Compression and Reswelling of Microgel Particles after an Osmotic Shock

Sleeboom, Jelle J. F.; Voudouris, Panayiotis; Punter, Melle T. J. J. M.; Aangenendt, Frank J.; Florea, Daniel; Schoot, Paul van der; Wyss, Hans M.

doi:10.1103/physrevlett.119.098001

Cited by 16 publications

(12 citation statements)

References 23 publications

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“…This radius is too large to allow for passive free diffusion and can thus create an osmotic pressure acting inward on the capsid. We note that the capsid still presents a finite permeability rather than zero permeability but over the time scale of the experiment, we consider PEG 6000 diffusion across the capsid to be negligible. The concentration dependence of osmotic pressure for PEG is well documented and the polymer has been used in several studies to control osmotic pressure in biological systems including bacteriophages. , It is worth noting that the viscosity of the PEG solutions can be a challenge for amplitude-modulation AFM imaging.…”

Section: Resultsmentioning

confidence: 99%

Virus Mechanics under Molecular Crowding

et al. 2021

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Viruses avoid exposure of the viral genome to harmful agents with the help of a protective protein shell known as the capsid. A secondary effect of this protective barrier is that macromolecules that may be in high concentration on the outside cannot freely diffuse across it. Therefore, inside the cell and possibly even outside, the intact virus is generally under a state of osmotic stress. Viruses deal with this type of stress in various ways. In some cases, they might harness it for infection. However, the magnitude and influence of osmotic stress on virus physical properties remains virtually unexplored for single-stranded RNA virusesthe most abundant class of viruses. Here, we report on how a model system for the positive-sense RNA icosahedral viruses, brome mosaic virus (BMV), responds to osmotic pressure. Specifically, we study the mechanical properties and structural stability of BMV under controlled molecular crowding conditions. We show that BMV is mechanically reinforced under a small external osmotic pressure but starts to yield after a threshold pressure is reached. We explain this mechanochemical behavior as an effect of the molecular crowding on the entropy of the "breathing" fluctuation modes of the virus shell. The experimental results are consistent with the viral RNA imposing a small negative internal osmotic pressure that prestresses the capsid. Our findings add a new line of inquiry to be considered when addressing the mechanisms of viral disassembly inside the crowded environment of the cell.

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Section: Resultsmentioning

confidence: 99%

Virus Mechanics under Molecular Crowding

et al. 2021

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“…Consequently, it should be possible to directly derive the effective interactions, valid at least at low concentrations, by measuring the single-particle elastic properties. These can be accessed by atomic force microscopy (AFM), , capillary micromechanics, or osmotic pressure experiments. These measurements should then be complemented by the evaluation of the effective interactions in order to validate the Hertzian theory.…”

Section: Introductionmentioning

confidence: 99%

Connecting Elasticity and Effective Interactions of Neutral Microgels: The Validity of the Hertzian Model

et al. 2019

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An important open problem in materials science is whether a direct connection exists between single-particle elastic properties and the macroscopic bulk behavior. Here we address this question by focusing on the archetype of soft colloids: thermoresponsive microgels. These colloidal-sized polymer networks are often assumed to interact through a simple Hertzian potential, a classic model in linear elasticity theory. By developing an appropriate methodology, that can be generalized to any kind of soft particle, we are able to calculate all the elastic moduli of non-ionic microgels across their volume phase transition (VPT). Remarkably, we reproduce many features seen in experiments, including the appearance of a minimum of the Poisson's ratio close to the VPT. By calculating the particle-particle effective interactions and the resulting collective behavior, we find that the Hertzian model works well up to moderate values of the packing fraction.

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“…For future applications of smart microgels the response kinetics are a crucial issue. The kinetics of the phase transition was up to now investigated only in a non-absolute way 30 , for related macroscopic systems 31 – 34 , for sub-domains of the particles 35 , or for cononsolvency induced phase transitions 36 . In this work, we utilize the shift of the VPTT by an applied pressure which is observed for microgels 37 and polymer brushes 38 to study the swelling/collapse kinetics of NNPAM microgels combining periodic pressure jumps with time-resolved small angle neutron scattering (TR-SANS) experiments exhibiting an up to now unprecedented time resolution.…”

Section: Introductionmentioning

confidence: 99%

Volume phase transition kinetics of smart N-n-propylacrylamide microgels studied by time-resolved pressure jump small angle neutron scattering

Wrede

Reimann

Lülsdorf

et al. 2018

Sci Rep

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The use of smart colloidal microgels for advanced applications critically depends on their response kinetics. We use pressure jump small angle neutron scattering with supreme time resolution to study the rapid volume phase transition kinetics of such microgels. Utilizing the pressure induced microphase separation inside the microgels we were able to resolve their collapse and swelling kinetics. While the collapse occurs on a time scale of 10 ms, the particle swelling turned out to be much faster. Photon correlation spectroscopy and static small angle neutron scattering unambiguously show, that the much slower collapse can be associated with the complex particle architecture exhibiting a loosely-crosslinked outer region and a denser inner core region. These insights into the kinetics of stimuli-responsive materials are of high relevance for their applications as nano-actuators, sensors or drug carriers. Moreover, the used refined pressure jump small angle neutron scattering technique is of broad interest for soft matter studies.

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Compression and Reswelling of Microgel Particles after an Osmotic Shock

Cited by 16 publications

References 23 publications

Virus Mechanics under Molecular Crowding

Virus Mechanics under Molecular Crowding

Connecting Elasticity and Effective Interactions of Neutral Microgels: The Validity of the Hertzian Model

Volume phase transition kinetics of smart N-n-propylacrylamide microgels studied by time-resolved pressure jump small angle neutron scattering

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