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Kissel A, Nogowski A, Kienle A, Foschum F. Flow Raman Spectroscopy for the Detection and Identification of Small Microplastics. SENSORS (BASEL, SWITZERLAND) 2025; 25:1390. [PMID: 40096217 PMCID: PMC11902776 DOI: 10.3390/s25051390] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2025] [Revised: 02/20/2025] [Accepted: 02/21/2025] [Indexed: 03/19/2025]
Abstract
The most commonly used methods for the detection and identification of small microplastics generally require a complex sample preparation procedure and only allow for static measurements. Quality control of food and drinking water therefore requires a lot of effort. Especially in view of the increasing amount of plastic waste in the environment, the rising public awareness of the issue and the indications for adverse effects of microplastics on human health, more sophisticated measuring methods are required. In this paper, we present a measuring setup for the detection and identification of microplastics using flow Raman spectroscopy. We demonstrate the ability to acquire Raman spectra of individual particles as small as about 4 µm, enabling the identification of their plastic type. We show measurements of differently generated and shaped particles and particles made of different plastic types, highlighting the observed challenges and differences. Finally, we show possible applications of the measuring method. We demonstrate that the measuring principle is suitable for detecting and identifying microplastic particles among other particles and that aged plastics can still be distinguished by their Raman spectra. Overall, our results show that flow Raman spectroscopy is a promising method that could significantly reduce the effort required to detect microplastics.
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Affiliation(s)
- Alexander Kissel
- Institut für Lasertechnologien in der Medizin und Meßtechnik an der Universität Ulm (ILM), Helmholtzstr. 12, 89081 Ulm, Germany; (A.K.)
- Faculty of Natural Sciences, Ulm University, 89069 Ulm, Germany
| | - André Nogowski
- SKZ-KFE gGmbH, Europäisches Zentrum für Dispersionstechnologien (EZD), Weissenbacher Str. 86, 95100 Selb, Germany
| | - Alwin Kienle
- Institut für Lasertechnologien in der Medizin und Meßtechnik an der Universität Ulm (ILM), Helmholtzstr. 12, 89081 Ulm, Germany; (A.K.)
- Faculty of Natural Sciences, Ulm University, 89069 Ulm, Germany
| | - Florian Foschum
- Institut für Lasertechnologien in der Medizin und Meßtechnik an der Universität Ulm (ILM), Helmholtzstr. 12, 89081 Ulm, Germany; (A.K.)
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2
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Guan M, Garabedian MV, Leutenegger M, Schuster BS, Good MC, Hammer DA. Incorporation and Assembly of a Light-Emitting Enzymatic Reaction into Model Protein Condensates. Biochemistry 2021; 60:3137-3151. [PMID: 34648259 PMCID: PMC9322593 DOI: 10.1021/acs.biochem.1c00373] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Eukaryotic cells partition enzymes and other cellular components into distinct subcellular compartments to generate specialized biochemical niches. A subclass of these compartments form in the absence of lipid membranes, via liquid-liquid phase separation of proteins to form biomolecular condensates or "membraneless organelles" such as nucleoli, stress granules, and P-bodies. Because of their propensity to form compartments from simple starting materials, membraneless organelles are an attractive target for engineering new functionalities in both living cells and protocells. In this work, we demonstrate incorporation of a novel enzymatic activity in protein coacervates with the light-generating enzyme, NanoLuc, to produce bioluminescence. Using condensates comprised of the disordered RGG domain of Caenorhabditis elegans LAF-1, we functionalized condensates with enzymatic activity in vitro and show that enzyme localization to coacervates enhances assembly and activity of split enzymes. To build condensates that function as light-emitting reactors, we designed a NanoLuc enzyme flanked by RGG domains. The resulting condensates concentrated NanoLuc by 10-fold over bulk solution and displayed significantly increased reaction rates. We further show that condensate viscosity impacts light emission due to diffusion-limited behavior. Because our model condensates have low viscosities, we predict NanoLuc diffusion-limited behavior in most other condensates and thus propose the condensate-Nanoluc system as a potential strategy for high-throughput screening of condensate targeting drugs. By splitting the NanoLuc enzyme into its constituent components, we demonstrate that NanoLuc activity can be reconstituted via co-condensation. In addition, we demonstrate control of the spatial localization of the enzyme within condensates by targettng NanoLuc to the surface of in vitro condensates. Collectively, this work demonstrates that membraneless organelles can be endowed with localized enzymatic activity and that this activity can be spatially and temporally controlled via biochemical reconstitution and design of protein surfactants.
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Affiliation(s)
- Muyang Guan
- Department of Chemical and Biomolecular Engineering, University of Pennsylvania, Philadelphia, PA 19104
| | - Mikael V. Garabedian
- Department of Cell and Developmental Biology, University of Pennsylvania, Philadelphia, PA 19104
| | - Marcel Leutenegger
- Max Planck Institute for Biophysical Chemistry, Department of NanoBiophotonics, Am Faßberg 11, 37077 Göttingen, Germany
| | - Benjamin S. Schuster
- Department of Chemical and Biochemical Engineering, Rutgers University, New Brunswick, New Jersey 08854, United States
| | - Matthew C. Good
- Department of Cell and Developmental Biology, University of Pennsylvania, Philadelphia, PA 19104
- Department of Bioengineering, University of Pennsylvania, Philadelphia, PA 19104
| | - Daniel A. Hammer
- Department of Chemical and Biomolecular Engineering, University of Pennsylvania, Philadelphia, PA 19104
- Department of Bioengineering, University of Pennsylvania, Philadelphia, PA 19104
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Hill SC, Pan YL, Williamson C, Santarpia JL, Hill HH. Fluorescence of bioaerosols: mathematical model including primary fluorescing and absorbing molecules in bacteria. OPTICS EXPRESS 2013; 21:22285-313. [PMID: 24104120 DOI: 10.1364/oe.21.022285] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
This paper describes a mathematical model of fluorescent biological particles composed of bacteria, viruses, or proteins. The fluorescent and/or light absorbing molecules included in the model are amino acids (tryptophan, etc.); nucleic acids (DNA, RNA, etc.); coenzymes (nicotinamide adenine dinucleotides, flavins, and vitamins B₆ and K and variants of these); and dipicolinates. The concentrations, absorptivities, and fluorescence quantum yields are estimated from the literature, often with large uncertainties. The bioparticles in the model are spherical and homogeneous. Calculated fluorescence cross sections for particles excited at 266, 280, and 355 nm are compared with measured values from the literature for several bacteria, bacterial spores and albumins. The calculated 266- and 280-nm excited fluorescence is within a factor of 3.2 of the measurements for the vegetative cells and proteins, but overestimates the fluorescence of spores by a factor of 10 or more. This is the first reported modeling of the fluorescence of bioaerosols in which the primary fluorophores and absorbing molecules are included.
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Esen C, Šurbek M, Baer S, Ostendorf A. Raman-Spektroskopie an einzelnen levitierten Partikeln. Raman Spectroscopy on Single Levitated Particles. CHEM-ING-TECH 2010. [DOI: 10.1002/cite.201000136] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Ray AK, Devarakonda V, Gao Z. Resonance-based light scattering techniques for investigation of microdroplet processes. Faraday Discuss 2008; 137:85-98; discussion 99-113. [DOI: 10.1039/b702122d] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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You Y, Kattawar GW, Li C, Yang P. Internal dipole radiation as a tool for particle identification. APPLIED OPTICS 2006; 45:9115-24. [PMID: 17151750 DOI: 10.1364/ao.45.009115] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
A numerical approach for the calculation of the internal dipole radiation associated with particles of arbitrary morphology is investigated by using the discrete-dipole approximation (DDA) method. The DDA and analytical solutions for the total radiated power and radiation pattern are compared in the case of spherical host particles. It is shown that the DDA can be quite accurate under the condition that m <or approximately 2, and mkd<0.5, where m is the refractive index of the host particle, k=2pi/lambda is the wavenumber in vacuum, and d is the distance between two adjacent dipoles in the DDA cubic dipole array. Furthermore, the DDA solutions for the dipole radiation patterns associated with nonspherical host particles are compared with their corresponding counterparts obtained from the finite-difference time-domain method. Excellent agreement between the two results is noted. The DDA method is also applied to the computation of the internal dipole radiation associated with simulated nonspherical sporelike particles. The results suggest that the internal dipole radiation patterns contain a great deal of information about the morphology and composition of the host particle.
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Affiliation(s)
- Yu You
- Texas A&M University, College Station, Texas 77843, USA
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Weigel T, Schulte J, Schweiger G. Inelastic scattering by particles of arbitrary shape. JOURNAL OF THE OPTICAL SOCIETY OF AMERICA. A, OPTICS, IMAGE SCIENCE, AND VISION 2006; 23:2797-802. [PMID: 17047706 DOI: 10.1364/josaa.23.002797] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
The shape effect of inelastic scattering by small particles is investigated using geometrical optics. The particles considered are described by surfaces composed of triangles. In order to determine the accuracy of this model, the results for an approximated sphere with different degrees of discretization are compared with the result for a smooth sphere. The triangulation method is then used for describing a superellipsoid. This enables us to consider inelastic scattering for a variety of particles by changing only a few parameters.
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Affiliation(s)
- Thomas Weigel
- Laseranwendungstechnik und Messsysteme, Ruhr-Universität Bochum, Universitätsstrasse 150, 44780 Bochum, Germany.
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Weigel T, Schulte J, Schweiger G. Inelastic scattering on particles with inclusions. JOURNAL OF THE OPTICAL SOCIETY OF AMERICA. A, OPTICS, IMAGE SCIENCE, AND VISION 2005; 22:1048-52. [PMID: 15984477 DOI: 10.1364/josaa.22.001048] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
The investigation of particles with inclusions is of high interest in many parts of scientific research. Raman scattering is very good at yielding information on the internal composition of the particle. We use a geometrical-optics-based technique to determine the angle dependence of the inelastic scattering on particles with several spherical inclusions.
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Affiliation(s)
- Thomas Weigel
- Laseranwendungstechnik und Messsysteme, Ruhr-Universität Bochum, Universitätsstrasse 150, 44780 Bochum, Germany.
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Sprynchak V, Esen C, Schweiger G. Enhancement of Raman scattering by deformation of microparticles. OPTICS LETTERS 2003; 28:221-223. [PMID: 12653354 DOI: 10.1364/ol.28.000221] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Raman scattering on deformed droplets levitated in an acoustic levitator and produced by a vibrating-orifice aerosol generator were investigated. Our samples experiments were diethyl hexyl sebecate (DEHS) droplets in the millimeter-size range and ethanol droplets in the size range 50-100 microm. The C-H stretching region from 2800 to 3100 cm(-1) was investigated. We found that the Raman intensity measured by a scattering angle of 90 degrees depended on the shape of the droplets. Raman scattering on spherical droplets was smaller than scattering on spheroidal droplets with the same volume. Similar results were observed for the fluorescence signal of Rhodamine 6G-doped DEHS droplets.
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Affiliation(s)
- Vitaliy Sprynchak
- Laseranwendungstechnik und Messsysteme, Ruhr-Universität Bochum, D-44780 Bochum, Germany
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Schulte J, Schweiger G. Resonant inelastic scattering by use of geometrical optics. JOURNAL OF THE OPTICAL SOCIETY OF AMERICA. A, OPTICS, IMAGE SCIENCE, AND VISION 2003; 20:317-324. [PMID: 12570298 DOI: 10.1364/josaa.20.000317] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
We investigate the inelastic scattering on spherical particles that contain one concentric inclusion in the case of input and output resonances, using a geometrical optics method. The excitation of resonances is included in geometrical optics by use of the concept of tunneled rays. To get a quantitative description of optical tunneling on spherical surfaces, we derive appropriate Fresnel-type reflection and transmission coefficients for the tunneled rays. We calculate the inelastic scattering cross section in the case of input and output resonances and investigate the influence of the distribution of the active material in the particle as well as the influence of the inclusion on inelastic scattering.
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Affiliation(s)
- Jörg Schulte
- Laseranwendungstechnik, Ruhr-Universität Bochum, Universitätsstrasse 150, Bochum D-44779, Germany.
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Veselovskii I, Griaznov V, Kolgotin A, Whiteman DN. Angle- and size-dependent characteristics of incoherent Raman and fluorescent scattering by microspheres. 2. Numerical simulation. APPLIED OPTICS 2002; 41:5783-5791. [PMID: 12269577 DOI: 10.1364/ao.41.005783] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
The results of numerical simulation of inelastic scattering by microspheres with the use of a dipole model are presented. The formulas that are derived speed up the computation, thereby permitting larger-sized microspheres to be studied. The angular scattering cross section and depolarization are calculated for a wide range of size parameters as well as for different orientations of incident wave polarization. Calculations performed with small incremental changes in size permit the influence of morphology-dependent resonance (MDR) on the power and angular distribution of scattered radiation to be studied. TM and TE types of MDR produce enhanced scattering of the incident wave with vertical and horizontal polarization; the corresponding shape of the phase function becomes oscillatory. Special attention is paid to the simulation of backward scattering by water droplets, which is important for Raman lidar applications.
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Affiliation(s)
- Igor Veselovskii
- Physics Instrumentation Center of General Physics Institute, Troitsk, Moscow Region, Russia.
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Pan YL, Hill SC, Wolf JP, Holler S, Chang RK, Bottiger JR. Backward-enhanced fluorescence from clusters of microspheres and particles of tryptophan. APPLIED OPTICS 2002; 41:2994-2999. [PMID: 12027190 DOI: 10.1364/ao.41.002994] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Measured fluorescence from single-particle clusters of dye-doped polystyrene microspheres, dried nonspherical particles of tryptophan, and single polystyrene microspheres is enhanced in the backward direction (180 degrees from the incident laser). This enhancement (a factor of 2-3 compared to 90 degrees), which can be interpreted as a consequence of the reciprocity principle, increases with the particle refractive index.
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Affiliation(s)
- Yong-Le Pan
- Physical Science Laboratory, New Mexico State University, Las Cruces 88003-8002, USA
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13
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Lock JA. Semiclassical scattering of an electric dipole source inside a spherical particle. JOURNAL OF THE OPTICAL SOCIETY OF AMERICA. A, OPTICS, IMAGE SCIENCE, AND VISION 2001; 18:3085-3097. [PMID: 11760206 DOI: 10.1364/josaa.18.003085] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Semiclassical scattering phenomena appearing in the far-zone scattered intensity of a point source of electromagnetic radiation inside a spherical particle are examined in the context of both ray theory and wave theory, and the evolution of the phenomena is studied as a function of source position. A number of semiclassical effects that do not occur for plane-wave scattering by the sphere appear prominently for scattering by an interior source. These include a series of scattering resonances and a new family of rainbows in regions of otherwise total internal reflection. Diffractive effects accompanying the semiclassical phenomena are also examined.
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Affiliation(s)
- J A Lock
- Department of Physics, Cleveland State University, Cleveland, Ohio 44115, USA.
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Barton JP. Electromagnetic fields for a spheroidal particle with an arbitrary embedded source. JOURNAL OF THE OPTICAL SOCIETY OF AMERICA. A, OPTICS, IMAGE SCIENCE, AND VISION 2000; 17:458-464. [PMID: 10708026 DOI: 10.1364/josaa.17.000458] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
A spheroidal coordinate separation-of-variables solution has been developed for the determination of the internal, near-surface, and scattered fields of a spheroid (either prolate or oblate) with an embedded source of arbitrary type, location, and orientation. Presented results for (1,0) and (1,1) electric multipoles embedded in 2:1 axis ratio prolate and oblate spheroids (equal volume sphere size parameter equal to 20) illustrate that the presence of the spheroid interface can have a profound effect on the corresponding far-field scattering pattern. The calculation procedure could be used, for example, to model the emission of inelastic scattered light (Raman, fluorescence, etc.) from biological particles of appreciably elongated (prolatelike) or appreciably flattened (oblatelike) geometries.
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Affiliation(s)
- J P Barton
- Department of Mechanical Engineering, College of Engineering and Technology, University of Nebraska-Lincoln, 68588-0656, USA
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