Tunable Chiroptical Properties from the Plasmonic Band to Metal-Ligand Charge Transfer Band of Cysteine-Capped Molybdenum Oxide Nanoparticles

Harnessing Synchronous Photothermal and Photocatalytic Effects of Substoichiometric MoO3-x Nanoparticle-Decorated Membranes for Clean Water Generation

Solar-driven interfacial evaporation provides a promising pathway for sustainable freshwater and energy generation. However, developing highly efficient photothermal and photocatalytic nanomaterials is challenging. Herein, substoichiometric molybdenum oxide (MoO3-x) nanoparticles are synthesized via step-by-step reduction treatment of l-cysteine under mild conditions for simultaneous photothermal conversion and photocatalytic reactions. The MoO3-x nanoparticles of low reduction degree are decorated on hydrophilic cotton cloth to prepare a MCML evaporator toward rapid water production, pollutant degradation, as well as electricity generation. The obtained MCML evaporator has a strong local light-to-heat effect, which can be attributed to excellent photothermal conversion via the local surface plasmon resonance effect in MoO3-x nanoparticles and the low heat loss of the evaporator. Meanwhile, the rich surface area of MoO3-x nanoparticles and the localized photothermal effect together effectively accelerate the photocatalytic degradation reaction of the antibiotic tetracycline. With the benefit of these advantages, the MCML evaporator attains a superior evaporation rate of 4.14 kg m-2 h-1, admirable conversion efficiency of 90.7%, and adequate degradation efficiency of 96.2% under 1 sun irradiation. Furthermore, after being rationally assembled with a thermoelectric module, the hybrid device can be employed to generate 1.0 W m-2 of electric power density. This work presents an effective complementary strategy for freshwater production and sewage treatment as well as electricity generation in remote and off-grid regions.

Multienzyme cascades analysis of α-glucosidase by oxygen deficient MoO3-x

BACKGROUND

Recently, the enzymatic cascade reactions during the cellular process are widely used for fabricating robust biosensors and they have attracted extensive attention in analyzing various clinical biomarkers. The enzymatic cascades analysis is commonly based on the peroxidase (POD)/oxidase coupled system. However, the requirement of harsh acidic environment, poor stability and interference from the oxidase further limit their analytical practicability. Herein, novel chromogenic nanomaterials with H2O2 sensitive features are urgently required to replace the POD nanozyme in enzymatic cascades based bioanalysis.

RESULTS

Herein, oxygen deficient MoO3-x with H2O2 sensitive features and near-infrared (NIR) absorption band have been ultra-fast synthesized and utilized for the enzymatic cascades analysis of α-Glucosidase's activity, and inhibitors screening. With the addition of 4-nitrophenyl-α-d-glucopyranoside, the simultaneous presence of α-Glucosidase and glucose oxidase (GOx) would fade their dark blue color and decrease the NIR absorption. The α-Glucosidase's activity can be analyzed by the absorption at 770 nm, and their limit of detection is 8 × 10-5 U/mL, indicating the superior performance of the proposed colorimetric assay. Moreover, this proposed α-Glucosidase assay is further utilized for inhibitors screening. Moreover, the activity of α-Glucosidase can also be analyzed by the smartphone and microplate reader through the agarose-based colorimetric portable kit.

SIGNIFICANCE

This MoO3-x involved enzymatic cascades assay would facilitate for the development of bio-analysis related to H2O2 generation or consumption. Moreover, this bio-analysis strategy will contribute to the development of other H2O2 sensitive chromogenic nanomaterials for the analysis of certain biomolecules and biological enzymes.

Defect engineering to tailor structure-activity relationship in biodegradable nanozymes for tumor therapy by dual-channel death strategies

Pursuing biodegradable nanozymes capable of equipping structure-activity relationship provides new perspectives for tumor-specific therapy. A rapidly degradable nanozymes can address biosecurity concerns. However, it may also reduce the functional stability required for sustaining therapeutic activity. Herein, the defect engineering strategy is employed to fabricate Pt-doping MoOx (PMO) redox nanozymes with rapidly degradable characteristics, and then the PLGA-assembled PMO (PLGA@PMO) by microfluidics chip can settle the conflict between sustaining therapeutic activity and rapid degradability. Density functional theory describes that Pt-doping enables PMO nanozymes to exhibit an excellent multienzyme-mimicking catalytic activity originating from synergistic catalysis center construction with the interaction of Pt substitution and oxygen vacancy defects. The peroxidase- (POD), oxidase- (OXD), glutathione peroxidase- (GSH-Px), and catalase- (CAT) mimicking activities can induce robust ROS output and endogenous glutathione depletion under tumor microenvironment (TME) response, thereby causing ferroptosis in tumor cells by the accumulation of lipid peroxide and inactivation of glutathione peroxidase 4. Due to the activated surface plasmon resonance effect, the PMO nanozymes can cause hyperthermia-induced apoptosis through 1064 nm laser irradiation, and augment multienzyme-mimicking catalytic activity. This work represents a potential biological application for the development of therapeutic strategy for dual-channel death via hyperthermia-augmented enzyme-mimicking nanocatalytic therapy.

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.

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.

Chiral Inorganic Nanomaterials for Photo(electro)catalytic Conversion

Chiral inorganic nanomaterials due to their unique asymmetric nanostructures have gradually demonstrated intriguing chirality-dependent performance in photo(electro)catalytic conversion, such as water splitting. However, understanding the correlation between chiral inorganic characteristics and the photo(electro)catalytic process remains challenging. In this perspective, we first highlight the chirality source of inorganic nanomaterials and briefly introduce photo(electro)catalysis systems. Then, we delve into an in-depth discussion of chiral effects exerted by chiral nanostructures and their photo-electrochemistry properties, while emphasizing the emerging chiral inorganic nanomaterials for photo(electro)catalytic conversion. Finally, the challenges and opportunities of chiral inorganic nanomaterials for photo(electro)catalytic conversion are prospected. This perspective provides a comprehensive overview of chiral inorganic nanomaterials and their potential in photo(electro)catalytic conversion, which is beneficial for further research in this area.

Histidine-Mediated Synthesis of Chiral Cobalt Oxide Nanoparticles for Enantiomeric Discrimination and Quantification

Chiral transition metal oxide nanoparticles (CTMOs) are attracting a lot of attention due to their fascinating properties. Nevertheless, elucidating the chirality induction mechanism often remains a major challenge. Herein, the synthesis of chiral cobalt oxide nanoparticles mediated by histidine (Co₃ O₄ @L-His and Co₃ O₄ @D-His for nanoparticles synthesized in the presence of L- and D-histidine, respectively) is investigated. Interestingly, these CTMOs exhibit remarkable and tunable chiroptical properties. Their analysis by x-ray photoelectron, Fourier transform infrared, and ultraviolet-visible absorption spectroscopy indicates that the ratio of Co²⁺ /Co³⁺ and their interactions with the imidazole groups of histidine are behind their chiral properties. In addition, the use of chiral Co₃ O₄ nanoparticles for the development of sensitive, rapid, and enantioselective circular dichroism-based sensors is demonstrated, allowing direct molecular detection and discrimination between cysteine or penicillamine enantiomers. The circular dichroism response of the chiral Co₃ O₄ exhibits a limit of detection and discrimination of cysteine and penicillamine enantiomers as low as 10 µm. Theoretical calculations suggest that the ligand exchange and the coexistence of both species adsorbed on the oxide surface are responsible for the enantiomeric discrimination. This research will enrich the synthetic approaches to obtain CTMOs and enable the extension of the applications and the discovery of new chiroptical properties.

Recent advances in chiral nanomaterials with unique electric and magnetic properties

Research on chiral nanomaterials (NMs) has grown radically with a rapid increase in the number of publications over the past decade. It has attracted a large number of scientists in various fields predominantly because of the emergence of unprecedented electric, optical, and magnetic properties when chirality arises in NMs. For applications, it is particularly informative and fascinating to investigate how chiral NMs interact with electromagnetic waves and magnetic fields, depending on their intrinsic composition properties, atomic distortions, and assembled structures. This review provides an overview of recent advances in chiral NMs, such as semiconducting, metallic, and magnetic nanostructures.

Chiroptical Transitions of Enantiomeric Ligand-Activated Nickel Oxides

Ligand-induced chirality in transition-metal oxide (TMO) nanostructures have great potential for designing materials with tunable chiroptical effects. Herein, a facile strategy is reported to prepare chiroptical active nickel-oxide hybrids combined with pH adjustment, and the redox treatment results in ligand transformation, which is attributable to multiple optical transitions in the TMO nanostructures. The theoretical calculation also explains the chiral origins based on their complex models based on empirical analysis. It is also shown that enantiomeric TMO nanoparticles can be used as chiral inducers for chiroptical sensitive polymerization. These results demonstrate that TMO nanostructures can provide rational control over photochemical synthesis and chiral transfer of inorganics nanoarchitecture chirality.

Chiral CuS nanoparticles and their photothermal properties

Chiral CuS NPs were prepared through a ligand-exchange process and CPL-controlled photothermal performance was realized.

Shining light on chiral inorganic nanomaterials for biological issues

The rapid development of chiral inorganic nanostructures has greatly expanded from intrinsically chiral nanoparticles to more sophisticated assemblies made by organics, metals, semiconductors, and their hybrids. Among them, lots of studies concerning on hybrid complex of chiral molecules with achiral nanoparticles (NPs) and superstructures with chiral configurations were accordingly conducted due to the great advances such as highly enhanced biocompatibility with low cytotoxicity and enhanced penetration and retention capability, programmable surface functionality with engineerable building blocks, and more importantly tunable chirality in a controlled manner, leading to revolutionary designs of new biomaterials for synergistic cancer therapy, control of enantiomeric enzymatic reactions, integration of metabolism and pathology via bio-to nano or structural chirality. Herein, in this review our objective is to emphasize current research state and clinical applications of chiral nanomaterials in biological systems with special attentions to chiral metal- or semiconductor-based nanostructures in terms of the basic synthesis, related circular dichroism effects at optical frequencies, mechanisms of induced optical chirality and their performances in biomedical applications such as phototherapy, bio-imaging, neurodegenerative diseases, gene editing, cellular activity and sensing of biomarkers so as to provide insights into this fascinating field for peer researchers.

Chiral Nanoceramics

The study of different chiral inorganic nanomaterials has been experiencing rapid growth during the past decade, with its primary focus on metals and semiconductors. Ceramic materials can substantially expand the range of mechanical, optical, chemical, electrical, magnetic, and biological properties of chiral nanostructures, further stimulating theoretical, synthetic, and applied research in this area. An ever-expanding toolbox of nanoscale engineering and self-organization provides a chirality-based methodology for engineering of hierarchically organized ceramic materials. However, fundamental discoveries and technological translations of chiral nanoceramics have received substantially smaller attention than counterparts from metals and semiconductors. Findings in this research area are scattered over a variety of sources and subfields. Here, the diversity of chemistries, geometries, and properties found in chiral ceramic nanostructures are summarized. They represent a compelling materials platform for realization of chirality transfer through multiple scales that can result in new forms of ceramic materials. Multiscale chiral geometries and the structural versatility of nanoceramics are complemented by their high chiroptical activity, enantioselectivity, catalytic activity, and biocompatibility. Future development in this field is likely to encompass chiral synthesis, biomedical applications, and optical/electronic devices. The implementation of computationally designed chiral nanoceramics for biomimetic catalysts and quantum information devices may also be expected.

Chiral Transition Metal Oxides: Synthesis, Chiral Origins, and Perspectives

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 symmetry-breaking effect. Although progressive investigations have been made for accurately controlled synthesis and relevant explanations on the chirality origin of such materials, the overall field of chiral TMOs is still in its infancy with adequate space for interdisciplinary communications and development. Herein, therefore, recent advances in both experimental phenomena and theoretical calculations in this area are reviewed, to elucidate the underlying chiral origin with respect to their fabrications process, triggering new insights for further evolution of this field.

Ligand-Induced Chirality in Asymmetric CdSe/CdS Nanostructures: A Close Look at Chiral Tadpoles

Ligand-induced chirality in asymmetric CdSe/CdS core-shell nanocrystals (NCs) has been extensively applied in chiral biosensors, regioselective syntheses and assemblies, circularly polarized luminescence (CPL), and chiroptic-based devices due to their excellent physiochemical properties, such as the tunable quantum confinement effects, surface functionality, and chemical stability. Herein, we present CdSe/CdS NCs with various morphologies such as nanoflowers, tadpoles, and dot/rods (DRs) with chirality induced by surface chiral ligands. The observed circular dichroism (CD) and CPL activities are closely associated with the geometrical characteristics of the nanostructures, such as the shell thickness and the aspect ratio of the CdSe/CdS NCs. Furthermore, in situ observations of the growth of tadpoles with a single tail indicate that the CD response is mainly attributed to the CdS shell, which has a maximum tail length of ∼45 nm (approximately λ/10 of the incident light wavelength). On the other hand, the CPL activity is only related to the CdSe core, and the activity benefits from a thin CdS shell with a relatively high photoluminescence quantum yield (QY). Further theoretical models demonstrated the aspect-ratio-dependent g-factor and QY variations in these asymmetric nanostructures. These findings provide insights into not only the asymmetric synthesis of CdSe/CdS NCs, but also the rational design of CdSe/CdS nanostructures with tunable CD and CPL activities.

Light-Induced Chiral Iron Copper Selenide Nanoparticles Prevent β-Amyloidopathy In Vivo

The accumulation and deposition of β-amyloid (Aβ) plaques in the brain is considered a potential pathogenic mechanism underlying Alzheimer's disease (AD). Chiral l/d-Fe_x Cu_y Se nanoparticles (NPs) were fabricated that interfer with the self-assembly of Aβ42 monomers and trigger the Aβ42 fibrils in dense structures to become looser monomers under 808 nm near-infrared (NIR) illumination. d-Fe_x Cu_y Se NPs have a much higher affinity for Aβ42 fibrils than l-Fe_x Cu_y Se NPs and chiral Cu_2-x Se NPs. The chiral Fe_x Cu_y Se NPs also generate more reactive oxygen species (ROS) than chiral Cu_2-x Se NPs under NIR-light irradiation. In living MN9D cells, d-NPs attenuate the adhesion of Aβ42 to membranes and neuron loss after NIR treatment within 10 min without the photothermal effect. In-vivo experiments showed that d-Fe_x Cu_y Se NPs provide an efficient protection against neuronal damage induced by the deposition of Aβ42 and alleviate symptoms in a mouse model of AD, leading to the recovery of cognitive competence.

Colloidally Stable CdS Quantum Dots in Water with Electrostatically Stabilized Weak-Binding, Sulfur-Free Ligands

Colloidal quantum dot (QD) photocatalysts have the electrochemical and optical properties to be highly effective for a range of redox reactions. QDs are proven photo-redox catalysts for a variety of reactions in organic solvents but are less prominent for aqueous reactions. Aqueous QD photocatalysts require hydrophilic ligand shells that provide long-term colloidal stability but are not so tight-binding as to prevent catalytic substrates from accessing the QD surface. Common thiolate ligands, which also poison many co-catalysts and undergo photo-oxidative desorption, are therefore often not an option. This paper describes a framework for the design of water-solubilizing ligands that are in dynamic exchange on and off the QD surface, but still provide long-term colloidal stability to CdS QDs. The binding affinity and inter-ligand electrostatic interactions of a bifunctional ligand, aminoethyl phosphonic acid (AEP), are tuned with the pH of the dispersion. The key to colloidal stability is electrostatic stabilization of the monolayer. This work demonstrates a means of mimicking the stabilizing power of a thiolate-bound ligand with a zwitterionic tail group, but without the thiolate binding group.

Tailoring Chiroptical Activity of Iron Disulfide Quantum Dot Hydrogels with Circularly Polarized Light

Chiral inorganic nanomaterials have recently attracted significant attention because of their many important applications, such as in asymmetric catalysis and chiral sensing. Here, chiral iron disulfide quantum dots (FeS₂ QDs) are synthesized via chirality transfer using l/d-cysteine (Cys) as chiral ligands. The chiral FeS₂ QDs are coassembled with two gelators to produce a cogel (l- or d-[Gel+FeS₂ ]) with a g-factor value of ±0.06. Interestingly, the cogels display intense circularly polarized luminescence. More significantly, the degree of twisting (twist pitch) and the diameter of the cogels can be markedly regulated by illumination with circularly polarized light (CPL) in the ranges of 120-213 and 37-65 nm, respectively, which is caused by the CPL-induced electron transfer. This research opens the way for the design of chiroptical devices with a wide range of functions and applications.

Water-soluble chiral CdSe/CdS dot/rod nanocrystals for two-photon fluorescence lifetime imaging and photodynamic therapy

Compared with traditional organic contrast agents, semiconductor nanocrystals (NCs) have unique optical properties that are vital for biological applications with ultrahigh sensitivities, such as long fluorescence lifetime and large multiphoton absorption (MPA). However, the MPA properties and biological applications of chiral-ligand-stabilized semiconductor NCs have scarcely been reported, which seriously hinders their relevant applications. In this work, we report the aqueous phase transfer of CdSe/CdS dot/rod NCs with the use of cysteine molecules, after which the NCs preserve their high fluorescence quantum yield, long lifetime, and efficient circular dichroism. More importantly, the investigated dot/rod NCs show extremely large two- and three-photon absorption action cross-sections in the first and second biological windows, with maximum values of ∼21 000 GM at 800 nm and ∼4.6 × 10-78 cm6 s2 per photon2 at 1300 nm, which are among the largest values reported for water-soluble fluorescent nanoparticles. Interestingly, the dot/rod NCs exhibit a high singlet oxygen generation efficiency of 35%. In addition, for the first time, two-photon fluorescence lifetime imaging and photodynamic therapy of the dot/rod NCs were successfully demonstrated. The performed investigation of the optical properties of these water-soluble CdSe/CdS dot/rod NCs indicates that they are promising candidates for nonlinear biological imaging applications.

Two-Photon Absorption-Based Upconverted Circularly Polarized Luminescence Generated in Chiral Perovskite Nanocrystals

Upconverted circularly polarized luminescence (UCPL) processes have attracted great interest, because the chiroptical properties could be expressed in different photophysical processes. In this Letter, the first example of two-photon absorption-based upconverted circularly polarized luminescence (TP-UCPL) is demonstrated. The chiral α-octylamine-modified cesium lead bromides perovskite nanocrystals exhibited TP-UCPL with a two-photon absorption cross section at 800 nm (σ_2,800 nm) up to 3.68 × 10⁴ GM and luminescence dissymmetric factor ( g_lum) up to 7.0 × 10^-3. Depending on the molecular chirality of the capping ligands, the TP-UCPL sense can be selected and the mirror-imaged CPL is obtained. It is envisaged that this approach will afford a new viewpoint for designing UCPL processes.

Spin Selectivity in Photoinduced Charge-Transfer Mediated by Chiral Molecules

Optical control and readout of electron spin and spin currents in thin films and nanostructures have remained attractive yet challenging goals for emerging technologies designed for applications in information processing and storage. Recent advances in room-temperature spin polarization using nanometric chiral molecular assemblies suggest that chemically modified surfaces or interfaces can be used for optical spin conversion by exploiting photoinduced charge separation and injection from well-coupled organic chromophores or quantum dots. Using light to drive photoexcited charge-transfer processes mediated by molecules with central or helical chirality enables indirect measurements of spin polarization attributed to the chiral-induced spin selectivity effect and of the efficiency of spin-dependent electron transfer relative to competitive relaxation pathways. Herein, we highlight recent approaches used to detect and to analyze spin selectivity in photoinduced charge transfer including spin-transfer torque for local magnetization, nanoscale charge separation and polarization, and soft ferromagnetic substrate magnetization- and chirality-dependent photoluminescence. Building on these methods through systematic investigation of molecular and environmental parameters that influence spin filtering should elucidate means to manipulate electron spins and photoexcited states for room-temperature optoelectronic and photospintronic applications.

Chiral CdSe nanoplatelets as an ultrasensitive probe for lead ion sensing

As opposed to traditional photoluminescence and ultra-violet based optical sensing, we present here a sensing system based on resolved optically active polarization with promising applications. It is based on the ultrathin CdSe nanoplatelets (NPLs) when modified with either l or d-cysteine molecules (l/d-cys) as bio-to-nano ligands. The chiral ligand transfers its chiroptical activity to the achiral nanoplatelets with an anisotropy factor of ∼10-4, which unlocks the chiral excitonic transitions and allows lead ion detection with a limit of detection (LOD) as low as 4.9 nM. Simulations and modelling based on time-dependent density functional theory (TD-DFT) reveal the chiral mechanism of l/d-cys capped CdSe NPLs. The presented CD-based sensing system illustrates an alternative possibility of using chiral CdSe NPLs as competitive chiral sensors for heavy metal ion detection.

Chiroptical Activity of Type II Core/Shell Cu2S/CdSe Nanocrystals

Ligand-induced chirality in core/shell nanocrystals (NCs) has attracted extensive attention because of many valuable potential applications. However, the cause of chirality especially in semiconductor nanomaterials is still under debate despite the creation of chiral type I core/shell structures. Herein, we synthesized a kind of new Cu₂S/CdSe core/shell nanostructure to study the underlying reason. Four samples of Cu₂S/CdSe were synthesized utilizing successive ion layer adsorption and reaction to vary the thickness of the CdSe shell upon a Cu₂S core with 5 nm diameter. The chirality of type II Cu₂S/CdSe NCs is imparted by l-/d-cysteine and penicillamine, which could be modulated with an increasing thickness of the CdSe shell. To the best of our knowledge, this is the first report of chiral type II core/shell semiconductor NCs. The hybridization theory can explain the variation trend of g factors with every increase in shell thickness from four monolayers (4 ML) to 7 ML. The results indicate that the chiroptical activity of semiconductor NCs is mainly due to hybridization between the holes in the valence band of NCs and the highest occupied molecular orbitals of the chiral ligands. In addition, Cu₂S/CdSe NCs show a better chiroptical intensity in comparison with the type I structure according to previous work. The first design of chiral type II Cu₂S/CdSe core/shell NCs and a detailed investigation of chiral variation trend help to give a better understanding of the chiral interaction between ligands and core/shell semiconductor nanostructures.

Strong multiphoton absorption in chiral CdSe/CdS dot/rod nanocrystal-doped poly(vinyl alcohol) films

Cysteine-capped cadmium selenide/cadmium sulfide (CdSe/CdS) dot/rod nanocrystals (NCs) were synthesized and then doped in poly(vinyl alcohol) (PVA) films. Compared with an L-/D-cysteine-capped NC solution (10^-4), the anisotropic factors of the circular dichroism and circular polarized luminescence in the doped PVA films increased by one order of magnitude, probably because of the enhanced anisotropy degree, crystal orientations, and ordered morphologies. The two- and three-photon absorption coefficients of the doped PVA films were determined as 0.58 cm/GW at 800 nm and 2.3×10^-4  cm³/GW² at 1300 nm, respectively. The chiral NC-doped PVA films are promising for applications in chirality-related nonlinear photonic devices.

A selective fluorescent sensor for cysteine detection with potential as a white light emitting fluorophore in living cell imaging

A novel fluorescent sensor CysW-1 was introduced for cysteine detection via the cleavage reaction of two fluorophores. Then a relatively steady and practical white light emitting system was successfully generated. The biocompatibility ensured the living cell imaging and further pre-clinical applications.