Tailoring chemical composition of solid electrolyte interphase by selective dissolution for long-life micron-sized silicon anode.

Micron-sized Si anode promises a much higher theoretical capacity than the traditional graphite anode and more attractive application prospect compared to its nanoscale counterpart. However, its severe volume expansion during lithiation requires solid electrolyte interphase (SEI) with reinforced mechanical stability. Here, we propose a solvent-induced selective dissolution strategy to in situ regulate the mechanical properties of SEI. By introducing a high-donor-number solvent, gamma-butyrolactone, into conventional electrolytes, low-modulus components of the SEI, such as Li alkyl carbonates, can be selectively dissolved upon cycling, leaving a robust SEI mainly consisting of lithium fluoride and polycarbonates. With this strategy, raw micron-sized Si anode retains 87.5% capacity after 100 cycles at 0.5 C (1500 mA g-1, 25°C), which can be improved to >300 cycles with carbon-coated micron-sized Si anode. Furthermore, the Si||LiNi0.8Co0.1Mn0.1O2 battery using the raw micron-sized Si anode with the selectively dissolved SEI retains 83.7% capacity after 150 cycles at 0.5 C (90 mA g-1). The selective dissolution effect for tailoring the SEI, as well as the corresponding cycling life of the Si anodes, is positively related to the donor number of the solvents, which highlights designing high-donor-number electrolytes as a guideline to tailor the SEI for stabilizing volume-changing alloying-type anodes in high-energy rechargeable batteries.

Controlled Growth of Single-Crystal Graphene Wafers on Twin-Boundary-Free Cu(111) Substrates.

Single-crystal graphene (SCG) wafers are needed to enable mass-electronics and optoelectronics owing to their excellent properties and compatibility with silicon-based technology. Controlled synthesis of high-quality SCG wafers can be done exploiting single-crystal Cu(111) substrates as epitaxial growth substrates recently. However, current Cu(111) films prepared by magnetron sputtering on single-crystal sapphire wafers still suffer from in-plane twin boundaries, which degrade the SCG chemical vapor deposition. Here, it is shown how to eliminate twin boundaries on Cu and achieve 4 in. Cu(111) wafers with ≈95% crystallinity. The introduction of a temperature gradient on Cu films with designed texture during annealing drives abnormal grain growth across the whole Cu wafer. In-plane twin boundaries are eliminated via migration of out-of-plane grain boundaries. SCG wafers grown on the resulting single-crystal Cu(111) substrates exhibit improved crystallinity with >97% aligned graphene domains. As-synthesized SCG wafers exhibit an average carrier mobility up to 7284 cm2 V-1 s-1 at room temperature from 103 devices and a uniform sheet resistance with only 5% deviation in 4 in. region.

Tracking of Protein Adsorption on Poly(l-lactic acid) Film Surfaces: The Role of Molar Mass.

Poly(l-lactic acid) (PLLA) has been extensively utilized as a biomaterial for various biomedical applications. The first and one of the most critical steps upon contact with biological fluids is the adsorption of proteins on the material's surface. Understanding the behavior of protein adsorption is vital for guiding the synthesis and preparation of PLLA for biomedical purposes. In this study, total internal reflection fluorescence microscopy was employed to investigate the adsorption of human serum albumin (HSA) on PLLA films with different molar masses. We found that molar mass affects HSA adsorption in such a way that it affects only the adsorption rate constants, but not the desorption rate constants. Additionally, we observed that HSA adsorption is spatially heterogeneous and exhibits many strong binding sites regardless of the molar mass of the PLLA films. We found that the free volume of PLLA plays a crucial role in determining its water uptake capacity and surface hydration, consequently impacting the adsorption of HSA.

Direct Observation of Topological Phonons in Graphene.

Phonons, as the most fundamental emergent bosons in condensed matter systems, play an essential role in the thermal, mechanical, and electronic properties of crystalline materials. Recently, the concept of topology has been introduced to phonon systems, and the nontrivial topological states also exist in phonons due to the constraint by the crystal symmetry of the space group. Although the classification of various topological phonons has been enriched theoretically, experimental studies were limited to several three-dimensional (3D) single crystals with inelastic x-ray or neutron scatterings. The experimental evidence of topological phonons in two-dimensional (2D) materials is absent. Here, using high-resolution electron energy loss spectroscopy following our theoretical predictions, we directly map out the phonon spectra of the atomically thin graphene in the entire 2D Brillouin zone, and observe two nodal-ring phonons and four Dirac phonons. The closed loops of nodal-ring phonons and the conical structure of Dirac phonons in 2D momentum space are clearly revealed by our measurements, in nice agreement with our theoretical calculations. The ability of 3D mapping (2D momentum space and energy space) of phonon spectra opens up a new avenue to the systematic identification of the topological phononic states. Our work lays a solid foundation for potential applications of topological phonons in superconductivity, dynamic instability, and phonon diode.

Combination of Rapid Intrinsic Activity Measurements and Machine Learning as a Screening Approach for Multicomponent Electrocatalysts.

Machine learning (ML) coupled with quantum chemistry calculations predicts catalyst properties with high accuracy; however, ML approaches in the design of multicomponent catalysts primarily rely on simulation data because obtaining sufficient experimental data in a short time is difficult. Herein, we developed a rapid screening strategy involving nanodroplet-mediated electrodeposition using a carbon nanocorn electrode as the support substrate that enables complete data collection for training artificial intelligence networks in one week. The inert support substrate ensures intrinsic activity measurement and operando characterization of the irreversible reconstruction of multinary alloy particles during the oxygen evolution reaction. Our approach works as a closed loop: catalyst synthesis-in situ measurement and characterization-database construction-ML analysis-catalyst design. Using artificial neural networks, the ML analysis revealed that the entropy values of multicomponent catalysts are proportional to their catalytic activity. The catalytic activities of high-entropy systems with different components varied little, and the overall catalytic activity was greater than that of the medium-low-entropy system. These findings will serve as a guideline for the design of catalysts.

Determination of the preferred epitaxy for III-nitride semiconductors on wet-transferred graphene.

Transferred graphene provides a promising III-nitride semiconductor epitaxial platform for fabricating multifunctional devices beyond the limitation of conventional substrates. Despite its tremendous fundamental and technological importance, it remains an open question on which kind of epitaxy is preferred for single-crystal III-nitrides. Popular answers to this include the remote epitaxy where the III-nitride/graphene interface is coupled by nonchemical bonds, and the quasi-van der Waals epitaxy (quasi-vdWe) where the interface is mainly coupled by covalent bonds. Here, we show the preferred one on wet-transferred graphene is quasi-vdWe. Using aluminum nitride (AlN), a strong polar III-nitride, as an example, we demonstrate that the remote interaction from the graphene/AlN template can inhibit out-of-plane lattice inversion other than in-plane lattice twist of the nuclei, resulting in a polycrystalline AlN film. In contrast, quasi-vdWe always leads to single-crystal film. By answering this long-standing controversy, this work could facilitate the development of III-nitride semiconductor devices on two-dimensional materials such as graphene.

Recognition Imaging of Trace E-cadherins on the Bladder Cancer Cells Surface during Epithelial-Mesenchymal Transition by Force-Distance Curve-Based AFM.

Tumor-associated epithelial-mesenchymal transition (EMT) contains a set of transitional cellular states usually judged by the EMT marker expression. E-cadherin is a down-regulated EMT epithelial marker, and the detection of E-cadherin is challenging on cancer cell surfaces in the middle and late stages of EMT. Here, the trace E-cadherins on the living bladder cancer T24 cell surface during EMT were investigated with force-distance curve-based atomic force microscopy. The results confirmed that T24 cells are still in an intermediate state and can be transferred into the mesenchymal phenotype by long-term TGF-ß1 induction. During EMT, E-cadherins on the T24 cell surface gradually decreased and rarely clustered. E-cadherin is not completely missing, even at the end of EMT, but is too sparse to cluster. This work provides us with a visual understanding of the expression and distribution of trace markers during EMT and a deep comprehension of the indispensable significance of E-cadherin in cancer cells.

Cryptotanshinone-Doped Photothermal Synergistic MXene@PDA Nanosheets with Antibacterial and Anti-Inflammatory Properties for Wound Healing.

Humans are threatened by bacteria and other microorganisms, resulting in countless pathogen-related infections and illnesses. Accumulation of reactive oxygen species (ROS) in infected wounds activates strong inflammatory responses. The overuse of antibiotics has led to increasing bacterial resistance. Therefore, effective ROS scavenging and bactericidal capacity are essential and the advanced development of collaborative therapeutic techniques to combat bacterial infections is needed. Here, this work developes an MXene@polydopamine-cryptotanshinone (MXene@PDA-CPT) antibacterial nanosystem with excellent reactive oxygen and nitrogen species scavenging ability, which effectively inactivates drug-resistant bacteria and biofilms, thereby promoting wound healing. In this system, the adhesion of polydopamine nanoparticles to MXene produced a photothermal synergistic effect and free radical scavenging activity, presenting a promising antibacterial and anti-inflammatory strategy. This nanosystem causes fatal damage to bacterial membranes. The loading of cryptotanshinone further expanded the advantages of the system, causing a stronger bacterial killing effect and inflammation mitigatory effect with desired biosafety and biocompatibility. In addition, combining nanomaterials and active ingredients of traditional Chinese medicine, this work provides a new rationale for the future development of wound dressings, which contributes to eliminating bacterial resistance, delaying disease deterioration, and alleviating the pain of patients.

Revealing the Effect of Photothermal Therapy on Human Breast Cancer Cells: A Combined Study from Mechanical Properties to Membrane HSP70.

Hyperthermia-induced overexpression of heat shock protein 70 (HSP70) leads to the thermoresistance of cancer cells and reduces the efficiency of photothermal therapy (PTT). In contrast, cancer cell-specific membrane-associated HSP70 has been proven to activate antitumor immune responses. The dual effect of HSP70 on cancer cells inspires us that in-depth research of membrane HSP70 (mHSP70) during PTT treatment is essential. In this work, a PTT treatment platform for human breast cancer cells (MCF-7 cells) based on a mPEG-NH2-modified polydopamine (PDA)-coated gold nanorod core-shell structure (GNR@PDA-PEG) is developed. Using the force-distance curve-based atomic force microscopy (FD-based AFM), we gain insight into the PTT-induced changes in the morphology, mechanical properties, and mHSP70 expression and distribution of individual MCF-7 cells with high-resolution at the single-cell level. PTT treatment causes pseudopod contraction of MCF-7 cells and generates a high level of intracellular reactive oxygen species, which severely disrupt the cytoskeleton, leading to a decrease in cellular mechanical properties. The adhesion maps, which are recorded by aptamer A8 functional probes using FD-based AFM, reveal that PTT treatment causes a significant upregulation of mHSP70 expression and it starts to exhibit a partial aggregation distribution on the MCF-7 cell surface. This work not only exemplifies that AFM can be a powerful tool for detecting changes in cancer cells during PTT treatment but also provides a better view for targeting mHSP70 for cancer therapy.

Molecular/Nanomechanical Insights into Electrostimulation-Inhibited Energy Metabolism Mechanisms and Cytoskeleton Damage of Cancer Cells.

Inhibiting energy metabolism of cancer cells is an effective way to treat cancer but remains a great challenge. Herein, electrostimulation (ES) is applied to effectively suppress energy metabolism of cancer cells to induce rapid cell death, and deeply reveal the underlying mechanisms at the molecular and nanomechanical levels by combined use of fluorescence imaging and atomic force microscopy. Cancer cells are found significantly less tolerant to ES than normal cells; and ES causes "domino effect" to induce mitochondrial dysfunction to impede electron transport chain (ETC) and tricarboxylic acid (TCA) cycle pathways, leading to fatal energy-supply crisis and death of cancer cells. From the perspective of cell mechanics, the Young's modulus decreases and cytoskeleton destruction of MCF-7 cell membranes caused by F-actin depolymerization occurs, along with down-regulation and sporadic distribution of glucose transporter 1 (GLUT1) after ES. Such a double whammy renders ES highly effective and promising for potential clinical cancer treatments.

Aptamer conjugated polydopamine-coated gold nanoparticles as a dual-action nanoplatform targeting ß-amyloid peptide for Alzheimer's disease therapy.

The accumulation and deposits of amyloid beta (Aß) peptide are an important pathological hallmark of Alzheimer's disease (AD). The development of multifunctional agents that can effectively clear Aß aggregates is one of the potential strategies to treat AD. Herein, aptamer conjugated polydopamine-coated gold nanoparticles (Au@PDA-Apt NPs) for targeting Aß1-40 peptides were designed. Au@PDA-Apt NPs exhibited a strong capability to inhibit Aß1-40 monomer fibrillization and disaggregate mature Aß1-40 fibrils. In addition, Au@PDA-Apt NPs could effectively alleviate Aß1-40-triggered cytotoxicity. Importantly, AFM quantitative nanomechanical measurements indicated that Au@PDA-Apt NPs could prevent cell membrane damage and decrease of cell mechanical properties caused by Aß1-40 aggregation. Taken together, this study provided a new dual-action nanoplatform for Aß-targeted AD therapy.

Integrated wafer-scale ultra-flat graphene by gradient surface energy modulation.

The integration of large-scale two-dimensional (2D) materials onto semiconductor wafers is highly desirable for advanced electronic devices, but challenges such as transfer-related crack, contamination, wrinkle and doping remain. Here, we developed a generic method by gradient surface energy modulation, leading to a reliable adhesion and release of graphene onto target wafers. The as-obtained wafer-scale graphene exhibited a damage-free, clean, and ultra-flat surface with negligible doping, resulting in uniform sheet resistance with only ~6% deviation. The as-transferred graphene on SiO2/Si exhibited high carrier mobility reaching up ~10,000 cm2 V-1 s-1, with quantum Hall effect (QHE) observed at room temperature. Fractional quantum Hall effect (FQHE) appeared at 1.7 K after encapsulation by h-BN, yielding ultra-high mobility of ~280,000 cm2 V-1 s-1. Integrated wafer-scale graphene thermal emitters exhibited significant broadband emission in near-infrared (NIR) spectrum. Overall, the proposed methodology is promising for future integration of wafer-scale 2D materials in advanced electronics and optoelectronics.

Size-effect on the intracellular antioxidative activity of Prussian blue nanoparticles investigated by atomic force microscopy.

Nanoparticles-based antioxidative therapy has been highlighted in a series of diseases triggered by excessive reactive oxygen species (ROS). Prussian blue nanoparticles (PBNPs), as a representative artificial nanozyme, have been proved as highly effective ROS scavengers. However, its detailed intracellular antioxidant mechanism is not clear yet. Herein, a series of PBNPs with different particle sizes were synthesized and their intracellular antioxidant activities were studied by atomic force microscopy (AFM) from a biomechanical perspective. We first validated the ROS scavenging ability of PBNPs in vitro. It indicated that PBNPs had great scavenging effect on multiple ROS, such as hydroxyl radicals (•OH), superoxide radicals (O2•-) and hydrogen peroxide (H2O2). By observing the changes in morphology and mechanical properties of human umbilical vascular endothelium cells (HUVECs), it was further found that PBNPs could apparently alleviate the decrease of Young's modulus caused by oxidative stress damage and kept cells in their normal morphology. In addition, the distribution of F-actin revealed that the enhancement of cytoskeleton stability by PBNPs might be a key way to protect HUVECs from oxidative damage. Importantly, the antioxidant activities of PBNPs were found to be size-dependent, which indicated the smaller particle size had better antioxidant activities compared with the larger particle size. This study serves as a novel medium to reveal the mechanism of nanoparticles on cells at the single-cell level and demonstrates the great potential of atomic force microscopy in studying the application of nanoparticles in cell biology.

The protective effect of biomineralized BSA-Mn3O4 nanoparticles on HUVECs investigated by atomic force microscopy.

Manganese-based nanozymes have been widely used in the field of cell protection due to their various enzyme-mimicking activities, but their effect on the mechanical properties of cells is not yet known. Here, bovine serum albumin-modified Mn3O4 nanoparticles (BSA-Mn3O4 NPs) with good biocompatibility were synthesized by a one-step biomineralization method using BSA as a template. BSA-Mn3O4 NPs possess scavenging activity against superoxide free radicals (O2˙-), hydroxyl radicals (˙OH) and hydrogen peroxide (H2O2). The excellent reactive oxygen species (ROS) scavenging activity of BSA-Mn3O4 NPs enables them to effectively reduce the intracellular ROS level, thus mitigating the damage of oxidative stress on human umbilical vein endothelial cells (HUVECs). Subsequently, the intracellular antioxidant mechanism of the BSA-Mn3O4 NPs was further investigated. The results show that the BSA-Mn3O4 NPs could inhibit the depolymerization of F-actin, help cells maintain their normal morphology, and reduce the decrease in Young's modulus of cells caused by oxidative stress.

Baicalin Targets HSP70/90 to Regulate PKR/PI3K/AKT/eNOS Signaling Pathways.

Baicalin is a major active ingredient of traditional Chinese medicine Scutellaria baicalensis, and has been shown to have antiviral, anti-inflammatory, and antitumor activities. However, the protein targets of baicalin have remained unclear. Herein, a chemical proteomics strategy was developed by combining baicalin-functionalized magnetic nanoparticles (BCL-N3@MNPs) and quantitative mass spectrometry to identify the target proteins of baicalin. Bioinformatics analysis with the use of Gene Ontology, STRING and Ingenuity Pathway Analysis, was performed to annotate the biological functions and the associated signaling pathways of the baicalin targeting proteins. Fourteen proteins in human embryonic kidney cells were identified to interact with baicalin with various binding affinities. Bioinformatics analysis revealed these proteins are mainly ATP-binding and/or ATPase activity proteins, such as CKB, HSP86, HSP70-1, HSP90, ATPSF1ß and ACTG1, and highly associated with the regulation of the role of PKR in interferon induction and the antiviral response signaling pathway (P = 10-6), PI3K/AKT signaling pathway (P = 10-5) and eNOS signaling pathway (P = 10-4). The results show that baicalin exerts multiply pharmacological functions, such as antiviral, anti-inflammatory, antitumor, and antioxidant functions, through regulating the PKR and PI3K/AKT/eNOS signaling pathways by targeting ATP-binding and ATPase activity proteins. These findings provide a fundamental insight into further studies on the mechanism of action of baicalin.

An Air-Stable High-Nickel Cathode with Reinforced Electrochemical Performance Enabled by Convertible Amorphous Li2 CO3 Modification.

High-nickel (Ni ≥ 90%) cathodes with high specific capacity hold great potential for next-generation lithium-ion batteries (LIBs). However, their practical application is restricted by the high interfacial reactivity under continuous air erosion and electrolyte assault. Herein, a stable high-nickel cathode is rationally designed via in situ induction of a dense amorphous Li2 CO3 on the particle surface by a preemptive atmosphere control. Among the residual lithium compounds, Li2 CO3 is the most thermodynamically stable one, so a dense Li2 CO3 coating layer can serve as a physical protection layer to isolate the cathode from contact with moist air. Furthermore, amorphous Li2 CO3 can be transformed into a robust F-rich cathode electrolyte interphase (CEI) during cycling, which reinforces the cathode's interfacial stability and improves the electrochemical performance. The assembled coin cell with this modified cathode delivers a high discharge capacity of 232.4 mAh g-1 with a superior initial Coulombic efficiency (CE) of 95.1%, and considerable capacity retention of 90.4% after 100 cycles. Furthermore, no slurry gelation occurs during the large-scale electrode fabrication process. This work opens a valuable perspective on the evolution of amorphous Li2 CO3 in LIBs and provides guidance on protecting unstable high-capacity cathodes for energy-storage devices.

Imaging and quantifying analysis the binding behavior of PD-L1 at molecular resolution by atomic force microscopy.

Immunotherapy has emerged as an effective treatment modality for cancer. The interaction of programmed cell death ligand-1 (PD-L1) and programmed cell death protein-1 (PD-1) plays a key role in tumor-related immune escape and has become one of the most extensive targets for immunotherapy. Herein, we investigated the interaction of PD-L1 with its antibody and PD-1 using atomic force microscopy-based single molecule force spectroscopy for the first time. It was found that the PD-L1/anti-PD-L1 antibody complex was easier to dissociate than PD-L1/PD-1. The unbinding forces of specific interaction of PD-L1 on T24 cells with its antibody and PD-1 were quantitatively measured and similar to those on substrate. In addition, the location of PD-L1 on T24 cells was mapped at the single-molecule level by force-volume mapping. The force maps revealed that PD-L1 randomly distributed on T24 cells surface. The recognition events on cells obviously increased after INF-γ treatment, which proved that INF-γ up-regulated the expression of PD-L1 on T24 cells. These findings enrich our understanding of the molecular mechanisms by which PD-L1 interacts with its antibody and PD-1. It provides useful information for the physical factors that is needed to be considered in the design of inhibitors for tumor immunology.

Bottom-Up-Etching-Mediated Synthesis of Large-Scale Pure Monolayer Graphene on Cyclic-Polishing-Annealed Cu(111).

Synthesis of large-scale single-crystalline graphene monolayers without multilayers involves the fabrication of proper single-crystalline substrates and the ubiquitous formation of multilayered graphene islands during chemical vapor deposition. Here, a method of cyclic electrochemical polishing combined with thermal annealing, which allows the conversion of commercial polycrystalline Cu foils to single-crystal Cu(111) with an almost 100% yield, is presented. A global "bottom-up-etching" method that is capable of fabricating large-area pure single-crystalline graphene monolayers without multilayers through selectively etching bottom multilayered graphene underneath large area as-grown graphene monolayer on Cu(111) surface is demonstrated. Terahertz time-domain spectroscopy (THz-TDS) measurement of the pure monolayer graphene film shows a high average sheet conductivity of 2.8 mS and mean carrier mobility of 6903 cm2 V-1 s-1 over a large area. Density functional theory (DFT) calculations show that the selective etching is induced by the much easier diffusion of hydrogen atoms than hydrocarbon radicals across the edges of the top graphene layer, and the simulated selective etching processes based on phase field modeling are well consistent with experimental observations. This work provides new ways toward the production of single-crystal Cu(111) and the synthesis of pure monolayer graphene with high electronic quality.

Hybrid solid electrolyte enabled dendrite-free Li anodes for high-performance quasi-solid-state lithium-oxygen batteries.

The dendrite growth of Li anodes severely degrades the performance of lithium-oxygen (Li-O2) batteries. Recently, hybrid solid electrolyte (HSE) has been regarded as one of the most promising routes to tackle this problem. However, before this is realized, the HSE needs to simultaneously satisfy contradictory requirements of high modulus and even, flexible contact with Li anode, while ensuring uniform Li+ distribution. To tackle this complex dilemma, here, an HSE with rigid Li1.5Al0.5Ge1.5(PO4)3 (LAGP) core@ultrathin flexible poly (vinylidene fluoride-hexafluoropropylene) (PVDF-HFP) shell interface has been developed. The introduced large amount of nanometer-sized LAGP cores can not only act as structural enhancer to achieve high Young's modulus but can also construct Li+ diffusion network to homogenize Li+ distribution. The ultrathin flexible PVDF-HFP shell provides soft and stable contact between the rigid core and Li metal without affecting the Li+ distribution, meanwhile suppressing the reduction of LAGP induced by direct contact with Li metal. Thanks to these advantages, this ingenious HSE with ultra-high Young's modulus of 25 GPa endows dendrite-free Li deposition even at a deposition capacity of 23.6 mAh. Moreover, with the successful inhibition of Li dendrites, the HSE-based quasi-solid-state Li-O2 battery delivers a long cycling stability of 146 cycles, which is more than three times that of gel polymer electrolyte-based Li-O2 battery. This new insight may serve as a starting point for further designing of HSE in Li-O2 batteries, and can also be extended to various battery systems such as sodium-oxygen batteries.

Studying the effect of PDA@CeO2 nanoparticles with antioxidant activity on the mechanical properties of cells.

Studying the influence of nanomaterials on the microstructure and mechanical properties of cells is essential to guide the biological applications of nanomaterials. In this article, the effects of the first synthesized PDA@CeO2 nanoparticles (NPs) with multiple ROS scavenging activities on cell ultra-morphology and mechanical properties were investigated by atomic force microscopy (AFM). After the cells were exposed to PDA@CeO2 NPs, there was no obvious change in cell morphology, but the Young's modulus of the cells was increased. On the contrary, after the cells were damaged by H2O2, the secreted molecules appeared on the cell surface, and the Young's modulus was decreased significantly. However, PDA@CeO2 NPs could effectively inhibit the reduction of the Young's modulus caused by oxidative stress damage. PDA@CeO2 NPs could also protect F-actin from oxidative stress damage and maintain the stability of the cytoskeleton. This work investigates the intracellular antioxidant mechanism of nanomaterials from the changes in the microstructure and biomechanics of living cells, providing a new analytical approach to explore the biological effects of nanomaterials.