B23-Circular Dichroism
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Xi
Lei
,
Sibo
Peng
,
Nijas
Aliu
,
Rohanah
Hussain
,
Giuliano
Siligardi
,
Tiberiu-Marius
Gianga
,
Xin
Jin
,
Sabrina
Ruggiero
,
Shilpa
Chokshi
,
Luca
Urbani
,
Bernhard F.
Gibbs
,
Elena
Klenova
,
Gurprit S.
Lall
,
Gabriela
Dekany
,
Dietmar
Cholewa
,
Steffen M.
Berger
,
Maryam
Abooali
,
Inna M.
Yasinska
,
Song
Xu
,
Elizaveta
Fasler-Kan
,
Vadim V.
Sumbayev
Diamond Proposal Number(s):
[36941, 38189]
Abstract: Human cancer cells and malignant tumours operate immune evasion machinery, which consists of a set of cross-linked biochemical pathways that suppress the activities of immune cells, such as cytotoxic T cells and natural killer cells. Recent evidence demonstrated that the immune evasion machinery operated by human cancer cells is self-sustaining. However, the mechanisms underlying self-regulation of cancer immune evasion networks remain to be understood. Here we report for the very first time that the cell surface receptor CD44 acts as an enhancer of immune evasion activity in human cancer cells rather than an immune checkpoint per se. Furthermore, upon interaction with galectin-9, CD44 was found to alter cell membrane potential and induce the secretion of TGF-β. Secreted TGF-β displays autocrine and paracrine activities following TGF-β receptor (TGFBR) engagement, which was shown to then activate the Smad3 transcriptional pathway. CD44 complexed to galectin-9 allosterically enhances activity of the TGFBR complex and this was shown to substantially amplify the expression of immune checkpoint proteins crucially associated with suppressing the anti-cancer activities of cytotoxic lymphoid cells. We also demonstrated that this is a fundamental pathway used by human embryos to prevent immune rejection and by innate immune cells to facilitate anti-bacterial innate immune response. Cancer cells and malignant tumours hijack and successfully adapt this fundamental pathway to escape immune surveillance and suppress anti-cancer immune reactions. As such, this autocrine loop allows for the self-regulation of immune evasion networks operated by cancer cells and can be considered as a promising target for highly efficient immunotherapy of cancer.
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Nov 2026
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B23-Circular Dichroism
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Claudio
Fontanesi
,
Andrea
Severini
,
Marianna
Burello
,
Alberta
Carella
,
Marco
Bonechi
,
Fabrizio
Roncaglia
,
Massimo
Innocenti
,
Francesco
Rossella
,
Suryakant
Mishra
,
Andrew Crandall
Jones
,
Rohanah
Hussain
,
Giuliano
Siligardi
Diamond Proposal Number(s):
[45826]
Open Access
Abstract: Enantiorecognition is a fundamental process in bioscience, ruling most life-related processes. This work focuses on the physics underlying chiral recognition, suggesting that the electron-spin/molecular-handedness interaction plays an important role here. Results obtained exploiting three complementary experimental techniques are compared, where metal surfaces are functionalized using a chiral porphyrin (cPorf): (1) cyclic voltammetry is used to probe the handedness of the electrode surface exploiting a chiral redox couple; (2) spin-dependent electrochemistry measurements were performed using a ferromagnetic electrode as spin injector; (3) magnetoconductive atomic force microscopy measurements proved that the charge transport through cPorf bundles adsorbed on a nickel surface is spin-polarized (spin polarization percentage, SP%, ranging between 20% and 50%). Mueller matrix polarimetry (MMP) spectra confirmed that the electronic circular dichroism of cPorf in solid-state thin films is not merely apparent but is true. The overall experimental results suggest that spin plays a fundamental role in the enantiorecognition process, as a possible manifestation of the Naaman−Waldeck chiral-induced spin selectivity effect.
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Sep 2026
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B23-Circular Dichroism
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Diamond Proposal Number(s):
[41438]
Open Access
Abstract: Understanding the interplay between different forms of chirality in organic materials is critical for tuning and optimizing their (chir)optical properties. There is a growing interest in chiral chromophores such as bay-substituted perylene diimides (PDIs) due to their intrinsic helicity (M/P) which, at a higher level of organization, can also generate supramolecular chirality (Ms/Ps). The relationship between helical and supramolecular chirality governs interchromophore coupling, rotatory strengths, and subsequently circular dichroism (CD) and circularly polarized luminescence (CPL) spectra. Herein, we report the first PDI dimers that match helical and supramolecular chirality, e.g., PP–Ps. In agreement with theory, this chiral synergy contributes to enhanced CD and broadband CPL with high CPL brightness, properties of significant value for optical filtering in next-generation chiral sensors and displays.
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Sep 2026
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I10-Beamline for Advanced Dichroism - scattering
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Duncan
Miertschin
,
Sundar
Kunwar
,
Balaram
Regmi
,
Poshan
Kandel
,
Sanjib
Thapa
,
Davis
Crater
,
Luca
Basso
,
Adam
Dodson
,
Zheng
Gai
,
Lide
Yao
,
Yu-Wei
Chen
,
Peter
Bencok
,
Armin
Kleibert
,
Yen-Lin
Huang
,
Andy
Mounce
,
Paul G.
Kotula
,
Sebastiaan
Van Dijken
,
Alessandro R.
Mazza
,
Thomas Z.
Ward
,
Nick
Shepelin
,
Alan
Farhan
Diamond Proposal Number(s):
[40992]
Open Access
Abstract: Multiferroics that combine ferroelectricity and magnetic order are attractive for electronic and spintronic technologies, yet chemical disorder that promotes relaxor ferroelectricity usually suppresses long-range magnetic order. Here, we report entropy-stabilized relaxor multiferroicity in epitaxial hexagonal (Tb0.2Dy0.2Ho0.2Lu0.2Yb0.2)FeO3 thin films. Structural, magnetic, dielectric, and synchrotron spectroscopic measurements show the coexistence of relaxor ferroelectricity and long-range ferromagnetic order. We find that improper ferroelectricity remains robust against A-site configurational disorder, while the Fe sublattice preserves magnetic exchange. This separation of the microscopic origins of the polar and magnetic responses enables chemically disordered multiferroicity. Our results establish entropy engineering in hexagonal ferrites as a route toward multifunctional oxide thin films and provide a general design strategy for high-entropy multiferroics.
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Sep 2026
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I10-Beamline for Advanced Dichroism - scattering
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Diamond Proposal Number(s):
[38952]
Open Access
Abstract: High-entropy perovskite oxides offer a promising platform for tailoring magnetic functionality through compositional complexity; however, it remains unclear how targeted substitution of 4d transition metals modifies oxygen-mediated electronic structure and element-specific magnetic interactions. To address this question, we investigate the effect of Mo and Ru substitution on the electronic structure and magnetism of high-entropy perovskite oxide thin films using O K-edge and transition-metal L-edge X-ray absorption spectroscopy, X-ray magnetic circular dichroism (XMCD), and X-ray linear dichroism. O K-edge spectra reveal that Ru enhances O 2p–metal d hybridization, whereas Mo modifies charge distribution and local exchange pathways within the transition-metal sublattice. Multiplet analysis shows that Mn and Ni retain stable Mn4+ and Ni2+ states, while Co acts as the primary charge-compensation reservoir through changes in the Co2+/Co3+ ratio. Temperature-dependent XMCD demonstrates that these substitutions selectively reshape the magnetic exchange network, redistributing spin polarization among the constituent elements. Quantitative XMCD sum-rule analysis reveals that Mo substitution produces the highest reconstructed total magnetic moment across the measured temperature range, reaching values at low temperature that are nearly an order of magnitude larger than those observed in the Ru-containing compositions. These results establish a composition-driven strategy for tuning covalency, charge redistribution, and the balance between localized and itinerant magnetism in high-entropy oxide thin films, providing a pathway toward the design of tunable spintronic and multifunctional oxide materials.
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Aug 2026
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B23-Circular Dichroism
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Carolina
Díaz-Norambuena
,
Juan Manuel
Moreno-Naranjo
,
David
Reger
,
Giuliano
Siligardi
,
César
Ray
,
Jessica
Colligan
,
Florencio
Moreno
,
Beatriz L.
Maroto
,
Gilles
Muller
,
Jorge
Bañuelos
,
Matthew J.
Fuchter
,
Santiago De La
Moya
Open Access
Abstract: Chiral organic thin films are emerging as key materials in advanced optoelectronic and chiroptical technologies, where the straightforward, solution-processed fabrication of chiroptically active neat films from small π-conjugated helical molecules is highly desirable for sustainable and scalable device integration. However, in such densely packed systems, the intrinsic chiroptical response is often compromised by macroscopic anisotropies (e.g., linear dichroism and birefringence) and aggregation-induced effects, which obscure genuine molecular signatures and induce or alter chiral exciton coupling. Here, we demonstrate that a readily accessible and conformationally flexible helically chiral boron-dipyrromethene dimer (helicoBODIPY) platform enables the reproducible fabrication of robust solution-processed neat thin films exhibiting a unique behavior: chiroptical isotropy while retaining the characteristic molecular chiroptical response arising from intramolecular chiral exciton coupling. Through systematic structural tuning, these systems exhibit enhanced electronic circular dichroism (ECD) and circularly polarized luminescence in solution. Remarkably, the sharp ECD couplets and absorption dissymmetry values measured in the corresponding films closely reproduce those observed in solution, indicating minimal contribution from anisotropic contributions and negligible perturbation of excitonic interactions in the condensed phase. These unique findings point to helically flexible helicoBODIPYs as an excellent molecular platform that bridges molecular design and thin-film performance, offering a potential tool for disentangling aggregation effects in chiral thin films and advancing the rational design of chiral organic materials with predictable chiroptical properties.
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Aug 2026
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B23-Circular Dichroism
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Diamond Proposal Number(s):
[34669]
Abstract: Achieving large optical rotation while preserving linear polarization and minimizing loss─“pure” optical rotation─remains a central challenge in chiral photonics. Solution-processed self-assembled materials can exhibit exceptional chiroptical responses (g-factor > 1) and are promising candidates with near-UV operation and scalability. However, their potential for optical rotation applications is limited because their regions of large circular birefringence (CB, which generates rotation) overlap with regions of absorption and circular dichroism (CD, which makes linear polarization elliptical). Here, we identify energetic nondegeneracy between constituent chromophores as a design principle for pure optical rotation in self-assembled systems. Using a coupled-oscillator framework, we show that detuning chromophore resonances produces collective states that generate CB in spectral regions where CD and absorption are naturally weak. We experimentally validate this mechanism using mixed assemblies of nondegenerate α- and β-CdS magic-size clusters, which exhibit the predicted emergent, off-resonant CB. With our model, we show that maximizing nondegenerate neighbors through ABAB ordering enhances the pure rotation performance. Using optical parameters from inorganic nanoclusters, simulations predict a 50 meV (12 THz) window with >20° optical rotation, >40% transmission, and <1° ellipticity at micron-scale thicknesses, performance metrics typically associated with lithographic metamaterials. Because the mechanism relies only on dipolar coupling and energetic detuning, it is broadly generalizable across wavelengths and chromophore platforms; for example, we show that in gold nanorod assemblies, aspect-ratio tuning can induce the required nondegeneracy. These results establish energetic nondegeneracy as a general mechanism for engineering chiroptical response and realizing pure optical rotation in self-assembled systems.
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Aug 2026
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I06-Nanoscience (XPEEM)
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Diamond Proposal Number(s):
[38242]
Open Access
Abstract: We report the evolution of the antiferromagnetic domain structure of epitaxial La0.45Sr0.55MnO3 (LSMO) ultrathin films with thickness in the range from 5–50 unit cells (uc), using x-ray photoemission electron microscopy (XPEEM). While the 5 uc thick LSMO shows no magnetic contrast down to ∼80K, thicker films display a multidomain antiferromagnetic configuration with a nonmonotonic variation in the characteristic domain size from 0.3 µm at 10 uc, to 3–5 µm at 15–16 uc and 1 µm for 50 uc. Post-growth annealing is found not to impact strongly the magnetic domain state. In contrast, for a 15 uc film grown on a substrate characterized by large atomic steps (∼1µm), we observe much larger antiferromagnetic domains and the presence of net magnetic moment in the form of stripes with alternating contrast, assigned to the signal from the top uncompensated spins of the A-type antiferromagnetic state of LSMO. From the combined antiferromagnetic domain structure and the net magnetic moment contrast, we determine the exact orientation of the Néel vector, including at domain walls. We describe the antiferromagnetic domain size distribution in terms of interface and bulk contributions to the density of defects that pin the antiferromagnetic domain walls and which determine the equilibrium domain configuration. Our results demonstrate the impact of thickness and defects on the antiferromagnetic domain size and constitute a stepping stone in controlling the antiferromagnetic domain state required for oxide antiferromagnetic device applications.
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Aug 2026
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B23-Circular Dichroism
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Diamond Proposal Number(s):
[32994, 34669]
Abstract: Reciprocity—the principle that a response is identical along the forward and backward paths—is a fundamental concept across physics. Non-reciprocity occurs when this symmetry is broken, resulting in direction-dependent behaviour. Achieving optical non-reciprocity typically requires complex metamaterials, exotic media or strong fields. Researchers have overlooked the possibility that conventional materials could support optical non-reciprocity. Here, through the Stokes–Mueller formalism, we predict a pathway to non-reciprocal absorption and emission of orthogonal linear polarizations. We test this idea using solution-processed films of CdS, CdSe and CdTe magic-size clusters with comparable circular and linear dichroism, and demonstrate non-reciprocal absorption and emission of linearly polarized light. Based on these findings, several design rules and practical applications are presented. Our work reveals that non-reciprocal linear dichroism and emission can be achieved in readily processable materials by harnessing chiral–linear optical interference, providing opportunities within polarization-based quantum optics and photonics such as direction-dependent optical routing or polarization-multiplexed encryption.
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Jul 2026
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B23-Circular Dichroism
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Diamond Proposal Number(s):
[36727]
Open Access
Abstract: We report a new chiral indaceno[1,2-b:5,6-b′]dithiophene bis-thiophenylpropynone (IDT-TPO) dye exhibiting very noticeable chiroptical properties in thin films. While freshly prepared samples are ECD-silent, aging triggers a giant dichroic response, with ellipticity values reaching approximately 18,000 mdeg, among the highest reported to date for thin films of chiral organic dyes as neat materials. This amplification is accompanied by an unusual flattening of the main UV-Vis absorption band, and the combination of these effects produces very large gabs values (exceeding 0.1). A thorough investigation, combining microscopy and spatially resolved chiroptical techniques with time-dependent density functional theory (TD-DFT) calculations, reveals that the intense chiroptical activity arises primarily from the consistent formation of right-handed three-dimensional (3D) helical architectures. Notably, the degree of circular polarization exhibits a non-monotonic dependence on film thickness: the maximum ECD intensity was found for a thinner film, rather than for the thickest one. This behavior is particularly promising for optoelectronic applications requiring efficient chiroptical responses in relatively thin active layers.
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Jul 2026
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