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.

Small Molecules Mediated the Chirality Transfer in Self-Assembled Nanocomposites with Strong Circularly Polarized Luminescence.

Manipulation of the chirality at all scales has a cross-disciplinary importance and may address key challenges at the heart of physical sciences. One critical question in this field is how the chirality of one entity can be transferred to the asymmetry of another entity. Here, we find that small molecules play a crucial role in the chirality transfer from chiral organic molecules to CdSe/CdS nanorods, where the handedness of the nanorod assemblies either agrees or disagrees with that of the molecular assemblies, leading to the positive or inverse chirality transfer. The assembling mode of nanorods on the molecular assemblies, where the nanorods are either lying or standing, is closely associated with the handedness of the nanorod assemblies, resulting in opposite chirality. Furthermore, we have found that circularly polarized emission from chiral assemblies of nanorods is dependent on molecular additives. The promoted luminescence dissymmetry factor (glum) of the nanocomposites with a high value of ∼0.3 could be attained under optimal conditions.

Controlled Hierarchical Self-Assembly of Nanoparticles and Chiral Molecules into Tubular Nanocomposites.

In this work, we show how the kinetics of molecular self-assembly can be coupled with the kinetics of the colloidal self-assembly of inorganic nanoparticles, which in turn drives the formation of several distinct hierarchically assembled tubular nanocomposites with lengths over tens of micrometers. These colloidal nanoparticles primarily serve as "artificial histones," around which the as-assembled supramolecular fibrils are wound into deeply kinetically trapped single-layered nanotubes, which leads to the formation of tubular nanocomposites that are resistant to supramolecular transformation thermally. Alternatively, when these nanoparticles are aggregated prior to the event of molecular self-assembly, these as-formed nanoparticle "oligomers" would be encapsulated into the thermodynamically favored double-layer supramolecular nanotubes, which enables the non-close-packing of nanoparticles inside the nanotubes and results in the nanoparticle superlattices with an open channel. Furthermore, increasing the amounts of nanoparticles enables the assembly of nanoparticles into pseudohexagonal superlattices at the external surface in a sequential fashion, which ultimately drives the formation of triple-layered hierarchically assembled tubular nanocomposites. Importantly, the sense of helicity transfers from the supramolecular nanotubes to the pseudo nanoparticle superlattices with a chiral vector of (2, 9). Our findings represent a strategy for controlling the hierarchical assembly bridging supramolecular chemistry to the inorganic solids to realize the complexity by design.

Large Optical Asymmetry in Silver Nanoparticle Assemblies Enabled by CH-π Interaction-Mediated Chirality Transfer.

Transfer of asymmetry from the molecular system to the other distinct system requires appropriate chemical interactions. Here, we show how the CH-π interaction, one of the weakest hydrogen bonds, can be applied to transfer the asymmetry from π-conjugated chiral molecules to the assemblies of plasmonic Ag nanoparticles, where the aliphatic chains of chiral molecules and the polystyrene chains grafted on Ag nanoparticles are served as the hydrogen donor and acceptor, respectively. The optical asymmetry g-factor of the chiral assemblies of plasmonic nanoparticles is strongly dependent on the molecular weight of the polystyrene ligand, the core structure of the molecule, and the aliphatic chain length of the chiral molecule. Importantly, we explore a molecular mixing strategy to enhance the asymmetry g-factor of chiral molecular assemblies, which consequently promotes the g-factor of chiral plasmonics efficiently, reaching a high value of ∼0.05 under optimal conditions. Overall, we rationalize the chirality transfer from chiral molecules to inorganic nanoparticles, providing the guidance for structural design of chiral nanocomposites with a high g-factor.

Functional Droplets Stabilized by Interfacially Self-Assembled Chiral Nanocomposites.

Here, we show that aqueous dispersions of inorganic nanoparticles bearing negative surface charges would trigger the chiral assembly of organic radical cations solubilized in organic solvent at the liquid-liquid interface, which consequently produces stable droplets covered by a layer of inorganic/organic chiral nanocomposites. We demonstrate that chirality transfer across the liquid-liquid interface from the chiral organic monomers to the nanoparticle assemblies is realized. Surprisingly, opposite handedness between molecular assemblies and nanoparticle assemblies is determined from both CD and CPL measurements. Moreover, the functionalities of these "chiral" droplets could be further engineered through either a simple mixing or a droplet merging strategy, which enables to produce fluorescent emissive-tunable, magnetic, as well as magnetofluorescent dual-functional droplets.

Folding of two-dimensional nanoparticle superlattices enabled by emulsion-confined supramolecular co-assembly.

Folding of two-dimensional nanoparticle superlattices is achieved through templated assembly on as-formed supramolecular nanosheets, which undergo a folding process within the emulsion droplets during the evaporation of the inner phase liquid. Building the folded nanoparticle superlattices opens a new gateway to reshape the properties of inorganic solids.

Diversifying Nanoparticle Superstructures and Functions Enabled by Translative Templating from Supramolecular Polymerization.

Biology exploits a transcription-translation approach to deliver structural information from DNA to the protein-building machines with high precision. Here, we show how the structural information of small synthetic molecules could be used to guide the assembly of inorganic nanoparticles into diversified yet long-range ordered superstructures, enabling the information transfer across four or five orders of magnitude in length scale. We designed three perylene diimide (PDI) based isomers differing by their site-specific substitutions of the methyl group, which were able to supramolecularly polymerize into diverse structures. Importantly, coassembly of these PDI isomers with nanoparticles (NPs) could produce diverse long-range ordered nanoparticle superstructures, including one-dimensional NPs chains, double helical NPs assemblies and two-dimensional NPs superlattices. Equally important, we demonstrate that the information originated from small molecules could diversify the functions of the self-assembled nanocomposites.

Chirality Inversion in Self-Assembled Nanocomposites Directed by Curvature-Mediated Interactions.

Nanoscale curvature-dependent interactions are of paramount importance in biological systems. Here, we report that nanoscale curvature plays an important role in regulating the chirality of self-assembled nanocomposites from chiral organic molecules and achiral nanoparticles. Specifically, we show that the supramolecular chirality of the nanocomposites markedly depends on the nanoparticle curvature, where small-sized nanoparticles of high curvature and large-sized nanoparticles of low curvature lead to nanocomposites with opposite chirality. Quantitative kinetic experiments and molecular dynamics simulations reveal that nanoparticle curvature plays a key role in promoting the pre-nucleation oligomerization of chiral molecules, which consequently regulates the supramolecular chirality of the nanocomposites. We anticipate that this study will aid in rational design of an artificial cooperative system giving rise to emergent assembling phenomena that can be surprisingly rich and often cannot be understood by studying the conventional noncooperative systems.

Active Regulation of Supramolecular Chirality through Integration of CdSe/CdS Nanorods for Strong and Tunable Circular Polarized Luminescence.

Building the cooperativity in artificial self-assembling systems will synergistically reshape their properties and expand their application spectrum. Here, we show how the cooperativity between achiral CdSe/CdS nanorods (NRs) and chiral perylene diimide (PDI)-based molecules is built upon their coassembly. We demonstrate that chirality transfer from chiral molecular assemblies to CdSe/CdS NRs is enabled by the encapsulation of NRs into PDI suprascrolls through chain-chain van der Waals interactions, which in turn gives rise to markedly enhanced circularly polarized luminescence of the nanocomposites. Additionally, the circularly polarized emissive bands of the nanocomposites could be finely tuned by engineering the emissive bands of NRs. More importantly, these nanocomposites are able to invert their chirality when NRs are self-assembled into chiral superlattices under a larger amount of NRs. Detailed mechanistic studies unveil that these jammed NRs assemblies hamper the folding of two-dimensional (2D) chiral nanosheets, which consequently suppress the interlayer excitonic coupling and implement the nanocomposites with inverted chirality. Our finding exemplifies a way to invert the chirality switching from folding to unfolding of 2D supramolecular nanosheets, akin to the chirality inversion in the helix-to-superhelix transition in conventional one-dimensional (1D) supramolecular systems. We also show that the strong van der Waals interactions from aliphatic chains are crucial in achieving such chirality transfer and inversion. Overall, we demonstrate that these achiral CdS/CdSe NRs could serve as artificial molecular chaperones to aid the unfolding of supramolecular nanosheets with controlled chirality.

Self-Assembled Open Porous Nanoparticle Superstructures.

Imparting porosity to inorganic nanoparticle assemblies to build up self-assembled open porous nanoparticle superstructures represents one of the most challenging issues and will reshape the property and application scope of traditional inorganic nanoparticle solids. Herein, we discovered how to engineer open pores into diverse ordered nanoparticle superstructures via their inclusion-induced assembly within 1D nanotubes, akin to the molecular host-guest complexation. The open porous structure of self-assembled composites is generated from nonclose-packing of nanoparticles in 1D confined space. Tuning the size ratios of the tube-to-nanoparticle enables the structural modulation of these porous nanoparticle superstructures, with symmetries such as C1, zigzag, C2, C4, and C5. Moreover, when the internal surface of the nanotubes is blocked by molecular additives, the nanoparticles would switch their assembly pathway and self-assemble on the external surface of the nanotubes without the formation of porous nanoparticle assemblies. We also show that the open porous nanoparticle superstructures can be ideal candidate for catalysis with accelerated reaction rates.

Discovering Topological Surface States of Dirac Points.

Dirac materials, unlike the Weyl materials, have not been found in experiments to support intrinsic topological surface states, as the surface arcs in existing systems are unstable against symmetry-preserving perturbations. Utilizing the proposed glide and time-reversal symmetries, we theoretically design and experimentally verify an acoustic crystal of two frequency-isolated three-dimensional Dirac points with Z_{2} monopole charges and four gapless helicoid surface states.

Monte Carlo simulations of stereocomplex formation in multiblock copolymers.

Currently, controlling the formation of stereocomplex crystallites (SCs) in enantiomeric PLA blends is a research hotspot. In the present work, we performed dynamic Monte Carlo simulations to study the formation mechanism of SCs in multiblock copolymers. The effects of block number and crystallization temperature on SC formation were revealed. The relative size of block length and crystal thickness is an important factor. In the multiblock copolymers with block length longer than crystal thickness, both the increases of crystallization temperature and block number lead to the increase of SC content attributed to the relatively high degree of supercooling for SC formation and the improved local miscibility between different blocks, respectively. In the multiblock copolymers with block length equal to crystal thickness, each block can just form one crystalline stem, and then different blocks can be more easily alternately parallel-packed during SC formation. The system thus reaches the upper limit of the ability to form SCs. Therefore, both the further increases in crystallization temperature and block number can no longer cause the enhancement in SC formation.

Stereocomplex formation in mixed polymers filled with two-dimensional nanofillers.

The presence of nanofillers, such as graphene, can effectively promote stereocomplex formation in poly(l-lactide)/poly(d-lactide) blends. However, the detailed microscopic mechanism of the improved formation of stereocomplex crystallites (SCs) in filled polylactides is still unclear. Therefore, we performed dynamic Monte Carlo simulations to reveal the underlying mechanism of the effect of two-dimensional nanofillers on the formation of SCs in polymer blends. It was observed that the nanofillers can lead to the occurrence of heterogeneous nucleation of mixed polymer chains. On one hand, the miscibility of mixed polymers is improved in the interfacial regions, attributed to attractive interactions between polymers and nanofillers. On the other hand, for the heterogeneous nucleation process, chains prefer to crystallize by means of intermolecular packing alignment. Both phenomena contribute to the promotion of SCs.

Ideal Weyl points and helicoid surface states in artificial photonic crystal structures.

Weyl points are the crossings of linearly dispersing energy bands of three-dimensional crystals, providing the opportunity to explore a variety of intriguing phenomena such as topologically protected surface states and chiral anomalies. However, the lack of an ideal Weyl system in which the Weyl points all exist at the same energy and are separated from any other bands poses a serious limitation to the further development of Weyl physics and potential applications. By experimentally characterizing a microwave photonic crystal of saddle-shaped metallic coils, we observed ideal Weyl points that are related to each other through symmetry operations. Topological surface states exhibiting helicoidal structure have also been demonstrated. Our system provides a photonic platform for exploring ideal Weyl systems and developing possible topological devices.

Controllability of Polymer Crystal Orientation Using Heterogeneous Nucleation of Deformed Polymer Loops Grafted on Two-Dimensional Nanofiller.

Nowadays, it is a research hotspot to realize the controllability of polymer crystal structure in polymer nanocomposites. However, polymer crystals induced by two-dimensional filler always exhibit random orientation, which somewhat limit the improvement of physical properties of polymer materials. In the current paper, dynamic Monte Carlo simulations were performed to explore the methods preparing crystals with uniform orientation. Heterogeneous nucleation of deformed polymer loops grafted on two-dimensional filler can induce the appearance of a special nanohybrid shish-kebab (NHSK) structure, in which the two-dimensional filler acts as "shish" and induces the formation of crystals with uniform orientation. The grafted deformed chains are first heterogeneously nucleated on filler surface, and then free chains participate in crystallization, resulting in the formation of the NHSK structure. The NHSK structure can only be formed in the systems with high interfacial interactions at high temperatures or moderate interfacial interactions at moderate temperatures or low interfacial interactions at low temperatures. The method proposed here can be used to achieve the controllability of polymer crystal orientation in experiments.

Surface plasmon resonance biosensor for sensitive detection of microRNA and cancer cell using multiple signal amplification strategy.

A sensitive and versatile surface plasmon resonance (SPR) biosensor was proposed for the detection of microRNA (miRNA) and cancer cell based on multiple signal amplification strategy. Thiol-modified hairpin probe, including a sequence complementary to the target miRNA, was first immobilized on the Au film. In the presence of target miRNA, the stem-loop structure of hairpin probe was unfolded, and then DNA-linked Au nanoparticles (AuNPs) were hybridized with the terminus of the unfolded hairpin probe. Subsequently, DNA-linked AuNPs initiated the formation of DNA supersandwich structure through the addition of two report DNA sequences. Owing to the electronic coupling between localized plasmon of the AuNPs and the surface plasmon wave, as well as the enhancement of the refractive index of the medium over the Au film induced by DNA supersandwich structure, the SPR response was significantly enhanced. Next, numerous positively charged silver nanoparticles (AgNPs) were absorbed onto the long-range DNA surpersandwich equably, resulting in a further increase of SPR response. Due to the enzyme-free multiple signal amplification strategy, as low as ca. 0.6 fM miRNA-21 could be detected. In addition, this biosensor showed high selectivity toward single-base mismatch. More importantly, this SPR biosensor was also used for cancer cell detection coupled with the cell-specific aptamer modified magnetic nanoparticles. Given that the biosensor avoided enzyme introduction, the limitation of the enzyme was overcome. The versatile biosensor has great potential for the broad applications in the field of clinical analysis.

High-Efficiency Broadband High-Harmonic Generation from a Single Quasi-Phase-Matching Nonlinear Crystal.

Nonlinear frequency conversion offers an effective way to expand the laser wavelength range based on birefringence phase matching (BPM) or quasi-phase-matching (QPM) techniques in nonlinear crystals. So far, efficient high-harmonic generation is enabled only via multiple cascaded crystals because of the extreme difficulty to simultaneously satisfy BPM or QPM for multiple nonlinear up-conversion processes within a single crystal. Here we report the design and fabrication of a chirped periodic poled lithium niobate (CPPLN) nonlinear crystal that offers controllable multiple QPM bands to support 2nd-8th harmonic generation (HG) simultaneously. Upon illumination of a mid-IR femtosecond pulse laser, we observe the generation of an ultrabroadband visible white light beam corresponding to 5th-8th HG with a record high conversion efficiency of 18%, which is high compared to conventional supercontinuum generation, especially in the HG parts. Our CPPLN scheme opens up a new avenue to explore and engineer novel nonlinear optical interactions in solid state materials for application in ultrafast lasers and broadband laser sources.

Observation of broadband unidirectional transmission by fusing the one-way edge states of gyromagnetic photonic crystals.

We experimentally demonstrate a broadband one-way transmission by merging the operating bands of two types of one-way edge modes that are associated with Bragg scattering and magnetic surface plasmon (MSP) resonance, respectively. By tuning the configuration of gyromagnetic photonic crystals and applied bias magnetic field, the fused bandwidth of unidirectional propagation is up to 2 GHz in microwave frequency range, much larger than either of the individual one-way bandwidth associated with Bragg scattering or MSP resonance. Our scheme for broadband one-way transmission paves the way for the practical applications of one-way transmission.

Isolated diastolic hypertension associated risk factors among Chinese in Anhui Province, China.

OBJECTIVE: To explore potential risk factors of isolated diastolic hypertension (IDH) among young and middle-aged Chinese. METHODS: A community-based cross-sectional study was conducted among 338 subjects, aged 25 years and above, using random sampling technique. There were 68 cases of IDH, 46 cases of isolated systolic hypertension (ISH), 89 cases of systolic and diastolic hypertension (SDH), and 135 of subjects with normal blood pressure. Cases and controls were matched on sex by frequency matching. Demographic characteristics, blood pressure and other relevant information were collected. RESULTS: Compared with controls, patients with IDH and ISH had significant higher level of triglyceride, high density lipoprotein, blood glucose and body mass index (BMI) (p < 0.05); while patients with SDH had significantly higher level of total cholesterol, triglyceride, glucose and BMI (p < 0.05). Linear mixed effects model showed that drinking tea, family history of hypertension (FHH), higher blood glucose, triglyceride and low density lipoprotein were related with elevated diastolic blood pressure (DBP) (p < 0.01); HFH, blood glucose, creatinine and BMI have positive effect on systolic blood pressure (SBP) (p < 0.05). CONCLUSIONS: Drinking tea, FHH, high levels of triglyceride, high density lipoprotein, blood glucose and BMI are associated with IDH among young and middle-aged Chinese.

A sensitive one-step method for quantitative detection of α-amylase in serum and urine using a personal glucose meter.

Assays of α-amylase (AMS) activity in serum and urine constitute the important indicator for the diagnosis of acute pancreatitis, mumps, renal disease and abdominal disorders. Since these diseases confer a heavy financial burden on the health care system, AMS detection in point-of-care is fundamental. Here, a one-step assay for direct determination of the AMS activity was developed using a portable personal glucose meter (PGM). In this assay, maltopentaose was used as a substrate for sensitive detection of AMS with the assistance of α-glucosidase. In the presence of AMS, maltopentaose can be readily hydrolyzed to form maltotriose and maltose quickly. With the enzymatic hydrolysis of α-glucosidase, maltotriose and maltose can be turned into glucose rapidly, which can be quantitatively measured using a portable PGM. This assay did not require any cumbersome and time consuming operations, such as surface modification, synthesis of invertase conjugate, washing and centrifugation. Detection of AMS can be achieved using only a one-step mixture, and the limit of detection was 20 U L(-1) which was lower than the clinical cutoff for AMS. More importantly, this sensitive and selective assay was also used for the detection of AMS in human serum/urine samples. The results showed that the recovery of AMS from human serum/urine samples was 91-107%. The rapid and easy-to-operate assay may have potential application in the fields of point-of-care (POC) clinical diagnosis, particularly in rural and remote areas where lab equipment may be limited.