic NPs is challenging due to the problem of self-quenching of the encapsulated dyes. Moreover, the photostability of organic dyes is much lower than that of quantum dots. To address both problems, we studied encapsulation into biodegradable polymer PLGA NPs of perylene diimide (PDI) derivatives, which are among the most photostable dyes reported to date. Two PDIs were tested, one bearing bulky hydrophobic groups at the imides, while the other was substituted in both imide and bay regions (Lumogen Red). Encapsulation of the former resulted in aggregation, which was accompanied by the emission color change from green to red, some decrease in the fluorescence quantum yield and a significant drop in the photostability, unexpected for PDI dyes. In contrast, Lumogen Red showed nearly no aggregation inside polymer NPs and maintained high quantum yield and photostability. According to wide-field fluorescence microscopy with a 532 nm excitation laser, our 40 nm PLGA NPs loaded with 1 wt% Lumogen Red were >10-fold brighter than quantum dots (QD-585). These NPs were stable in biological media, including serum, and entered spontaneously into HeLa cells by endocytosis showing no sign of cytotoxicity. Due to excellent photostability, these nanoparticles could be considered as biodegradable substitutes of quantum dots in bioimaging.
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Affiliation(s)
- Kateryna Trofymchuk
- Laboratoire de Biophotonique et Pharmacologie, UMR 7213 CNRS, Université de Strasbourg, Faculté de Pharmacie, 74, Route du Rhin, 67401 ILLKIRCH Cedex, France.
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19
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Maffre P, Brandholt S, Nienhaus K, Shang L, Parak WJ, Nienhaus GU. Effects of surface functionalization on the adsorption of human serum albumin onto nanoparticles - a fluorescence correlation spectroscopy study. BEILSTEIN JOURNAL OF NANOTECHNOLOGY 2014; 5:2036-47. [PMID: 25551031 PMCID: PMC4273259 DOI: 10.3762/bjnano.5.212] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/18/2014] [Accepted: 10/15/2014] [Indexed: 05/18/2023]
Abstract
By using fluorescence correlation spectroscopy (FCS), we have studied the adsorption of human serum albumin (HSA) onto Fe-Pt nanoparticles (NPs, 6 nm radius), CdSe/ZnS quantum dots (QDs, 5 nm radius) and Au and Ag nanoclusters (1-4 nm radius), which are enshrouded by various water-solubilizing surface layers exposing different chemical functional groups (carboxyl, amino and both), thereby endowing the NPs with different surface charges. We have also measured the effects of modified surface functionalizations on the protein via succinylation and amination. A step-wise increase in hydrodynamic radius with protein concentration was always observed, revealing formation of protein monolayers coating the NPs, independent of their surface charge. The differences in the thickness of the protein corona were rationalized in terms of the different orientations in which HSA adsorbs onto the NPs. The midpoints of the binding transition, which quantifies the affinity of HSA toward the NP, were observed to differ by almost four orders of magnitude. These variations can be understood in terms of specific Coulombic interactions between the proteins and the NP surfaces.
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Affiliation(s)
- Pauline Maffre
- Institute of Applied Physics and Center for Functional Nanostructures, Karlsruhe Institute of Technology (KIT), Wolfgang-Gaede-Strasse 1, 76131 Karlsruhe, Germany
| | - Stefan Brandholt
- Institute of Applied Physics and Center for Functional Nanostructures, Karlsruhe Institute of Technology (KIT), Wolfgang-Gaede-Strasse 1, 76131 Karlsruhe, Germany
| | - Karin Nienhaus
- Institute of Applied Physics and Center for Functional Nanostructures, Karlsruhe Institute of Technology (KIT), Wolfgang-Gaede-Strasse 1, 76131 Karlsruhe, Germany
| | - Li Shang
- Institute of Applied Physics and Center for Functional Nanostructures, Karlsruhe Institute of Technology (KIT), Wolfgang-Gaede-Strasse 1, 76131 Karlsruhe, Germany
| | - Wolfgang J Parak
- Department of Physics, Philipps University Marburg, Renthof 7, 35037 Marburg, Germany
| | - G Ulrich Nienhaus
- Institute of Applied Physics and Center for Functional Nanostructures, Karlsruhe Institute of Technology (KIT), Wolfgang-Gaede-Strasse 1, 76131 Karlsruhe, Germany
- Department of Physics, University of Illinois at Urbana-Champaign, 1110 West Green Street, Urbana, IL 61801, USA
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20
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Dong C, Liu H, Ren J. Assessing the blinking state of fluorescent quantum dots in free solution by combining fluorescence correlation spectroscopy with ensemble spectroscopic methods. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2014; 30:12969-12976. [PMID: 25290853 DOI: 10.1021/la503055v] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
The current method for investigating the blinking behavior is to immobilize quantum dots (QDs) in the matrix and then apply a fluorescent technique to monitor the fluorescent trajectories of individual QDs. So far, no method can be used to directly assess the blinking state of ensemble QDs in free solution. In this study, a new method was described to characterize the blinking state of the QDs in free solution by combining single molecule fluorescence correlation spectroscopy (FCS) with ensemble spectroscopic methods. Its principle is based on the observation that the apparent concentration of bright QDs obtained by FCS is less than its actual concentration measured by ensemble spectroscopic method due to the QDs blinking. We proposed a blinking index (Kblink) for characterizing the blinking state of QDs, and Kblink is defined as the ratio of the actual concentration (Cb,actual) measured by the ensemble spectroscopic method to the apparent concentration (Cb,app) of QDs obtained by FCS. The effects of certain factors such as laser intensity, growth process, and ligands on blinking of QDs were investigated. The Kblink data of QDs obtained were successfully used to characterize the blinking state of QDs and explain certain experimental results.
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Affiliation(s)
- Chaoqing Dong
- School of Chemistry & Chemical Engineering, State Key Laboratory of Metal Matrix Composites, Shanghai Jiao Tong University , 800 Dongchuan Road, Shanghai 200240, P. R. China
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21
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Multiphoton imaging of tumor biomarkers with conjugates of single-domain antibodies and quantum dots. NANOMEDICINE-NANOTECHNOLOGY BIOLOGY AND MEDICINE 2014; 10:1701-9. [DOI: 10.1016/j.nano.2014.05.014] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/16/2013] [Revised: 04/29/2014] [Accepted: 05/29/2014] [Indexed: 11/19/2022]
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22
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Dong C, Liu H, Zhang A, Ren J. Controllable Blinking-to-Nonblinking Behavior of Aqueous CdTeS Alloyed Quantum Dots. Chemistry 2014; 20:1940-6. [DOI: 10.1002/chem.201303605] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2013] [Revised: 11/21/2013] [Indexed: 11/06/2022]
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de Thomaz AA, Almeida DB, Cesar CL. Measuring the hydrodynamic radius of quantum dots by Fluorescence Correlation Spectroscopy. Methods Mol Biol 2014; 1199:85-91. [PMID: 25103801 DOI: 10.1007/978-1-4939-1280-3_6] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Fluorescence Correlation Spectroscopy (FCS) is an optical technique that allows the measurement of the diffusion coefficient of molecules in a diluted sample. From the diffusion coefficient it is possible to calculate the hydrodynamic radius of the molecules. For colloidal quantum dots (QDs) the hydrodynamic radius is valuable information to study interactions with other molecules or other QDs. In this chapter we describe the main aspects of the technique and how to use it to calculate the hydrodynamic radius of quantum dots (QDs).
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Affiliation(s)
- André A de Thomaz
- Quantum Electronics Department, Institute of Physics Gleb Wataghin, State University of Campinas (UNICAMP), Cidade Universitária Zeferino Vaz S/N, Barão Geraldo, 13083-970, Campinas, São Paulo, Brazil
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24
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Jung ME, Trzoss M, Tsay JM, Weiss S. A Bis(phosphine)-Modified Peptide Ligand for Stable and Luminescent Quantum Dots in Aqueous Media. SYNTHESIS-STUTTGART 2013; 45:2426-2430. [PMID: 24729639 DOI: 10.1055/s-0033-1339340] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
We describe a new class of ligands for semiconductor nanoparticles (quantum dots = QDs), which bind well and allow for their facile dissolution in aqueous solution. As a proof of principle, we have designed and synthesized a novel bis(phosphine)-modified peptide (BPMP) and shown that it has the ability to solubilize quantum dots in aqueous media. We further showed that the corresponding phosphine oxide derivatives of these new ligands are less good at solubilizing the quantum dots. These new bis(phosphine)-modified peptide ligands are easy to prepare and may well replace thiol-containing binding sequences in functionalized peptides for quantum dot coating, potentially resulting in quantum dots with higher quantum yields.
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Affiliation(s)
- Michael E Jung
- Department of Chemistry and Biochemistry, California NanoSystems Institute, and Department of Physiology, University of California at Los Angeles, Los Angeles, CA 90095-1569, USA
| | - Michael Trzoss
- Department of Chemistry and Biochemistry, California NanoSystems Institute, and Department of Physiology, University of California at Los Angeles, Los Angeles, CA 90095-1569, USA
| | - James M Tsay
- Department of Chemistry and Biochemistry, California NanoSystems Institute, and Department of Physiology, University of California at Los Angeles, Los Angeles, CA 90095-1569, USA
| | - Shimon Weiss
- Department of Chemistry and Biochemistry, California NanoSystems Institute, and Department of Physiology, University of California at Los Angeles, Los Angeles, CA 90095-1569, USA
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25
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Preparation and characterization of gold nanoparticles with amino acids, examination of their stability. Indian J Clin Biochem 2013; 29:306-14. [PMID: 24966478 DOI: 10.1007/s12291-013-0358-4] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2013] [Accepted: 06/25/2013] [Indexed: 10/26/2022]
Abstract
We report a novel strategy for the synthesis and capping of gold nanoparticles (GNPs) by tryptophan, glutamic acid and aspartic acid. The ratio of chloroaurate ions to amino acid was optimized in the reaction medium to obtain monodispersed GNPs. The size of nanoparticles and size distribution were controlled by sodium dodecyl sulfate which demonstrated high stability in aqueous solution over a period of time. GNPs were characterized by UV-Vis spectroscopy, dynamic light scattering and transmission electron microscopy.
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26
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Petryayeva E, Algar WR, Medintz IL. Quantum dots in bioanalysis: a review of applications across various platforms for fluorescence spectroscopy and imaging. APPLIED SPECTROSCOPY 2013; 67:215-52. [PMID: 23452487 DOI: 10.1366/12-06948] [Citation(s) in RCA: 298] [Impact Index Per Article: 27.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Semiconductor quantum dots (QDs) are brightly luminescent nanoparticles that have found numerous applications in bioanalysis and bioimaging. In this review, we highlight recent developments in these areas in the context of specific methods for fluorescence spectroscopy and imaging. Following a primer on the structure, properties, and biofunctionalization of QDs, we describe select examples of how QDs have been used in combination with steady-state or time-resolved spectroscopic techniques to develop a variety of assays, bioprobes, and biosensors that function via changes in QD photoluminescence intensity, polarization, or lifetime. Some special attention is paid to the use of Förster resonance energy transfer-type methods in bioanalysis, including those based on bioluminescence and chemiluminescence. Direct chemiluminescence, electrochemiluminescence, and charge transfer quenching are similarly discussed. We further describe the combination of QDs and flow cytometry, including traditional cellular analyses and spectrally encoded barcode-based assay technologies, before turning our attention to enhanced fluorescence techniques based on photonic crystals or plasmon coupling. Finally, we survey the use of QDs across different platforms for biological fluorescence imaging, including epifluorescence, confocal, and two-photon excitation microscopy; single particle tracking and fluorescence correlation spectroscopy; super-resolution imaging; near-field scanning optical microscopy; and fluorescence lifetime imaging microscopy. In each of the above-mentioned platforms, QDs provide the brightness needed for highly sensitive detection, the photostability needed for tracking dynamic processes, or the multiplexing capacity needed to elucidate complex systems. There is a clear synergy between advances in QD materials and spectroscopy and imaging techniques, as both must be applied in concert to achieve their full potential.
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Affiliation(s)
- Eleonora Petryayeva
- Department of Chemistry, University of British Columbia, Vancouver, BC V6T 1Z1, Canada
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27
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Dong C, Chowdhury B, Irudayaraj J. Probing site-exclusive binding of aqueous QDs and their organelle-dependent dynamics in live cells by single molecule spectroscopy. Analyst 2013; 138:2871-6. [DOI: 10.1039/c3an36906d] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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28
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Blades ML, Grekova E, Wobma HM, Chen K, Chan WCW, Cramb DT. Three-Color Fluorescence Cross-Correlation Spectroscopy for Analyzing Complex Nanoparticle Mixtures. Anal Chem 2012; 84:9623-31. [DOI: 10.1021/ac302572k] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Megan L. Blades
- Department of Chemistry, University of Calgary, 2500 University Drive NW, T3A
0J1, Calgary, Alberta, Canada
| | - Ekaterina Grekova
- Department of Chemistry, University of Calgary, 2500 University Drive NW, T3A
0J1, Calgary, Alberta, Canada
| | - Holly M. Wobma
- Department of Chemistry, University of Calgary, 2500 University Drive NW, T3A
0J1, Calgary, Alberta, Canada
| | - Kun Chen
- Institute of Biomaterials and
Biomedical Engineering, Donnelly Centre for Cellular and Biomolecular
Research, Chemistry, Materials Science and Engineering, and Chemical
Engineering, University of Toronto, 160
College Street, Toronto, Ontario, Canada M5S 3E1
| | - Warren C. W. Chan
- Institute of Biomaterials and
Biomedical Engineering, Donnelly Centre for Cellular and Biomolecular
Research, Chemistry, Materials Science and Engineering, and Chemical
Engineering, University of Toronto, 160
College Street, Toronto, Ontario, Canada M5S 3E1
| | - David T. Cramb
- Department of Chemistry, University of Calgary, 2500 University Drive NW, T3A
0J1, Calgary, Alberta, Canada
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29
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Dong C, Irudayaraj J. Hydrodynamic size-dependent cellular uptake of aqueous QDs probed by fluorescence correlation spectroscopy. J Phys Chem B 2012; 116:12125-32. [PMID: 22950363 DOI: 10.1021/jp305563p] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Aqueous quantum dots (QDs) directly synthesized with various thiol ligands have been investigated as imaging probes in living cells. However, the effect of the surface chemistry of these ligands on QDs' cellular uptakes and their intracellular fate remains poorly understood. In this work, four CdTe QDs were directly synthesized under aqueous conditions using four different thiols as stabilizers and their interactions with cells were investigated. Fluorescence correlation spectroscopy (FCS), X-ray photoelectron spectroscopy (XPS), and zeta potential measurements on QDs primarily show that the surface structure of these QDs is highly dependent on the thiol ligands used in the preparation of QDs' precursors, including its layer thicknesses, densities, and surface charges. Subsequently, FCS integrated with the maximum-entropy-method-based FCS (MEMFCS) was used to investigate the concentration distribution and dynamics of these QDs in living A-427 cells. Our findings indicate that QDs' surface characteristics affect cell membrane adsorption and subsequent internalization. More critically, we show that the cellular uptake of aqueous QDs is dependent on their hydrodynamic diameter and might have the potential to escape trapped environments to accumulate in the cytoplasm.
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Affiliation(s)
- Chaoqing Dong
- Department of Agricultural and Biological Engineering, Bindley Bioscience Center, Purdue University, West Lafayette, Indiana 47907, USA
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30
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Yang F, Xu Z, Wang J, Zan F, Dong C, Ren J. Microwave-assisted aqueous synthesis of new quaternary-alloyed CdSeTeS quantum dots; and their bioapplications in targeted imaging of cancer cells. LUMINESCENCE 2012; 28:392-400. [DOI: 10.1002/bio.2395] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2012] [Revised: 05/08/2012] [Accepted: 05/16/2012] [Indexed: 01/21/2023]
Affiliation(s)
- Fengzhao Yang
- College of Chemistry & Chemical Engineering, State Key Laboratory of Metal Matrix Composites; Shanghai Jiaotong University; Shanghai; 200240; People's Republic of China
| | - Zhancheng Xu
- College of Chemistry & Chemical Engineering, State Key Laboratory of Metal Matrix Composites; Shanghai Jiaotong University; Shanghai; 200240; People's Republic of China
| | - Jinjie Wang
- College of Chemistry & Chemical Engineering, State Key Laboratory of Metal Matrix Composites; Shanghai Jiaotong University; Shanghai; 200240; People's Republic of China
| | - Feng Zan
- College of Chemistry & Chemical Engineering, State Key Laboratory of Metal Matrix Composites; Shanghai Jiaotong University; Shanghai; 200240; People's Republic of China
| | - Chaoqing Dong
- College of Chemistry & Chemical Engineering, State Key Laboratory of Metal Matrix Composites; Shanghai Jiaotong University; Shanghai; 200240; People's Republic of China
| | - Jicun Ren
- College of Chemistry & Chemical Engineering, State Key Laboratory of Metal Matrix Composites; Shanghai Jiaotong University; Shanghai; 200240; People's Republic of China
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31
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Mixed-surface, lipid-tethered quantum dots for targeting cells and tissues. Colloids Surf B Biointerfaces 2012; 94:27-35. [DOI: 10.1016/j.colsurfb.2012.01.015] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2011] [Revised: 01/08/2012] [Accepted: 01/08/2012] [Indexed: 11/21/2022]
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32
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Oriented conjugates of single-domain antibodies and quantum dots: toward a new generation of ultrasmall diagnostic nanoprobes. NANOMEDICINE-NANOTECHNOLOGY BIOLOGY AND MEDICINE 2012; 8:516-25. [DOI: 10.1016/j.nano.2011.07.007] [Citation(s) in RCA: 126] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/10/2011] [Revised: 07/13/2011] [Accepted: 07/16/2011] [Indexed: 11/24/2022]
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Overview of stabilizing ligands for biocompatible quantum dot nanocrystals. SENSORS 2011; 11:11036-55. [PMID: 22247651 PMCID: PMC3251968 DOI: 10.3390/s111211036] [Citation(s) in RCA: 98] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/12/2011] [Revised: 11/21/2011] [Accepted: 11/22/2011] [Indexed: 11/17/2022]
Abstract
Luminescent colloidal quantum dots (QDs) possess numerous advantages as fluorophores in biological applications. However, a principal challenge is how to retain the desirable optical properties of quantum dots in aqueous media while maintaining biocompatibility. Because QD photophysical properties are directly related to surface states, it is critical to control the surface chemistry that renders QDs biocompatible while maintaining electronic passivation. For more than a decade, investigators have used diverse strategies for altering the QD surface. This review summarizes the most successful approaches for preparing biocompatible QDs using various chemical ligands.
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Tagit O, Tomczak N, Jafarpour A, Jańczewski D, Han MY, Vancso GJ, Herek JL. Influence of the length and grafting density of PNIPAM chains on the colloidal and optical properties of quantum dot/PNIPAM assemblies. NANOTECHNOLOGY 2011; 22:265701. [PMID: 21576806 DOI: 10.1088/0957-4484/22/26/265701] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Structural and optical characterization of water soluble, thermo-responsive quantum dot/poly(N-isopropyl acrylamide) (QD/PNIPAM) hybrid particles using fluorescence correlation spectroscopy (FCS) and time-correlated single photon counting (TCSPC) measurements performed at temperatures below and above the lower critical solution temperature (LCST) of PNIPAM is reported. By increasing the temperature above the LCST, the signature of the PNIPAM chain collapse covering the QDs is revealed by FCS measurements. Despite the significant structural change, the TCSPC measurements show that the fluorescence lifetimes remain of the same order of magnitude at T > LCST. Such QD/PNIPAM hybrid particles with water solubility and robust thermo-responsive behavior at physiologically relevant temperatures are potentially useful for (bio)molecular sensing and separation applications.
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Affiliation(s)
- Oya Tagit
- Optical Sciences, Faculty of Science and Technology and MESA+ Institute for Nanotechnology, University of Twente, Enschede, The Netherlands
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Dong C, Ren J. Water-soluble mercaptoundecanoic acid (MUA)-coated CdTe quantum dots: one-step microwave synthesis, characterization and cancer cell imaging. LUMINESCENCE 2011; 27:199-203. [PMID: 21692166 DOI: 10.1002/bio.1330] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2011] [Revised: 05/11/2011] [Accepted: 05/12/2011] [Indexed: 11/08/2022]
Abstract
In this study, a one-step approach for aqueous synthesis of highly luminescent semiconductors, CdTe quantum dots (QDs), using long-chain thiols-mercaptoundecanoic acid (MUA) as surface ligand, was developed in a microwave irradiation system. The synthetic conditions were systematically investigated. The as-prepared MUA-coated QDs were characterized by various spectroscopy techniques, transmission electron microscopy (TEM) and X-ray powder diffraction (XRD). The experimental results document that MUA-coated CdTe QDs have small diameter, good stability, high luminescence and long lifetime. Particularly, it was confirmed, using fluorescence correlation spectroscopy (FCS) that, compared with other ligand, MUA formed a thicker ligand layer on the QD surfaces, which will help their stability and conjugation with biomolecules. Furthermore, MUA-coated QDs were successfully used for HeLa cell imaging.
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Affiliation(s)
- Chaoqing Dong
- School of Chemistry and Chemical Engineering, State Key Laboratory of Metal Matrix Composites, 800 Dongchuan Road, Shanghai 200240, People's Republic of China
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36
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Targeted extracellular nanoparticles enable intracellular detection of activated epidermal growth factor receptor in living brain cancer cells. NANOMEDICINE-NANOTECHNOLOGY BIOLOGY AND MEDICINE 2011; 7:896-903. [PMID: 21683807 DOI: 10.1016/j.nano.2011.05.002] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/07/2010] [Revised: 04/15/2011] [Accepted: 05/02/2011] [Indexed: 01/03/2023]
Abstract
UNLABELLED Mechanistic study of biological processes via Quantum Dots (QDs) remain constrained by inefficient QD delivery methods and consequent altered cell function. Here the authors present a rapid method to label activated receptor populations in live cancer cells derived from medulloblastoma and glioma tumors. The authors used QDs to bind the extracellular domain of Epidermal Growth Factor Receptor (EGF-R) proteins and then induced receptor activation to facilitate specific detection of intracellular, activated EGF-R subpopulations. Such labeling enables rapid identification of biological markers characteristic of tumor type, grade and chemotherapy resistance. FROM THE CLINICAL EDITOR In this paper, a rapid, quantum dot-based method is presented with the goal of labeling activated receptor populations in live cancer cells. More accurate characterization of medulloblastoma and glioma cancer cells using this biomarker detection technique may lead to a more specific targeted therapy.
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37
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Clarke S, Tamang S, Reiss P, Dahan M. A simple and general route for monofunctionalization of fluorescent and magnetic nanoparticles using peptides. NANOTECHNOLOGY 2011; 22:175103. [PMID: 21411925 DOI: 10.1088/0957-4484/22/17/175103] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Nanoparticles are now utilized in many diverse biological and medical applications. Despite this, it remains challenging to tailor their surface for specific molecular targeting while maintaining high biocompatibility. To address this problem, we evaluate a phytochelatin-related peptide surface coating to produce functional and biocompatible nanoparticles (NPs) based on fluorescent InP/ZnS and CdSe/ZnS or superparamagnetic FePt and Fe(3)O(4). Using a combination of transmission electron microscopy, size-exclusion chromatography and gel electrophoresis (GE), we demonstrate the excellent colloidal properties of the peptide-coated NPs (pNPs) and the compact nature of the coating (∼4 nm thickness). We develop a simple protocol for the monofunctionalization of the pNPs with targeting biomolecules, by combining covalent conjugation with GE purification. We then employ functionalized InP/ZnS pNPs in a live-cell, single-molecule imaging application to specifically target and detect individual proteins in the cell membrane. These findings showcase the versatility of the peptides for preparing compact NPs of various compositions and sizes, which are easily functionalized, and suitable for a broad range of biomedical applications.
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Affiliation(s)
- Samuel Clarke
- Laboratoire Kastler Brossel, CNRS UMR 8552, Département de Physique et Institut de Biologie, Ecole Normale Supérieure, Université Pierre et Marie Curie (Paris6), 46 rue d'Ulm 75005 Paris, France.
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Abstract
Coming from the material sciences, fluorescent semiconductor nanocrystals, also known as quantum dots (QDs), have emerged as powerful fluorescent probes for a wide range of biological imaging applications. QDs have several advantages over organic dyes which include higher brightness, better resistance to photobleaching, and simplified multicolor target detection. In this chapter, we describe a rapid assay for the direct imaging of multiple repetitive subnuclear genetic sequences using QD-based FISH probes. Streptavidin-coated QDs (SAvQDs) are functionalized with short biotinylated oligonucleotides and used in a single hybridization/detection step. These QD-FISH probes penetrate both intact interphase nuclei and metaphase chromosomes and show good targeting of dense chromatin domains. Importantly, the broad absorption spectra of QDs allows two sequence specific QD-FISH probes of different colors to be simultaneously imaged with a single laser excitation wavelength. This method, which requires minimal custom conjugation, is easily expandable and offers the experimentalist a new alternative to increase flexibility in multicolor cytogenetic FISH applications of repetitive DNAs.
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Bestvater F, Seghiri Z, Kang MS, Gröner N, Lee JY, Im KB, Wachsmuth M. EMCCD-based spectrally resolved fluorescence correlation spectroscopy. OPTICS EXPRESS 2010; 18:23818-23828. [PMID: 21164726 DOI: 10.1364/oe.18.023818] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
We present an implementation of fluorescence correlation spectroscopy with spectrally resolved detection based on a combined commercial confocal laser scanning/fluorescence correlation spectroscopy microscope. We have replaced the conventional detection scheme by a prism-based spectrometer and an electron-multiplying charge-coupled device camera used to record the photons. This allows us to read out more than 80,000 full spectra per second with a signal-to-noise ratio and a quantum efficiency high enough to allow single photon counting. We can identify up to four spectrally different quantum dots in vitro and demonstrate that spectrally resolved detection can be used to characterize photophysical properties of fluorophores by measuring the spectral dependence of quantum dot fluorescence emission intermittence. Moreover, we can confirm intracellular cross-correlation results as acquired with a conventional setup and show that spectral flexibility can help to optimize the choice of the detection windows.
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Affiliation(s)
- Felix Bestvater
- Cell Biophysics Group, Institut Pasteur Korea, Sampyeong-dong 696, Bundang-gu, Seongnam-si, Gyeonggi-do, Republic of Korea
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Li Z, Dong C, Tang L, Zhu X, Chen H, Ren J. Aqueous synthesis of CdTe/CdS/ZnS quantum dots and their optical and chemical properties. LUMINESCENCE 2010; 26:439-48. [DOI: 10.1002/bio.1250] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2010] [Revised: 06/28/2010] [Accepted: 08/09/2010] [Indexed: 11/10/2022]
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Clarke S, Pinaud F, Beutel O, You C, Piehler J, Dahan M. Covalent monofunctionalization of peptide-coated quantum dots for single-molecule assays. NANO LETTERS 2010; 10:2147-2154. [PMID: 20433164 DOI: 10.1021/nl100825n] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Fluorescent probes for biological imaging of single molecules (SM) have many stringent design requirements. In the case of quantum dot (QD) probes, it remains a challenge to control their functional properties with high precision. Here, we describe the simple preparation of QDs with reduced size and monovalency. Our approach combines a peptide surface coating, stable covalent conjugation of targeting units and purification by gel electrophoresis. We precisely characterize these probes by ensemble and SM techniques and apply them to tracking individual proteins in living cells.
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Affiliation(s)
- Samuel Clarke
- Laboratoire Kastler Brossel, CNRS UMR 8552, Département de Physique et Biologie, Ecole Normale Supérieure, Université Pierre et Marie Curie (Paris6), 46 rue d'Ulm 75005 Paris, France
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Pinaud F, Clarke S, Sittner A, Dahan M. Probing cellular events, one quantum dot at a time. Nat Methods 2010; 7:275-85. [DOI: 10.1038/nmeth.1444] [Citation(s) in RCA: 338] [Impact Index Per Article: 24.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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Sperling RA, Parak WJ. Surface modification, functionalization and bioconjugation of colloidal inorganic nanoparticles. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2010; 368:1333-83. [PMID: 20156828 DOI: 10.1098/rsta.2009.0273] [Citation(s) in RCA: 875] [Impact Index Per Article: 62.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Inorganic colloidal nanoparticles are very small, nanoscale objects with inorganic cores that are dispersed in a solvent. Depending on the material they consist of, nanoparticles can possess a number of different properties such as high electron density and strong optical absorption (e.g. metal particles, in particular Au), photoluminescence in the form of fluorescence (semiconductor quantum dots, e.g. CdSe or CdTe) or phosphorescence (doped oxide materials, e.g. Y(2)O(3)), or magnetic moment (e.g. iron oxide or cobalt nanoparticles). Prerequisite for every possible application is the proper surface functionalization of such nanoparticles, which determines their interaction with the environment. These interactions ultimately affect the colloidal stability of the particles, and may yield to a controlled assembly or to the delivery of nanoparticles to a target, e.g. by appropriate functional molecules on the particle surface. This work aims to review different strategies of surface modification and functionalization of inorganic colloidal nanoparticles with a special focus on the material systems gold and semiconductor nanoparticles, such as CdSe/ZnS. However, the discussed strategies are often of general nature and apply in the same way to nanoparticles of other materials.
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Affiliation(s)
- R A Sperling
- Institut Català de Nanotecnologia, Campus Universitat Autònoma de Barcelona, Bellaterra, Spain.
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Measuring properties of nanoparticles in embryonic blood vessels: Towards a physicochemical basis for nanotoxicity. Chem Phys Lett 2010. [DOI: 10.1016/j.cplett.2010.02.016] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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Lee W, Lee YI, Lee J, Davis LM, Deininger P, Soper SA. Cross-talk-free dual-color fluorescence cross-correlation spectroscopy for the study of enzyme activity. Anal Chem 2010; 82:1401-10. [PMID: 20073480 PMCID: PMC2846527 DOI: 10.1021/ac9024768] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
We have developed an instrument for spectral cross-talk-free dual-color fluorescence cross-correlation spectroscopy (FCCS), which provides a readout modality for the study of enzyme activity in application areas such as high-throughput screening. Two spectrally distinct (approximately 250 nm) fluorophores, Cy3 and IRD800, were excited simultaneously using two different excitation sources: one poised at 532 nm and the other at 780 nm. The fluorescence information was processed on two different color channels monitored with single-photon avalanche diodes (SPADs) that could transduce events at the single-molecule level. The system provided no color cross-talk (cross-excitation and/or cross-emission) and/or fluorescence resonance energy transfer (FRET), significantly improving data quality. To provide evidence of cross-talk-free operation, the system was evaluated using bright microspheres (lambda(abs) = 532 nm, lambda(em) = 560 nm) and quantum dots (lambda(abs) = 532 nm, lambda(em) = 810 nm). Experimental results indicated that no color leakage from the microspheres or quantum dots into inappropriate color channels was observed. To demonstrate the utility of the system, the enzymatic activity of APE1, which is responsible for nicking the phosphodiester backbone in DNA on the 5' side of an apurinic/apyrimidinic site, was monitored by FCCS using a double-stranded DNA substrate dual labeled with Cy3 and IRD800. Activity of APE1 was also monitored in the presence of an inhibitor (7-nitroindole-2-carboxylic acid) of the enzyme using this cross-talk-free FCCS platform. In all cases, no spectral leakage from single-molecule events into inappropriate color channels was observed.
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Affiliation(s)
- Wonbae Lee
- Department of Chemistry, Louisiana State University, Baton Rouge, Louisiana 70803-1804, USA
| | - Yong-Ill Lee
- Department of Chemistry, Changwon National University, Changwon, 641-773, South Korea
| | - Jeonghoon Lee
- Department of Chemistry, Louisiana State University, Baton Rouge, Louisiana 70803-1804, USA
| | - Lloyd M. Davis
- Center for Laser Applications, University of Tennessee Space Institute, Tullahoma, TN 37388, USA
| | - Prescott Deininger
- Tulane University, Department of Epidemiology and Tulane Cancer Center, New Orleans, LA 70112, USA
| | - Steven A. Soper
- Department of Chemistry, Louisiana State University, Baton Rouge, Louisiana 70803-1804, USA
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Dong C, Ren J. Measurements for molar extinction coefficients of aqueous quantum dots. Analyst 2010; 135:1395-9. [DOI: 10.1039/c0an00063a] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Gould TJ, Bewersdorf J, Hess ST. A Quantitative Comparison of the Photophysical Properties of Selected Quantum Dots and Organic Fluorophores. ACTA ACUST UNITED AC 2009. [DOI: 10.1524/zpch.2008.6011] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Quantum dots (QDs) are becoming an increasingly popular fluorescent probe in biological imaging and single molecule applications. With advantages and disadvantages over traditional organic fluorophores, quantitative characterization of the photophysical properties of QDs is a required task for optimizing their performance. For example, maximizing the number of collected photons is essential for high-quality fluorescence imaging and yet is often a limiting factor in biological applications. Using fluorescence correlation spectroscopy (FCS), we compare important photophysical properties (count rates, photobleaching quantum yields, dark state occupancy and dark-state-to-bright-state interconversion rates, among others) of typical commercial CdSe/ZnS QDs against commonly used organic fluorophores relevant to biological applications. Two-photon action cross sections are measured using a novel version of the reference method in a laser-scanning confocal microscope geometry. FCS results for QDs show a correlation between reduced brightness, high fraction of molecules in dark states, and slow interconversion rates between the bright state and dark state(s) consistent with previous work. We confirm large two-photon action cross sections (103−104 GM) and broad two-photon excitation spectra that suggest QDs as advantageous probes for multicolor multiphoton imaging. FCS results show Alexa546 is a particularly bright probe suited for use when probe size is a limitation. While superior in count rate to Alexa555, Alexa546 bleaches faster when used in one-photon excitation.
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Saint-Michel E, Giannone G, Choquet D, Thoumine O. Neurexin/neuroligin interaction kinetics characterized by counting single cell-surface attached quantum dots. Biophys J 2009; 97:480-9. [PMID: 19619462 DOI: 10.1016/j.bpj.2009.04.044] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2008] [Revised: 04/17/2009] [Accepted: 04/27/2009] [Indexed: 12/19/2022] Open
Abstract
We report what to our knowledge is a new method to characterize kinetic rates between cell-surface-attached adhesion molecules. Cells expressing specific membrane receptors are surface-labeled with quantum dots coated with their respective ligands. The progressive diminution in the total number of surface-diffusing quantum dots tracked over time collectively reflects intrinsic ligand/receptor interaction kinetics. The probability of quantum dot detachment is modeled using a stochastic analysis of bond formation and dissociation, with a small number of ligand/receptor pairs, resulting in a set of coupled differential equations that are solved numerically. Comparison with the experimental data provides an estimation of the kinetic rates, together with the mean number of ligands per quantum dot, as three adjustable parameters. We validate this approach by studying the calcium-dependent neurexin/neuroligin interaction, which plays an important role in synapse formation. Using primary neurons expressing neuroligin-1 and quantum dots coated with purified neurexin-1beta, we determine the kinetic rates between these two binding partners and compare them with data obtained using other techniques. Using specific molecular constructs, we also provide interesting information about the effects of neurexin and neuroligin dimerization on the kinetic rates. As it stands, this simple technique should be applicable to many types of biological ligand/receptor pairs.
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Affiliation(s)
- Edouard Saint-Michel
- Physiologie Cellulaire de la synapse, Centre National de la Recherche Scientifique and University of Bordeaux, Bordeaux, France
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Antelman J, Wilking-Chang C, Weiss S, Michalet X. Nanometer distance measurements between multicolor quantum dots. NANO LETTERS 2009; 9:2199-205. [PMID: 19374434 PMCID: PMC2748936 DOI: 10.1021/nl901163k] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Quantum dot dimers made of short double-stranded DNA molecules labeled with different color quantum dots at each end were imaged using multicolor stage-scanning confocal microscopy. This approach eliminates chromatic aberration and color registration issues usually encountered in other multicolor imaging techniques. We demonstrate nanometer accuracy in individual distance measurement by suppression of quantum dot blinking and thoroughly characterize the contribution of different effects to the variability observed between measurements. Our analysis opens the way to accurate structural studies of biomolecules and biomolecular complexes using multicolor quantum labeling.
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Affiliation(s)
| | | | | | - Xavier Michalet
- CORRESPONDING AUTHOR FOOTNOTE. Correspondence should be address to XM (, Ph: 310 794-6693, Fax: 310 267-4672)
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Rife JC, Long JP, Wilkinson J, Whitman LJ. Particle tracking single protein-functionalized quantum dot diffusion and binding at silica surfaces. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2009; 25:3509-3518. [PMID: 19708242 DOI: 10.1021/la802144e] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
We evaluate commercial QD585 and QD605 streptavidin-functionalized quantum dots (QDs) for single-particle tracking microscopy at surfaces using total internal reflectance fluorescence and measure single QD diffusion and nonspecific binding at silica surfaces in static and flow conditions. The QD diffusion coefficient on smooth, near-ideal, highly hydroxylated silica surfaces is near bulk-solution diffusivity, as expected for repulsive surfaces, but many QD trajectories on rougher, less-than-ideal surfaces or regions display transient adsorptions. We attribute the binding to defect sites or adsorbates, possibly in conjunction with protein conformation changes, and estimate binding energies from the transient adsorption lifetimes. We also assess QD parameters relevant to tracking, including hydrodynamic radius, charge state, signal levels, blinking reduction with reducing solutions, and photoinduced blueing and bleaching.
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Affiliation(s)
- Jack C Rife
- Naval Research Laboratory, Washington, D.C. 20375, USA.
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