Nematic Director Configuration, Local Order and Microviscosity in a PSLC Cell

Bacchiocchi, Corrado; Foschi, Giulia; Miglioli, Isabella; Shoarinejad, S.; Arcioni, Alberto; Zannoni, Claudio

doi:10.1080/15421406.2015.1049474

Cited by 4 publications

(2 citation statements)

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“…The ability of the CSL spin probe to report correctly the local nematic order of the CB11CB LC can be assessed by noticing that CSL was able to consistently report the local order and the director organization of the 5CB LC in previous studies 43,44 . It has also been shown by Oganesyan et al, using molecular dynamics simulations of the CSL probe in 5CB 45 , that the order parameter of the probe and of the mesogen are in good agreement.…”

Section: Resultsmentioning

confidence: 99%

Director configuration in the twist-bend nematic phase of CB11CB

et al. 2016

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The director distribution in the nematic phases exhibited by the 1",11"-bis(4-cyanobiphenyl-4'-yl)undecane (CB11CB) liquid crystal has been studied in the bulk using the EPR spin probe technique. EPR spectra confirmed the presence of a higher temperature uniaxial nematic phase and of a lower temperature nematic phase in which the director distribution is not uniform. Spectra recorded in the lower temperature nematic phase were not fully compatible with theoretical EPR spectra calculated according to the recently proposed model for the twist-bend phase in which the local domain director twists around an axis with a fixed tilt angle, theta_0, but were well described by a ‘‘distributed-tilt’’ model in which the director has a relatively narrow distribution, centred at theta_0

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Section: Resultsmentioning

confidence: 99%

Director configuration in the twist-bend nematic phase of CB11CB

et al. 2016

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“…This would benefit cancer research, where the unlabeled nitroxides either in the form of antioxidants or labeled with chemotherapeutic drugs are widely used. − Even the detection of reactive oxygen species (ROS) such as OH • , O 2 •– , etc., which play an important role in cancer metastasis are detected via unlabeled nitroxide-based spin traps. − In this regard, OH-EPRI would be very beneficial to give subcellular details of ROS production, an aspect currently not possible with conventional EPRI. Furthermore, for properties like microviscosity, pH, and redox status, polarity for which the nitroxides are highly sensitive to, ,,− the OH-EPRI method can allow obtaining such information in a highly cell-localized manner.…”

Section: Discussionmentioning

confidence: 99%

Harnessing Electron Spin Hyperpolarization in Chromophore–Radical Spin Probes for Subcellular Resolution in Electron Paramagnetic Resonance Imaging: Concept and Feasibility

Rane

2022

J. Phys. Chem. B

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Obtaining a subcellular resolution for biological samples doped with stable radicals at room temperature (RT) is a long-sought goal in electron paramagnetic resonance imaging (EPRI). The spatial resolution in current EPRI methods is constrained either because of low electron spin polarization at RT or the experimental limitations associated with the field gradients and the radical linewidth. Inspired by the recent demonstration of a large electron spin hyperpolarization in chromophore-nitroxyl spin probe molecules, the present work proposes a novel optically hyperpolarized EPR imaging (OH-EPRI) method, which combines the optical method of two-photon confocal microscopy for hyperpolarization generation and the rapid scan (RS) EPR method for signal detection. An important aspect of OH-EPRI is that it is not limited by the abovementioned restrictions of conventional EPRI since the large hyperpolarization in the spin probes overcomes the poor thermal spin polarization at RT, and the use of two-photon optical excitation of the chromophore naturally generates the required spatial resolution, without the need for any magnetic field gradient. Simulations based on time-dependent Bloch equations, which took into account both the RS field modulation and the hyperpolarization generation by optical means, were performed to examine the feasibility of OH-EPRI. The simulation results revealed that a spatial resolution of up to 2 fL can be achieved in OH-EPRI at RT under in vitro conditions. Notably, the majority of the requirements for an OH-EPRI experiment can be fulfilled by the currently available technologies, thereby paving the way for its easy implementation. Thus, the proposed method could potentially bridge the sensitivity gap between the optical and magnetic imaging techniques.

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