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Vahid H, Scacchi A, Sammalkorpi M, Ala-Nissila T. Adsorption of polyelectrolytes in the presence of varying dielectric discontinuity between solution and substrate. J Chem Phys 2024; 161:134907. [PMID: 39360687 DOI: 10.1063/5.0223124] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2024] [Accepted: 09/16/2024] [Indexed: 10/04/2024] Open
Abstract
We examine the interactions between polyelectrolytes (PEs) and uncharged substrates under conditions corresponding to a dielectric discontinuity between the aqueous solution and the substrate. To this end, we vary the relevant system characteristics, in particular the substrate dielectric constant ɛs under different salt conditions. We employ coarse-grained molecular dynamics simulations with rodlike PEs in salt solutions with explicit ions and implicit water solvent with dielectric constant ɛw = 80. As expected, at low salt concentrations, PEs are repelled from the substrates with ɛs < ɛw but are attracted to substrates with a high dielectric constant due to image charges. This attraction considerably weakens for high salt and multivalent counterions due to enhanced screening. Furthermore, for monovalent salt, screening enhances adsorption for weakly charged PEs, but weakens it for strongly charged ones. Meanwhile, multivalent counterions have little effect on weakly charged PEs, but prevent adsorption of highly charged PEs, even at low salt concentrations. We also find that correlation-induced charge inversion of a PE is enhanced close to the low dielectric constant substrates, but suppressed when the dielectric constant is high. To explore the possibility of a PE monolayer formation, we examine the interaction of a pair of like-charged PEs aligned parallel to a high dielectric constant substrate with ɛs = 8000. Our main conclusion is that monolayer formation is possible only for weakly charged PEs at high salt concentrations of both monovalent and multivalent counterions. Finally, we also consider the energetics of a PE approaching the substrate perpendicular to it, in analogy to polymer translocation. Our results highlight the complex interplay between electrostatic and steric interactions and contribute to a deeper understanding of PE-substrate interactions and adsorption at substrate interfaces with varying dielectric discontinuities from solution, ubiquitous in biointerfaces, PE coating applications, and designing adsorption setups.
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Affiliation(s)
- Hossein Vahid
- Department of Applied Physics, Aalto University, P.O. Box 15600, FI-00076 Aalto, Finland
- Department of Chemistry and Materials Science, Aalto University, P.O. Box 16100, FI-00076 Aalto, Finland
- Academy of Finland Center of Excellence in Life-Inspired Hybrid Materials (LIBER), Aalto University, P.O. Box 16100, FI-00076 Aalto, Finland
| | - Alberto Scacchi
- Department of Applied Physics, Aalto University, P.O. Box 15600, FI-00076 Aalto, Finland
- Academy of Finland Center of Excellence in Life-Inspired Hybrid Materials (LIBER), Aalto University, P.O. Box 16100, FI-00076 Aalto, Finland
- Department of Bioproducts and Biosystems, Aalto University, P.O. Box 16100, FI-00076 Aalto, Finland
- Department of Mechanical and Materials Engineering, University of Turku, Vesilinnantie 5, FI-20014 Turku, Finland
| | - Maria Sammalkorpi
- Department of Chemistry and Materials Science, Aalto University, P.O. Box 16100, FI-00076 Aalto, Finland
- Academy of Finland Center of Excellence in Life-Inspired Hybrid Materials (LIBER), Aalto University, P.O. Box 16100, FI-00076 Aalto, Finland
| | - Tapio Ala-Nissila
- Department of Applied Physics, Aalto University, P.O. Box 15600, FI-00076 Aalto, Finland
- Quantum Technology Finland Center of Excellence, Department of Applied Physics, Aalto University, P.O. Box 15600, FI-00076 Aalto, Finland
- Interdisciplinary Centre for Mathematical Modelling and Department of Mathematical Sciences, Loughborough University, Loughborough Leicestershire LE11 3TU, United Kingdom
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Audoin B. Principles and advances in ultrafast photoacoustics; applications to imaging cell mechanics and to probing cell nanostructure. PHOTOACOUSTICS 2023; 31:100496. [PMID: 37159813 PMCID: PMC10163675 DOI: 10.1016/j.pacs.2023.100496] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/05/2022] [Revised: 03/29/2023] [Accepted: 04/12/2023] [Indexed: 05/11/2023]
Abstract
In this article we first present the foundations of ultrafast photoacoustics, a technique where the acoustic wavelength in play can be considerably shorter than the optical wavelength. The physics primarily involved in the conversion of short light pulses into high frequency sound is described. The mechanical disturbances following the relaxation of hot electrons in metals and other processes leading to the breaking of the mechanical balance are presented, and the generation of bulk shear-waves, of surface and interface waves and of guided waves is discussed. Then, efforts to overcome the limitations imposed by optical diffraction are described. Next, the principles behind the detection of the so generated coherent acoustic phonons with short light pulses are introduced for both opaque and transparent materials. The striking instrumental advances, in the detection of acoustic displacements, ultrafast acquisition, frequency and space resolution are discussed. Then secondly, we introduce picosecond opto-acoustics as a remote and label-free novel modality with an excellent capacity for quantitative evaluation and imaging of the cell's mechanical properties, currently with micron in-plane and sub-optical in depth resolution. We present the methods for time domain Brillouin spectroscopy in cells and for cell ultrasonography. The current applications of this unconventional means of addressing biological questions are presented. This microscopy of the nanoscale intra-cell mechanics, based on the optical monitoring of coherent phonons, is currently emerging as a breakthrough method offering new insights into the supra-molecular structural changes that accompany cell response to a myriad of biological events.
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Scholz M, Morgenroth M, Cho MJ, Choi DH, Lenzer T, Oum K. Coherent acoustic phonon dynamics in chiral copolymers. STRUCTURAL DYNAMICS (MELVILLE, N.Y.) 2019; 6:064502. [PMID: 31893213 PMCID: PMC6927817 DOI: 10.1063/1.5124438] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/14/2019] [Accepted: 12/04/2019] [Indexed: 06/10/2023]
Abstract
Coherent phonon oscillations in the UV-Vis transient absorption and circular dichroism response of two chiral polyfluorene-based copolymer thin films are investigated. A slow oscillation in the hundred picosecond regime indicates the propagation of a longitudinal acoustic phonon with a frequency in the gigahertz range through cholesteric films of PFPh and PFBT, which allow for the optical determination of the longitudinal sound velocity in these polymers, with values of (2550 ± 140) and (2490 ± 150) m s-1, respectively. The oscillation is induced by a strain wave, resulting in a pressure-induced periodic shift of the electronic absorption bands, as extracted from a Fourier analysis of the transient spectra. The acoustic phonon oscillation is also clearly detected in the transient circular dichroism (TrCD) response of PFPh, indicating a transient pressure-induced shift of the CD spectrum and possibly also phonon-induced chirality changes via pitch length modulation of the cholesteric helical polymer stack.
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Affiliation(s)
- Mirko Scholz
- Physical Chemistry, University of Siegen, Adolf-Reichwein-Str. 2, 57076 Siegen, Germany
| | - Marius Morgenroth
- Physical Chemistry, University of Siegen, Adolf-Reichwein-Str. 2, 57076 Siegen, Germany
| | - Min Ju Cho
- Department of Chemistry, Research Institute for Natural Sciences, Korea University, 5 Anam-dong, Sungbuk-gu, Seoul 136-701, South Korea
| | - Dong Hoon Choi
- Department of Chemistry, Research Institute for Natural Sciences, Korea University, 5 Anam-dong, Sungbuk-gu, Seoul 136-701, South Korea
| | - Thomas Lenzer
- Physical Chemistry, University of Siegen, Adolf-Reichwein-Str. 2, 57076 Siegen, Germany
| | - Kawon Oum
- Physical Chemistry, University of Siegen, Adolf-Reichwein-Str. 2, 57076 Siegen, Germany
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Zeuschner SP, Parpiiev T, Pezeril T, Hillion A, Dumesnil K, Anane A, Pudell J, Willig L, Rössle M, Herzog M, von Reppert A, Bargheer M. Tracking picosecond strain pulses in heterostructures that exhibit giant magnetostriction. STRUCTURAL DYNAMICS (MELVILLE, N.Y.) 2019; 6:024302. [PMID: 31041360 PMCID: PMC6447272 DOI: 10.1063/1.5084140] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/04/2018] [Accepted: 02/26/2019] [Indexed: 05/06/2023]
Abstract
We combine ultrafast X-ray diffraction (UXRD) and time-resolved Magneto-Optical Kerr Effect (MOKE) measurements to monitor the strain pulses in laser-excited TbFe2/Nb heterostructures. Spatial separation of the Nb detection layer from the laser excitation region allows for a background-free characterization of the laser-generated strain pulses. We clearly observe symmetric bipolar strain pulses if the excited TbFe2 surface terminates the sample and a decomposition of the strain wavepacket into an asymmetric bipolar and a unipolar pulse, if a SiO2 glass capping layer covers the excited TbFe2 layer. The inverse magnetostriction of the temporally separated unipolar strain pulses in this sample leads to a MOKE signal that linearly depends on the strain pulse amplitude measured through UXRD. Linear chain model simulations accurately predict the timing and shape of UXRD and MOKE signals that are caused by the strain reflections from multiple interfaces in the heterostructure.
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Affiliation(s)
| | - T Parpiiev
- Institut des Molécules et Matériaux du Mans (UMR CNRS 6283), Université du Maine, 72085 Le Mans Cedex, France
| | - T Pezeril
- Institut des Molécules et Matériaux du Mans (UMR CNRS 6283), Université du Maine, 72085 Le Mans Cedex, France
| | - A Hillion
- Institut Jean Lamour (UMR CNRS 7198), Université de Lorraine, 54000 Nancy, France
| | - K Dumesnil
- Institut Jean Lamour (UMR CNRS 7198), Université de Lorraine, 54000 Nancy, France
| | - A Anane
- Unité Mixte de Physique, CNRS, Thales, Univ. Paris-Sud, Université Paris-Saclay, 91767, Palaiseau, France
| | - J Pudell
- Institute of Physics and Astronomy, University of Potsdam, Karl-Liebknecht-Straße 24-25, 14476 Potsdam, Germany
| | - L Willig
- Institute of Physics and Astronomy, University of Potsdam, Karl-Liebknecht-Straße 24-25, 14476 Potsdam, Germany
| | - M Rössle
- Helmholtz-Zentrum Berlin, Wilhelm-Conrad-Röntgen-Campus, BESSY II, Albert-Einstein-Straße 15, 12489 Berlin, Germany
| | - M Herzog
- Institute of Physics and Astronomy, University of Potsdam, Karl-Liebknecht-Straße 24-25, 14476 Potsdam, Germany
| | - A von Reppert
- Institute of Physics and Astronomy, University of Potsdam, Karl-Liebknecht-Straße 24-25, 14476 Potsdam, Germany
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Liu R, Yang Y, Cui Q, Xu W, Peng R, Li L. A Diarylethene-Based Photoswitch and its Photomodulation of the Fluorescence of Conjugated Polymers. Chemistry 2018; 24:17756-17766. [DOI: 10.1002/chem.201803473] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2018] [Revised: 09/11/2018] [Indexed: 12/17/2022]
Affiliation(s)
- Ronghua Liu
- State Key Lab for Advanced Metals and Materials, School of Materials Science and Engineering; University of Science and Technology Beijing; Beijing 100083 P.R. China
| | - Yu Yang
- State Key Lab for Advanced Metals and Materials, School of Materials Science and Engineering; University of Science and Technology Beijing; Beijing 100083 P.R. China
| | - Qianling Cui
- State Key Lab for Advanced Metals and Materials, School of Materials Science and Engineering; University of Science and Technology Beijing; Beijing 100083 P.R. China
| | - Wenqiang Xu
- State Key Lab for Advanced Metals and Materials, School of Materials Science and Engineering; University of Science and Technology Beijing; Beijing 100083 P.R. China
| | - Rui Peng
- State Key Lab for Advanced Metals and Materials, School of Materials Science and Engineering; University of Science and Technology Beijing; Beijing 100083 P.R. China
| | - Lidong Li
- State Key Lab for Advanced Metals and Materials, School of Materials Science and Engineering; University of Science and Technology Beijing; Beijing 100083 P.R. China
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