Robust vibrational coherence protected by a core-shell structure in silver nanoclusters.

Vibrational coherence has attracted considerable research interests because of its potential functions in light harvesting systems. Although positive signs of vibrational coherence in metal nanoclusters have been observed, the underlying mechanism remains to be verified. Here, we demonstrate that robust vibrational coherence with a lifetime of 1 ps can be clearly identified in Ag44(SR)30 core-shell nanoclusters, in which an icosahedral Ag12 core is well protected by a dodecahedral Ag20 cage. Ultrafast spectroscopy reveals that two vibrational modes at around 2.4 THz and 1.6 THz, corresponding to the breathing mode and quadrupolar-like mode of the icosahedral Ag12 core, respectively, are responsible for the generation of vibrational coherence. In addition, the vibrational coherence of Ag44 has an additional high frequency mode (2.4 THz) when compared with that of Ag29, in which there is only one low frequency vibration mode (1.6 THz), and the relatively faster dephasing in two-layer Ag29 relative to that in Ag44 further supports the fact that the robust vibrational coherence in Ag44 is ascribed to its unique matryoshka-like core-shell structure. Our findings not only present unambiguous experimental evidence for a multi-layer core-shell structure protected vibrational coherence under ambient conditions but also offers a practical strategy for the design of highly efficient quantum optoelectronic devices.

A hydrogel-functionalized silver nanocluster for bacterial-infected wound healing.

The ever-growing challenges of traditional antibiotic therapy and chronic wound healing have created a hot topic for the development and application of new antimicrobial agents. Silver nanoclusters (Ag NCs) with ultrasmall sizes (<2 nm) and antibacterial effects are promising candidates for next-generation antibiotics, particularly against multi-drug resistant strains. However, the biosafety in the clinical application of Ag NCs remains suboptimal despite some existing studies of Ag NCs for biomedical applications. Considering this, an ultrasmall Ag NC with excellent water solubility was synthesized by a two-phase ligand-exchange method, which exhibits broad-spectrum antibacterial performance. The minimum inhibitory concentrations of Ag NCs against MRSA, S. aureus, P. aeruginosa and E. coli were evaluated as 50, 80, 5 and 5 µg mL-1, respectively. Furthermore, a carbomer hydrogel was prepared to be incorporated into the Ag NCs for achieving excellent biocompatibility and biosafety. In vitro experiments demonstrate that the Ag NC-gel exhibits good antibacterial properties with lower cytotoxicity. Finally, in vivo experiments suggest that this ultrasmall Ag NC functionalized with the hydrogel can serve as an effective and safe antimicrobial agent to aid in wound healing.

The road to evolution of ProTx2: how to be a subtype-specific inhibition of human Nav1.7.

The human voltage-gated sodium channel Nav1.7 is a widely proven target for analgesic drug studies. ProTx2, a 30-residue polypeptide from Peruvian green tarantula venom, shows high specificity to activity against human Nav1.7, suggesting its potential to become a non-addictive analgesic. However, its high sensitivity to human Nav1.4 raises concerns about muscle side effects. Here, we engineered three mutants (R13A, R13D, and K27Y) of ProTx2 to evaluate their pharmacological activities toward Nav1.7 and Nav1.4. It is demonstrated that the mutant R13D maintained the analgesic effect in mice while dramatically reducing its muscle toxicity compared with ProTx2. The main reason is the formation of a strong electrostatic interaction between R13D and the negatively charged amino acid residues in DII/S3-S4 of Nav1.7, which is absent in Nav1.4. This study advances our understanding and insights on peptide toxins, paving the way for safer, effective non-addictive analgesic development.

Ultrathin Cu9S5 Nanosheets with Sulfur Vacancy for Multimodal Tumor Therapy.

Multimodal tumor therapy with nanotechnology is an effective and integrative strategy to overcome the limitations of therapeutic efficacy and possible side effects associated with monotherapy. However, the construction of multimodal treatment nanoplatforms often involves various functional components, leading to certain challenges, such as time-consuming synthesis processes, low product yield, and inadequate biocompatibility. To address these issues, we have developed a straightforward method for preparing ultrathin Cu9S5 nanosheets (NSs) with surface defects for photothermal/photodynamic/chemodynamic therapy. The ultrathin morphology of the Cu9S5 NSs (with 2-3 nm) not only confers excellent biocompatibility but also enables broad-spectrum absorption with a remarkable photothermal conversion efficiency (58.96%) under 1064 nm laser irradiation. Moreover, due to the presence of a S vacancy, these Cu9S5 NSs exhibit favorable enzyme-like properties, including reactive oxygen species generation and glutathione consumption, particularly under laser irradiation. The efficacy of related tumor therapy and antibacterial treatment is significantly enhanced by the synergistic activation of photothermal/photodynamic/chemodynamic therapy through 1064 nm laser irradiation, as demonstrated by both in vitro and in vivo experiments. This study presents a novel strategy for multimodal tumor therapy with the prepared ultrathin Cu9S5 NSs, which holds promising pathways for photodynamic therapy in the NIR-II region.

Large-scale synthesis, mechanism, and application of a luminescent copper hydride nanocluster.

Elucidating the structure-property relationships of ultra-small metal nanocluster with basic nuclear is of great significance for understanding the evolution mechanism in both the structures and properties of polynuclear metal nanoclusters. In this study, an ultra-small copper hydride (CuH for short) nanocluster was simply synthesized with high yield, and the large-scale preparation was also achieved. Single crystal X-ray diffractometer (SC-XRD) analysis shows that this copper NC contains a tetrahedral Cu4 core co-capped by four PPh2Py ligands and two Cl in which the existence of the central H atom in tetrahedron was further identified experimentally and theoretically. This CuH nanocluster exhibits bright yellow emission, which is proved to be the mixture of phosphorescence and fluorescence by the sensitivity of both emission intensity and lifetime to O2. Furthermore, the temperature-dependent emission spectra and density functional theory (DFT) calculations suggest that the luminescence of CuH mainly originates from the metal-to-ligand charge transfer and cluster-centered triplet excited states. This work offers new insights into understanding the structure-property relationship of basic nuclear CuH nanocluster.

Biosynthesis of Vanillin by Rational Design of Enoyl-CoA Hydratase/Lyase.

Vanillin holds significant importance as a flavoring agent in various industries, including food, pharmaceuticals, and cosmetics. The CoA-dependent pathway for the biosynthesis of vanillin from ferulic acid involved feruloyl-CoA synthase (Fcs) and enoyl-CoA hydratase/lyase (Ech). In this research, the Fcs and Ech were derived from Streptomyces sp. strain V-1. The sequence conservation and structural features of Ech were analyzed by computational techniques including sequence alignment and molecular dynamics simulation. After detailed study for the major binding modes and key amino acid residues between Ech and substrates, a series of mutations (F74W, A130G, A130G/T132S, R147Q, Q255R, ΔT90, ΔTGPEIL, ΔN1-11, ΔC260-287) were obtained by rational design. Finally, the yield of vanillin produced by these mutants was verified by whole-cell catalysis. The results indicated that three mutants, F74W, Q147R, and ΔN1-11, showed higher yields than wild-type Ech. Molecular dynamics simulations and residue energy decomposition identified the basic residues K37, R38, K561, and R564 as the key residues affecting the free energy of binding between Ech and feruloyl-coenzyme A (FCA). The large changes in electrostatic interacting and polar solvating energies caused by the mutations may lead to decreased enzyme activity. This study provides important theoretical guidance as well as experimental data for the biosynthetic pathway of vanillin.

Short-term legacy effects of long-term nitrogen and water addition on soil chemical properties and micro-bial characteristics in a temperate grassland.

Nitrogen deposition and summer precipitation in eastern Inner Mongolia are predicted to increase in recent decades. However, such increases in nitrogen inputs and precipitation may not be continuous under the future new patterns of global change, with the direction and magnitude of which may change or weaken. The legacy effects of nitrogen and water addition after cessation on ecosystems are still unclear. Based on a 13-year nitrogen and water addition experiment in temperate grassland of northern China, we examined the short-term (2 years) legacy effects of historical nitrogen and water addition on soil physicochemical properties and microbial properties after the cessation of nitrogen and water addition in the 14th year. The results showed that the positive effects of historical nitrogen addition on most of soil nutrient variables diminished after two years of cessation, including ammonium nitrogen, nitrate nitrogen, dissolved organic carbon and nitrogen, and Olsen-P concentrations. In contrast, there were legacy effects on soil microbial characteristics. For example, the historical nitrogen input of 15 g N·m-2·a-1 reduced microbial biomass carbon, respiration, and alkaline phosphomonoesterase activity by 73.3%, 81.9%, and 70.3% respectively. It implied that microbial parameters restored slowly in comparison with soil nutrients, showing a hysteresis effect. Results of Pearson's correlation and redundancy analysis showed that the legacy effects of historical nitrogen addition on microbial parameters could be attributed to the negative effects of nitrogen addition on soil pH. Historical water addition showed significant legacy effects on soil pH, ammonium nitrogen, dissolved organic carbon and nitrogen, respiration, and soil enzyme activities, which significantly interacted with historical nitrogen addition. These results are of great significance to predict the changes in grassland ecosystem functions and services under the local environmental improvement conditions, and to reveal the restoration mechanism of degraded grassland.

Self-Assembly of a Linear-Dendritic Polymer Containing Cisplatin and Norcantharidin into Raspberry-like Multimicelle Clusters for the Efficient Chemotherapy of Liver Cancer.

Combination chemotherapy has been proved to be an effective strategy in the clinic, and nanoformulations have drawn much attention in the field of drug delivery. However, conventional nanocarriers suffer from shortcomings such as inefficient coloading and undesired molar ratios of the combined drugs, preleakage of cargos during systemic circulation, and lack of cancer-selective drug release. To achieve tumor-specific codelivery of cisplatin (CDDP) and norcantharidin (NCTD) for synergistic treatment of liver cancer, a novel linear-dendritic polymer, termed as G1(PPDC)x, was designed and synthesized, where a prodrug consisting of cisplatin (CDDP) and norcantharidin (NCTD) was conjugated to PEG2000 via ester bonds to fabricate linear polymer-drug conjugates, and the conjugates were subsequently grafted to the terminal hydroxyls of a dendritic polycarbonate core. Benefiting from the hydrogen bond interactions, G1(PPDC)x could spontaneously self-assemble into a unique type of raspberry-like multimicelle clusters in solution (G1(PPDC)x-PMs). G1(PPDC)x-PMs possessed an optimal synergistic ratio of CDDP and NCTD, without obvious premature release or disassembly in biological environments. Intriguingly, upon extravasation into the interstitial tumor tissues, G1(PPDC)x-PMs (132 nm in diameter) could disassemble and reassemble into smaller micelles (40 nm in diameter) in response to the mildly acidic tumor microenvironment, which would enhance the deep tumor penetration and cellular accumulation of drugs. In vivo delivery of G1(PPDC)x-PMs led to a significantly prolonged blood circulation half-life, which is beneficial to achieve sufficient tumor accumulation through the enhanced permeability and retention (EPR) effect. G1(PPDC)x-PMs displayed the best antitumor activity in H22 tumor-bearing mice with a tumor inhibition rate of 78.87%. Meanwhile, G1(PPDC)x-PMs alleviated both myelosuppression toxicities of CDDP and vascular irritation of NCTD. Our results demonstrated that G1(PPDC)x-PMs could serve as an effective drug delivery system for codelivery of CDDP and NCTD to treat liver cancer efficiently.

Synergistic Antibacterial Activity of Benzalkonium Bromide and Cu-Bearing Duplex Stainless Steel against Pseudomonas aeruginosa.

The bactericide benzalkonium bromide is widely used to kill Pseudomonas aeruginosa, which causes microbiologically influenced corrosion (MIC). However, the extensive use of benzalkonium bromide will enhance bacterial drug resistance and cause environmental pollution. In this study, benzalkonium bromide combined with Cu-bearing 2205 duplex stainless steel (2205-Cu DSS) was used to kill Pseudomonas aeruginosa; the germicidal rate of the combination of benzalkonium bromide and 2205-Cu DSS was 24.2% higher than that of using benzalkonium bromide alone, after five days. The antibacterial efficacy was evaluated using an antibacterial test and biofilm observation. The results showed that, in the presence of P. aeruginosa, the combination of 23.44 ppm benzalkonium bromide and 2205-Cu DSS showed the best antibacterial efficacy.

[Sleep deprivation aggravates cognitive impairment in septic rats by activating neuronal glycolytic isoenzyme PFKFB3].

OBJECTIVE: To evaluate the effect of sleep deprivation on cognitive function in septic rats and its relationship with neuronal glycolysis isoenzyme phosphofructokinase-2/fructose-2, 6-diphosphatase 3 (PFKFB3). METHODS: Fifty-six healthy male Sprague-Dawley (SD) rats were randomly divided into 4 groups (n = 14): control group (Con group), sepsis group (LPS group), sepsis+sleep deprivation group (LPS+SD group), sepsis+sleep deprivation+glycolysis inhibitor 3-PO treatment group (LPS+SD+3-PO group). The sepsis model was established by intraperitoneal injection of lipopolysaccharide (LPS) 10 mg/kg. Rats in LPS+SD group were treated with sleep deprivation using a sleep deprivation instrument 24 hours after LPS injection. The LPS+SD+3-PO group was intraperitoneally injected with LPS for 24 hours, and then injected with 3-PO 50 mg/kg, followed by sleep deprivation. Novel object recognition experiments were performed 72 hours after LPS injection. Subsequently, blood and brain tissue samples were collected. The contents of lactate (Lac), reactive oxygen species (ROS) and serum tumor necrosis factor-α (TNF-α), neuron-specific enolase (NSE), pyruvate in brain tissue were detected by enzyme-linked immunosorbent assay (ELISA). Then, the lactate/pyruvate ratio was calculated. Na+-K+-ATPase activity in brain tissue was detected by colorimetry. Morphological changes in hippocampus were detected by hematoxylin-eosin (HE) staining. And the protein expression levels of PFKFB3, ZO-1 and cleaved caspase-3 were measured by Western blotting. RESULTS: Compared with Con group, the novel object recognition index of LPS group was decreased, the levels of NSE, TNF-α, lactate/pyruvate ratio in serum and the levels of Lac, ROS and dry-wet weight ratio in brain tissue were significantly increased, Na+-K+-ATPase activity in brain tissue was decreased, the protein expressions of PFKFB3, caspase-3 were up-regulated, ZO-1 expression was down-regulated, and the neurons in hippocampus were slightly degenerated. Compared with LPS group, the novel object recognition index of LPS+SD group was further decreased [(39.4±5.3)% vs. (54.5±7.6)%)], serum NSE, TNF-α, lactate/pyruvate ratio and brain tissue Lac, ROS, dry-wet weight ratio were further increased [NSE (µg/L): 3.21±0.42 vs. 2.55±0.36, TNF-α (ng/L): 139.4±19.7 vs. 92.2±13.5, lactate/pyruvate ratio: 29.7±5.5 vs. 19.2±4.2, Lac (µmol/g): 19.51±2.33 vs. 11.34±1.52, ROS (kU/g): 117.4±18.7 vs. 78.2±11.8, dry-wet weight ratio: (81.3±9.2)% vs. (64.3±6.6)%], and Na+-K+-ATPase activity was further decreased (mmol×L-1×h-1: 1.88±0.34 vs. 2.91±0.39), the protein expressions of PFKFB3, caspase-3 were further up-regulated and ZO-1 expression was further down-regulated (PFKFB3/ß-actin: 0.80±0.11 vs. 0.45±0.07, caspase-3/ß-actin: 0.71±0.09 vs. 0.37±0.05, ZO-1/ß-actin: 0.31±0.05 vs. 0.61±0.08). The differences were statistically significant (all P < 0.05). HE staining showed that the degeneration of neurons in hippocampus was significantly aggravated. Compared with LPS+SD group, the novel object recognition index of LPS+SD+3-PO group was increased [(50.8±5.9)% vs. (39.4±5.3)%], NSE, TNF-α, lactate/pyruvate ratio of serum and Lac, ROS, dry-wet weight ratio of brain tissue were significantly decreased [NSE (µg/L): 2.60±0.33 vs. 3.21±0.42, TNF-α (ng/L): 103.7±18.3 vs. 139.4±19.7, lactate/pyruvate ratio: 17.4±5.1 vs. 29.7±5.5, Lac (µmol/g): 13.68±2.02 vs. 19.51±2.33, ROS (kU/g): 86.9±14.5 vs. 117.4±18.7, dry-wet weight ratio: (67.7±6.9)% vs. (81.3±9.2)%], and Na+-K+-ATPase activity was increased (mmol×L-1×h-1: 2.82±0.44 vs. 1.88±0.34). The protein expressions of PFKFB3, caspase-3 were down-regulated and ZO-1 expression was up-regulated (PFKFB3/ß-actin: 0.50±0.06 vs. 0.80±0.11, caspase-3/ß-actin: 0.43±0.06 vs. 0.71±0.09, ZO-1/ß-actin: 0.52±0.06 vs. 0.31±0.05). The differences were statistically significant (all P < 0.05). HE staining showed that the degeneration of neurons in hippocampus was significantly improved. CONCLUSIONS: Sleep deprivation could aggravate neuroinflammation, neuronal degeneration and apoptosis in septic rats, resulting in destruction of blood-brain barrier and cognitive impairment. 3-PO treatment significantly alleviate the injury and degeneration of hippocampal neurons in septic rats, inhibit neuroinflammation and apoptosis, and improve cognitive dysfunction, which may be related to the inhibition of glycolytic isoenzyme PFKFB3.

Scorpion Neurotoxin Syb-prII-1 Exerts Analgesic Effect through Nav1.8 Channel and MAPKs Pathway.

Trigeminal neuralgia (TN) is a common type of peripheral neuralgia in clinical practice, which is usually difficult to cure. Common analgesic drugs are difficult for achieving the desired analgesic effect. Syb-prII-1 is a ß-type scorpion neurotoxin isolated from the scorpion venom of Buthus martensi Karsch (BmK). It has an important influence on the voltage-gated sodium channel (VGSCs), especially closely related to Nav1.8 and Nav1.9. To explore whether Syb-prII-1 has a good analgesic effect on TN, we established the Sprague Dawley (SD) rats' chronic constriction injury of the infraorbital nerve (IoN-CCI) model. Behavioral, electrophysiological, Western blot, and other methods were used to verify the model. It was found that Syb-prII-1 could significantly relieve the pain behavior of IoN-CCI rats. After Syb-prII-1 was given, the phosphorylation level of the mitogen-activated protein kinases (MAPKs) pathway showed a dose-dependent decrease after IoN-CCI injury. Moreover, Syb-prII-1(4.0 mg/kg) could significantly change the steady-state activation and inactivation curves of Nav1.8. The steady-state activation and inactivation curves of Nav1.9 were similar to those of Nav1.8, but there was no significant difference. It was speculated that it might play an auxiliary role. The binding mode, critical residues, and specific interaction type of Syb-prII-1 and VSD2rNav1.8 were clarified with computational simulation methods. Our results indicated that Syb-prII-1 could provide a potential treatment for TN by acting on the Nav1.8 target.

Au nanocluster-modulated macrophage polarization and synoviocyte apoptosis for enhanced rheumatoid arthritis treatment.

The persistent progression of synovial inflammation and cartilage destruction contributes to the crosstalk between pro-inflammatory macrophages and activated fibroblast-like synoviocytes (FLSs) in a synovial microenvironment. In this work, structurally well-defined Au25 nanoclusters were synthesized to induce phenotypic polarization of pro-inflammatory macrophages and apoptosis of activated FLSs for enhanced rheumatoid arthritis treatment. These ultra-small nanoclusters significantly modulated phenotypic polarization of a pro-inflammatory M1 phenotype to an anti-inflammatory phenotype M2 for relieving inflammation. Additionally, Au25 nanoclusters can efficiently activate reactive oxygen species (ROS)-mediated apoptotic signaling pathways by inactivating thioredoxin reductase (TrxR), resulting in imbalance of the cellular redox homeostasis and initiation of FLS apoptosis. In an adjuvant-induced arthritis rat model, Au25 nanoclusters efficiently ameliorated the hyperplasia of the synovium and reduced inflammatory cell infiltration with negligible side effects. This study provided a new insight into Au nanoclusters for treating rheumatoid arthritis.

Mitochondrial HSF1 triggers mitochondrial dysfunction and neurodegeneration in Huntington's disease.

Aberrant localization of proteins to mitochondria disturbs mitochondrial function and contributes to the pathogenesis of Huntington's disease (HD). However, the crucial factors and the molecular mechanisms remain elusive. Here, we found that heat shock transcription factor 1 (HSF1) accumulates in the mitochondria of HD cell models, a YAC128 mouse model, and human striatal organoids derived from HD induced pluripotent stem cells (iPSCs). Overexpression of mitochondria-targeting HSF1 (mtHSF1) in the striatum causes neurodegeneration and HD-like behavior in mice. Mechanistically, mtHSF1 facilitates mitochondrial fission by activating dynamin-related protein 1 (Drp1) phosphorylation at S616. Moreover, mtHSF1 suppresses single-stranded DNA-binding protein 1 (SSBP1) oligomer formation, which results in mitochondrial DNA (mtDNA) deletion. The suppression of HSF1 mitochondrial localization by DH1, a unique peptide inhibitor, abolishes HSF1-induced mitochondrial abnormalities and ameliorates deficits in an HD animal model and human striatal organoids. Altogether, our findings describe an unsuspected role of HSF1 in contributing to mitochondrial dysfunction, which may provide a promising therapeutic target for HD.

Atomically Precise Au42 Nanorods with Longitudinal Excitons for an Intense Photothermal Effect.

Metallic-state gold nanorods are well known to exhibit strong longitudinal plasmon excitations in the near-infrared region (NIR) suitable for photothermal conversion. However, when the size decreases below ∼2 nm, Au nanostructures become nonmetallic, and whether the longitudinal excitation in plasmonic nanorods can be inherited is unknown. Here, we report atomically precise rod-shaped Au42(SCH2Ph)32 with a hexagonal-close-packed Au20 kernel of aspect ratio as high as 6.2, which exhibits an intense absorption at 815 nm with a high molar absorption coefficient of 1.4 × 105 M-1 cm-1. Compared to other rod-shaped nanoclusters, Au42 possesses a much more effective photothermal conversion with a large temperature increase of ∼27 °C within 5 min (λex = 808 nm, 1 W cm-2) at an ultralow concentration of 50 µg mL-1 in toluene. Density functional theory calculations show that the NIR transition is mainly along the long axis of the Au20 kernel in Au42, i.e., a longitudinal excitonic oscillation, akin to the longitudinal plasmon in metallic-state nanorods. Transient absorption spectroscopy reveals that the fast decay in Au42 is similar to that of shorter-aspect-ratio nanorods but is followed by an additional slow decay with a long lifetime of 2400 ns for the Au42 nanorod. This work provides the first case that an intense longitudinal excitation is obtained in molecular-like nanorods, which can be used as photothermal converters and hold potential in biomedical therapy, photoacoustic imaging, and photocatalysis.

BmK DKK13, A Scorpion Toxin, Alleviates Pain Behavior in a Rat Model of Trigeminal Neuralgia by Modulating Voltage-Gated Sodium Channels and MAPKs/CREB Pathway.

BmK DKK13 (DKK13) is a mutated recombinant peptide, which has a significant antinociception in a rat model of the inflammatory pain. The purpose of this study was to evaluate the antinociceptive effect of DKK13 on trigeminal neuralgia (TN) in rats. Male Sprague-Dawley (SD) rats were treated with the chronic constriction injury of the infraorbital nerve (IoN-CCI) model to induce stable symptoms of TN. DKK13 (1.0 mg/kg, 2.0 mg/kg and 4.0 mg/kg, i.v.) or morphine (4.0 mg/kg, i.v.) was administered by tail vein once on day 14 after IoN-CCI injury. Behavioral tests, electrophysiology and western blotting were performed to investigate the role and underlying mechanisms of DKK13 on IoN-CCI model. Behavioral test results showed that DKK13 could significantly increase the mechanical pain and thermal radiation pain thresholds of IoN-CCI rats and inhibit the asymmetric spontaneous pain scratching behavior. Electrophysiological results showed that DKK13 could significantly reduce the current density of Nav1.8 in the ipsilateral side of trigeminal ganglion (TG) neurons in IoN-CCI rats, and the steady-state activation and inactivation curves of Nav1.8 shifted, respectively, to the direction of hyperpolarization and depolarization. Western blotting results showed that DKK13 significantly reduced the expression of Nav1.8 and the phosphorylation levels of key proteins of MAPKs/CREB pathway in TG tissues of IoN-CCI rats. In brief, DKK13 has a significant antinociceptive effect on IoN-CCI rats, which may be achieved by changing the dynamic characteristics of Nav1.8 channel and regulating the protein phosphorylation in MAPKs/CREB pathway.

Atomic structure of a seed-sized gold nanoprism.

The growth of nanoparticles along one or two directions leads to anisotropic nanoparticles, but the nucleation (i.e., the formation of small seeds of specific shape) has long been elusive. Here, we show the total structure of a seed-sized Au56 nanoprism, in which the side Au{100} facets are surrounded by bridging thiolates, whereas the top/bottom {111} facets are capped by phosphine ligands at the corners and Br- at the center. The bromide has been proved to be the key to effectively stabilize the Au{111} to fulfill a complete face-centered-cubic core. In femtosecond electron dynamics analysis, the non-evolution of transient absorption spectra of Au56 is similar to that of larger-sized gold nanoclusters (n > 100), which is ascribed to the completeness of the prismatic Au56 core and an effective electron relaxation pathway created by the stronger Au-Au bonds inside. This work provides some insights for the understanding of plasmonic nanoprism formation.

Optical Activity from Anisotropic-Nanocluster-Assembled Supercrystals in Achiral Crystallographic Point Groups.

Accomplishing optical activity in achiral materials has long been a challenge. Achiral nanomaterials that crystallize in achiral point groups are generally optically inactive. Herein we report the surprising observation of optical activity in several achiral point groups for supercrystals assembled from anisotropic metal nanoclusters with atomic precision. By analyzing multiple achiral nanoclusters with different molecular structures and symmetry space groups, we have identified that the molecular anisotropy of nanocluster entities and their asymmetric arrangement in point groups of supercrystals are the two key factors for the realization of optical activity in such supercrystals. We have further exploited the polarization effect of the nanocluster supercrystals as a polarization switch that can alter the polarized state of the linearly polarized light. Our findings have broadened the fundamental principles for producing nanomaterial-based optical activity and devices with polarization effects.

Exploring the Pivotal Components Influencing the Side Effects Induced by an Analgesic-Antitumor Peptide from Scorpion Venom on Human Voltage-Gated Sodium Channels 1.4 and 1.5 through Computational Simulation.

Voltage-gated sodium channels (VGSCs, or Nav) are important determinants of action potential generation and propagation. Efforts are underway to develop medicines targeting different channel subtypes for the treatment of related channelopathies. However, a high degree of conservation across its nine subtypes could lead to the off-target adverse effects on skeletal and cardiac muscles due to acting on primary skeletal muscle sodium channel Nav1.4 and cardiac muscle sodium channel Nav1.5, respectively. For a long evolutionary process, some peptide toxins from venoms have been found to be highly potent yet selective on ion channel subtypes and, therefore, hold the promising potential to be developed into therapeutic agents. In this research, all-atom molecular dynamic methods were used to elucidate the selective mechanisms of an analgesic-antitumor ß-scorpion toxin (AGAP) with human Nav1.4 and Nav1.5 in order to unravel the primary reason for the production of its adverse reactions on the skeletal and cardiac muscles. Our results suggest that the rational distribution of residues with ring structures near position 38 and positive residues in the C-terminal on AGAP are critical factors to ensure its analgesic efficacy. Moreover, the substitution for residues with benzene is beneficial to reduce its side effects.

Effect of single electrons on the excited state dynamics of rod-shaped Au25 nanoclusters.

The excited state dynamics of small-sized metal nanoclusters are dependent on their crystal structures, while the effect of the charge state remains largely unknown. Here, we report the influence of single electrons on the excited-state dynamics of non-superatom Au clusters by comparing the transient absorption isotropy and anisotropy dynamics of two rod-shaped Au25 nanoclusters protected by organic ligands. Two decay lifetimes (0.9 ps and 2.3 µs) can be identified in the excited state relaxation of Au252+ rods, which are assigned to the internal conversion from a higher to lower excited state and the relaxation to the ground state, respectively. With the addition of one electron, an additional 660 ps decay is observed in Au25+, which should originate from the presence of a single electron occupied molecular orbital. Transient anisotropy measurements reveal a 500 ps rotational diffusion process in both the nanoclusters, while the initial dipole moment orientation is found to be highly dependent on the charge state. These results are of importance to understanding the effect of the charge state on the optical properties of metal nanoclusters.

A double helical 4H assembly pattern with secondary hierarchical complexity in an Ag70 nanocluster crystal.

The hierarchical assemblies of well-defined structural nanoclusters can help to better understand those of biologically important molecules such as DNA and proteins. Herein, we disclose the synthesis and characterization of a new silver nanocluster, that is Ag70(SR)42(PPh3)5 (Ag70-TPP). Directed by the ligands, Ag70-TPP nanoclusters undergo self-hierarchical assembly into a highly space-efficient complex secondary structure of a double helical 4H (DH4H) close packing pattern. The chirality of Ag70-TPP, and the van der Waals forces interactions between the ligands are believed to drive its DH4H arrangement, and the observed interlocking of the phosphine ligands of adjacent Ag70-TPP nanoclusters also contributed. Overall, this work has yielded important and unprecedented insights into the internal structure and crystallographic arrangement of nanoclusters.