B23-Circular Dichroism
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Abstract: The interaction between lipids and proteins impacts on a multitude of cellular processes and may contribute to the onset of several pathologies and ageing. Such processes are frequently linked to oxidative stress, whereby polyunsaturated fatty acids act as substrates for in vivo lipoxidation. The subsequent lipid peroxidation and/or isomerisation is known to affect membrane organization, as well as to modify proteins and DNA, leading to functional alterations. Aim of this study was to evaluate the capacity of UV denaturation experiments to induce lipid modification and to investigate the influence of lipid presence on the conformational stability of selected soluble model proteins. To this end, the UV-denaturation experiment developed at the B23 beamline of the Diamond Light Source (UK) is employed, which high photon flux and brilliance of the incident beamlight induce protein denaturation when repeated consecutive synchrotron radiation circular dichroism spectra are acquired in the far-UV region, diagnostic of protein folding. This allows the estimation of protein photostability. Our findings show that the presence of lipid vesicles (SUVs) significantly impacts the UV-denaturation of proteins, preserving the native structure in proteins with a high helical content. This suggests that lipids may play a protective role against light-induced damage to proteins.
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May 2025
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B23-Circular Dichroism
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Leah E. M.
White
,
Tiberiu-M.
Gianga
,
F.
Pradaux-Caggiano
,
Chiara
Faverio
,
Andrea
Taddeucci
,
Henry S.
Rzepa
,
Christian
Jonhannesen
,
Lauren E.
Hatcher
,
Giuliano
Siligardi
,
David R.
Carbery
,
G. Dan
Pantos
Diamond Proposal Number(s):
[33876]
Open Access
Abstract: The ability to synthesise lemniscular molecules to allow for the study and application of their chiroptical properties is a notable technical challenge. Herein, we report the design and synthesis of enantiomers of a [5]helicenoid derived molecular lemniscate, in which two homochiral helicenes are linked via the formation of two azine motifs. We demonstrate that these molecules, and their helicenoid constituents, are also excellent chiral dopants that induce dissymmetry in the ground and excited states of the achiral emissive polymer F8BT, leading to high CPL activity. The ability to control the handedness of the helicenoid dopants via enantiopure synthesis affords control of the sign of CP emission. This manipulation of circularly polarised light is of great interest for optoelectronic technologies.
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Mar 2025
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B23-Circular Dichroism
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Maryam
Abooali
,
Stephanie
Schlichtner
,
Xi
Lei
,
Nijas
Aliu
,
Sabrina
Ruggiero
,
Sonia
Loges
,
Martin
Ziegler
,
Franziska
Hertel
,
Anna-Lena
Volckmar
,
Albrecht
Stenzinger
,
Petros
Christopoulos
,
Michael
Thomas
,
Elena
Klenova
,
N. Helge
Meyer
,
Stergios
Boussios
,
Nigel
Heaton
,
Yoh
Zen
,
Ane
Zamalloa
,
Shilpa
Chokshi
,
Luca
Urbani
,
Sophie
Richard
,
Kavitha
Kirubendran
,
Rohanah
Hussain
,
Giuliano
Siligardi
,
Dietmar
Cholewa
,
Steffen M.
Berger
,
Inna M.
Yasinska
,
Elizaveta
Fasler-Kan
,
Vadim V.
Sumbayev
Diamond Proposal Number(s):
[24509, 20755, 21202]
Open Access
Abstract: V-domain Ig-containing suppressor of T cell activation (VISTA) is a unique immune checkpoint protein, which was reported to display both receptor and ligand activities. However, the mechanisms of regulation of VISTA activity and functions by factors of tumour microenvironment (TME) remain unclear and understanding these processes is required in order to develop successful personalised cancer immunotherapeutic strategies and approaches. Here we report for the very first time that VISTA interacts with another immune checkpoint protein galectin-9 inside the cell most likely facilitating its interaction with TGF-β-activated kinase 1 (TAK1). This process is required for protection of lysosomes, which is crucial for many cell types and tissues. We found that VISTA expression can be differentially controlled by crucial factors present in TME, such as transforming growth factor beta type 1 (TGF-β) and hypoxia as well as other factors activating hypoxic signalling. We confirmed that involvement of these important pathways modulated by TME differentially influences VISTA expression in different cell types. These networks include: TGF-β-Smad3 pathway, TAK1 (TGF-β-activated kinase 1) or apoptosis signal-regulating kinase 1 (ASK1)-induced activation of activating transcription factor 2 (ATF-2) and hypoxic signalling pathway. Based on this work we determined the five critical functions of VISTA and the role of TME factors in controlling (modulating or downregulating) VISTA expression.
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Feb 2025
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B23-Circular Dichroism
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Thomas
Ugras
,
River B.
Carson
,
Reilly P.
Lynch
,
Haoyang
Li
,
Yuan
Yao
,
Lorenzo
Cupellini
,
Kirt A.
Page
,
Da
Wang
,
Arantxa
Arbe
,
Sara
Bals
,
Louisa
Smieska
,
Arthur R.
Woll
,
Oriol
Arteaga
,
Tamas
Javorfi
,
Giuliano
Siligardi
,
Gennaro
Pescitelli
,
Steven J.
Weinstein
,
Richard D.
Robinson
Diamond Proposal Number(s):
[32994]
Abstract: INTRODUCTION: The creation of mesoscale chiroptic materials from nanoscale achiral building blocks has been previously realized through exciton coupling in organic supramolecular assemblies and with plasmons in inorganic metal nanoparticle assemblies, but extending excitonic chirality to inorganic semiconducting systems has remained elusive. Among the many challenges to achieving this goal is the need for degenerate excited electronic states, which are difficult to obtain in nanocrystals with nonzero size distributions, and the requirement for aligned transition dipoles, an unlikely characteristic in spherical nanocrystals that lack a distinct axis. This goal is consequential, as introducing chirality into the band structure of semiconductors enables simultaneous control over light, spin, and charge, key capabilities for driving innovations in next-generation photonic, optoelectronic, and spintronic technologies. RATIONALE: We hypothesized that magic-sized nanoclusters could overcome these obstacles to form an exciton-coupled chiroptic inorganic assembly. Magic-sized nanoclusters are atomically and electronically identical, enabling greater wavefunction overlap and coupling between neighboring nanoclusters. And they need not be spherical, allowing for anisotropic arrangements of their transition dipoles through dipole-dipole interactions during solution processing. Additionally, the bandgap, composition, and size of semiconducting magic-sized clusters can be rationally synthesized to tailor the chiroptic responses over a range of wavelengths. RESULTS: Following our hypothesis, we found that three different species of nanoclusters [cadmium sulfide (CdS), cadmium selenide (CdSe), and cadmium telluride (CdTe)] could be assembled through meniscus-guided evaporative processing into films with strong circular dichroic (CD) responses. Films made from CdS achieved dissymmetry factors, the CD figure of merit, as large as 1.30 for unpatterned, drop-cast films and 1.06 for patterned assemblies, values that approach the theoretical maximum. CD maps collected with Mueller matrix polarimetry showed that controlling the evaporative processing geometry enabled the creation of millimeter-scale homochiral domains that continuously transition between left- and right-handed, with their spatial organization adjustable through processing parameters. The mechanism behind these organized assemblies is elucidated through linear dichroism (LD), small-angle x-ray scattering (SAXS), and in situ microscopy, which reveal that the meniscus guides highly concentrated fibrous solutions, aligning their transition dipoles within fibrous bands as they deposit on a substrate. These bands are subsequently twisted by fluid flows, generating homochiral domains. CONCLUSION: We report on a method to form chiral films of three different inorganic semiconductor nanocrystals, with near-limit dissymmetry factors and large homochiral domains. Our results for the three different semiconducting nanocluster systems demonstrate the generality of the method, suggesting the applicability to other nanocluster species or colloidal nanoplatelets. Our experiments uncovered the key mechanisms for achieving these chiroptic films by the meniscus-guided deposition process, including the alignment of transition dipoles of the constituents and the fluid flows responsible for twisting the fibers, and make a connection to emergent chiral properties. Harnessing methods to form chiral films from achiral, solution-processable semiconductors offers an opportunity in the design and fabrication of complex chiroptical metamaterials in ways that are both scalable and versatile. Beyond nanocluster films, this study provides valuable insights into the complexities of hierarchical assembly found in nature and offers a pathway to extend these principles to other chiral molecules and nanomaterials for engineering sophisticated, twisted structures.
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Jan 2025
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B23-Circular Dichroism
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Gianluigi
Albano
,
Marco
Bertuolo
,
Francesco
Zinna
,
Andrea
Taddeucci
,
Tamas
Javorfi
,
Rohanah
Hussain
,
Gianluca M.
Farinola
,
Gennaro
Pescitelli
,
Angela
Punzi
,
Giuliano
Siligardi
,
Lorenzo
Di Bari
Diamond Proposal Number(s):
[36727]
Abstract: The development of chiral organic materials with strong non-reciprocal chiroptical features may have major implications for cutting-edge technological applications. In this work, a new ad hoc synthesized chiral 1,4-diketo-3,6-dithienylpyrrolo[3,4-c]pyrrole dye, bearing two (S)-3,7-dimethyl-1-octyl alkyl chains on the lactam moieties and functionalized with two lateral 9-anthracenyl π-conjugated units, exhibited strong non-reciprocal chiroptical properties in thin films, with some important differences between samples prepared by drop casting and spin coating. A detailed study was performed to unravel the intimate structure–property relationship, involving computational analysis, different microscopy techniques and synchrotron radiation Mueller matrix polarimetry imaging (SR-MMPi) investigation. Through SR-MMPi, exploiting the highly collimated synchrotron radiation (SR) light of Diamond Light Source B23 beamline, we determined the size of the linear contributions responsible for the strong non-reciprocal features, and how they manifest in the various 2D chiral meso-domains.
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Jan 2025
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B23-Circular Dichroism
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Diamond Proposal Number(s):
[30198]
Open Access
Abstract: The nanoscale chiral arrangement in a bicomponent organic material system comprising donor and acceptor small molecules is shown to depend on the thickness of a film that is responsive to chiral light in an optoelectronic device. In this bulk heterojunction, a previously unreported chiral bis(diketopyrrolopyrrole) derivative was combined with an achiral non-fullerene acceptor. The optical activity of the chiral compound is dramatically different in the pure material and the composite, showing how the electron acceptor influences the donor’s arrangement compared with the pure molecule. Mueller matrix polarimetric imaging shows the authenticity of this effect and the homogeneity of short range chiral orientations between the molecules, as well as more heterogeneous short and longer range arrangements in the films observed in linear dichroic and birefringent effects. The two-dimensional circular dichroism (CD) maps and spectra show the uniformity of the short range supramolecular interactions both in spun-cast films on quartz and blade-coated films on photovoltaic device substrates, where evidence for the chiral arrangement is uniquely provided by the synchrotron CD measurements. The external quantum efficiency of the devices depends upon the handedness of the light used to excite them and the film thickness, that influences the supramolecular arrangement and organization in the film, and determines the selectivity for left or right circularly polarised light. The difference in external quantum efficiency of the photovoltaic devices between the two handedness’ of light correlates with the apparent differential absorbance (g-factor) of the films.
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Dec 2024
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B23-Circular Dichroism
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Mateusz
Pawlak
,
Adam
Pierzchała
,
Elie
Benchimol
,
Jacopo
Tessarolo
,
Lukas
Rebholz
,
Marjan
Krstić
,
Benedikt
Zerulla
,
Ivan
Fernandez-Corbaton
,
Tamas
Javorfi
,
Giuliano
Siligardi
,
Guido H.
Clever
,
Carsten
Rockstuhl
,
Wiktor
Lewandowski
Diamond Proposal Number(s):
[34687]
Abstract: Circularly polarized luminescence (CPL) in purely organic materials is limited by the almost exclusively electric nature of electronic transitions. Resolving this problem is possible through structuring organic materials at dimensions comparable to the wavelength of visible light. Here, the study explores the use of thin films made of chiral organic nanotubes for the enhanced induction of CPL. The study first performs multi-scale modeling of the chiroptical properties of organic nanotubes using the T-matrix method. Combined with chiroptical measurements, including Mueller matrix polarimetry, the study discusses the chiroptical properties of organic materials within the frames of their multi-scale structuring. When embedding aggregation-induced fluorogens (AIEgens) into the structured films, composites featured with gigantic glum factors reaching ≈10−1 are obtained. Importantly, a series of control experiments is performed to exclude common parasitic effects that can lead to the apparent CPL signals. The enhanced chiroptical properties of the composite films of organic nanotubes and AIEgens enable visual discrimination of their handedness both in the absorption and emission realms. The uncovered multi-mode enhancement of CPL directs future endeavors for anticounterfeiting or holography applications.
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Dec 2024
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B23-Circular Dichroism
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Diamond Proposal Number(s):
[2083, 17666, 15028, 10537, 8674]
Open Access
Abstract: A new technology to write and read covert information in authentication labels is described. This technology uses the phenomenon of photo-induced chirality in Ge2Sb2Te5 thin films to encode the left- or right-circular or linear polarization of the laser beam used to write the label. The written polarization can be revealed by a simple reading device, which is demonstrated to provide the same qualitative information as reading based on cyclotron circular dichroism spectroscopy and imaging. The suggested method, while based on existing manufacturing approaches, offers a balance between technological complexity for writing and simplicity for reading, and may be advantageous as a new authentication technology.
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Oct 2024
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B23-Circular Dichroism
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Diamond Proposal Number(s):
[29151]
Open Access
Abstract: Circular dichroism spectroscopy is a key probe of the structural and optical properties of chiral materials, however, commercial circular dichroism spectrometers are large, prohibitively expensive and rarely offer environmental control of the sample under test. Using Fresnel rhombs as inexpensive broadband quarter-wave plates, we demonstrate two novel, low-cost (<£2,000) and portable imaging systems controlled by our own bespoke open-source control software which are capable of spatially mapping the circular dichroism of chiral solid state films. By coupling these imaging systems with a temperature controlled stage, we show that we can rapidly identify the thermal processing conditions required to maximise circular dichroism in chiral solid state films by measuring circular dichroism in situ during thermal annealing of a sample under test. The accuracy and spatial resolution of these circular dichroism imagers are cross-compared against our previous studies using an existing circular dichroism imaging system at the Diamond Light Source and are shown to be in good agreement, with a sensitivity down to 250 mdeg and a spatial resolution of 100 μm.
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Jun 2024
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B23-Circular Dichroism
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Juan Manuel
Moreno-Naranjo
,
Francesco
Furlan
,
Jingxiang
Wang
,
Seán T. J.
Ryan
,
Tomas
Matulaitis
,
Zhiyu
Xu
,
Qianyi
Zhang
,
Louis
Minion
,
Marta
Di Girolamo
,
Tamas
Javorfi
,
Giuliano
Siligardi
,
Jessica
Wade
,
Nicola
Gasparini
,
Eli
Zysman‐colman
,
Matthew J.
Fuchter
Diamond Proposal Number(s):
[29153]
Open Access
Abstract: Organic light-emitting diodes (OLEDs) that are able to emit high levels of circularly polarized (CP) light hold significant promise in numerous future technologies. Such devices require chiral emissive materials to enable CP electroluminescence. However, the vast majority of current OLED emitter classes, including the state-of-the-art triplet-harvesting Thermally Activated Delayed Fluorescence (TADF) materials, produce very low levels of CP electroluminescence. Here we showcase a host-guest strategy that allows for energy transfer between a chiral polymer host and a representative chiral TADF emitter. Such a mechanism results in large amplification of the circular polarization of the emitter. As such, this study presents a promising avenue to further boost the performance of CP-OLED devices, enabling their further development and eventual commercialization.
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Jun 2024
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