Label-free super-resolution chemical imaging of biomedical specimens

Guilbert, Julien; Negash, Awoke; Labouesse, Simon; Gigan, Sylvain; Sentenac, Anne; Hb, de Aguiar

doi:10.1101/2021.05.14.444185

Cited by 8 publications

(6 citation statements)

References 17 publications

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“…Our results demonstrate the power of Raman imaging, particularly over other popular optical imaging methods such as reflection/scattering microscopy, for providing label-free microscopic chemical information especially in material science applications. Combining such techniques with super-resolution 53,54 or tip-enhanced [55][56][57] approaches will allow access to the sub-100 nm resolution limit and broaden the set of systems that can be examined, e.g. polymer ABSs and phase separations at electrified interfaces.…”

Section: Discussionmentioning

confidence: 99%

Direct Imaging of Micrometer Thick Interfaces in Salt-Salt Aqueous Biphasic Systems

Degoulange

Pandya

Deschamps

et al. 2022

Preprint

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Unlike the interface between two immiscible electrolyte solutions (ITIES) formed between water and polar solvents, molecular understanding of the liquid-liquid interface formed for aqueous biphasic systems (ABSs) is relatively limited and mostly relies on surface tension measurements and thermodynamic models. Here, high-resolution Raman imaging is used to provide spatial and chemical resolution of the interface of LiCl-LiTFSI-water and HCl-LiTFSI-water, prototypical salt-salt ABSs found in a range of electrochemical applications. The concentration profiles of both TFSI anions and water are found to be sigmoidal, in agreement with an increasing surface tension as a function of concentration, both being typical of a negative adsorption mechanism. More striking, however, is the length at which the concentration profiles extend, ranging from 11 to 2 m with increasing concentrations, compared to a few nanometers for ITIES. We thus reveal that unlike ITIES, salt-salt ABSs do not have a molecularly sharp interface but rather form an interphase with a gradual change of environment from one phase to the other. This knowledge represents a major stepping-stone in the understanding of aqueous interfaces, key for mastering ion or electron transfer dynamics in a wide range of biological and technological settings including novel battery technologies such as membraneless redox flow and dual ion batteries.

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Section: Discussionmentioning

confidence: 99%

Direct Imaging of Micrometer Thick Interfaces in Salt-Salt Aqueous Biphasic Systems

Degoulange

Pandya

Deschamps

et al. 2022

Preprint

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“…Increasing the time-resolution of Raman (imaging) will allow faster scan rates to be explored and using optically or electronically-gated methods 18,42 it may even be possible to probe pico-to nanosecond processes such as electron-transfer and ion (de)solvation 43 . Enhancing the spatial resolution of Raman imaging with near-field 44 or super-resolution 45,46 methods will further aid answering of such questions. Automation to allow scanning over large numbers of particles and correlation with complementary techniques such as X-Ray imaging/TEM 14,47 will be key to further enhance the utility of such methods 48,49 .…”

Section: Discussionmentioning

confidence: 99%

Competing oxygen evolution reaction mechanisms revealed by high-speed compressive Raman imaging

Pandya

Dorchies

Romanin

et al. 2022

Preprint

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Transition metal oxides are state-of-the-art materials for catalysing the oxygen evolution reaction (OER), whose slow kinetics currently limit the efficiency of water electrolysis. However, microscale physicochemical heterogeneity between particles, dynamic reactions both in the bulk and at the surface, and an interplay between particle reactivity and electrolyte makes probing the OER challenging. Here, we overcome these limitations by applying state-of-the-art compressive Raman imaging to uncover competing bias-dependent mechanisms for the OER in a solid electrocatalyst, α-Li2IrO3. By spatially and temporally tracking changes in the in- and out-of-plane Ir-O stretching modes – identified by density functional theory calculations – we follow catalytic activation and charge accumulation following ion exchange under a variety of electrolytes, particle compositions and cycling conditions. We extract velocities of phase fronts and demonstrate that at low overpotentials oxygen is evolved by the combination of an electrochemical-chemical mechanism and a classical electrocatalytic adsorbate mechanism, whereas at high overpotentials only the latter occurs. These results provide strategies to promote mechanisms for enhanced OER performances, and highlight the power of compressive Raman imaging for low-cost, chemically specific tracking of microscale reaction dynamics in a broad range of systems where ion and electron exchange can be coupled to structural changes, i.e. catalysts, battery materials, memristors, etc.

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“…To date, only one report has shown noninvasive focusing using highly sparse samples (therefore focusing convergence is guaranteed) [94], highlighting the need to develop tools for deep Raman imaging, although recent work has shown that variance-based computational methods allow for 'chemical' focusing using wavefront shaping [88]. Finally, speckles have been used to enable super-resolution in Raman-based processes [95], opening another research venue for exploiting computational tools in deep imaging.…”

Section: Advances In Science and Technology To Meet Challengesmentioning

confidence: 99%

Roadmap on wavefront shaping and deep imaging in complex media

et al. 2022

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The last decade has seen the development of a wide set of tools, such as wavefront shaping, computational or fundamental methods, that allow to understand and control light propagation in a complex medium, such as biological tissues or multimode fibers. A vibrant and diverse community is now working on this field, that has revolutionized the prospect of diffraction-limited imaging at depth in tissues. This roadmap highlights several key aspects of this fast developing field, and some of the challenges and opportunities ahead.

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Label-free super-resolution chemical imaging of biomedical specimens

Cited by 8 publications

References 17 publications

Direct Imaging of Micrometer Thick Interfaces in Salt-Salt Aqueous Biphasic Systems

Direct Imaging of Micrometer Thick Interfaces in Salt-Salt Aqueous Biphasic Systems

Competing oxygen evolution reaction mechanisms revealed by high-speed compressive Raman imaging

Roadmap on wavefront shaping and deep imaging in complex media

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