Polarization-sensitive optoionic membranes from chiral plasmonic nanoparticles

Strain-enhanced dynamic regulation of chiroptical responses in 3D suspended nested metamaterials

Three-dimensional (3D) chiral metamaterials, which exhibit strong chiroptical responses, have attracted tremendous attention in the broad fields of next-generation photonic devices and chiroptical spectroscopy techniques. There is an urgent need for a novel fabrication approach that enables the rapid and straightforward preparation of 3D chiral nanostructures, along with a robust strategy for achieving dynamic regulation. Here, we proposed a strain-enhanced strategy for dynamically regulating the chiroptical responses of 3D suspended nested metamaterials from the transformation of a 2D precursor. The local strain enhancement could effectively resolve the bottleneck of insufficient strain and low precision for the buckling strain self-assembly. The changing morphology and circular dichroism (CD) of 3D suspended chiral metamaterials were analyzed under the impact of a strain-enhanced effect. Then, the uplifted heights of these 3D nanostructures increased with the substrate's pre-strain (ɛpre). Its CD reached up to 0.79, mainly resulting from ring electric dipoles. Interestingly, the chiroptical responses of 3D nanopyramids were regulated dynamically by controlling the substrate's pre-strain. Such a strategy provides a new pathway for achieving high-performance chiral metamaterials and offers promising applications in circularly polarized light detection, super-chiral light sources, optical communication, and advanced nanophotonic systems.

Controlling Circularly Polarized Luminescence Enabled by Chirality and Energy Transfer from Optimized Chiral Molecules to Quantum Dots

Chirality transfer/amplification and energy transfer in artificial assembly systems are longstanding challenges inspired by biological systems. In particular, controlling intercomponent interactions to engineer CPL-active materials in multicomponent chiral coassemblies remains difficult. Here, we report the simultaneous realization of chirality and energy transfer in self-assembled hybrid systems comprising quantum dots with high photoluminescence quantum yield and organic molecules featuring aggregation-induced emission (AIE). Three chiral AIE molecules based on the tetraphenylethylene core, differing in the number and/or position of alkyl chains, were designed and synthesized. These structural variations led to distinct self-assembled morphologies, including helical fibrils, fibril bundles, and ribbons. Co-assembly with luminescent CdSe/CdS nanorods yielded organic-inorganic hybrid nanocomposites, where chirality transfer from the organic molecules to the nanorods strongly depended on the molecular structure. In parallel, efficient energy transfer from chiral donors to the nanorod acceptors was observed across all systems. Notably, the synergistic action of both chirality and energy transfer enabled the construction of CPL-active materials with high luminescence asymmetry factors. This work presents a strategy for designing chiroptical systems with enhanced chiroptical performance.

Multiplexed Detection of Pancreatic-Specific Nucleic Acids and Protein Biomarkers Using a Logic Nanofluidic Platform

Early detection of pancreatic cancer is vital for patient survival. However, current diagnostic approaches remain constrained by insufficient precision and specificity inherent to single-biomarker detection strategies. Herein, we develop a nanochannel biosensing platform implementing cooperative dual-signal detection of pancreatic-specific biomarkers CA19-9 and miRNA-196a. Using liquid-liquid interface self-assembly, we constructed anodic aluminum oxide (AAO)-Au hybrid nanochannels integrated with a surface-modified double-key DNA nanolock (DDN). The conformational switch of DDN logic gating triggered by miRNA-196a exposes the CA19-9-aptamer, enabling specific target recognition and consequent ion current signal attenuation. Simultaneously, released miRNA-196a is quantified by catalytic hairpin assembly and hybridization chain reaction-mediated cascade amplification. Experiments show that the present DDN-based logic nanofluidic platform could achieve an ultralow detection limit of 0.000027 U·mL-1 for CA19-9 and 4.74 aM for miRNA-196a, which is 2-3 orders of magnitude higher than traditional ELISA/qPCR methods. Finally, clinical sample analysis confirms the high specificity of this platform in distinguishing pancreatic cancer and acute pancreatitis from healthy individuals. This DDN-functionalized nanofluidic biosensor provides valuable insights into designing precision detection platforms for pancreatic cancer, highlighting its significant potential for clinical diagnostics.

Chiral Bimetallic Pt@Au Octapods with Spiral Four-Petal Flower-Like Symmetric Configuration as Sensitive SERS Probes

Here, we synthesized chiral bimetallic Pt@Au octapods by using l/d-cysteine-threonine (CT) dipeptide as chiral ligands. These had a distinct spiral four-petal flower-like symmetric configuration with a twisted concave morphology on each facet. The twisted concave structure of the Pt@Au octapods facilitated intraparticle coupling, resulting in highly concentrated electric fields within the concave regions, thus creating "hot spots" that produced a potent surface-enhanced Raman scattering (SERS) effect. The l-Pt@Au octapods showed a nearly twofold stronger SERS response to Aβ40 and Aβ42 monomers and fibrils than the d-Pt@Au octapods. The different association constants arose from the unique chiral recognition capabilities of the CT ligands on the surfaces of the l-Pt@Au octapods, which allowed them to form specific hydrogen bonds with Aβ40 and Aβ42 monomers and fibrils, producing significant differences in their Raman spectra. The data from clinical cerebrospinal fluid (CSF) samples showed that the quantitative analysis of the Aβ42/Aβ40 ratio with Raman spectroscopy can be used as an effective biomarker for the early diagnosis of Alzheimer's disease (AD), with a cut-off value of 0.085. Our results pave the way for the use of chiral nanomaterials with strong optical activities in the development of clinical testing instruments with biomedical applications.

Chiral Gold Nanostructure Monolayers as SERS Substrates for Ultrasensitive Detection of Enantiomer Biomarkers of Alzheimer's Disease

The early diagnosis of neurodegenerative diseases, such as Alzheimer's disease (AD), requires the identification of sensitive and specific biomarkers. Detecting chiral molecules at concentrations relevant to disease states remains challenging. Herein, a new type of chiral gold nanostructure induced by D-/L-cysteine-leucine dipeptides with a g-factor of 0.1 was successfully synthesized for enantiomer biomarker detection. To enhance the discrimination performance, the chiral gold nanostructures were assembled into D-/L-Au monolayers. As surface-enhanced Raman scattering (SERS) substrates, the D-/L-Au monolayers simultaneously deliver molecular structural specificity and enantioselectivity within a single spectrum, which can be a versatile, label-free chiral discrimination strategy for the detection of D-/L-kynurenine (Kyn). The mechanism was unveiled to involve high enantioselective adsorption energies between L- and D-Kyn on the lattice plane (221), resulting in enantioselective sensing. The results showed that the L-Au monolayer reached a limit of detection (LOD) of 3.7 nm for L-Kyn, while the D-Au monolayer reached an LOD of 3.6 nM for D-Kyn. Notably, there was a significant difference in D-Kyn levels between AD patients and healthy individuals in serum samples, a distinction not observed for L-Kyn, which positioned D-Kyn as a potential novel biomarker for clinical prediagnosis of AD patients, marking the first report of its kind worldwide. This study provides a robust tool for advancing biomedical science and clinical diagnostics.

Gradient-Metasurface-Contact Photodetector for Visible-to-Near-Infrared Spin Light

Spin light detection is a rapidly advancing field with significant impact on diverse applications in biology, medicine, and photonics. Developing integrated circularly polarized light (CPL) detectors is pivotal for next-generation compact polarimeters. However, previous compact CPL detectors, based on natural materials or artificial resonant nanostructures, exhibit intrinsically weak CPL polarization sensitivity, are susceptible to other polarization states, and suffer from limited bandwidths. A gradient-metasurface-contact CPL photodetector is demonstrated operating at zero-bias with a high discrimination ratio (≈1.6 ✗ 104), broadband response (500-1100 nm), and immunity to non-CPL field components. The photodetector integrates InSe flakes with CPL-selective metasurface contacts, forming an asymmetric junction interface driven by CPL-dependent unidirectional propagating surface plasmon waves, generating zero-bias vectorial photocurrents. Furthermore, it is implemented the developed CPL photodetector in a multivalued logic system and demonstrated the optical decoding of CPL-encrypted communication signals. This metasurface contact engineering represents a new paradigm in light property detection, paving the way for future integrated optoelectronic systems for on-chip polarization detection.

Modulation anisotropy of nanomaterials toward monolithic integrated polarization-sensitive photodetectors

By virtue of the unique ability of providing additional information beyond light intensity and spectra, polarization-sensitive photodetectors could precisely identify targets in several concealed, camouflaged, and non-cooperative backgrounds, making them highly suitable for potential applications in remote sensing, astronomical detection, medical diagnosis, etc. Therefore, to provide a comprehensive design guideline for a wide range of interdisciplinary researchers, this review provides a general overview of state-of-the-art linear, circular, and full-Stokes polarization-sensitive photodetectors. In particular, from the perspectives of technological progress and the development of nanoscience, the detailed discussion focuses on strategies to simplify high-performance polarization-sensitive photodetectors, reducing their size and achieving a smaller volume. In addition, to lay a solid foundation for modulating the properties of future nanostructure-based polarization-sensitive photodetectors, insights into light-matter interactions in low-symmetry materials and asymmetric structures are provided here. Meanwhile, the corresponding opportunities and challenges in this research field are identified.

Reversal of chirality in solutions and aggregates of chiral tetrachlorinated diperylene diimides towards efficient circularly polarized light detection

Helicenes exhibit promise as active layer materials for circularly polarized light (CPL) detectors due to their strong chiroptical activity. However, their practical application is limited by the complicated synthesis and loosely solid-state packing. This study introduces a chiral induction strategy towards the synthesis of helicene derivatives, chiral tetrachlorinated diperylene diimides ((SSSS)-4CldiPDI or (RRRR)-4CldiPDI). When incorporating the chiral (S/R)-1-cyclohexylethyl (Cy) substituents, the chirality is directly transferred to the π-aromatic core and forms the PP- or MM-helicene subunit. Notably, (SSSS)-Cy induces preferred PP helicity while (RRRR)-Cy leads to the MM helicity in the monomers. However, these molecules exhibit reversed chirality in crystals, where (SSSS)-Cy controls MM helicity and (RRRR)-Cy induces PP helicity. Theoretical calculations reveal that the (SSSS)-PP structure demonstrates lower energy distribution in monomers, whereas the (SSSS)-MM structure exhibits lower energy in crystals. Then, the CPL detection based on n-type PDI-helicene derivatives is achieved by using (SSSS)-4CldiPDI or (RRRR)-4CldiPDI crystals. The maximum photocurrent dissymmetry factor gph of +0.16 for (RRRR)-4CldiPDI and -0.15 for (SSSS)-4CldiPDI is obtained. Our work demonstrates a novel chiral induction strategy for designing helicene-based materials with both high dissymmetry factor and large charge carrier mobility, which offers great potential for the advancement of CPL detection.

Enantioselective synthesis of chiroplasmonic helicoidal nanoparticles by nanoconfinement in chiral dielectric shells

Helicoid metal nanoparticles with intrinsic chirality have unveiled tailorable properties and unlocked many chirality-related applications across various fields. Nevertheless, the existing strategies for enantioselective synthesis of helicoid metal nanoparticles have been predominantly limited to gold. Here, we demonstrate a robust and versatile strategy for the enantioselective synthesis of helicoid nanoparticles beyond gold, leveraging chiral nanoconfinement provided by chiral SiO2 or nanoshells. The chiral nanoconfinement strategy enables the decoupling of ligand-directed crystal growth from chiral induction, allowing for the independent tuning of these two critical aspects. As a result, this approach can not only facilitate the replication of chiral shapes from the chiral nanoshells but also allow the generation of alternative chiral shapes. By employing this approach, we demonstrate the enantioselective synthesis of helicoid Pt, Au@Pt, Au@Pd, Au@Ag, and Au@Cu nanoparticles. The chiroplasmonic properties of Pt- and Pd-based chiral nanoparticles have been discovered, and the inversion of chiroplasmonic properties of Ag-based chiral nanoparticles via facet control has been documented and theoretically explained. The chiral nanoconfinement strategy enriches the toolbox for creating chiral nanoparticles and supports their exploration in diverse applications.

Chiral Inorganic Nanomaterial-Based Diagnosis and Treatments for Neurodegenerative Diseases

Chiral nanomaterials are widely investigated over recent decades due to their biocompatibility and unique chiral effects. These key properties have significantly promoted the rapid development of chiral nanomaterials in bioengineering and medicine. In this review, the basic principles of constructing chiral nanomaterials along with the latest progress in research are comprehensively summarized. Then, the application of chiral nanomaterials for the diagnosis of neurodegenerative diseases (NDDs) is systematically described. In addition, the significant potential and broad prospects of chiral nanomaterials in the treatment of NDDs are highlighted from several aspects, including the disaggregation of neurofibrils, the scavenging of reactive oxygen species, regulation of the microbial-gut-brain axis, the elimination of senescent cells, and the promotion of directed differentiation in neural stem cells. Finally, a perspective of the challenges and future development of chiral nanomaterials for the treatment of NDDs is provided.

Autocatalytic Nucleation and Self-Assembly of Inorganic Nanoparticles into Complex Biosimilar Networks

Self-replication of bioorganic molecules and oil microdroplets have been explored as models in prebiotic chemistry. An analogous process for inorganic nanomaterials would involve the autocatalytic nucleation of metal, semiconductor, or ceramic nanoparticles-an area that remains largely uncharted. Demonstrating such systems would be both fundamentally intriguing and practically relevant, especially if the resulting particles self-assemble into complex structures beyond the capabilities of molecules or droplets. Here, we show that autocatalytic nucleation occurs with silver nanoparticles, which subsequently self-assemble into chains through spatially restricted attachment. In dispersions containing "hedgehog" particles, these reactions produce complex colloids with hierarchical spike organization. On solid surfaces, autocatalytic nucleation of nanoparticles yields conformal networks with hierarchical organization, including nanoparticle "colonies." We analyzed the complexity of both types of solid-stabilized particle assemblies via graph theory (GT). The complexity index of idealized spiky colloids is comparable to that of complex algal skeletons. The GT analysis of the percolating nanoparticle networks revealed their similarities to the bacterial, but not fungal, biofilms. We conclude that coupling autocatalytic nucleation with self-assembly enables the generation of complex, biosimilar particles and films. This work establishes mathematical and structural parallels between biotic and abiotic matter, integrating self-organization, autocatalytic nucleation, and theoretical description of complex systems. Utilization of quantitative descriptors of connectivity patterns opens possibility to GT-based biomimetic engineering of conductive coatings and other complex nanostructures.

Generating Strong Circularly Polarized Luminescence from Self-assembled Films of Chiral Selenium Nanoparticles and Upconversion Nanoparticles

Circularly polarized luminescence (CPL) has garnered significant research attention. Achieving a high luminescence dissymmetry factor (glum) is a key challenge in this field. Herein, we reported, for the first time, the fabrication of a chiral assembled film consisting of chiral D-/L-Selenium nanoparticles (D-/L-Se NPs) and DSPE-PEG-NH2 modified upconversion nanoparticles (DPNUCNPs) with remarkable CPL properties that were generated by the interfacial self-assembly technique. The chiral Se/DPNUCNPs films, consisting of three layers (3L) of D-/L-Se films and 3L DPNUCNPs films, exhibited the highest circular dichroism (CD) response and the strongest CPL signals. Under laser excitation at 980 nm, the 3L D-/L-Se/3L DPNUCNPs assembled films displayed symmetric CPL signals between 400 and 600 nm, with a maximum |glum| value of 0.68. The interaction between DPNUCNPs and Se NPs involves energy transfer and chirality transfer, along with the formation of spin-polarized excitons, thereby resulting in CPL activity. Furthermore, the chiral Se/DPNUCNPs films were patterned for anti-counterfeit and encryption applications. Our study provides a novel guide for fabricating chiral nanomaterials with strong CPL response.

Emerging devices based on chiral nanomaterials

As advanced materials, chiral nanomaterials have recently gained vast attention due to their special geometry-based physical and chemical properties. The fast development of the related science and technology means that various devices involving polarization-based information encryption, photoelectronic and spintronic devices, 3D displays, biomedical sensors and measurement, photonic engineering, electronic engineering, solar devices, etc., been explored extensively. These fields are at their beginning, and much effort needs to be made, including improving the optical, electronic, and magnetic properties of advanced chiral nanomaterials, precisely designing materials, and developing more efficient construction methods. This review tries to offer a whole picture of these state-of-the-art conditions in these fields and offers perspectives on future development.

Recent Advances in Chiral Gold Nanomaterials: From Synthesis to Applications

In recent years, the field of chiral gold nanomaterials has witnessed significant advancements driven by their unique properties and diverse applications in various scientific domains. This review provides an in-depth examination of the synthesis methodologies and evolving applications of chiral gold nanomaterials, which have emerged as vital tools in areas such as antibacterial therapies, biosensing, catalysis, and nanomedicine. We start by discussing various synthesis techniques, focused on seed-mediated growth and circularly polarized light-assisted methods, each contributing to the controlled synthesis of chiral gold nanostructures with tailored optical activities. This review further delves into the applications of these nanomaterials, showcasing their potential in combating antibiotic-resistant bacteria, improving cancer immunotherapy, promoting tissue regeneration, and enabling precise biosensing through enhanced sensitivity and selectivity. We highlight the fundamental principles of chirality and its critical role in biological systems, emphasizing the importance of chiral gold nanomaterials in enhancing optical signals and facilitating molecular interactions. By consolidating recent findings and methodologies, this review endeavors to illuminate the promising future of chiral gold nanomaterials and their critical role in addressing contemporary scientific challenges.

Chiral Au@CeO2 Helical Nanorods with Spatially Separated Structures for Polarization-Dependent N2 Photofixation

Chiral photocatalytic nanomaterials possess numerous unique properties and hold promise for various applications in chemical synthesis, environmental protection, energy conversion, and photoelectric devices. Nevertheless, it is uncommon to develop effective means to enhance the asymmetric catalytic performances of chiral plasmonic nanomaterials. In this study, a type of L/D-Au@CeO2 helical nanorods (HNRs) was fabricated by selectively growing CeO2 on the surface of Au HNRs via a facile wet-chemistry construction method. Chiral Au@CeO2 HNRs, featuring Au and CeO2 with spatially separated structures, exhibited the highest photocatalytic performance for N2 fixation, being 50.80±2.64 times greater than that of Au HNRs. Furthermore, when L-Au@CeO2 HNRs were exposed to left circularly polarized light (CPL) and D-Au@CeO2 HNRs were exposed to right CPL, their photocatalytic efficiency was enhanced by 3.06±0.06 times compared to the samples illuminated with the opposite CPL, which can be attributed to the asymmetrical generation of hot carriers upon CPL excitation. This study not only offers a simple approach to enhance the photocatalytic performance of chiral plasmonic nanomaterials but also demonstrates the potential of chiral plasmonic materials for application in specific photocatalytic reactions, such as N2 fixation.

Discriminating circular polarization of light: Left or right?

Achiral dielectric nanostructures provide an efficient method for discriminating left- and right-circularly polarized photons, leveraging the photothermoelectric effect.

Amyloid inspired single amino acid (phenylalanine)-based supramolecular functional assemblies: from disease to device applications

In the evolving landscape of biomolecular supramolecular chemistry, recent studies on phenylalanine (Phe) have revealed important insights into the versatile nature of this essential aromatic amino acid. Phe can spontaneously self-assemble into fibrils with amyloid-like properties linked to the neurological disorder phenylketonuria (PKU). Apart from its pathological implications, Phe also displays complex phase behavior and can undergo structural changes in response to external stimuli. Its ability to co-assemble with other amino acids opens up new possibilities for studying biomolecular interactions. Furthermore, Phe's coordination with metal ions has led to the development of enzyme-mimicking catalytic systems for applications in organic chemistry, environmental monitoring, and healthcare. Research on L and D enantiomers of Phe, particularly on bio-MOFs, has highlighted their potential in advanced technologies, including bioelectronic devices. This review provides a comprehensive overview of the advancements in Phe-based supramolecular assemblies, emphasizing their interdisciplinary relevance. The Phe assemblies show great potential for future therapeutic and functional biomaterial developments, from disease treatments to innovations in bionanozymes and bioelectronics. This review presents a compelling case for the ongoing exploration of Phe's biomolecular supramolecular chemistry as a fundamental framework for developing sustainable and efficient methodologies across various scientific disciplines.

Chiroptical response of an array of isotropic plasmonic particles having a chiral arrangement under coherent interaction

The chirality and chiroptical response of materials have attracted significant attention for their potential to introduce the new science of light-matter interactions. We demonstrate that collective mode formation under modal coupling between localized surface plasmon resonances (LSPRs) with a chiral arrangement and Fabry-Pérot (FP) nanocavity modes can induce chiroptical responses. We fabricated a cluster of isotropic gold nanodisks with a chiral arrangement (gold nano-windmills, Au-NWs) on the FP nanocavities of TiO2 and Au film. The differential absorption of the Au-NWs coupled with the FP nanocavities under left- and right-handed circularly polarized light irradiations in the far field was significantly enhanced compared with the differential absorption without the FP nanocavities. Far- and near-field analyses by numerical simulation revealed that the Au-NWs coupled with the FP nanocavities formed a collective mode in the near field, and the collective mode represented the chiroptical response in the far field. The light field with the large helicity, can be used in chiral light-matter interactions. The concept of collective mode formation using isotropic metal nanodisks coupled with FP nanocavities provides a platform for controlling complex light fields.

Green Synthesis of Biocompatible Chiral Gold Nanoparticles

Chiral gold nanoparticles (Au NPs) have been investigated widely and have shown great potential in biomedical applications, such as biosensing, combating bacterial infections and tissue regeneration. However, some stabilizers and reducing agents for the synthesis of chiral Au NPs can produce toxicity in living organisms. Therefore, it is interesting to design green methods to prepare chiral gold nanoparticles that are nontoxic, environment-friendly, and low-cost. Herein, novel biocompatible chiral Au NPs with a diameter of 54.4 ± 14.9 nm were prepared by the in situ reduction of HAuCl4 with alginates as the green reducing agent and chiral-inducing and stabilizing agent. XPS, TGA, UV-Vis and CD analyses demonstrated that alginate-stabilized chiral Au NPs (ALG-Au NPs) were successfully prepared, while biocompatibility assessment showed that cell viability was 116.0% when the concentration of ALG-Au NPs arrived at 300 μg/mL, which indicated that ALG-AuNPs showed excellent biocompatibility. Furthermore, the ALG-Au NPs can respond to metal ions, such as Ca2+, Cu2+, Mn2+ and so on, implying potential application for biosensing.

Mechanically Driven, Continuous Synthesis of Chiroplasmonic Assemblies

Chiral plasmonic nanomaterials─with their significant applications in protein detection, drug screening, and enantioselective sensing─necessitate an industrialized fabrication procedure to enhance their commercial viability. However, the prevailing manufacturing of chiral plasmonic nanoparticles and assemblies heavily leans on manual intervention, causing time-consuming and quality-inconsistent concerns. Here, we develop an automated, continuous mechanical synthesis system that consistently sprays metal nanowires to create chiroplasmonic assemblies: a macroscopic twisted layered structure comprising equivalent linear birefringence layers, approximate linear polarizer layers, and a precise angular offset between them. Utilizing the synthesis-with-automation system, we scale up the production of chiral plasmonic films, generating high optical asymmetry (g-factor, with the order of 10-1) across a broadband ranging from ultraviolet to near-infrared wavelengths. We further introduce the portable chiral sensing, expanding plasmonic assemblies into flexible materials and integrating them with wearable real-time display devices. Our mechanically driven, continuous synthesis of chiral plasmonic structures presents an intriguing pathway to facilitate functional chiral structures toward practice.

Unveiling Spatial and Temporal Dynamics of Plasmon-Enhanced Localized Fields in Metallic Nanoframes through Ultrafast Electron Microscopy

Plasmonic nanomaterials, particularly noble metal nanoframes (NFs), are important for applications such as catalysis, biosensing, and energy harvesting due to their ability to enhance localized electric fields and atomic efficiency via localized surface plasmon resonance (LSPR). Yet the fundamental structure-function relationships and plasmonic dynamics of the NFS are difficult to study experimentally and thus far rely predominately on computational methodologies, limiting their utilization. This study leverages the capabilities of ultrafast electron microscopy (UEM), specifically photon-induced near-field electron microscopy (PINEM), to probe the light-matter interactions within plasmonic NF structures. The effects of shape, size, and plasmonic coupling of Pt@Au core-shell NFs on spatial and temporal characteristics of plasmon-enhanced localized electric fields are explored. Importantly, time-resolved PINEM analysis reveals that the plasmonic fields around hexagonal NF prisms exhibit a spatially dependent excitation and decay rate, indicating a nuanced interplay between the spatial geometry of the NF and the temporal evolution of the localized electric field. These results and observations uncover nanophotonic energy transfer dynamics in NFs and highlight their potential for applications in biosensing and photocatalysis.

Unveiling the Loss Mode Enabled Tunable Plasmonic Chirality at Flat Metal Surface

Plasmonic chirality has garnered significant interest in the past decade due to its enhanced chiral light-matter interactions. Current methods for achieving plasmonic chirality often rely on complex nanostructures or metamaterials, which are hampered by intricate fabrication processes. In this work, we present an approach to generate plasmonic chiral structured surface plasmon polariton (s-SPP) fields on a single, flat metal surface, bypassing elaborate fabrication techniques. The plasmonic chiral s-SPP fields are excited by the superposition of multiple differently oriented transverse magnetic polarized plane waves. We demonstrate, both theoretically and experimentally, the flexible tuning of chiral plasmonic patterns by adjusting the symmetry and phase differences of the incident waves. This method provides a facile mean to optically tailor plasmonic chiral properties on a subwavelength scale, offering potential applications in sensing, enantioselective reactions, imaging, and reconfigurable chiral switches.

Chiral Intranasal Nanovaccines as Antivirals for Respiratory Syncytial Virus

This study aimed to develop an intranasal nanovaccine by combining chiral nanoparticles with the RSV pre-fusion protein (RSV protein) to create L-nanovaccine (L-Vac). The results showed that L-NPs increased antigen attachment in the nasal cavity by 3.83 times and prolonged its retention time to 72 h. In vivo experimental data demonstrated that the intranasal immunization with L-Vac induced a 4.86-fold increase in secretory immunoglobulin A (sIgA) secretion in the upper respiratory tract, a 1.85-fold increase in the lower respiratory tract, and a 20.61-fold increase in RSV-specific immunoglobin G (IgG) titer levels in serum, compared with the commercial Alum Vac, while the neutralizing activity against the RSV authentic virus is 1.66-fold higher. The mechanistic investigation revealed that L-Vac activated the tumor necrosis factor (TNF) signaling pathway in nasal epithelial cells (NECs), in turn increasing the expression levels of interleukin-6 (IL-6) and C-C motif chemokine ligand 20 (CCL20) by 1.67-fold and 3.46-fold, respectively, through the downstream nuclear factor kappa-B (NF-κB) signaling pathway. Meanwhile, CCL20 recruited dendritic cells (DCs) and L-Vac activated the Toll-like receptor signaling pathway in DCs, promoting IL-6 expression and DCs maturation, and boosted sIgA production and T-cell responses. The findings suggested that L- Vac may serve as a candidate for the development of intranasal medicine against various types of respiratory infections.

Co-Assembly of Soft and Hard Nanoparticles into Macroscopic Colloidal Composites with Tailored Mechanical Property and Processability

Colloidal composites, translating the great potential of nanoscale building bricks into macroscopic dimensions, have emerged as an appealing candidate for new materials with applications in optics, energy storage, and biomedicines. However, it remains a key challenge to bridge the size regimes from nanoscopic colloidal particles to macroscale composites possessing mechanical robustness. Herein, a bottom-up approach is demonstrated to manufacture colloidal composites with customized macroscopic forms by virtue of the co-assembly of nanosized soft polymeric micelles and hard inorganic nanoparticles. Upon association, the hairy micellar corona can bind with the hard nanoparticles, linking individual hard constituents together in a soft-hard alternating manner to form a collective entity. This permits the integration of block copolymer micelles with controlled amounts of hard nanoparticles into macroscopic colloidal composites featuring diverse internal microstructures. The resultant composites showed tunable microscale mechanical strength in a range of 90-270 MPa and macroscale mechanical strength in a range of 7-42 MPa for compression and 2-24 MPa for bending. Notably, the incorporation of soft polymeric micelles also imparts time- and temperature-dependent dynamic deformability and versatile capacity to the resulting composites, allowing their application in the low-temperature plastic processing for functional fused silica glass.

High discrimination ratio, broadband circularly polarized light photodetector using dielectric achiral nanostructures

The on-chip measurement of polarization states plays an increasingly crucial role in modern sensing and imaging applications. While high-performance monolithic linearly polarized photodetectors have been extensively studied, integrated circularly polarized light (CPL) photodetectors are still hindered by inadequate discrimination capability. This study presents a broadband CPL photodetector utilizing achiral all-dielectric nanostructures, achieving an impressive discrimination ratio of ~107 at a wavelength of 405 nm. Our device shows outstanding CPL discrimination capability across the visible band without requiring intensity calibration. It functions based on the CPL-dependent near-field modes within achiral structures: under left or right CPL illumination, distinct near-field modes are excited, resulting in asymmetric irradiation of the two electrodes and generating a photovoltage with directions determined by the chirality of the incident light field. The proposed design strategy facilitates ultra-compact CPL detection across diverse materials, structures, and spectral ranges, presenting a novel avenue for achieving high-performance monolithic CPL detection.

Atomically Precise Chiral Metal Nanoclusters for Circularly Polarized Light Detection

Circularly polarized light (CPL) detection is of great significance in various applications such as drug identification, sensing and imaging. Atomically precise chiral metal nanoclusters with intense circular dichroism (CD) signals are promising candidates for CPL detection, which can further facilitate device miniaturization and integration. Herein, we report the preparation of a pair of optically active chiral silver nanoclusters [Ag7(R/S-DMA)2(dpppy)3] (BF4)3 (R/S-Ag7) for direct CPL detection. The crystal structure and molecular formula of R/S-Ag7 clusters are confirmed by single-crystal X-ray diffraction and high-resolution mass spectrometry. R/S-Ag7 clusters exhibit strong CD spectra and CPL both in solution and solid states. When used as the photoactive materials in photodetectors, R/S-Ag7 enables effective discrimination between left-handed circularly polarized and right-handed circularly polarized light at 520 nm with short response time, high responsivity and considerable discrimination ratio. This study is the first report on using atomically precise chiral metal nanoclusters for CPL detection.

Chiral Transfer and Evolution in Cysteine Induced Cobalt Superstructures

Chiral organic additives have unveiled the extraordinary capacity to form chiral inorganic superstructures, however, complex hierarchical structures have hindered the understanding of chiral transfer and growth mechanisms. This study introduces a simple hydrothermal synthesis method for constructing chiral cobalt superstructures with cysteine, demonstrating specific recognition of chiral molecules and outstanding electrocatalytic activity. The mild preparation conditions allow in situ tracking of chirality evolution in the chiral cobalt superstructure, offering unprecedented insights into the chiral transfer and amplification mechanism. The resulting superstructures exhibit a universal formation process applicable to other metal oxides, extending the understanding of chiral superstructure evolution. This work contributes not only to the fundamental understanding of chirality in self-assembled structures but also provides a versatile method for designing chiral inorganic nanomaterials with remarkable molecular recognition and electrocatalytic capabilities.

Cysteine-Induced Chirality Evolution of Molybdenum Disulfide Nanodots from a Bottom-Up Strategy

The transfer of chirality from molecules to synthesized nanomaterials has recently attracted significant attention. Although most studies have focused on graphene and plasmonic metal nanostructures, layered transition metal dichalcogenides (TMDs), particularly MoS2, have recently garnered considerable attention due to their semiconducting and electrocatalytic characteristics. Herein, we report a new approach for the synthesis of chiral molybdenum sulfide nanomaterials based on a bottom-up synthesis method in the presence of chiral cysteine enantiomers. In the synthesis process, molybdenum trioxide and sodium hydrosulfide serve as molybdenum and sulfur sources, respectively. In addition, ascorbic acid acts as a reducing agent, resulting in the formation of zero-dimensional MoS2 nanodots. Moreover, the addition of cysteine enantiomers to the growth solutions contributes to the chirality evolution of the MoS2 nanostructures. The chirality is attributed to the cysteine enantiomer-induced preferential folding of the MoS2 planes. The growth mechanism and chiral structure of the nanomaterials are confirmed through a series of characterization techniques. This work combines chirality with the bottom-up synthesis of MoS2 nanodots, thereby expanding the synthetic methods for chiral nanomaterials. This simple synthesis approach provides new insights for the construction of other chiral TMD nanomaterials with emerging structures and properties. More significantly, the as-formed MoS2 nanodots exhibited highly defect-rich structures and chiroptical performance, thereby inspiring a high potential for emerging optical and electronic applications.

Chiral Au-Pd Alloy Nanorods with Tunable Optical Chirality and Catalytically Active Surfaces

Integrating the plasmonic chirality with excellent catalytic activities in plasmonic hybrid nanostructures provides a promising strategy to realize the chiral nanocatalysis toward many chemical reactions. However, the controllable synthesis of catalytically active chiral plasmonic nanoparticles with tailored geometries and compositions remains a significant challenge. Here it is demonstrated that chiral Au-Pd alloy nanorods with tunable optical chirality and catalytically active surfaces can be achieved by a seed-mediated coreduction growth method. Through manipulating the chiral inducers, Au nanorods selectively transform into two different intrinsically chiral Au-Pd alloy nanorods with distinct geometric chirality and tunable optical chirality. By further adjusting several key synthetic parameters, the optical chirality, composition, and geometry of the chiral Au-Pd nanorods are fine-tailored. More importantly, the chiral Au-Pd alloy nanorods exhibit appealing chiral catalytic activities as well as polarization-dependent plasmon-enhanced nanozyme catalytic activity, which has great potential for chiral nanocatalysis and plasmon-induced chiral photochemistry.

Polyoxometalate-based plasmonic electron sponge membrane for nanofluidic osmotic energy conversion

Nanofluidic membranes have demonstrated great potential in harvesting osmotic energy. However, the output power densities are usually hampered by insufficient membrane permselectivity. Herein, we design a polyoxometalates (POMs)-based nanofluidic plasmonic electron sponge membrane (PESM) for highly efficient osmotic energy conversion. Under light irradiation, hot electrons are generated on Au NPs surface and then transferred and stored in POMs electron sponges, while hot holes are consumed by water. The stored hot electrons in POMs increase the charge density and hydrophilicity of PESM, resulting in significantly improved permselectivity for high-performance osmotic energy conversion. In addition, the unique ionic current rectification (ICR) property of the prepared nanofluidic PESM inhibits ion concentration polarization effectively, which could further improve its permselectivity. Under light with 500-fold NaCl gradient, the maximum output power density of the prepared PESM reaches 70.4 W m-2, which is further enhanced even to 102.1 W m-2 by changing the ligand to P5W30. This work highlights the crucial roles of plasmonic electron sponge for tailoring the surface charge, modulating ion transport dynamics, and improving the performance of nanofluidic osmotic energy conversion.

Expanding the Horizons of Machine Learning in Nanomaterials to Chiral Nanostructures

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.

Bright Circularly Polarized Mechanoluminescence from 0D Hybrid Manganese Halides

Hybrid metal halides (HMHs) with efficient circularly polarized luminescence (CPL) have application prospects in many fields, due to their abundant host-guest structures and high photoluminescence quantum yield (PLQY). However, CPLs in HMHs are predominantly excited by light or electricity, limiting their use in multivariate environments. It is necessary to explore a novel excitation method to extend the application of chiral HMHs as smart stimuli-responsive optical materials. In this work, an enantiomeric pair of 0D hybrid manganese bromides, [H2(2R,4R)-(+)/(2S,4S)-(-)-2,4-bis(diphenylphosphino)pentane]MnBr4 [(R/S)-1] is presented, which exhibits efficient CPL emissions with near-unity PLQYs and high dissymmetry factors of ± 2.0 × 10-3. Notably, (R/S)-1 compounds exhibit unprecedented and bright circularly polarized mechanoluminescence (CPML) emissions under mechanical stimulation. Moreover, (R/S)-1 possess high mechanical force sensitivities with mechanoluminescence (ML) emissions detectable under 0.1 N force stimulation. Furthermore, this ML emission exhibits an extraordinary antithermal quenching effect in the temperature range of 300-380 K, which is revealed to originate from a thermal activation energy compensation mechanism from trap levels to Mn(II) 4T1 level. Based on their intriguing optical properties, these compounds as chiral force-responsive materials are demonstrated in multilevel confidential information encryption.

Constructing Chiral Covalent-Organic Frameworks for Circularly Polarized Light Detection

The use of chiral covalent organic frameworks (COFs) as active elements in photodetectors to directly identify circularly polarized light (CPL) can meet the requirement of integration and miniaturization of the as-fabricated devices. Herein, the design and synthesis of two isoreticular chiral two-dimensional (2D) COFs (CityU-7 and CityU-8) by introducing photosensitive porphyrin-based amines (5,10,15,20-tetrakis(4-aminophenyl)porphyrin) to enhance the optical absorption and chiral aldehyde linkage (2,5-bis((S/R))-2-methylbutoxy)terephthalaldehyde) to engender chirality for direct CPL detection  are  reported. Their crystalline structures  were  confirmed by powder X-ray diffraction, Fourier-transform infrared spectroscopy, and low-dose transition electron microscopy. Employing both chiral COFs as the active layers in photodetectors, left-handed circularly (LHC) and right-handed circularly (RHC) polarized light at 405 nm can be well distinguishable with short response time, high responsivity, and satisfying detectivity. The study provides the first example on the design and synthesis of chiral COFs for direct detection of CPL.

Sensitive organic/inorganic polarized photodetectors enhanced by charge transfer with image sensing capacity

Organic photodetectors (OPDs) have attracted increasing attention in the future wearable sensing and real-time health monitoring, due to their intrinsic features including the mechanical flexibility, low-cost processing and cooling-free operations; while their performances are lagging as the results of inferior carrier mobility and small exciton diffusion coefficient of organic molecules. Graphene exhibits the great photoresponse with wide spectral bandwidth and high response speed. However, weak light absorption and the absence of a gain mechanism have limited its photoresponsivity. Here, we report a sensitive organic/inorganic phototransistor with fast response speed by coupling PTCDA organic single crystal with the monolayer graphene. The long range exciton diffusion in highly ordered π-conjugated molecules, efficient exciton dissociation and charge transfer at the PTCDA/graphene heterointerfaces, and the high mobility of graphene enable a high responsivity (8 × 104A/W), short response time (220 µs) and excellent specific detectivity (>1011 Jones), which is higher than the level of commercial on-chip device. This interfacial photogating effect is verified by the high-resolution spatial photocurrent mapping experiment. In addition, the high sensitivity to polarization is clear and the ultrahigh photoconductive gain enables a near-infrared (NIR) response for 980 and 1550 nm. Finally, high-speed visible and NIR imaging applications are successfully demonstrated. This work suggests that high quality organic single crystal/graphene is a promising platform for future high performance optoelectronic systems and imaging applications.

Direct-write 3D printing of plasmonic nanohelicoids by circularly polarized light

Chiral plasmonic surfaces with 3D "forests" from nanohelicoids should provide strong optical rotation due to alignment of helical axis with propagation vector of photons. However, such three-dimensional nanostructures also demand multi-step nanofabrication, which is incompatible with many substrates. Large-scale photonic patterns on polymeric and flexible substrates remain unattainable. Here, we demonstrate the substrate-tolerant direct-write printing and patterning of silver nanohelicoids with out-of-plane 3D orientation using circularly polarized light. Centimeter-scale chiral plasmonic surfaces can be produced within minutes using inexpensive medium-power lasers. The growth of nanohelicoids is driven by the symmetry-broken site-selective deposition and self-assembly of the silver nanoparticles (NPs). The ellipticity and wavelength of the incident photons control the local handedness and size of the printed nanohelicoids, which enables on-the-fly modulation of nanohelicoid chirality during direct writing and simple pathways to complex multifunctional metasurfaces. Processing simplicity, high polarization rotation, and fine spatial resolution of the light-driven printing of stand-up helicoids provide a rapid pathway to chiral plasmonic surfaces, accelerating the development of chiral photonics for health and information technologies.

Chiral Nanomaterials for Cancer Vaccines

Chirality is a fundamental characteristic of living organisms and is commonly observed at the biomolecule, cellular, and tissue levels. Chiral nanomaterials play an irreplaceable role in nanomedicine and nanobiology because of their unique enantioselectivity with biological components. Here, research progress relating to chiral nanomaterials in the field of vaccines is reviewed, including antigen presenting systems, immune adjuvants, and cancer vaccines. First, the common synthesis methods are outlined for different types of chiral nanomaterials, as well as their chiral sources, optical properties, and potential biological applications. Then, the application of chiral nanomaterials are discussed in the field of vaccines with reference to the promotion of antigen presentation and activation of the immune system for tumor immunotherapy. Finally, the current obstacles and future research directions of chiral nanomaterials are revealed with regard to regulating the immune system.

Tuning the Chiral Growth of Plasmonic Bipyramids via the Wavelength and Polarization of Light

Circularly polarized light (CPL) is a versatile tool to prepare chiral nanostructures, but the mechanism for inducing enantioselectivity is not well understood. This work shows that the energy and polarization of visible photons can initiate photodeposition at different sites on plasmonic nanocrystals. Here, CPL on achiral gold bipyramids (AuBPs) creates hot holes that oxidatively deposit PbO2 asymmetrically. We show for the first time that the location of PbO2 photodeposition and hence optical dissymmetry depends on the CPL wavelength. Specifically, 488 and 532 nm CPL induce PbO2 growth in the middle of AuBPs, whereas 660 nm CPL induces PbO2 growth at the tips. Our observations show that wavelength-dependent plasmonic field distributions are more important than surface lightning rod effects in localizing plasmon-mediated photochemistry. The largest optical dissymmetry occurs at excitation wavelengths between the transverse and longitudinal resonances of the AuBPs because higher-order modes are required to induce chiral electric fields.

Universal Chiral-Plasmon-Induced Upward and Downward Transfer of Circular Dichroism to Achiral Molecules

Electromagnetic chirality transfer represents an effective means of the nanoscale manipulation of optical chirality. While most of the previous reports have exclusively focused on the circular dichroism (CD) transfer from UV-responsive chiral molecules toward visible-resonant achiral colloidal nanoparticles, here we demonstrate a reverse process in which plasmonic chirality can be transferred to achiral molecules, either upward from visible to UV or downward from visible to near infrared (NIR). By hybridizing achiral UV- or NIR-responsive dye molecules with chiral metal nanoparticles in solution, we observe a chiral-plasmon-induced CD (CPICD) signal at the intrinsically achiral molecular absorption bands. Full-wave electromagnetic modeling reveals that both near-field Coulomb interaction and far-field radiative coupling contribute to the observed CPICD, indicating that the mechanism considered here is universal for different material systems and types of optical resonances. Our study provides a set of design guidelines for broadband nanophotonic chiral sensing from the UV to NIR spectral regime.

Iontronic Photoelectrochemical Biorecognition Probing

Herein, the first iontronic photoelectrochemical (PEC) biorecognition probing is devised by rational engineering of a dual-functional bioconjugate, i.e., a light-sensitive intercalated structural DNA, as a smart gating module confined within a nanotip, which could respond to both the incident light and biotargets of interest. Light stimulation of the bioconjugate could intensify the negative charge at the nano-orifice to sustain enhanced ionic current. The presence of proteins (e.g., acetylcholinesterase, AChE) or nucleic acids (e.g., microRNA (miR)-10b) could lead to bioconjugate release with altered ionic signaling. The practical applicability of the methodology is confirmed by AChE detection in human serum and miR-10b detection in single cells.

Chiral nanomaterial-based approaches for diagnosis and treatment of protein-aggregated neurodiseases: current status and future opportunities

Protein misfolding and its aggregation, known as amyloid aggregates (Aβ), are some of the major causes of more than 20 diseases such as Parkinson's disease, Alzheimer's disease, and type 2 diabetes. The process of Aβ formation involves an energy-driven oligomerization of Aβ monomers, leading to polymerization and eventual aggregation into fibrils. Aβ fibrils exhibit multilevel chirality arising from its amino acid residues and the arrangement of folded polypeptide chains; thus, a chirality-driven approach can be utilized for the detection and inhibition of Aβ fibrils. In this regard, chiral nanomaterials have recently opened new possibilities for various biomedical applications owing to their stereoselective interaction with biological systems. Leveraging this chirality-driven approach with chiral nanomaterials against protein-aggregated diseases could yield promising results, particularly in the early detection of Aβ forms and the inhibition of Aβ aggregate formation via specific and strong "chiral-chiral interaction." Despite the advantages, the development of advanced theranostic systems using chiral nanomaterials against protein-aggregated diseases has received limited attention so far because of considerably limited formulations for chiral nanomaterials and lack of information of their chiroptical behavior. This review aims to present the current status of chiral nanomaterials explored for detecting and inhibiting Aβ forms. This review covers the origin of chirality in amyloid fibrils and nanomaterials and different chiral detection methods; furthermore, different chiral nanosystems such as chiral plasmonic nanomaterials, chiral carbon-based nanomaterials, and chiral nanosurfaces, which have been used so far for different therapeutic applications against protein-aggregated diseases, are discussed in detail. The findings from this review may pave the way for the development of novel approaches using chiral nanomaterials to combat diseases resulting from protein misfolding and can further be extended to other disease forms.

How Oratosquilla oratoria compound eye response to the polarization of light: In the perspective of vision genes and related proteins

The special rhabdom structure of the mid-band ommatidium in compound eye contributes to the mantis shrimp being the only animal species known to science that can recognize circularly polarized light (CPL). Although the number of mid-band ommatidium of Oratosquilla oratoria is reduced, the mid-band ommatidium still has orthogonal geometric interleaved rhabdom and short oval distal rhabdom, which may mean that the O. oratoria has weakened circular polarized light vision (CPLV). Here we explored the molecular mechanisms of how O. oratoria response to the polarization of light. Based on the specific expression patterns of vision-related functional genes and proteins, we suggest that the order of light response by O. oratoria compound eye was first natural light, then left-circularly polarized light (LCPL), linearly polarized light, right-circularly polarized light (RCPL) and dark. Meanwhile, we found that the expression levels of vision-related functional genes and proteins in O. oratoria compound eye under RCPL were not significantly different from those in DL, which may imply that O. oratoria cannot respond to RCPL. Furthermore, the response of LCPL is likely facilitated by the differential expression of opsin and microvilli - related functional genes and proteins (arrestin and sodium-coupled neutral amino acid transporter). In conclusion, this study systematically illustrated for the first time how O. oratoria compound eye response to the polarization of light at the genetic level, and it can improve the visual ecological theory behind polarized light vision evolution.

Low-Dimensional-Materials-Based Photodetectors for Next-Generation Polarized Detection and Imaging

The vector characteristics of light and the vectorial transformations during its transmission lay a foundation for polarized photodetection of objects, which broadens the applications of related detectors in complex environments. With the breakthrough of low-dimensional materials (LDMs) in optics and electronics over the past few years, the combination of these novel LDMs and traditional working modes is expected to bring new development opportunities in this field. Here, the state-of-the-art progress of LDMs, as polarization-sensitive components in polarized photodetection and even the imaging, is the main focus, with emphasis on the relationship between traditional working principle of polarized photodetectors (PPs) and photoresponse mechanisms of LDMs. Particularly, from the view of constitutive equations, the existing works are reorganized, reclassified, and reviewed. Perspectives on the opportunities and challenges are also discussed. It is hoped that this work can provide a more general overview in the use of LDMs in this field, sorting out the way of related devices for "more than Moore" or even the "beyond Moore" research.

Recent Advances in the 3D Chiral Plasmonic Nanomaterials

From the view of geometry, chirality is that an object cannot overlap with its mirror image, which has been a fundamental scientific problem in biology and chemistry since the 19th century. Chiral inorganic nanomaterials serve as ideal templates for investigating chiral transfer and amplification mechanisms between molecule and bulk materials, garnering widespread attentions. The chiroptical property of chiral plasmonic nanomaterials is enhanced through localized surface plasmon resonance effects, which exhibits distinctive circular dichroism (CD) response across a wide wavelength range. Recently, 3D chiral plasmonic nanomaterials are becoming a focal research point due to their unique characteristics and planar-independence. This review provides an overview of recent progresses in 3D chiral plasmonic nanomaterials studies. It begins by discussing the mechanisms of plasmonic enhancement of molecular CD response, following by a detailed presentation of novel classifications of 3D chiral plasmonic nanomaterials. Finally, the applications of 3D chiral nanomaterials such as biology, sensing, chiral catalysis, photology, and other fields have been discussed and prospected. It is hoped that this review will contribute to the flourishing development of 3D chiral nanomaterials.

Circularly Polarized Light Emission from Nonchiral Perovskites Incorporated into Nanoporous Cholesteric Polymer Templates

Chiral perovskites have garnered significant attention, owing to their chiroptical properties and emerging applications. Current fabrication methods often involve complex chemical synthesis routes. Herein, an alternative approach for introducing chirality into nonchiral hybrid organic-inorganic perovskites (HOIPs) using nanotemplates composed of cholesteric polymeric networks is proposed. This method eliminates the need for additional molecular design. In this process, HOIP precursors are incorporated into a porous cholesteric polymer film, and two-dimensional (2D) HOIPs grow inside the nanopores. Circularly polarized light emission (CPLE) was observed even though the selective reflection band of the cholesteric polymer films containing a representative HOIP deviated from the emission wavelength of the 2D HOIP. This effect was confirmed by the induced circular dichroism (CD) observed in the absorbance band of the HOIP. The observed CPLE and CD are attributed to the chirality induced by the template in the originally nonchiral 2D HOIP. Additionally, the developed 2D HOIP exhibited a long exciton lifetime and good stability under harsh conditions. These findings provide valuable insights into the development and design of innovative optoelectronic materials.

Near-Infrared Chiroptical Activity Titanium Dioxide Supraparticles with Circularly Polarized Light Induced Antibacterial Activity

Titanium dioxide (TiO2) has attracted significant attention in the fields of antibacterial activity and pollutant degradation due to its well-known photocatalytic properties. However, the application of TiO2 is significantly limited by its large band gap width, which only allows excitation by ultraviolet light below 400 nm. Here, we propose the use of surface chiral functionalization of TiO2 to tune its band gap width, thus enabling it to be excited by near-infrared-region light (NIR), resulting in the effective separation of electron-hole pairs. By controlling the solvent polarity and forming numerous weak interactions (such as hydrogen bonding) between chiral ligands and TiO2, we successfully prepared chiral TiO2 superparticles (SPs) that exhibited a broad circular dichroism (CD) absorption at 792 nm. Under circularly polarized light (CPL) at 808 nm, the chiral SPs induced the separation of electron-hole pairs in TiO2, thus generating hydroxyl and singlet oxygen radicals. Antibacterial tests under CPL in NIR showed that the chiral TiO2 SPs exhibited excellent antibacterial performance, with inhibition rates of 99.4% and 100% against Gram-positive and Gram-negative bacteria, respectively. Recycling-reuse experiments and biocompatibility evaluation of the material demonstrated that the chiral TiO2 SPs are stable and safe antibacterial materials, thus indicating the potential application of chiral TiO2 SPs in antibacterial aspects of medical implants.

Janus particles with tunable patch symmetry and their assembly into chiral colloidal clusters

Janus particles, which have an attractive patch on the otherwise repulsive surface, have been commonly employed for anisotropic colloidal assembly. While current methods of particle synthesis allow for control over the patch size, they are generally limited to producing dome-shaped patches with a high symmetry (C∞). Here, we report on the synthesis of Janus particles with patches of various tunable shapes, having reduced symmetries ranging from C2v to C3v and C4v. The Janus particles are synthesized by partial encapsulation of an octahedral metal-organic framework particle (UiO-66) in a polymer matrix. The extent of encapsulation is precisely regulated by a stepwise, asymmetric dewetting process that exposes selected facets of the UiO-66 particle. With depletion interaction, the Janus particles spontaneously assemble into colloidal clusters reflecting the particles' shapes and patch symmetries. We observe the formation of chiral structures, whereby chirality emerges from achiral building blocks. With the ability to encode symmetry and directional bonding information, our strategy could give access to more complex colloidal superstructures through assembly.

Enantioselective Oral Absorption of Molecular Chiral Mesoporous Silica Nanoparticles

Inspired by the unique pharmacological effects of chiral drugs in the asymmetrical body environments, it is assumed that the chirality of nanocarriers is also a key factor to determine their oral adsorption efficiency, apart from their size, shape, etc. Herein, l/d-tartaric acid modified mesoporous silica nanoparticles (l/d-CMSNs) are fabricated via a one-pot cocondensation method, and focused on whether the oral adsorption of nanocarriers will be benefited from their chirality. It is found that l-CMSN performed better in the sequential oral absorption processes, including mucus permeation, mucosa bio-adhesion, cellular uptake, intestinal transport and gastrointestinal tract (GIT) retention, than those of the d-chiral (d-CMSN), racemic (dl-CMSN), and achiral (MSN) counterparts. The multiple chiral recognition mechanisms are experimentally and theoretically demonstrated following simple differential adsorption on biointerfaces, wherein electrostatic interaction is the dominant energy. During the oral delivery task, l-CMSN, which is proven to be stable, nonirritative, biocompatible, and biodegradable, is efficiently absorbed into the blood (1.72-2.05-fold higher than other nanocarriers), and helps the loaded doxorubicin (DOX) to achieve better intestinal transport (2.32-27.03-times higher than other samples), satisfactory bioavailability (449.73%) and stronger antitumor effect (up to 95.43%). These findings validated the dominant role of chirality in determining the biological fate of nanocarriers.

A colorimetric sensor with dual-ratio and dual-mode for detection of nicotine in tobacco samples

Nicotine (NIC) is a harmful substance, drug, pesticide and chemical that is widely found in tobacco. It has carcinogenic, teratogenic and neurotoxic effects that have raised serious concerns. Herein, a colorimetric sensor with dual-ratio and dual-mode for the detection of NIC in tobacco samples was reported. The localized surface plasmon resonance signals of gold nanoparticles (AuNPs) and AuNPs-NIC are used as dual-ratio signals. The absorbance ratio of NIC to AuNPs or the absorbance ratio of NIC to AuNPs-NIC and the wavelength shift value of AuNPs-NIC are applied as dual-mode. Transmission electron microscopy, energy dispersive spectroscopy, dynamic light scattering spectroscopy, ultraviolet-visible spectrophotometry, cyclic voltammetry, and potentiostatic methods were used to characterize the sensor. Further analysis of NIC was conducted through morphological fitting and theoretical calculations. Under optimal conditions, the sensor shows a wide linear range of 5-500 μM. The detection limits for NIC are 2.48 μM, 1.63 μM and 1.34 μM, respectively. The experimental result shows that the dual-ratio signal of AuNPs and AuNPs-NIC has good selectivity and sensitivity, and can effectively reduce the interference of impurities on NIC detection. And the dual-mode of detection for NIC improves the accuracy and comparability of the result significantly. In addition, the proposed sensor was also applied to test NIC in tobacco samples with satisfactory recovery.

Unidirectional asymmetry transmission based on quasi-accidental bound states in the continuum

The unidirectional asymmetry transmission is demonstrated based on quasi-accidental bound states in the continuum by a one-dimensional chiral photonic crystal slab (CPhCs) composed of tilted silicon nano-pillars. The chirality breaks symmetries on the far field polarization and radiation Q-factor between the upward and downward radiation channels. Accordingly, the CPhCs only supports the unidirectional maximal asymmetry transmission at fixed incident and conical angles. The numerical simulation indicates that the CPhCs obtains a circular dichroism of 0.99 and Q-factor of 753.7 at λ = 1.565 μm. In addition, the handedness of polarization is also effectively converted between the incidence and transmission, and the handedness depends on the incident direction and conical angle. Our scheme provides a feasible route for applications in manipulating polarization and chiral sensing.

Using a molecular additive to control chiral supramolecular assembly and the subsequent chirality transfer process

Hierarchical assembly of chiral molecules is achieved through the introduction of molecular additives, which enables the chiral assembly of nanosheets into helical nanorods with inverted chirality. Moreover, the hierarchical assembly of chiral molecules in the presence of a molecular additive can lead to the subsequent chirality transfer from a molecular system to nanoparticle assemblies.