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Asgari N, Baaske MD, Ton J, Orrit M. Exploring Rotational Diffusion with Plasmonic Coupling. ACS PHOTONICS 2024; 11:634-641. [PMID: 38405388 PMCID: PMC10885195 DOI: 10.1021/acsphotonics.3c01482] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/16/2023] [Revised: 01/22/2024] [Accepted: 01/24/2024] [Indexed: 02/27/2024]
Abstract
Measuring the orientation dynamics of nanoparticles and nonfluorescent molecules in real time with optical methods is still a challenge in nanoscience and biochemistry. Here, we examine optoplasmonic sensing taking the rotational diffusion of plasmonic nanorods as an experimental model. Our detection method is based on monitoring the dark-field scattering of a relatively large sensor gold nanorod (GNR) (40 nm in diameter and 112 nm in length) as smaller plasmonic nanorods cross its near field. We observe the rotational motion of single small gold nanorods (three samples with about 5 nm in diameter and 15.5, 19.1, and 24.6 nm in length) in real time with a time resolution around 50 ns. Plasmonic coupling enhances the signal of the diffusing gold nanorods, which are 1 order of magnitude smaller in volume (about 300 nm3) than those used in our previous rotational diffusion experiments. We find a better angular sensitivity with plasmonic coupling in comparison to the free diffusion in the confocal volume. Yet, the angle sensitivity we find with plasmonic coupling is reduced compared to the sensitivity expected from simulations at fixed positions due to the simultaneous translational and rotational diffusion of the small nanorods. To get a reliable plasmonic sensor with the full angular sensitivity, it will be necessary to construct a plasmonic assembly with positions and orientations nearly fixed around the optimum geometry.
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Affiliation(s)
- Nasrin Asgari
- Huygens-Kamerlingh
Onnes Laboratory, Leiden University, Postbus 9504, 2300 RA Leiden, The Netherlands
| | - Martin Dieter Baaske
- Huygens-Kamerlingh
Onnes Laboratory, Leiden University, Postbus 9504, 2300 RA Leiden, The Netherlands
- Max
Planck Institute of Biophysics, Max-von-Laue-Str. 3, 60438 Frankfurt am Main, Germany
| | - Jacco Ton
- Huygens-Kamerlingh
Onnes Laboratory, Leiden University, Postbus 9504, 2300 RA Leiden, The Netherlands
| | - Michel Orrit
- Huygens-Kamerlingh
Onnes Laboratory, Leiden University, Postbus 9504, 2300 RA Leiden, The Netherlands
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Wang Y, Adhikari S, van der Meer H, Liu J, Orrit M. Thousand-Fold Enhancement of Photothermal Signals in Near-Critical CO 2. THE JOURNAL OF PHYSICAL CHEMISTRY. C, NANOMATERIALS AND INTERFACES 2023; 127:3619-3625. [PMID: 36865992 PMCID: PMC9969513 DOI: 10.1021/acs.jpcc.2c08575] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/07/2022] [Revised: 01/25/2023] [Indexed: 06/18/2023]
Abstract
Photothermal (PT) microscopy has shown strong promise in imaging single absorbing nano-objects in soft matter and biological systems. PT imaging at ambient conditions usually requires a high laser power for a sensitive detection, which prevents application to light-sensitive nanoparticles. In a previous study of single gold nanoparticles, we showed that the photothermal signal can be enhanced more than 1000-fold in near-critical xenon compared to that in glycerol, a typical medium for PT detection. In this report, we show that carbon dioxide (CO2), a much cheaper gas than xenon, can enhance PT signals in a similar way. We confine near-critical CO2 in a thin capillary which easily withstands the high near-critical pressure (around 74 bar) and facilitates sample preparation. We also demonstrate enhancement of the magnetic circular dichroism signal of single magnetite nanoparticle clusters in supercritical CO2. We have performed COMSOL simulations to support and explain our experimental findings.
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Affiliation(s)
- Yonghui Wang
- Huygens-Kamerlingh
Onnes Laboratory, Leiden University; 2300 RA Leiden, The Netherlands
- School
of Mechatronics Engineering, Harbin Institute
of Technology; Harbin 150001, P. R. China
| | - Subhasis Adhikari
- Huygens-Kamerlingh
Onnes Laboratory, Leiden University; 2300 RA Leiden, The Netherlands
| | - Harmen van der Meer
- Huygens-Kamerlingh
Onnes Laboratory, Leiden University; 2300 RA Leiden, The Netherlands
| | - Junyan Liu
- School
of Mechatronics Engineering, Harbin Institute
of Technology; Harbin 150001, P. R. China
| | - Michel Orrit
- Huygens-Kamerlingh
Onnes Laboratory, Leiden University; 2300 RA Leiden, The Netherlands
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West CA, Lee SA, Shooter J, Searles EK, Goldwyn HJ, Willets KA, Link S, Masiello DJ. Nonlinear effects in single-particle photothermal imaging. J Chem Phys 2023; 158:024202. [PMID: 36641380 DOI: 10.1063/5.0132167] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Although photothermal imaging was originally designed to detect individual molecules that do not emit or small nanoparticles that do not scatter, the technique is now being applied to image and spectroscopically characterize larger and more sophisticated nanoparticle structures that scatter light strongly. Extending photothermal measurements into this regime, however, requires revisiting fundamental assumptions made in the interpretation of the signal. Herein, we present a theoretical analysis of the wavelength-resolved photothermal image and its extension to the large particle scattering regime, where we find the photothermal signal to inherit a nonlinear dependence upon pump intensity, together with a contraction of the full-width-at-half-maximum of its point spread function. We further analyze theoretically the extent to which photothermal spectra can be interpreted as an absorption spectrum measure, with deviations between the two becoming more prominent with increasing pump intensities. Companion experiments on individual 10, 20, and 100 nm radius gold nanoparticles evidence the predicted nonlinear pump power dependence and image contraction, verifying the theory and demonstrating new aspects of photothermal imaging relevant to a broader class of targets.
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Affiliation(s)
- Claire A West
- Department of Chemistry, University of Washington, Seattle, Washington 98195, USA
| | - Stephen A Lee
- Department of Chemistry, Rice University, Houston, Texas 77005, USA
| | - Jesse Shooter
- Department of Chemistry, Rice University, Houston, Texas 77005, USA
| | - Emily K Searles
- Department of Chemistry, Rice University, Houston, Texas 77005, USA
| | - Harrison J Goldwyn
- Department of Chemistry, University of Washington, Seattle, Washington 98195, USA
| | - Katherine A Willets
- Department of Chemistry, Temple University, Philadelphia, Pennsylvania 19122, USA
| | - Stephan Link
- Department of Chemistry, Rice University, Houston, Texas 77005, USA
| | - David J Masiello
- Department of Chemistry, University of Washington, Seattle, Washington 98195, USA
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