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Abstract: Background: VISTA is a unique multifunctional immune checkpoint protein, which can display both receptor and ligand properties. It plays a crucial role in the cancer immune evasion machinery operated by a wide range of human malignancies and may thus be considered as a potential target for immunotherapy of cancer. Receptors of VISTA through which this protein transmits immunosuppressive signals under various normal and pathological conditions remain to be identified. Materials and Methods: To conduct the study, we used human recombinant proteins and various human cell lines as well as primary T cells. A wide range of techniques including tissue culture and co-cultures, Western blot analysis, on-cell Western, ELISA, co-immunoprecipitation, biochemical assays and synchrotron radiation circular dichroism spectroscopy were employed. Results: Here we report for the first time that VISTA has affinity to PD-1 and binds it as a ligand. We found that when interacting with PD-1, VISTA suppresses IL-2 production by T helper cells. These effects were confirmed in the in vitro and ex vivo experiments. Affinity of VISTA to PD-1 was also characterised and found to be moderate, with a Kd of approximately 2.3 μM detected by synchrotron radiation circular dichroism spectroscopy. Conclusions: These results open a completely new chapter in our understanding of the concept of immune checkpoint proteins, where some of them clearly show both ligand and receptor activities and display multifunctional properties.

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Abstract: Connections between magnetic field induced optical activity and chirality have a rich and complicated history. Although the broken inversion symmetry of chiral molecules generates ‘natural’ optical activity, magnetic optical activity is generated by breaking time reversal symmetry. Therefore, molecular chirality is not expected to influence magnetic optical phenomena, such as Faraday rotation. Here we show that the chiral supramolecular assembly of polymers can result in large Faraday effects (Verdet constants = 105 °T–1m–1). This strong Faraday rotation, which is amongst the highest value known for organic materials, originates from the so-called Faraday B term. Typically, B term Faraday responses are weak. We demonstrate large amplification through excitonic coupling within the supramolecular assembly, where the chirality of the system controls the assembly formed. These observations provide an alternative means to enhance the Faraday rotation of low symmetry systems and clarify the role of chirality in previous reported materials.

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Abstract: The development of molecules that interact with G-quadruplex (G4) sequences requires effective evaluation methods. Several techniques are currently available, including nuclear magnetic resonance (NMR) spectroscopy and X-ray crystallography, surface plasmon resonance (SPR), isothermal titration calorimetry (ITC) and mass spectrometry (MS), fluorescence using FRET-melting, G4-fluorescent intercalator displacement assay (G4-FID) and affinity chromatography. Among these, CD spectroscopy is gaining prominence due to its lower material requirements, faster experimentation and quicker data processing. However, conventional CD methods have limitations, such as higher sample volume required and the inability to handle high-throughput analysis efficiently. The use of synchrotron radiation in high-throughput analysis methods (HT-SRCD) has further advanced the investigation of small-molecule interactions with DNA G4 structures in the presence of various monovalent cations. HT-SRCD offers the capability to analyze multiple samples simultaneously, overcoming the limitations of conventional CD methods. To validate this approach, three biologically relevant G4 sequences—HTelo1, G3T3 and T95-2T—were investigated. Their interactions with a library of small tetrazole-based molecules, synthesized via a four-component Ugi reaction, and with a peptide sequence deriving from RHAU helicases (Rhau25), were evaluated. The results demonstrate that this method not only effectively discriminates between different ligands but also provides valuable insights into the selectivity and the modes of interaction of these ligands with the G4 sequences.

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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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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.