Extraordinary phase transition revealed in a van der Waals antiferromagnet.

While the surface-bulk correspondence has been ubiquitously shown in topological phases, the relationship between surface and bulk in Landau-like phases is much less explored. Theoretical investigations since 1970s for semi-infinite systems have predicted the possibility of the surface order emerging at a higher temperature than the bulk, clearly illustrating a counterintuitive situation and greatly enriching phase transitions. But experimental realizations of this prediction remain missing. Here, we demonstrate the higher-temperature surface and lower-temperature bulk phase transitions in CrSBr, a van der Waals (vdW) layered antiferromagnet. We leverage the surface sensitivity of electric dipole second harmonic generation (SHG) to resolve surface magnetism, the bulk nature of electric quadrupole SHG to probe bulk spin correlations, and their interference to capture the two magnetic domain states. Our density functional theory calculations show the suppression of ferromagnetic-antiferromagnetic competition at the surface is responsible for this enhanced surface magnetism. Our results not only show counterintuitive, richer phase transitions in vdW magnets, but also provide viable ways to enhance magnetism in their 2D form.

Large oscillatory thermal hall effect in kagome metals.

The thermal Hall effect recently provided intriguing probes to the ground state of exotic quantum matters. These observations of transverse thermal Hall signals lead to the debate on the fermionic versus bosonic origins of these phenomena. The recent report of quantum oscillations (QOs) in Kitaev spin liquid points to a possible resolution. The Landau level quantization would most likely capture only the fermionic thermal transport effect. However, the QOs in the thermal Hall effect are generally hard to detect. In this work, we report the observation of a large oscillatory thermal Hall effect of correlated Kagome metals. We detect a 180-degree phase change of the oscillation and demonstrate the phase flip as an essential feature for QOs in the thermal transport properties. More importantly, the QOs in the thermal Hall channel are more profound than those in the electrical Hall channel, which strongly violates the Wiedemann-Franz (WF) law for QOs. This result presents the oscillatory thermal Hall effect as a powerful probe to the correlated quantum materials.

Quantum oscillations evidence for topological bands in kagome metal ScV6Sn6.

Metals with kagome lattice provide bulk materials to host both the flat-band and Dirac electronic dispersions. A new family of kagome metals is recently discovered inAV6Sn6. The Dirac electronic structures of this material needs more experimental evidence to confirm. In the manuscript, we investigate this problem by resolving the quantum oscillations in both electrical transport and magnetization in ScV6Sn6. The revealed orbits are consistent with the electronic band structure models. Furthermore, the Berry phase of a dominating orbit is revealed to be aroundπ, providing direct evidence for the topological band structure, which is consistent with calculations. Our results demonstrate a rich physics and shed light on the correlated topological ground state of this kagome metal.

A novel tumor immunotherapy-related signature for risk stratification, prognosis prediction, and immune status in hepatocellular carcinoma.

Immunotherapy as a strategy to deal with cancer is increasingly being used clinically, especially in hepatocellular carcinoma (HCC). We aim to create an immunotherapy-related signature that can play a role in predicting HCC patients' survival and therapeutic outcomes. Immunotherapy-related genes were discovered first. Clinical information and gene expression data were extracted from GSE140901. By a series of bioinformatics methods to analyze, overlapping genes were used to build an immunotherapy-related signature that could contribute to predict both the prognosis of people with hepatocellular carcinoma and responder to immune checkpoint blockade therapy of them in TCGA database. Differences of the two groups in immune cell subpopulations were then compared. Furthermore, A nomogram was constructed, based on the immunotherapy-related signature and clinicopathological features, and proved to be highly predictive. Finally, immunohistochemistry assays were performed in HCC tissue and normal tissue adjacent tumors to verify the differences of the four genes expression. As a result of this study, a prognostic protein profile associated with immunotherapy had been created, which could be applied to predict patients' response to immunotherapy and may provide a new perspective as clinicians focus on non-apoptotic treatment for patients with HCC.

Resonant torque differential magnetometry with high frequency quartz oscillators.

Sensitive magnetometry has been a powerful probe for investigating quantum materials. Extreme conditions, such as sub-kelvin cryogenic temperatures and ultrahigh magnetic fields, demand further durability for sensitive magnetometry. However, significant mechanical vibrations and rapid magnetic field changes give enormous challenges to conventional magnetometry. This article presents a possible solution to this problem by developing a new magnetometry technique using high-frequency quartz oscillators. The technique takes advantage of the symmetry and geometry of mechanical vibration configurations of standard commercially available MHz quartz oscillators, and the setup keeps the high quality factor resonance with the sample mounted on the oscillator. We further demonstrate the sensitivity of the technique using bismuth single crystals and a Fe0.25TaS2 ferromagnetic material. Quantum oscillations are observed in the magnetometry response below 1 T, and the detected oscillation frequency is shown to come from the electron pockets of the bismuth.

Neuroprotective effects of maize tetrapeptide-anchored gold nanoparticles in Alzheimer's disease.

Nanopeptide assembled from peptide-anchored nanoparticles possess an enormous research potential in the field of cellular medicine and disease treatment. The aim of this study was to explore the neuroprotective effects of maize tetrapeptide anchored gold nanoparticles against l-glutamic acid-induced PC12 cell apoptosis and a murine Alzheimer's disease model induced by aluminum chloride and d-galactose. The results revealed that the nanopeptide antioxidant inhibited intracellular ROS accumulation and promoted cell differentiation than that of maize bioactive tetrapeptide. Compared with untreated Alzheimer's disease model mice, nanopeptide administration shortened the escape latency time in a water maze test and improved the movements in the autonomic activity test. After 16 days of nanopeptide administration, the central cholinergic system function of acetylcholine and cholineacetyltransferase were enhanced, and the level of acetylcholinesterase was reduced. It also increased superoxide dismutase and glutathione peroxidase activity in sera and hypothalami. Moreover, nanopeptide treatment upregulated cerebral nuclear factor erythroid 2-related factor 2 and heme-oxygenase-1 and downregulated kelch-like ECH-associated protein 1 relative to untreated Alzheimer's disease model mice. Thus, the novel nanopeptide is expected to be used as the neuroprotective agent to prevent Alzheimer's disease.

Multiple magnetic phase transitions, electrical and optical properties of FeTe2 single crystals.

Single-crystalline FeTe2 in marcasite phase with orthorhombic structure was prepared via chemical vapor transport. Cooling FeTe2 single crystals from room temperature down to [Formula: see text], multiple magnetic phase transitions were observed. Paramagnetic (PM) to antiferromagnetic (AFM) and then to ferromagnetic (FM) occurred at [Formula: see text] and [Formula: see text] for in-plane, [Formula: see text] and [Formula: see text] for out-of-plane, respectively. A strong uniaxial magnetic anisotropy was found due to FeTe6 octahedron distortion and structural modulation in FM region. The novel negative volume expansion (NVE) initiated in the vicinity of AFM to FM transition. An abrupt frequency shift of the most intense mode at [Formula: see text] and evolution of the Te-Te stretching mode near [Formula: see text], corresponding to the phase transition from AFM to FM were observed. The temperature-dependent resistance revealed an anomaly (semiconductor to metallic transition) around AFM-FM transition, which can easily be suppressed and move to high temperature by the applied magnetic field. The results from XRD, Raman and resistivity indicated that the structural parameters, vibration frequency and transport are sensitive to the phase transition from AFM to FM. The nature of direct band gap with [Formula: see text] was identified through UV-Vis-NIR spectrum of FeTe2 single crystals at room temperature.

Enhanced thermal effect of plasmonic nanostructures confined in discoidal porous silicon particles.

The design of plasmonic nanostructures could have many exciting applications since it enhances or provides valuable control over efficient energy conversion. A three-dimensional (3D) space is a realistic hotspot matrix harvesting a wide conversion that has been shown in zero-dimensional nanoparticles, one-dimensional linear structures, or two-dimensional films. A novel 3D plasmonic nanostructure platform consisting of plasmonic metal nanoparticles in discoidal porous silicon particles is used in this study. Plasmonic gold nanoparticles are anchored inside the discoidal porous silicon (DPS) particles by in situ reduction synthesis. The novel plasmonic nanostructures can tailor the plasmon band and overcome the instability of photothermal materials. The "trapping well" for the anchored nanoparticles in 3D space can result in a huge change of plasmonic band of metal nanoparticles to the near-IR region in a novel 3D geometry. A multifunctional scaffold, Au-DPS particle, composed of doxorubicin conjugated to poly-(l-glutamic acid) (pDOX), was developed for combinatorial chemo-photothermal cancer therapy. The therapeutic efficacy was examined in treatment of the A549 cell line under near-IR laser irradiation. The highly efficient photothermal conversion can also be demonstrated in the laser desorption/ionization time-of-flight mass spectrometry detection analysis. The limit of detection was obviously improved in the detection of angiotensin II, P14R, and ACTH fragments 18-39 peptides. Overall, we envision that Au-DPS particles may be used in ultrasensitive theranostics in the future.

A novel nanozyme based on selenopeptide-modified gold nanoparticles with a tunable glutathione peroxidase activity.

In this study, we successfully prepared a selenium-containing pentapeptide (Sec-Arg-Gly-Asp-Cys)-modified gold nanozyme that exhibited glutathione peroxidase (GPx) activity. The nanozyme catalyzed the reduction of H2O2 by GSH, and its GPx activity was about 14 times that of free selenopeptide. Kinetic analysis indicated that the nanozyme changed the catalytic mechanism from the ping-pong mechanism of the peptide to an ordered mechanism. This indicated that the gold nanoparticle acts as a scaffold that may limit the mobility and constrain the conformation of the peptides, hence exposing the active center to the substrates, and allowing the multivalent selenopeptide to act cooperatively to increase the catalytic rate. Furthermore, upon addition of cysteamine to regulate the surface chemistry of gold nanoparticles and thereby modify the microenvironment of the active center, this nanozyme system could achieve a tunable GPx activity that was about 20 times that of free selenopeptide. Thus, the rational design of the nanozyme greatly improved and amplified the catalytic activity of the 'active unit' peptide. This study provides an alternative strategy to establish GPx mimics and provides new insights for the use of gold nanoparticles to develop nanozymes with biological applications.

Microfluidic device for the analysis of MDR cancerous cell-derived exosomes' response to nanotherapy.

Exosomes are membrane-enclosed extracellular vesicles which have been indicated as important biomarkers of cancerous cell functionality, such as multiple drug resistance (MDR). Nanoparticles based chemotherapy is a promising strategy to overcome MDR by interfering the production and composition of exosomes. Therefore, tumor-derived exosomes post-treatment by nanotherapy are implied to play critical roles of biomarkers on cancer MDR analysis. However, the efficient isolation of such exosomes from extracellular environment for their therapeutic response analysis remains challenging. In this study, we presented a microfluidic device featured exosome specific anti-CD63 immobilized ciliated micropillars, which were capable to isolate cancer-derived exosomes from cell culture medium. The captured exosomes can be recovered intact by dissolving the cilia on the micropillars using PBS soaking. Owing to the immobilized antibody in the microfluidic device, nearly 70% of exosome from the biofluid could be isolated. So the secreted exosomes of the MDR and ordinary human breast cancer cells pre-treated by free drug or nanotherapy could be isolated with high purity. The drug contents of the isolated exosomes were measured to analysis of the exosomal pathway response of MDR cells to different chemotherapeutic formulations. Such analyses and further definition of the biomarkers of these exosomes could benefit the future investigations of accurately and reliably determine design principle, functional activity, and mechanisms of nanotherapy for MDR overcoming.

Chemotherapy Sensitizes Therapy-Resistant Cells to Mild Hyperthermia by Suppressing Heat Shock Protein 27 Expression in Triple-Negative Breast Cancer.

Purpose: Triple-negative breast cancer (TNBC) is a clinically aggressive disease with poor prognosis. Conventional chemotherapeutics are generally able to shrink the tumor mass, but often fail to completely eradicate cancer stem-like cells (CSCs) that are responsible for high risk of relapse and frequent metastases. In this study, we examined thermal sensibility of CSCs, developed an approach that enabled concurrent elimination of both the bulk of cancer cells and CSCs, and investigated the underlying mechanism.Experimental Design: We designed a platform consisting of gold nanoparticle-coated porous silicon microparticle (AuPSM) that was also loaded with docetaxel micelles (mDTXs) to enable concurrent killing of the bulk of cancer cells by released mDTX and CSCs by mild hyperthermia upon stimulation of AuPSM with near infrared. In addition, we examined the role of heat shock proteins in sensitizing CSC killing. Finally, we applied mDTX-loaded AuPSM to treat mice with SUM159 and 4T1 orthotopic tumors and evaluated tumor growth and tumor metastasis.Results: MDA-MB-231 and SUM159 TNBC cells treated with mDTX-loaded AuPSM and mild hyperthermia displayed significantly reduced efficiencies in mammosphere formation than those treated with mDTX alone or mild hyperthermia alone. Combination treatment also completely inhibited SUM159 orthotopic tumor growth and 4T1 tumor metastasis. Mechanistically, DTX treatment suppressed expression of heat shock protein 27 in cancer cells including the CSCs, rendering cells sensitive to mild hyperthermia.Conclusions: Our results indicate that chemotherapy sensitizes CSC to mild hyperthermia. We have developed an effective therapeutic approach to eliminate therapy-resistant cells in TNBC. Clin Cancer Res; 24(19); 4900-12. ©2018 AACR.

Silver-Nanoparticle-Embedded Porous Silicon Disks Enabled SERS Signal Amplification for Selective Glutathione Detection.

As the major redox couple and nonprotein thiol source in human tissues, the level of glutathione (GSH) has been a concern for its relation with many diseases. However, the similar physical and chemical properties of interference molecules such as cysteine (Cys) and homocysteine (Hcy) make discriminative detection of GSH in complex biological fluids challenging. Here we report a novel surface-enhanced Raman scattering (SERS) platform, based on silver-nanoparticle-embedded porous silicon disks (PSDs/Ag) substrates for highly sensitive and selective detection of GSH in biofluids. Silver nanoparticles (AgNPs) were reductively synthesized and aggregated directly into pores of PSDs, achieving a SERS enhancement factor (EF) up to 2.59 × 107. Ellman's reagent 5,5'-ditho-bis (2-nitrobenzoic acid) (DTNB) was selected as the Raman reactive reporting agent, and the GSH quantification was determined using enzymatic recycling method, and allowed the detection limit of GSH to be down to 74.9 nM using a portable Raman spectrometer. Moreover, the significantly overwhelmed enhancement ratio of GSH over other substances enables the discrimination of GSH detection in complex biofluids.

In Situ Reductive Synthesis of Structural Supported Gold Nanorods in Porous Silicon Particles for Multifunctional Nanovectors.

Porous silicon nanodisks (PSD) were fabricated by the combination of photolithography and electrochemical etching of silicon. By using PSD as a reducing agent, gold nanorods (AuNR) were in situ synthesized in the nanopores of PSD, forming PSD-supported-AuNR (PSD/AuNR) hybrid particles. The formation mechanism of AuNR in porous silicon (pSi) was revealed by exploring the role of pSi reducibility and each chemical in the reaction. With the PSD support, AuNR exhibited a stable morphology without toxic surface ligands (CTAB). The PSD/AuNR hybrid particles showed enhanced plasmonic property compared to free AuNR. Because high-density "hot spots" can be generated by controlling the distribution of AuNR supported in PSD, surface-enhanced raman scattering (SERS) using PSD/AuNR as particle substrates was demonstrated. A multifunctional vector, PSD/AuNR/DOX, composed of doxorubicin (DOX)-loaded PSD/AuNR capped with agarose (agar), was developed for highly efficient, combinatorial cancer treatment. Their therapeutic efficacy was examined using two pancreatic cancer cell lines, PANC-1 and MIA PaCa-2. PSD/AuNR/DOX (20 µg Au and 1.25 µg DOX/mL) effectively destroyed these cells under near-IR laser irradiation (810 nm, 15 J·cm(-2) power, 90 s). Overall, we envision that PSD/AuNR may be a promising injectable, multifunctional nanovector for biomedical application.