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![A) Top: Rotations of crystalline structures of d‐ and l‐cysteine‐capped Co3O4 NCs. Middle: g‐Factor curves of d‐, l‐, and dl‐cysteine‐capped Co3O4 NCs (left) and emission intensities of fluorescent paper plus the NCs gel in front with a magnetic field (red and blue) and without a magnetic field (green) (excitation, 280 nm). Bottom: Photographs of light transmission through the NCs, with the rotation of the linear analyzer counterclockwise (−10°), and clockwise (+10°) (left), and photographs of blue‐emitting light from the fluorescent paper. Adapted with permission.[⁴⁴] Copyright 2018, American Association for the Advancement of Science. B) Top panel: Sketches of chiral amino acids interact with WO3−x NCs for induced chirality (left) and MD simulations of the atomic structure in the minimum energy state for ligand‐free, l‐Asp, and d‐Asp NCs. Bottom: CD spectra of l‐ and d‐Asp‐NCs (red and blue) (inset: NIR range of corresponding CD spectra) and l‐ and d‐Pro‐NCs (red and blue) (inset: NIR range of corresponding CD spectra) containing different concentrations of water. Reproduced with permission.[⁴⁵] Copyright 2017, American Chemical Society. C) Top: Illustration of the synthesis of chiral MoO3−x NCs and their real images. The different amounts of cysteine could reduce the MoO3 to obtain various cationic valence. Reproduced with permission.[²⁷] Copyright 2018, Wiley‐VCH. D) Top: Schematic illustration of the preparation of CuxO NCs via chiral molecules. Bottom: HRTEM images with STEM and energy‐dispersive X‐ray spectroscopy (EDS) mapping, and 3D electron tomography reconstruction images of CuxO NCs prepared using l‐phenylalanine. Reproduced with permission.[²] Copyright 2019, American Chemical Society. E) Top: STEM (left) and TEM (right) images of (+)‐diphenylethylenediamine‐capped TiO2 nanoparticles. Black scale bars represent 10 nm. Bottom: (Left) CD spectra (blue) and absorption spectra (black) of (+)‐diphenylethylenediamine‐ (solid) and (−)‐diphenylethlenediamine‐ (dotted) capped TiO2 nanoparticles. (Right) Excitation spectra of (+)‐diphenylethylenediamine‐capped TiO2 nanoparticles. Reproduced with permission.[⁴⁶] Copyright 2017, Wiley‐VCH.](publication/343396138/figure/fig3/AS:11431281173299318@1688833151081/A-Top-Rotations-of-crystalline-structures-of-d-and-l-cysteine-capped-Co3O4-NCs.png)
A) Top: Rotations of crystalline structures of d‐ and l‐cysteine‐capped Co3O4 NCs. Middle: g‐Factor curves of d‐, l‐, and dl‐cysteine‐capped Co3O4 NCs (left) and emission intensities of fluorescent paper plus the NCs gel in front with a magnetic field (red and blue) and without a magnetic field (green) (excitation, 280 nm). Bottom: Photographs of light transmission through the NCs, with the rotation of the linear analyzer counterclockwise (−10°), and clockwise (+10°) (left), and photographs of blue‐emitting light from the fluorescent paper. Adapted with permission.[⁴⁴] Copyright 2018, American Association for the Advancement of Science. B) Top panel: Sketches of chiral amino acids interact with WO3−x NCs for induced chirality (left) and MD simulations of the atomic structure in the minimum energy state for ligand‐free, l‐Asp, and d‐Asp NCs. Bottom: CD spectra of l‐ and d‐Asp‐NCs (red and blue) (inset: NIR range of corresponding CD spectra) and l‐ and d‐Pro‐NCs (red and blue) (inset: NIR range of corresponding CD spectra) containing different concentrations of water. Reproduced with permission.[⁴⁵] Copyright 2017, American Chemical Society. C) Top: Illustration of the synthesis of chiral MoO3−x NCs and their real images. The different amounts of cysteine could reduce the MoO3 to obtain various cationic valence. Reproduced with permission.[²⁷] Copyright 2018, Wiley‐VCH. D) Top: Schematic illustration of the preparation of CuxO NCs via chiral molecules. Bottom: HRTEM images with STEM and energy‐dispersive X‐ray spectroscopy (EDS) mapping, and 3D electron tomography reconstruction images of CuxO NCs prepared using l‐phenylalanine. Reproduced with permission.[²] Copyright 2019, American Chemical Society. E) Top: STEM (left) and TEM (right) images of (+)‐diphenylethylenediamine‐capped TiO2 nanoparticles. Black scale bars represent 10 nm. Bottom: (Left) CD spectra (blue) and absorption spectra (black) of (+)‐diphenylethylenediamine‐ (solid) and (−)‐diphenylethlenediamine‐ (dotted) capped TiO2 nanoparticles. (Right) Excitation spectra of (+)‐diphenylethylenediamine‐capped TiO2 nanoparticles. Reproduced with permission.[⁴⁶] Copyright 2017, Wiley‐VCH.
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Transition metal oxides (TMOs) consist of a series of solid materials, exhibiting a wide variety of structures with tunability and versatile physicochemical properties. Such a statement is undeniably true for chiral TMOs since the introduction of chirality brings in not only active optical activities but also geometrical anisotropy due to the symme...
Citations
... NPs often have asymmetric faces, edges, and vertices, as well as both surface and bulk defects and dislocations present in the crystal structure. Chiral arrangements of chiral defects [249,250] or distortions [251][252][253][254] of the crystal lattice (e.g., screw dislocations) [255] can in fact induce chiroptical activity in NPs. The use of chiral ligands, either in situ or by post-synthetic treatment, increases the probability of generating chiral defects and distortions. ...
... 2024, 2308912 the presence of chiral ligands, this results in the induction of some type of chirality. Depending on various factors, this can lead to the formation of a chiral shape (mostly for plasmonic particles), [210,211,215,219,[234][235][236][238][239][240][241][242][243][244][245][246][247] chiral defects in the volume and on the surface of the NP, [208,250] embedding or intercalation of chiral molecules between layers of layered materials (e.g., perovskites and layered double hydroxides) [279] and in the case of chemical bonding with the NP surface, hybridization of electronic energy levels [26,[263][264][265][266][267][268] and distortion of surface atoms. [251] The concentration of chiral agents, as well as other chemical precursors, is of great importance for the induction of chirality. ...
Machine learning holds significant research potential in the field of nanotechnology, enabling nanomaterial structure and property predictions, facilitating materials design and discovery, and reducing the need for time‐consuming and labor‐intensive experiments and simulations. In contrast to their achiral counterparts, the application of machine learning for chiral nanomaterials is still in its infancy, with a limited number of publications to date. This is despite the great potential of machine learning to advance the development of new sustainable chiral materials with high values of optical activity, circularly polarized luminescence, and enantioselectivity, as well as for the analysis of structural chirality by electron microscopy. In this review, an analysis of machine learning methods used for studying achiral nanomaterials is provided, subsequently offering guidance on adapting and extending this work to chiral nanomaterials. An overview of chiral nanomaterials within the framework of synthesis–structure–property–application relationships is presented and insights on how to leverage machine learning for the study of these highly complex relationships are provided. Some key recent publications are reviewed and discussed on the application of machine learning for chiral nanomaterials. Finally, the review captures the key achievements, ongoing challenges, and the prospective outlook for this very important research field.
... For instance, chiral metal oxides have been shown to act as spin lters and result in spin selective photocatalysis, which reduces the reaction overpotential and increases the faradaic efficiency of the reaction. [18][19][20][21][22][23][24][25] Because O 2 forms on a triplet potential energy surface, spin selective photocatalysis can guide the reaction towards a triplet product and increase the kinetics of O 2 generation. [26][27][28] Despite the application of chiral oxides for photocatalytic water splitting, the concept of spin polarized photocatalysis has yet to be evaluated for achiral magnetic semiconductors in which spin polarization results from magnetic exchange interactions rather than structural chirality. ...
This work presents a spectroscopic and photocatalytic comparison of water splitting using yttrium iron garnet (Y3Fe5O12, YIG) and hematite (α-Fe2O3) photoanodes. Despite similar electronic structures, YIG significantly outperforms widely studied hematite, displaying more than an order of magnitude increase in photocurrent density. Probing the charge and spin dynamics by ultrafast, surface-sensitive XUV spectroscopy reveals that the enhanced performance arises from (1) reduced polaron formation in YIG compared to hematite and (2) an intrinsic spin polarization of catalytic photocurrents in YIG. Ultrafast XUV measurements show a reduction in the formation of surface electron polarons compared to hematite due to site-dependent electron–phonon coupling. This leads to spin polarized photocurrents in YIG where efficient charge separation occurs on the Td sub-lattice compared to fast trapping and electron/hole pair recombination on the Oh sub-lattice. These lattice-dependent dynamics result in a long-lived spin aligned hole population at the YIG surface, which is directly observed using XUV magnetic circular dichroism. Comparison of the Fe M2,3 and O L1-edges show that spin aligned holes are hybridized between O 2p and Fe 3d valence band states, and these holes are responsible for highly efficient, spin selective water oxidation by YIG. Together, these results point to YIG as a new platform for highly efficient, spin selective photocatalysis.
... Chirality describes the inability of a substance's structure to be overlapped with its mirror image [14]. The emerging chiral TMO has made great progress in recent years [15]. Considering that the SHG effect originates from the symmetry breaking of structural variations, it is expected that SHG may be achieved in chiral materials. ...
... The broad peaks at 250-450 nm derived from the charge transfer of O 2− 2p → Cu 2+ 3d and Cu 2+ -O 2− -Cu 2+ [19,20]. As depicted in Fig. 2(b), all chiral CuO NSs demonstrated similar and mirrorimaged CD spectra, caused by the orbital hybridization and short-range dipole-dipole interactions between the chiral ligand and the achiral CuO NSs [15]. In addition, all of them display two bands, i.e., 380 and 478 nm for L-Phe-CuO, 385 and 541 nm for L-Pro-CuO, 380 and 476 nm for L-Ala-CuO, and 370 and 468 nm for L-Leu-CuO NSs, respectively. ...
Chiral transition metal oxides (TMOs) are in the forefront of research as potential active materials in various optoelectronic applications. However, the nonlinear optical (NLO) properties of the chiral TMOs have not been fully understood. Here, several kinds of copper oxide nanosheets capped with different chiral amino acids are synthesized. Notably, we investigate the NLO activities of these materials, including broadband second harmonic generation and transformation of nonlinear optical properties from saturable absorption to reverse saturable absorption. This work will broaden the use of chiral TMO materials in nonlinear photonic devices.
... Chiral inorganic nanostructures [15][16][17][18][19] such as metals, semiconductors, and ceramics are beginning to be applied in the biomedical field. [20][21][22][23] Many researchers have reported that chiral nanoparticles exhibit low toxicity and high intracellular stability in living organisms. ...
The chemical, physical and biological effects of chiral nanomaterials have inspired general interest and demonstrated the important advantages in fundamental science. Here, we fabricated chiral iron oxide supraparticles (Fe 3 O 4 SPs) modified by chiral penicillamine (Pen) molecules with a g ‐factor of approximately 2 × 10 ⁻³ at 415 nm, these SPs acted as a high‐quality magnetic resonance imaging (MRI) contrast agent. Therein, the transverse relaxation efficiency and T 2 ‐MRI results demonstrated the chiral Fe 3 O 4 SPs had a r 2 relaxivity of 157.39 ± 2.34 mM ⁻¹ ·S ⁻¹ for D ‐Fe 3 O 4 SPs and 136.21 ± 1.26 mM ⁻¹ ·S ⁻¹ for L ‐Fe 3 O 4 SPs due to the enhanced electronic transition dipole moment for D ‐Fe 3 O 4 SPs compared with L ‐Fe 3 O 4 SPs. The in vivo MRI results showed that D ‐Fe 3 O 4 SPs exhibited a two‐fold lower contrast ratio than L ‐Fe 3 O 4 SPs, which enhanced targeted enrichment in tumor tissue, such as prostate cancer, melanoma, and brain glioma tumor. Notably, it w as found that D ‐Fe 3 O 4 SPs had a 7.7‐fold higher affinity for the tumor cell surface receptor cluster‐of‐differentiation 47 (CD47) than L ‐Fe 3 O 4 SPs. These findings uncovered that chiral Fe 3 O 4 SPs act as a highly effective MRI contrast agent for targeting and imaging broad tumors, thus accelerating the practical application of chiral nanomaterials and deepening the understanding of chirality in the biological and non‐biological environments.
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... For instance, chiral metal oxides have been shown to act as spin filters and result in spin-selective photocatalysis, which reduces the reaction overpotential and increases the Faradaic efficiency of the reaction. [18][19][20][21][22][23][24][25] The improved Faradaic efficiency of chiral electrocatalysts refers to the branching pathways between O 2 and H 2 O 2 production, where H 2 O 2 limits the energy conversion efficiency of water oxidation and can lead to catalyst degradation. [26][27][28][29] Because O 2 forms on a triplet potential energy surface, while H 2 O 2 forms on a singlet surface, spin-selective photocatalysis can guide the branching point between these two products. ...
This work presents a detailed spectroscopic and kinetic comparison of yttrium iron garnet (Y3Fe5O12, YIG) and hematite (α-Fe2O3) for photocatalytic water splitting. Despite similar electronic structures, YIG significantly outperforms hematite as a water oxidation catalyst, displaying nearly an order of magnitude increase in photocurrent density and a factor of two increase in Faradaic efficiency. Probing the charge and spin dynamics by ultrafast, surface-sensitive XUV spectroscopy reveals that the enhanced performance arises from 1) reduced polaron formation in YIG compared to hematite and 2) an intrinsic spin polarization of catalytic photocurrents in YIG. Linear XUV measurements show a significant reduction in the formation of surface electron polarons in YIG compared to hematite due to site-dependent electron-phonon coupling in YIG leading to spin-polarized currents upon photoexcitation. Direct observation of surface spin accumulation with chemical state resolution at the Fe M2,3 and O L1 edges using XUV magnetic circular dichroism provides a detailed picture of the spin-polarized electron dynamics. Together, these results point to YIG as a new platform for highly efficient, spin-selective photocatalysis.
... [30][31][32][33][34][35] The combination of chirality and magnetism in magnetic oxide nanomaterials (MONs) provides chiral MONs (CMONs) with novel functionalities and potential applications as shown in Figure 1. [36][37][38][39][40] The electromagnetic properties of chiral materials have been investigated under a static magnetic field by manipulating the interaction behaviors with light. The chiral dichroism (CD) effect of CMONs with different handedness is contributed by the natural CD (NCD) or OA in the absence of magnetic field, magnetic CD (MCD, Faraday/Kerr effect), and magnetochiral dichroism (MChD, induced by the orientation of κ and the magnetic field B), so the absorption of light by chiral materials subjected to a magnetic field B follows the equation below [41,42] , , · ...
Chiral magnetic oxide nanomaterials (CMONs), which combine the beneficial effects of chirality and magnetism in a single unit, have found applications in biomedical, optical, and electronic devices as well as in catalysis and sensing. This is largely due to the simultaneous presence of magnetic properties, catalytic activity, biocompatibility and optical activity, or magneto‐optical effects, which are circular polarization and magnetization dependent. This review summarizes the key findings derived from recent research works on the synthesis, properties, and applications of CMONs. The three main approaches in the synthesis and property tuning of CMONs, namely, post‐functionalization, in situ approach, and assembly with soft templates, are discussed. A summary and some future prospects of the CMONs with respect to their synthetic routes, chirality origin, and applications are also provided.
... 20,40 However, larger GQDs tend to deform the membrane with the formation of hemisphere vesicles and cause potential damage. 41,42 Moreover, the chirality originated by lattice distortion at nanoscale are influenced by the size of NP lattices, 43 Figure 2c). The chirality corresponding to the nanoscale distortion was observed at a low-energy peak (250−300 nm) in CD spectra. ...
... Overall, the results suggested that small D-Cys-GQDs can permeate 3T3 exosome membranes most efficiently, which can be attributed to the relative size of GQD to exosomal membrane thickness 41,42 and size-associated chirality generated from distortion of NP lattices. 43,46,47 (which was not certified by peer review) is the author/funder. All rights reserved. ...
As nanoscale extracellular vesicles secreted by cells, exosomes have enormous potential as safe and effective vehicles to deliver drugs into lesion locations. Despite promising advances with exosome-based drug delivery systems, there are still challenges to drug loading into exosome, which hinder the clinical applications of exosomes. Herein, we report an exogenous drug-agnostic chiral graphene quantum dots (GQDs) exosome-loading platform, based on chirality matching with the exosome lipid bilayer. Both hydrophobic and hydrophilic chemical and biological drugs can be functionalized or adsorbed onto GQDs by π–π stacking and van der Waals interactions. By tuning the ligands and GQD size to optimize its chirality, we demonstrate drug loading efficiency of 66.3% and 64.1% for Doxorubicin and siRNA, which is significantly higher than other reported exosome loading techniques.
... 8,9 Also, Transition metal oxides are synthesized using various methodologies 10 to obtain nanomaterials with unique shapes, different sizes, surface area, stability, and porosity and furnish good photo and electrocatalytic activities. 11 Contrastingly, Binary transition metal oxides (BTMOs), are considered nonpareil owing to their synergistic coupling and bonding effects by two components. 12,13 For example, the Mnand Co-based binary transition metal oxides are extensively employed in electrochemical applications owing to their excellent redox stability and outstanding catalytic performances. ...
We report on the fabrication and electrochemical evaluation of a Vitamin B2-riboflavin (RF) sensor based on binary transition metal oxide (ZnO-MnO) core-shell nanocomposites (CSNs) on the surface of the glassy carbon electrode (GCE). The nanocomposites are attained through a one-step hydrothermal synthesis route using zinc acetate and manganese acetate as precursors where ZnO acts as a core and MnO forms as a shell. As-synthesized binary transition metal oxide-based composite was scrutinized through various physicochemical techniques, demonstrating excellent physiochemical features. ZnO-MnO/GCE composite delivers synergistic features of improving the electrochemical properties toward detection of RF at an operational voltage of 0.42 V, with increased active sites because of its structural morphology and high surface area. ZnO-MnO/GCE is examined through electrochemical impedance spectroscopy, cyclic voltammetry, differential pulse voltammetry, and linear sweep voltammetry. Furthermore, ZnO-MnO/GCE shows a remarkable kinetic transfer rate and superior electron transfer rate over other modified electrodes. It also exemplifies a wider linear range (0.05 – 1102 µM), with Nanomolar level detection of 13 nM aided with a sensitivity of 0.3746 µA µM-1 cm-2, respectively. The proposed ZnO-MnO/GCE sensor demonstrates excellent selectivity over the presence of co-interfering species exquisite repeatability, reproducibility, and stability.
... The chiral oxides were compiled very complete by Halasyamani and Poeppelmeier [61]. Yiwen Li et al. [62] focused on chiral transition metal oxides. Recently, the properties of chiral, nanostructured materials and their applications [63] have been reviewed [63]. ...
Chirality depends on particular symmetries. For crystal structures it describes the absence of mirror planes and inversion centers, and in addition to translations, only rotations are allowed as symmetry elements. However, chiral space groups have additional restrictions on the allowed screw rotations as a symmetry element, because they always appear in enantiomorphous pairs. This study classifies and distinguishes the chiral structures and space groups. Chirality is quantified using Hausdorff distances and continuous chirality measures and selected crystal structures are reported. Chirality is discussed for bulk solids and their surfaces. Moreover, the band structure, and thus, the density of states, is found to be affected by the same crystal parameters as chirality. However, it is independent of handedness. The Berry curvature, as a topological measure of the electronic structure, depends on the handedness but is not proof of chirality because it responds to the inversion of a structure. For molecules, optical circular dichroism is one of the most important measures for chirality. Thus, it is proposed in this study that the circular dichroism in the angular distribution of photoelectrons in high symmetry configurations can be used to distinguish the handedness of chiral solids and their surfaces.
... Interestingly, nanoscale chirality can also be realized from directed self-assembly of achiral functional nanoparticles using various chiral soft templates such as DNA [22][23][24][25] , peptide and protein 26,27 , liquid crystal (LC) 1,2,28,29 , chiral polymer [30][31][32] , and organogelators [33][34][35][36][37] ( Fig. 1c). Chiral nanomaterials based on emerging soft templates have been considered as the model system for investigating their inter-particle coupling, high-order selforganized nanostructures, and responsive dynamic properties, which can bring up a variety of potential applications [38][39][40] . For example, chiral nanomaterials based on nanoscale plasmonic building blocks, i.e., chiral plasmonic nanomaterials, have been demonstrated to show novel plasmon coupling or collective plasmonic properties that are usually absent in their discrete counterparts [41][42][43][44][45][46][47] . ...
Chiral nanomaterials with intrinsic chirality or spatial asymmetry at the nanoscale are currently in the limelight of both fundamental research and diverse important technological applications due to their unprecedented physicochemical characteristics such as intense light-matter interactions, enhanced circular dichroism, and strong circularly polarized luminescence. Herein, we provide a comprehensive overview of the state-of-the-art advances in liquid crystal-templated chiral nanomaterials. The chiroptical properties of chiral nanomaterials are touched, and their fundamental design principles and bottom-up synthesis strategies are discussed. Different chiral functional nanomaterials based on liquid-crystalline soft templates, including chiral plasmonic nanomaterials and chiral luminescent nanomaterials, are systematically introduced, and their underlying mechanisms, properties, and potential applications are emphasized. This review concludes with a perspective on the emerging applications, challenges, and future opportunities of such fascinating chiral nanomaterials. This review can not only deepen our understanding of the fundamentals of soft-matter chirality, but also shine light on the development of advanced chiral functional nanomaterials toward their versatile applications in optics, biology, catalysis, electronics, and beyond. This review focuses on liquid crystal-templated chiral functional nanomaterials, including chiral plasmonic nanomaterials and chiral luminescent nanomaterials, introducing their underlying mechanisms, chiroptical properties, and potential applications.
