Microrheology with optical tweezers: peaks &amp; troughs

Tassieri, Manlio

doi:10.1016/j.cocis.2019.02.006

Cited by 37 publications

(30 citation statements)

References 74 publications

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“…At thermal equilibrium, PVPT microrheology measurements have the potential of revealing the frequency‐dependent linear mechanical properties of the surrounding media, which in the case of solid‐like materials (like gels) can be narrowed down to a single component defined by the (almost) frequency‐independent shear elastic modulus G ′. [ 51–53 ] In Figure 2B–G are compared the results obtained from PVPT microrheology and bulk rheology measurements, with the latter performed under different loadings of normal force. Notice that, only relatively soft hydrogels were tested with PVPT, namely those at PEG concentrations of 3.5% and 5% w/v.…”

Section: Figurementioning

confidence: 99%

What Caging Force Cells Feel in 3D Hydrogels: A Rheological Perspective

Ciccone

Dobre

Gibson

et al. 2020

Adv Healthcare Materials

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It has been established that the mechanical properties of hydrogels control the fate of (stem) cells. However, despite its importance, a one‐to‐one correspondence between gels' stiffness and cell behavior is still missing from literature. In this work, the viscoelastic properties of poly(ethylene‐glycol) (PEG)‐based hydrogels are investigated by means of rheological measurements performed at different length scales. The outcomes of this work reveal that PEG‐based hydrogels show significant stiffening when subjected to a compressional deformation, implying that conventional bulk rheology measurements may overestimate the stiffness of hydrogels by up to an order of magnitude. It is hypothesized that this apparent stiffening is caused by an induced “tensional state” of the gel network, due to the application of a compressional normal force during sample loading. Moreover, it is shown that the actual stiffness of the hydrogels is instead accurately determined by means of both passive‐video‐particle‐tracking (PVPT) microrheology and nanoindentation measurements, which are inherently performed at the cell's length scale and in absence of any externally applied force in the case of PVPT. These results underpin a methodology for measuring hydrogels' linear viscoelastic properties that are representative of the mechanical constraints perceived by cells in 3D hydrogel cultures.

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Section: Figurementioning

confidence: 99%

What Caging Force Cells Feel in 3D Hydrogels: A Rheological Perspective

Ciccone

Dobre

Gibson

et al. 2020

Adv Healthcare Materials

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“…where R is the bead radius and d Δr 2 ω ð Þ h iis the Fourier transform of the MSD (Tassieri 2019). Concerning active microrheology (AMR), a sinusoidal trap oscillation with a force F at a frequency ω is applied to a trapped bead (Fig.…”

Section: Passive and Active Microrheologymentioning

confidence: 99%

“…Some recent reviews provide a full derivation of these formulas (Eqs. 10 and 11), range of applicability, and advantages and limitations of the technique (Brau et al 2007;Guo et al 2014;Tassieri 2019).…”

Section: Passive and Active Microrheologymentioning

confidence: 99%

Probing force in living cells with optical tweezers: from single-molecule mechanics to cell mechanotransduction

Arbore¹,

Perego²,

Σεργίδης³

et al. 2019

Biophys Rev

105

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The invention of optical tweezers more than three decades ago has opened new avenues in the study of the mechanical properties of biological molecules and cells. Quantitative force measurements still represent a challenging task in living cells due to the complexity of the cellular environment. Here, we review different methodologies to quantitatively measure the mechanical properties of living cells, the strength of adhesion/receptor bonds, and the active force produced during intracellular transport, cell adhesion, and migration. We discuss experimental strategies to attain proper calibration of optical tweezers and molecular resolution in living cells. Finally, we show recent studies on the transduction of mechanical stimuli into biomolecular and genetic signals that play a critical role in cell health and disease.

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“…Figures. S1-S7 285 Table S1 References (25)(26)(27)(28)(29)(30)(31)(32)(33)(34)(35)(36)(37)(38)(39)(40)…”

Section: Supplementary Materialsmentioning

confidence: 99%

Microrheology reveals microscale viscosity gradients in planktonic systems

Guadayol

Mendonça

Segura-Noguera

et al. 2020

Preprint

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Microbial activity in planktonic systems creates a dynamic and heterogeneous microscale 15 seascape that harbours a diverse community of microorganisms and ecological interactions of global significance. Over recent decades a great deal of effort has been put into understanding this complex system, particularly focusing on the role of chemical patchiness, while overlooking a governing feature of microbial life affected by biological activity: viscosity. Here we use microrheological techniques to measure viscosity at length scales relevant to microorganisms. 20Our results reveal the viscous nature and the spatial extent of the phycosphere and show heterogeneity in viscosity at the microscale. Such heterogeneity affects the distribution of chemicals and microorganisms, with pervasive and profound implications for the functioning of the entire planktonic ecosystem.One Sentence Summary: Microrheology measurements unveil the existence of viscous layers 25 around phytoplankton cells and aggregates.Main Text:

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Microrheology with optical tweezers: peaks & troughs

Cited by 37 publications

References 74 publications

What Caging Force Cells Feel in 3D Hydrogels: A Rheological Perspective

What Caging Force Cells Feel in 3D Hydrogels: A Rheological Perspective

Probing force in living cells with optical tweezers: from single-molecule mechanics to cell mechanotransduction

Microrheology reveals microscale viscosity gradients in planktonic systems

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