1
|
Kim Y, Vogel SS. Measuring two-photon microscopy ultrafast laser pulse duration at the sample plane using time-correlated single-photon counting. JOURNAL OF BIOMEDICAL OPTICS 2020; 25:1-9. [PMID: 31994362 PMCID: PMC6987257 DOI: 10.1117/1.jbo.25.1.014516] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/15/2019] [Accepted: 01/16/2020] [Indexed: 06/10/2023]
Abstract
<p>Two-photon microscopy (2PM) has revolutionized biomedical imaging by allowing thin optical sectioning in relatively thick biological specimens. Because dispersive microscope components in 2PM, such as objective lens, can alter temporal laser pulse width (typically being broader at the sample plane), for accurate measurements of two-photon absorption properties, it is important to characterize pulse duration at the sample plane. We present a simple modification to a two-photon microscope light path that allows for second-harmonic-generation-based interferometric autocorrelation measurements to characterize ultrafast laser pulse duration at the sample plane using time-correlated single-photon counting (TCSPC). We show that TCSPC can be used as a simple and versatile method to estimate the zero time delay step value between two adjacent ultrafast laser pulses for these measurements. To demonstrate the utility of this modification, we measured the Coherent Chameleon-Ultra II Ti:sapphire laser pulse width at the sample plane using a 10 × air, 40 × air, or 63 × water-immersion objective lens. At 950-nm two-photon excitation, the measured pulse width was 154 ± 32, 165 ± 13, and 218 ± 27 fs (<italic>n</italic> = 6, mean ± standard deviation), respectively.</p>.
Collapse
Affiliation(s)
- Youngchan Kim
- U.S. National Institutes of Health, National Institute on Alcohol Abuse and Alcoholism, Section on Cellular Biophotonics, Laboratory of Molecular Physiology, Bethesda, Maryland, United States
| | - Steven S. Vogel
- U.S. National Institutes of Health, National Institute on Alcohol Abuse and Alcoholism, Section on Cellular Biophotonics, Laboratory of Molecular Physiology, Bethesda, Maryland, United States
| |
Collapse
|
2
|
Narimousa M, Sabaeian M, Mousavi Ghahfarrokhi SM, Panahi O. Second-order interferometric autocorrelation for measuring group velocity dispersion and pulse broadening of femtosecond pulses. APPLIED OPTICS 2018; 57:5011-5018. [PMID: 30117960 DOI: 10.1364/ao.57.005011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/30/2018] [Accepted: 05/09/2018] [Indexed: 06/08/2023]
Abstract
Femtosecond pulse broadening and group velocity dispersion (GVD) were measured using a second-order interferometric autocorrelation technique. Two reference laser pulses of 36 fs and 55 fs were generated first in a Ti:sapphire oscillator and then passed through the optical elements of Ti:sapphire crystal and BK7 and fused silica glasses. For rectangular Ti:sapphire crystal and BK7 and fused silica slabs, material dispersion, and for fused silica prisms, material as well as angular dispersions were systematically measured. The experimental results were then compared with theoretical models, showing excellent agreement. The result of this work shows that one can rely very well on theoretical expressions to calculate the GVD of materials mentioned in this work and femtosecond pulse broadening.
Collapse
|
3
|
ANISHA THAYIL KN, GUALDA EJ, PSILODIMITRAKOPOULOS S, CORMACK IG, AMAT-ROLDÁN I, MATHEW M, ARTIGAS D, LOZA-ALVAREZ P. Starch-based backwards SHG for in situ MEFISTO pulse characterization in multiphoton microscopy. J Microsc 2008; 230:70-5. [DOI: 10.1111/j.1365-2818.2008.01956.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
|
4
|
D'Alfonso L, Collini M, Cannone F, Chirico G, Campanini B, Cottone G, Cordone L. GFP-mut2 proteins in trehalose-water matrixes: spatially heterogeneous protein-water-sugar structures. Biophys J 2007; 93:284-93. [PMID: 17416616 PMCID: PMC1914445 DOI: 10.1529/biophysj.106.090621] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
We report investigations on the properties of nanoenvironments around single-GFP-mut2 proteins in trehalose-water matrixes. Single-GFPmut2 molecules embedded in thin trehalose-water films were characterized in terms of their fluorescence brightness, bleaching dynamics, excited state lifetime, and fluorescence polarization. For each property, sets of approximately 100-150 single molecules have been investigated as a function of trehalose content and hydration. Three distinct and interconverting families of proteins have been found which differ widely in terms of bleaching dynamics, brightness, and fluorescence polarization, whose relative populations sizably depend on sample hydration. The reported results evidence the simultaneous presence of different protein-trehalose-water nanostructures whose rigidity increases by lowering the sample hydration. Such spatial inhomogeneity is in line with the well-known heterogeneous dynamics in supercooled fluids and in nonsolid carbohydrate glasses and gives a pictorial representation of the sharp, sudden reorganization of the above structures after uptake <==>release of water molecules.
Collapse
Affiliation(s)
- Laura D'Alfonso
- Dipartimento di Fisica, Università di Milano Bicocca, Milano, Italy
| | | | | | | | | | | | | |
Collapse
|
5
|
Cannone F, Chirico G, Bizzarri AR, Cannistraro S. Quenching and Blinking of Fluorescence of a Single Dye Molecule Bound to Gold Nanoparticles. J Phys Chem B 2006; 110:16491-8. [PMID: 16913781 DOI: 10.1021/jp0625816] [Citation(s) in RCA: 81] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A fluorescein derivative (SAMSA) bound to gold nanoparticles of different diameters is investigated by time-resolved fluorescence at the single molecule level in a wide dynamic range, from nanosecond to second time scale. The significant decrease of both SAMSA excited state lifetime and fluorescence quantum yield observed upon binding to gold nanoparticles can be essentially traced back to an increase of the nonradiative deactivation rate, probably due to energy transfer, that depends on the nanoparticle size. A slow single molecule fluorescence blinking, in the ms time scale, has a marked dependence on the excitation intensity both under single and under two photon excitation. The blinking dynamics is limited by a low probability nonlinear excitation to a high energy state from which a transition to a dark state occurs. The results point out a strong coupling between the vibro-electronic configuration of the dye and the plasmonic features of the metal nanoparticles that provide dye radiationless deactivation channels on a wide dynamic range.
Collapse
Affiliation(s)
- Fabio Cannone
- Laboratory for Advanced BioSpectroscopy (LABS), INFM-CNR, Physics Department, University of Milano-Bicocca, Milano I-20126, Italy
| | | | | | | |
Collapse
|
6
|
Chirico G, Cannone F, Diaspro A. Unfolding time distribution of GFP by single molecule fluorescence spectroscopy. EUROPEAN BIOPHYSICS JOURNAL: EBJ 2006; 35:663-74. [PMID: 16786346 DOI: 10.1007/s00249-006-0075-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/23/2006] [Revised: 05/05/2006] [Accepted: 05/18/2006] [Indexed: 11/27/2022]
Abstract
We have studied the unfolding of single molecules of GFP-mut2 mutant trapped in wet silica gels in a wide range of GuHCl concentration. After the addition of denaturant, the number of fluorescent molecules decreases with unfolding rates (of the order of 0.01 min(-1)) that are in very good agreement with bulk fluorescence and circular dichroism data. Unexpectedly, single molecule experiments show rare fluctuations in the number of fluorescent proteins at equilibrium. On the other hand, although a first approximate description of the number decays can be reasonably performed by single exponential functions, the distributions of the single molecule unfolding times show a maximum at times congruent with 50-100 min up to the denaturation midpoint concentration of [GuHCl] congruent with 2.5 M. A theoretical analysis of the distributions indicates that this feature is a fingerprint of the competition between unfolding and refolding processes when the protein is very far from the midpoint denaturant concentration.
Collapse
Affiliation(s)
- G Chirico
- Department of Physics, University of Milano Bicocca, Piazza della Scienza 3, Milano, Italy.
| | | | | |
Collapse
|
7
|
Collini M, Caccia M, Chirico G, Barone F, Dogliotti E, Mazzei F. Two-photon fluorescence cross-correlation spectroscopy as a potential tool for high-throughput screening of DNA repair activity. Nucleic Acids Res 2005; 33:e165. [PMID: 16244220 PMCID: PMC1266075 DOI: 10.1093/nar/gni166] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Several lines of evidence indicate that differences in DNA repair capacity are an important source of variability in cancer risk. However, traditional assays for measurement of DNA repair activity in human samples are laborious and time-consuming. DNA glycosylases are the first step in base excision repair of a variety of modified DNA bases. Here, we describe the development of a new sensitive DNA glycosylase assay based on fluorescence cross-correlation spectroscopy (FCCS) with two-photon excitation. FCCS was applied to the measurement of uracil DNA glycosylase activity of human cell extracts and validated by comparison with standard gel electrophoresis assay. Our results indicate that FCCS can be adapted to efficient assays for DNA glycosylase activity in protein extracts from human cells. This method has a potential for the development of automated screening of large number of samples.
Collapse
Affiliation(s)
- Maddalena Collini
- Department of Physics, University of Milano-BicoccaPiazza della Scienza 3, 20126 Milan, Italy
- CNR-INFMGenoa, Italy
| | - Michele Caccia
- Department of Physics, University of Milano-BicoccaPiazza della Scienza 3, 20126 Milan, Italy
| | - Giuseppe Chirico
- Department of Physics, University of Milano-BicoccaPiazza della Scienza 3, 20126 Milan, Italy
- CNR-INFMGenoa, Italy
| | - Flavia Barone
- Department of Environment and Primary Prevention, Istituto Superiore di SanitàViale Regina Elena 299, 00161 Rome, Italy
| | - Eugenia Dogliotti
- Department of Environment and Primary Prevention, Istituto Superiore di SanitàViale Regina Elena 299, 00161 Rome, Italy
| | - Filomena Mazzei
- Department of Environment and Primary Prevention, Istituto Superiore di SanitàViale Regina Elena 299, 00161 Rome, Italy
- To whom correspondence should be addressed. Tel: +39 06 49902612; Fax: +39 06 49903650;
| |
Collapse
|
8
|
Cannone F, Bologna S, Campanini B, Diaspro A, Bettati S, Mozzarelli A, Chirico G. Tracking unfolding and refolding of single GFPmut2 molecules. Biophys J 2005; 89:2033-45. [PMID: 15994904 PMCID: PMC1366706 DOI: 10.1529/biophysj.105.064584] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The unfolding and refolding kinetics of >600 single GFPmut2 molecules, entrapped in wet nanoporous silica gels, were followed by monitoring simultaneously the fluorescence emission of the anionic and neutral state of the chromophore, primed by two-photon excitation. The rate of unfolding, induced by guanidinium chloride, was determined by counting the number of single molecules that disappear in fluorescence images, under conditions that do not cause bleaching or photoinduced conversion between chromophore protonation states. The unfolding rate is of the order of 0.01 min(-1), and its dependence on denaturant concentration is very similar to that previously reported for high protein load gels. Upon rinsing the gels with denaturant-free buffer, the GFPmut2 molecules refold with rates >10 min(-1), with an apparently random distribution between neutral and anionic states, that can be very different from the preunfolding equilibrium. A subsequent very slow (lifetime of approximately 70 min) relaxation leads to the equilibrium distribution of the protonation states. This mechanism, involving one or more native-like refolding intermediates, is likely rate limited by conformational rearrangements that are undetectable in circular dichroism experiments. Several unfolding/refolding cycles can be followed on the same molecules, indicating full reversibility of the process and, noticeably, a bias of denaturated molecules toward refolding in the original protonation state.
Collapse
Affiliation(s)
- Fabio Cannone
- Department of Physics, University of Milan Bicocca, 20126 Milan, Italy
| | | | | | | | | | | | | |
Collapse
|
9
|
Caccia M, Camozzi E, Collini M, Zaccolo M, Chirico G. Photon moment analysis in cells in the presence of photo-bleaching. APPLIED SPECTROSCOPY 2005; 59:227-236. [PMID: 15720764 DOI: 10.1366/0003702053084981] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
The photon counting histogram (PCH) analysis of the fluorescence fluctuations provides the molecular brightness (epsilon) and the average number of fluorophores (N) in an open observation volume. PCH, which is based on the analysis of the whole of the photon counting histogram, has been recently improved by taking into account the detector dead time effect, which is relevant at high fluorescence rates. We investigate here the possibility of quantitatively applying the PCH analysis in the simplified form of photon moment analysis, in which only the first two moments of the photon counting histogram are computed. We have applied this analysis to low fluorescence signals from living cells in the presence of cell micro-movements and molecular photo-bleaching and describe a simple algorithm for its routine application. The algorithm has been tested on Saccharomyces Cerevisiae (yeast) cells labeled with Dimethyl-pepep and Rhodamine 6G, and Chinese Hamster Ovary (CHO) cells stably expressing the regulatory subunit (RII) of protein kinase A fused to the cyan-emitting variant of GFP (CFP). Our statistical analysis allows us to estimate the local concentrations and the brightness of the fluorophores in different cellular compartments (nucleus, membrane, and cytoplasm) despite the occurrence of microscopic cell movements and significant photo-bleaching.
Collapse
Affiliation(s)
- Michele Caccia
- Department of Physics, University of Milan Bicocca, Milan, Italy
| | | | | | | | | |
Collapse
|
10
|
Chirico G, Cannone F, Diaspro A, Bologna S, Pellegrini V, Nifosì R, Beltram F. Multiphoton switching dynamics of single green fluorescent proteins. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2004; 70:030901. [PMID: 15524497 DOI: 10.1103/physreve.70.030901] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/19/2004] [Indexed: 05/24/2023]
Abstract
Multi-photon driven photo-switching between dark and bright (fluorescent) states of a green fluorescent protein (GFP) mutant is demonstrated. A single-protein investigation shows the existence of two distinct bright states that display sharp two-photon cross-section bands peaked at 780 nm and at 870 nm. Fluorescence of these two species can be independently switched on and off. These results highlight a new photoconversion pathway for photochromic GFPs and can have significant applications in multi-photon confocal microscopy and in optical data-storage architectures.
Collapse
Affiliation(s)
- G Chirico
- INFM and Department of Physics, University of Milano Bicocca, Piazza della Scienza 3, 20126 Milano, Italy
| | | | | | | | | | | | | |
Collapse
|
11
|
Quercioli F, Tiribilli B, Vassalli M, Ghirelli A. Laser spectral characterization in multiphoton microscopy. APPLIED OPTICS 2004; 43:3055-3060. [PMID: 15176192 DOI: 10.1364/ao.43.003055] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Spectral and temporal characterization is a fundamental task when a tunable Ti:sapphire ultrafast laser system is operated for multiphoton microscopy applications. In the present paper simple procedures are reported that perform laser-peak-emission wavelength and bandwidth measurements without the need of any further instrumentation but a simple and inexpensive diffraction grating, by taking advantage of the confocal microscope imaging capabilities.
Collapse
Affiliation(s)
- Franco Quercioli
- Istituto Nazionale di Ottica Applicata, Laboratorio di Biofotonica, Largo Enrico Fermi 6, 50125 Firenze, Italy.
| | | | | | | |
Collapse
|
12
|
Quercioli F, Ghirelli A, Tiribilli B, Vassalli M. Ultracompact autocorrelator for multiphoton microscopy. Microsc Res Tech 2004; 63:27-33. [PMID: 14677131 DOI: 10.1002/jemt.10420] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Pulse temporal characterization is a fundamental task when operating a Ti:Sapphire ultrafast laser system for multiphoton microscopy applications. In the present report, an ultracompact autocorrelator setup and a simple procedure is reported to perform pulse width measurements at the focal plane of the microscope objective without the need of any further instrumentation, aside from a few optical elements, since the confocal microscope, detection, data acquisition, processing, and displaying capabilities are used.
Collapse
Affiliation(s)
- F Quercioli
- Istituto Nazionale di Ottica Applicata, Biophotonics Laboratory, Largo Enrico Fermi 6, 50125 Firenze, Italy.
| | | | | | | |
Collapse
|
13
|
Diaspro A. Rapid dissemination of two-photon excitation microscopy prompts new applications. Microsc Res Tech 2003; 63:1-2. [PMID: 14677126 DOI: 10.1002/jemt.10424] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
|