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Han D, Jiang D, Valenti G, Paolucci F, Kanoufi F, Chaumet PC, Fang D, Sojic N. Optics Determines the Electrochemiluminescence Signal of Bead-Based Immunoassays. ACS Sens 2023; 8:4782-4791. [PMID: 37978286 DOI: 10.1021/acssensors.3c01878] [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: 11/19/2023]
Abstract
Electrochemiluminescence (ECL) is an optical readout technique that is successfully applied for the detection of biomarkers in body fluids using microbead-based immunoassays. This technology is of utmost importance for in vitro diagnostics and thus a very active research area but is mainly focused on the quest for new dyes and coreactants, whereas the investigation of the ECL optics is extremely scarce. Herein, we report the 3D imaging of the ECL signals recorded at single microbeads decorated with the ECL labels in the sandwich immunoassay format. We show that the optical effects due to the light propagation through the bead determine mainly the spatial distribution of the recorded ECL signals. Indeed, the optical simulations based on the discrete dipole approximation compute rigorously the electromagnetic scattering of the ECL emission by the microbead and allow for reconstructing the spatial map of ECL emission. Thus, it provides a global description of the ECL chemical reactivity and the associated optics. The outcomes of this 3D imaging approach complemented by the optical modeling provide insight into the ECL optics and the unique ECL chemical mechanism operating on bead-based immunoassays. Therefore, it opens new directions for mechanistic investigations, ultrasensitive ECL bioassays, and imaging.
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Affiliation(s)
- Dongni Han
- CNRS, Bordeaux INP, ISM, UMR 5255, ENSCBP,Univ. Bordeaux, 33607 Pessac, France
- School of Pharmacy, Nanjing Medical University, Nanjing, Jiangsu 211126, China
| | - Dechen Jiang
- State Key Laboratory of Analytical Chemistry for Life Science and School of Chemistry and Chemical Engineering, Nanjing University, Nanjing, Jiangsu 210023, China
| | - Giovanni Valenti
- Department of Chemistry "G. Ciamician", University of Bologna, Via Selmi 2, 40126 Bologna, Italy
| | - Francesco Paolucci
- Department of Chemistry "G. Ciamician", University of Bologna, Via Selmi 2, 40126 Bologna, Italy
- Institute of Condensed Matter Chemistry and Technologies for Energy, ICMATE-CNR, Corso Stati Uniti 4, 35127 Padova, Italy
| | | | - Patrick C Chaumet
- Institut Fresnel, Aix Marseille Univ, CNRS, Centrale Marseille, 13013 Marseille, France
| | - Danjun Fang
- School of Pharmacy, Nanjing Medical University, Nanjing, Jiangsu 211126, China
| | - Neso Sojic
- CNRS, Bordeaux INP, ISM, UMR 5255, ENSCBP,Univ. Bordeaux, 33607 Pessac, France
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Andrade UMS, Garcia AM, Rocha MS. Bessel beam optical tweezers for manipulating superparamagnetic beads. APPLIED OPTICS 2021; 60:3422-3429. [PMID: 33983247 DOI: 10.1364/ao.420600] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/22/2021] [Accepted: 03/26/2021] [Indexed: 06/12/2023]
Abstract
We propose a Bessel beam optical tweezers setup that can stably trap superparamagnetic beads. The trap stiffness measured is practically independent of the radius of the Bessel beam and of the bead height (distance from the coverlip of the sample chamber), indicating that the beads can be trapped with high accuracy within a wide range of such parameters. On the other hand, the trap stiffness exhibits the expected linear increase with the laser power, despite the non-negligible absorption coefficient of the superparamagnetic beads. A geometrical optics model that considers spherical aberration and light absorption by the beads was used to predict the optical forces and trap stiffness, showing excellent agreement with the experimental data. We believe the results presented here advance the field of optical trapping manipulation of absorbing magnetic particles, and future applications will involve, for example, the design of new hybrid optomagnetic tweezers.
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Moura TA, Andrade UMS, Mendes JBS, Rocha MS. Silicon microparticles as handles for optical tweezers experiments. OPTICS LETTERS 2020; 45:1055-1058. [PMID: 32108768 DOI: 10.1364/ol.383139] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/14/2019] [Accepted: 01/19/2020] [Indexed: 06/10/2023]
Abstract
We study the behavior of silicon microparticles in a 1064 nm Gaussian-beam optical tweezers, showing that this semiconductor can be used to perform different types of optical manipulation experiments. Depending on the focal position and the laser power used, the particles can present an oscillatory dynamics in the tweezers or can be stably 3D-trapped with a trap stiffness that allows the application of femtoNewton forces with accuracy. A new, to the best of our knowledge, interpretation based on the photoexcitation of electrons in the valence band is proposed to explain the oscillations, and the quantities associated with such dynamics (e.g., amplitude, period, etc.) were characterized as a function of relevant parameters to optical tweezers setups.
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