Bandgap-Engineered Germanene Nanosheets as an Efficient Photodynamic Agent for Cancer Therapy

Two-dimensional (2D) monoelemental materials (Xenes) show considerable potential in bioapplications owing to their unique 2D physicochemical features and the favored biosafety resulting from their monoelemental composition. However, the narrow band gaps of Xenes prevent their broad applications in biosensors, bioimaging and phototherapeutics. In this study, it is demonstrated that 2D germanene terminated with −H via surface chemical engineering, shows a much broadened direct band gap of 1.65 eV, which enables the material to be used as a novel inorganic photosensitizer for the photodynamic therapy of singlet oxygen. Through theoretical analysis and in vitro studies, H-germanene nanosheets demonstrate a substantially enlarged band gap and favorable biodegradability, demonstrating a substantial cancer treatment capacity. This study demonstrates the feasibility of constructing novel therapeutic photodynamic agents by surface covalent engineering for catalytic tumor therapy.     

The Covalent Functionalization of Layered Black Phosphorus by Nucleophilic Reagents

Layered black phosphorus has been attracting great attention due to its interesting material properties which lead to a plethora of proposed applications. Several approaches are demonstrated here for covalent chemical modifications of layered black phosphorus in order to form P−C and P‐O‐C bonds. Nucleophilic reagents are highly effective for chemical modification of black phosphorus. Further derivatization approaches investigated were based on radical reactions. These reagents are not as effective as nucleophilic reagents for the surface covalent modification of black phosphorus. The influence of covalent modification on the electronic structure of black phosphorus was investigated using ab initio calculations. Covalent modification exerts a strong effect on the electronic structure including the change of band‐gap width and spin polarization.     

Steering Surface Reaction Dynamics with a Self‐Assembly Strategy: Ullmann Coupling on Metal Surfaces

Ullmann coupling of 4‐bromobiphenyl thermally catalyzed on Ag(111), Cu(111), and Cu(100) surfaces was scrutinized by scanning tunneling microscopy as well as theoretical calculations. Detailed experimental evidence showed that initial formation of organometallic intermediates on the surface, as self‐assembled structures or sparsely dispersed species, is determined by the subsequent reaction pathway. Specifically, the assembled organometallic intermediates at full coverage underwent a single‐barrier process to directly convert into the final coupling products, while the sparsely dispersed intermediates at low coverage went through a double‐barrier process via newly identified clover‐shaped intermediates prior to formation of the final coupling products. These findings demonstrate that a self‐assembly strategy can efficiently steer surface reaction pathways and dynamics.     

Room‐Temperature Activation of H2 by a Surface Frustrated Lewis Pair

Surface frustrated Lewis pairs (SFLPs) have been implicated in the gas‐phase heterogeneous (photo)catalytic hydrogenation of CO₂ to CO and CH₃OH by In₂O_3?x(OH)_y. A key step in the reaction pathway is envisioned to be the heterolysis of H₂ on a proximal Lewis acid–Lewis base pair, the SFLP, the chemistry of which is described as In???In‐OH + H₂ → In‐OH₂⁺???In‐H^?. The product of the heterolysis, thought to be a protonated hydroxide Lewis base In‐OH₂⁺ and a hydride coordinated Lewis acid In‐H^?, can react with CO₂ to form either CO or CH₃OH. While the experimental and theoretical evidence is compelling for heterolysis of H₂ on the SFLP, all conclusions derive from indirect proof, and direct observation remains lacking. Unexpectedly, we have discovered rhombohedral In₂O_3?x(OH)_y can enable dissociation of H₂ at room temperature, which allows its direct observation by several analytical techniques. The collected analytical results lean towards the heterolysis rather than the homolysis reaction pathway.     

Surface Modification Based on Diselenide Dynamic Chemistry: Towards Liquid Motion and Surface Bioconjugation

Surface modification is an important technique in fields, such as, self‐cleaning, surface patterning, sensing, and detection. The diselenide bond was shown to be a dynamic covalent bond that can undergo a diselenide metathesis reaction simply under visible light irradiation. Herein we develop this diselenide dynamic chemistry into a versatile surface modification method with a fast response and reversibility. The diselenide bond could be modified onto various substrates, such as, PDMS, quartz, and ITO conductive film glass. Different functional diselenide molecules could then be immobilized onto the surface via diselenide metathesis reaction. We demonstrated that by using this modification method we could achieve liquid motion in a capillary tube under light illumination. We also show that this approach has the potential to serve as an efficient modification method for surface bioconjugation, which has practical applications in clinical usage.     

Nanoscale Surface Modification of Lithium‐Rich Layered‐Oxide Composite Cathodes for Suppressing Voltage Fade

Lithium‐rich layered oxides are promising cathode materials for lithium‐ion batteries and exhibit a high reversible capacity exceeding 250 mAh g⁻¹. However, voltage fade is the major problem that needs to be overcome before they can find practical applications. Here, Li_1.2Mn_0.54Ni_0.13Co_0.13O₂ (LLMO) oxides are subjected to nanoscale LiFePO₄ (LFP) surface modification. The resulting materials combine the advantages of both bulk doping and surface coating as the LLMO crystal structure is stabilized through cationic doping, and the LLMO cathode materials are protected from corrosion induced by organic electrolytes. An LLMO cathode modified with 5 wt % LFP (LLMO–LFP5) demonstrated suppressed voltage fade and a discharge capacity of 282.8 mAh g⁻¹ at 0.1 C with a capacity retention of 98.1 % after 120 cycles. Moreover, the nanoscale LFP layers incorporated into the LLMO surfaces can effectively maintain the lithium‐ion and charge transport channels, and the LLMO–LFP5 cathode demonstrated an excellent rate capacity.     

Direct Monitoring of Cell Membrane Vesiculation with 2D AuNP@MnO2 Nanosheet Supraparticles at the Single‐Particle Level

We herein demonstrate robust two‐dimensional (2D) UFO‐shaped plasmonic supraparticles made of gold nanoparticles (AuNPs) and MnO₂ nanosheets (denoted as AMNS‐SPs) for directly monitoring cell membrane vesiculation at the single‐particle level. Because the decorated MnO₂ nanosheets are ultrathin (4.2 nm) and have large diameters (230 nm), they are flexible enough for deformation and folding for parceling of the AuNPs during the endocytosis process. Correspondingly, the surrounding refractive index of the AuNPs increases dramatically, which results in a distinct red‐shift of the localized surface plasmon resonance (LSPR). Such LSPR modulation provides a convenient and accurate means for directly monitoring the dynamic interactions between 2D nanomaterials and cell membranes. Furthermore, for the endocytosed AMNS‐SPs, the subsequent LSPR blue‐shift induced by etching effects of reducing molecules is promising for exploring the local environment redox states at the single‐cell level.     

Improved Biocompatibility of Black Phosphorus Nanosheets by Chemical Modification

Black phosphorus nanosheets (BPs) show great potential for various applications including biomedicine, thus their potential side effects and corresponding improvement strategy deserve investigation. Here, in vitro and in vivo biological effects of BPs with and without titanium sulfonate ligand (TiL₄) modification are investigated. Compared to bare BPs, BPs with TiL₄ modification (TiL₄@BPs) can efficiently escape from macrophages uptake, and reduce cytotoxicity and proinflammation. The corresponding mechanisms are also discussed. These findings may not only guide the applications of BPs, but also propose an efficient strategy to further improve the biocompatibility of BPs.     

Orientation of an Amphiphilic Copolymer to a Lamellar Structure on a Hydrophobic Surface and Implications for CO2 Capture Membranes

The structural orientation of an amphiphilic crystalline polymer to a highly ordered microphase‐separated lamellar structure on a hydrophobic surface is presented. It is formed by the surface graft polymerization of poly(ethylene glycol)behenyl ether methacrylate onto poly(trimethylsilyl) propyne in the presence of allylamine. In particular, allylamine plays a pivotal role in controlling the crystalline phase, configuration, and permeation properties. The resulting materials are effectively used to improve the CO₂ capture property of membranes. Upon the optimization of the reaction conditions, a high CO₂ permeability of 501 Barrer and a CO₂/N₂ ideal selectivity of 77.2 are obtained, which exceed the Robeson upper bound limit. It is inspiring to surpass the upper bound limit via a simple surface modification method.