Near-surface microrheology reveals dynamics and viscoelasticity of soft matter

Soft Matter ◽  
2018 ◽  
Vol 14 (48) ◽  
pp. 9764-9776 ◽  
Author(s):  
Wei Liu ◽  
Xiangjun Gong ◽  
To Ngai ◽  
Chi Wu
Keyword(s):  
Magnetic Field ◽  
Polymer Solution ◽  
Total Internal Reflection ◽  
Soft Matter ◽  
Colloidal Dispersions ◽  
Internal Reflection ◽  
Surface Dynamics ◽  
Near Surface ◽  
Total Internal Reflection Microscopy ◽  
Viscoelastic Behaviors

We report the development of a microrheology technique that incorporates a magnetic-field-induced simulator on total internal reflection microscopy (TIRM) to probe the near-surface dynamics and viscoelastic behaviors of soft matter like polymer solution/gels and colloidal dispersions.

scholarly journals Sensing of Surface and Bulk Refractive Index Using Magnetophotonic Crystal with Hybrid Magneto-Optical Response

Sensors ◽  
2021 ◽  
Vol 21 (6) ◽  
pp. 1984
Author(s):  
Daria Ignatyeva ◽  
Pavel Kapralov ◽  
Polina Golovko ◽  
Polina Shilina ◽  
Anastasiya Khramova ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Refractive Index ◽  
Photonic Crystal ◽  
Total Internal Reflection ◽  
Polarized Light ◽  
Optical Response ◽  
Internal Reflection ◽  
Surface Mode ◽  
Optical Resonance ◽  
Near Surface

We propose an all-dielectric magneto-photonic crystal with a hybrid magneto-optical response that allows for the simultaneous measurements of the surface and bulk refractive index of the analyzed substance. The approach is based on two different spectral features of the magneto-optical response corresponding to the resonances in p- and s-polarizations of the incident light. Angular spectra of p-polarized light have a step-like behavior near the total internal reflection angle which position is sensitive to the bulk refractive index. S-polarized light excites the TE-polarized optical Tamm surface mode localized in a submicron region near the photonic crystal surface and is sensitive to the refractive index of the near-surface analyte. We propose to measure a hybrid magneto-optical intensity modulation of p-polarized light obtained by switching the magnetic field between the transverse and polar configurations. The transversal component of the external magnetic field is responsible for the magneto-optical resonance near total internal reflection conditions, and the polar component reveals the resonance of the Tamm surface mode. Therefore, both surface- and bulk-associated features are present in the magneto-optical spectra of the p-polarized light.

Measurement of Ca2+ signaling dynamics in exocrine cells with total internal reflection microscopy

2006 ◽  
Vol 291 (1) ◽  
pp. G146-G155 ◽  
Author(s):  
Jong Hak Won ◽  
David I. Yule
Keyword(s):  
Plasma Membrane ◽  
Total Internal Reflection ◽  
Acinar Cells ◽  
Internal Reflection ◽  
Pancreatic Acinar Cells ◽  
Wide Field ◽  
Exocrine Cells ◽  
Parotid Acinar Cells ◽  
Signaling Dynamics ◽  
Total Internal Reflection Microscopy

In nonexcitable cells, such as exocrine cells from the pancreas and salivary glands, agonist-stimulated Ca2+ signals consist of both Ca2+ release and Ca2+ influx. We have investigated the contribution of these processes to membrane-localized Ca2+ signals in pancreatic and parotid acinar cells using total internal reflection fluorescence (TIRF) microscopy (TIRFM). This technique allows imaging with unsurpassed resolution in a limited zone at the interface of the plasma membrane and the coverslip. In TIRFM mode, physiological agonist stimulation resulted in Ca2+ oscillations in both pancreas and parotid with qualitatively similar characteristics to those reported using conventional wide-field microscopy (WFM). Because local Ca2+ release in the TIRF zone would be expected to saturate the Ca2+ indicator (Fluo-4), these data suggest that Ca2+ release is occurring some distance from the area subjected to the measurement. When acini were stimulated with supermaximal concentrations of agonists, an initial peak, largely due to Ca2+ release, followed by a substantial, maintained plateau phase indicative of Ca2+ entry, was observed. The contribution of Ca2+ influx and Ca2+ release in isolation to these near-plasma membrane Ca2+ signals was investigated by using a Ca2+ readmission protocol. In the absence of extracellular Ca2+, the profile and magnitude of the initial Ca2+ release following stimulation with maximal concentrations of agonist or after SERCA pump inhibition were similar to those obtained with WFM in both pancreas and parotid acini. In contrast, when Ca2+ influx was isolated by subsequent Ca2+ readmission, the Ca2+ signals evoked were more robust than those measured with WFM. Furthermore, in parotid acinar cells, Ca2+ readdition often resulted in the apparent saturation of Fluo-4 but not of the low-affinity dye Fluo-4-FF. Interestingly, Ca2+ influx as measured by this protocol in parotid acinar cells was substantially greater than that initiated in pancreatic acinar cells. Indeed, robust Ca2+ influx was observed in parotid acinar cells even at low physiological concentrations of agonist. These data indicate that TIRFM is a useful tool to monitor agonist-stimulated near-membrane Ca2+ signals mediated by Ca2+ influx in exocrine acinar cells. In addition, TIRFM reveals that the extent of Ca2+ influx in parotid acinar cells is greater than pancreatic acinar cells when compared using identical methodologies.

scholarly journals A light scattering model for total internal reflection microscopy of geometrically anisotropic particles

2019 ◽  
Vol 66 (10) ◽  
pp. 1139-1151 ◽  
Author(s):  
Adrian Doicu ◽  
Alina A. Vasilyeva ◽  
Dmitry S. Efremenko ◽  
Christopher L. Wirth ◽  
Thomas Wriedt
Keyword(s):  
Light Scattering ◽  
Total Internal Reflection ◽  
Internal Reflection ◽  
Anisotropic Particles ◽  
Scattering Model ◽  
Total Internal Reflection Microscopy

scholarly journals Fluorescence-detected magnetic field effects on radical pair reactions from femtolitre volumes

2015 ◽  
Vol 51 (38) ◽  
pp. 8023-8026 ◽  
Author(s):  
C. A. Dodson ◽  
C. J. Wedge ◽  
M. Murakami ◽  
K. Maeda ◽  
M. I. Wallace ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Fluorescence Microscopy ◽  
Total Internal Reflection ◽  
Radical Pair ◽  
Internal Reflection ◽  
Total Internal Reflection Fluorescence ◽  
Magnetic Field Effects ◽  
Field Effects

Using total internal reflection fluorescence microscopy the effects of applied magnetic fields on radical pair reactions can be sensitively measured from sample volumes as low as ∼100 fL.

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