Photothermal Killing of Cancer Cells by the Controlled Plasmonic Coupling of Silica‐Coated Au/Fe2O3 Nanoaggregates

Tumor ablation by thermal energy via the irradiation of plasmonic nanoparticles is a relatively new oncology treatment. Hybrid plasmonic‐superparamagnetic nanoaggregates (50–100 nm in diameter) consisting of SiO₂‐coated Fe₂O₃ and Au (≈30 nm) nanoparticles were fabricated using scalable flame aerosol technology. By finely tuning the Au interparticle distance using the SiO₂ film thickness (or content), the plasmonic coupling of Au nanoparticles can be finely controlled bringing their optical absorption to the near‐IR that is most important for human tissue transmittance. The SiO₂ shell facilitates also dispersion and prevents the reshaping or coalescence of Au particles during laser irradiation, thereby allowing their use in multiple treatments. These nanoaggregates have magnetic resonance imaging (MRI) capability as shown by measuring their r2 relaxivity while their effectiveness as photothermal agents is demonstrated by killing human breast cancer cells with a short, four minute near‐IR laser irradiation (785 nm) at low flux (4.9 W cm^‐2).     

Hydrophobic Nanoreactor Soft‐Templating: A Supramolecular Approach to Yolk@Shell Materials

Due to their unique morphology‐related properties, yolk@shell materials are promising materials for catalysis, drug delivery, energy conversion, and storage. Despite their proven potential, large‐scale applications are however limited due to demanding synthesis protocols. Overcoming these limitations, a simple soft‐templated approach for the one‐pot synthesis of yolk@shell nanocomposites and in particular of multicore metal nanoparticle@metal oxide nanostructures (M_NP@MO_x) is introduced. The approach here, as demonstrated for Au_NP@ITO_TR (ITO_TR standing for tin‐rich ITO), relies on polystyrene‐block‐poly(4‐vinylpyridine) (PS‐b‐P4VP) inverse micelles as two compartment nanoreactor templates. While the hydrophilic P4VP core incorporates the hydrophilic metal precursor, the hydrophobic PS corona takes up the hydrophobic metal oxide precursor. As a result, interfacial reactions between the precursors can take place, leading to the formation of yolk@shell structures in solution. Once calcined these micelles yield Au_NP@ITO_TR nanostructures, composed of multiple 6 nm sized Au NPs strongly anchored onto the inner surface of porous 35 nm sized ITO_TR hollow spheres. Although of multicore nature, only limited sintering of the metal nanoparticles is observed at high temperatures (700 °C). In addition, the as‐synthesized yolk@shell structures exhibit high and stable activity toward CO electrooxidation, thus demonstrating the applicability of our approach for the design of functional yolk@shell nanocatalysts.     

Plasmonic Heterostructure TiO2‐MCs/WO3−x‐NWs with Continuous Photoelectron Injection Boosting Hot Electron for Methane Generation

Nonmetallic plasmonic heterostructure TiO₂‐mesocrystals/WO_3?x‐nanowires (TiO₂‐MCs/WO_3?x‐NWs) are constructed by coupling mesoporous crystal TiO₂ and plasmonic WO_3?x through a solvothermal procedure. The continuous photoelectron injection from TiO₂ stabilizes the free carrier density and leads to strong surface plasmon resonance (SPR) of WO_3?x, resulting in strong light absorption in the visible and near‐infrared region. Photocatalytic hydrogen generation of TiO₂‐MCs/WO_3?x‐NWs is attributed to plasmonic hot electrons excited on WO_3?x‐NWs under visible light irradiation. However, utilization of injected photoelectrons on WO_3?x‐NWs has low efficiency for hydrogen generation and a co‐catalyst (Pt) is necessary. TiO₂‐MCs/WO_3?x‐NWs are used as co‐catalyst free plasmonic photocatalysts for CO₂ reduction, which exhibit much higher activity (16.3 µmol g^?1 h^?1) and selectivity (83%) than TiO₂‐MCs (3.5 µmol g^?1 h^?1, 42%) and WO_3?x‐NWs (8.0 µmol g^?1 h^?1, 64%) for methane generation under UV–vis light irradiation. A photoluminescence study demonstrates the photoelectron injection from TiO₂ to WO_3?x, and the nonmetallic SPR of WO_3?x plays a great role in the highly selective methane generation during CO₂ photoreduction.     

A New Phase Boundary in (Bi1/2Na1/2)TiO3−BaTiO3 Revealed via a Novel Method of Electron Diffraction Analysis

A new phase boundary is revealed in (1–x)(Bi_1/2Na_1/2)TiO₃?xBaTiO₃, the most extensively studied lead‐free piezoelectric solid solution. This discovery results from a novel method of electron diffraction analysis, which allows the precise determination of oxygen octahedra tilting in multi‐domain perovskite ferroelectrics. The study using this method supports the recently proposed Cc symmetry for pure (Bi_1/2Na_1/2)TiO₃, and, more importantly, indicates the crystal structure evolves into the R3c symmetry with the addition of BaTiO₃, forming a Cc/R3c phase boundary at x = 3–4%. In the poling field E_pol versus composition x phase diagram for polycrystalline ceramics, this phase boundary exists with E_pol below 5.5 kV mm^?1; the Cc phase is transformed to the R3c phase during poling at higher fields. The results reported here provide the microstructural origin for the previously unexplained strain behavior and clarify the low‐BaTiO₃‐content phase relationship in this popular lead‐free piezoelectric system.     

Plasmon‐Enhanced Blue Upconversion Luminescence by Indium Nanocrystals

Numerous endeavors have been undertaken to gain enhanced upconversion luminescence via surface plasmon resonance (SPR) generated by specially designed nanostructures of noble metals (e.g., Au, Ag). However, the SPR response of these metals is usually weak in the ultraviolet (UV) region because of their intrinsic electronic configurations; thus, only green and red upconversion emissions can undergo significant plasmonic enhancement yet without selectivity, while an efficient approach to selectively enhancing the blue upconversion luminescence has been lacking. Herein, by integrating the pronounced UV SPR of silica‐coated indium nanocrystals (InNCs) with blue‐emission upconversion nanoparticles (UCNPs) of NaYbF₄:Tm, an up to tenfold selective luminescence enhancement at 450 nm is obtained upon 980 nm laser excitation. Precise manipulation of the silica shell thickness suggests an optimal working distance of 3 nm between InNCs and UCNPs. This study has, for the first time, realized selective blue upconversion luminescence enhancement by using an inexpensive, non‐noble metal material, which will not only enrich the fundamental investigations of SPR‐enhanced upconversion emission, but also widen the applications of blue light‐emitting nanomaterials, for example, in therapeutics.     

Selective Pd Deposition on Au Nanobipyramids and Pd Site‐Dependent Plasmonic Photocatalytic Activity

The synthesis of anisotropic metal nanostructures is strongly desired for exploring plasmon‐enabled applications. Herein, the preparation of anisotropic Au/SiO₂ and Au/SiO₂/Pd nanostructures is realized through selective silica coating on Au nanobipyramids. For silica coating at the ends of Au nanobipyramids, the amount of coated silica and the overall shape of the coated nanostructures exhibit a bell‐shaped dependence on the cationic surfactant concentration. For both end and side silica coating on Au nanobipyramids, the size of the silica component can be varied by changing the silica precursor amount. Silica can also be selectively deposited on the corners or facets of Au nanocubes, suggesting the generality of this method. The blockage of the predeposited silica component on Au nanobipyramids enables further selective Pd deposition. Suzuki coupling reactions carried out with the different bimetallic nanostructures functioning as plasmonic photocatalysts indicate that the plasmonic photocatalytic activity is dependent on the site of Pd nanoparticles on Au nanobipyramids. Taken together, these results suggest that plasmonic hot spots play an important role in hot‐electron‐driven plasmonic photocatalysis. This study opens up a promising route to the construction of anisotropic bimetallic nanostructures as well as to the design of bimetallic plasmonic‐catalytic nanostructures as efficient plasmonic photocatalysts.     

One‐Pot Synthesis of Au25(SG)18 2‐ and 4‐nm Gold Nanoparticles and Comparison of Their Size‐Dependent Properties

A one‐pot synthesis of glutathione (denoted as ‐SG) capped gold nanoparticles, including Au₂₅(SG)₁₈ (ca. 1 nm in diameter) 2‐ and 4‐nm particles is reported. These nanoparticles are isolated by methanol‐induced precipitation with a controlled amount of added methanol. Except for their particle size, these nanoparticles have an identical chemical composition (i.e., gold and ‐SG content), synthetic history, and surface conditions, which allows for precise comparison of their size‐dependent properties, in particular the magnetic property as this could be attributed to contamination by trace iron impurities. Specifically, the structure, optical, and magnetic properties of these gold nanoparticles are compared. A trend from non‐fcc (fcc = face centered cubic) Au₂₅(SG)₁₈ nanoclusters (ca. 1 nm) to 2‐ and 4‐nm fcc‐crystalline Au nanocrystals is revealed. The Au₂₅(SG)₁₈ nanoparticles resemble molecules and exhibit multiple optical absorption peaks ascribed to one‐electron transitions, whereas the 4‐nm nanoparticles exhibit surface plasmon resonance at around 520 nm related to the collective excitation of conduction electrons upon optical excitation. The transition from the non‐fcc cluster state to the fcc crystalline state occurs at around 2 nm. Interestingly, both 2‐ and 4‐nm particles exhibit paramagnetism, whereas the Au₂₅(SG)₁₈ (anionic) clusters are diamagnetic. The information attained on the evolution of the properties of nanoparticles from nanoclusters to fcc‐structured nanocrystals is of major importance and provides insight into structure—property relationships.     

Tetragonal BaTiO3 nanoparticles: An efficient photocatalyst for the degradation of organic pollutants

Photocatalytically active cubic and tetragonal phase BaTiO₃ nanoparticles have been prepared by polymeric complex method. The prepared samples were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Photoluminescence spectroscopy (PL), Ultraviolet-visible (UV–vis) diffuse reflectance spectrophotometry (UV-DRS). In addition, the morphology of BaTiO₃ was investigated using Transmission electron microscopy (TEM). The cubic and tetragonal phases of the prepared BaTiO₃ were confirmed by XRD and Raman spectra. Methylene blue dye was used as a probe to evaluate the photocatalytic activities of cubic and tetragonal BaTiO₃. This investigation revealed that BaTiO₃ with tetragonal phase showed higher photocatalytic activity than that of the cubic BaTiO₃. The photoluminescence result also supported the improved photocatalytic activity of tetragonal BaTiO₃. However, a noticeable change in photocatalytic property could be observed on varying the amount of BaTiO₃. The enhanced photocatalytic activity of tetragonal BaTiO₃ makes it an excellent photocatalyst candidate for the degradation of pollutants.     

Nanoimprint Lithography Facilitated Plasmonic-Photonic Coupling for Enhanced Photoconductivity and Photocatalysis

Imprint lithography has emerged as a reliable, reproducible, and rapid method for patterning colloidal nanostructures. As a promising alternative to top-down lithographic approaches, the fabrication of nanodevices has thus become effective and straightforward. In this study, a fusion of interference lithography (IL) and nanosphere imprint lithography on various target substrates ranging from carbon film on transmission electron microscope grid to inorganic and dopable polymer semiconductor is reported. 1D plasmonic photonic crystals are printed with 75% yield on the centimeter scale using colloidal ink and an IL-produced polydimethylsiloxane stamp. Atomically smooth facet, single-crystalline, and monodisperse colloidal building blocks of gold (Au) nanoparticles are used to print 1D plasmonic grating on top of a titanium dioxide (TiO₂) slab waveguide, producing waveguide-plasmon polariton modes with superior 10 nm spectral line-width. Plasmon-induced hot electrons are confirmed via two-terminal current measurements with increased photoresponsivity under guiding conditions. The fabricated hybrid structure with Au/TiO₂ heterojunction enhances photocatalytic processes like degradation of methyl orange (MO) dye molecules using the generated hot electrons. This simple colloidal printing technique demonstrated on silicon, glass, Au film, and naphthalenediimide polymer thus marks an important milestone for large-scale implementation in optoelectronic devices.     

Gold‐ and Silver‐Coated Barium Titanate Nanocomposites as Probes for Two‐Photon Multimodal Microspectroscopy

Improved multiphoton‐excited imaging and microspectroscopy require nanoprobes that can give different nonlinear optical signals. Here, composite nanostructures with a barium titanate core and a plasmonic moiety at their surface are synthesized and characterized. It is found that the core provides a high second‐order nonlinear susceptibility for sensitive second harmonic generation (SHG) imaging in living cells. As a second function in the two‐photon regime, the plasmonic part yields high local fields for resonant and nonresonant surface enhanced hyper Raman scattering (SEHRS). SEHRS complements the one‐photon surface enhanced Raman scattering (SERS) spectra that are also enhanced by the plasmonic shells. Barium titanate silver core–shell (Ag@BaTiO₃) composites are specifically suited for SEHRS and SHG excited at 1064 nm, while gold at barium titanate (Au@BaTiO₃) nanoparticles can be useful in a combination of SHG and SERS at lower wavelengths, here at 785 nm and 850 nm. The theoretical models show that the optical properties of the BaTiO₃ dielectric core depend on probing frequency, shape, size, and plasmonic properties of the surrounding gold nanoparticles so that they can be optimized for a particular type of experiment. These versatile, tunable probes give new opportunities for combined multiphoton probing of morphological structure and chemical properties of biosystems.     

Vertical 3D Printed Forest-Inspired Hierarchical Plasmonic Superstructure for Photocatalysis

Efficient light-harvesting is of significant importance to achieve high solar energy utilization efficiency for various solar-driven technologies. Compared with a 2D planar structure, a 3D plasmonic structure can largely increase the light adsorption/interaction areas and also utilizes the plasmonic effect to achieve much higher light utilization efficiency. However, this remains challenging in terms of structural design, reliable manufacturing, and ability to scale up. Herein, inspired by the light absorption strategy of natural forests, a hierarchical plasmonic superstructure is demonstrated composed of vertical TiO₂ pillar arrays (as tree trunks), dense nanorod arrays (as branches), and a large number of plasmonic Au nanoparticles (as leaves). Such a forest-like plasmonic superstructure can effectively absorb light from the surface plasmonic resonance effects of Au nanoparticles and the multiple scattering of light in the hierarchical branched structure. The strong light absorption and abundant photocatalytic active sites help yield a 15-fold higher nitrogen photo-fixation activity than that of the flat TiO₂ films decorated with Au nanoparticles. The study provides an effective strategy to construct 3D plasmonic superstructures with excellent light-harvesting efficiency and high stability and can be readily applied to a range of light-driven applications     

Facile Fabrication of High‐Density Sub‐1‐nm Gaps from Au Nanoparticle Monolayers as Reproducible SERS Substrates

The fabrication of ultrasmall nanogaps (sub‐1 nm) with high density is of significant interest and importance in physics, chemistry, life science, materials science, surface science, nanotechnology, and environmental engineering. However, it remains a challenge to generate uncovered and clean sub‐1‐nm gaps with high density and uniform reproducibility. Here, a facile and low‐cost approach is demonstrated for the fabrication of high‐density sub‐1‐nm gaps from Au nanoparticle monolayers as reproducible surface‐enhanced Raman scattering (SERS) substrates. Au nanoparticles with larger diameters possess lower surface charge, thus the obtained large‐area nanoparticle monolayer generates a high‐density of sub‐1‐nm gaps. In addition, a remarkable SERS performance with a 10¹¹ magnitude for the Raman enhancement is achieved for 120 nm Au nanoparticle monolayers due to the dramatic increase in the electromagnetic field enhancement when the obtained gap is smaller than 0.5 nm. The Au nanoparticle monolayer is also transferred onto a stretchable PDMS substrate and the structural stability and reproducibility of the high‐density sub‐1‐nm gaps in Au monolayer films are illustrated. The resultant Au nanoparticle monolayer substrates with an increasing particle diameter exhibit tunable plasmonic properties, which control the plasmon‐enhanced photocatalytic efficiency for the dimerization of p‐aminothiophenol. The findings reported here offer a new opportunity for expanding the SERS application.     

A New Single 808 nm NIR Light‐Induced Imaging‐Guided Multifunctional Cancer Therapy Platform

The NIR light‐induced imaging‐guided cancer therapy is a promising route in the targeting cancer therapy field. However, up to now, the existing single‐modality light‐induced imaging effects are not enough to meet the higher diagnosis requirement. Thus, the multifunctional cancer therapy platform with multimode light‐induced imaging effects is highly desirable. In this work, captopril stabilized‐Au nanoclusters Au₂₅(Capt)₁₈?(Au₂₅) are assembled into the mesoporous silica shell coating outside of Nd³⁺‐sensitized upconversion nanoparticles (UCNPs) for the first time. The newly formed Au₂₅ shell exhibits considerable photothermal effects, bringing about the photothermal imaging and photoacoustic imaging properties, which couple with the upconversion luminescence imaging. More importantly, the three light‐induced imaging effects can be simultaneously achieved by exciting with a single NIR light (808 nm), which is also the triggering factor for the photothermal and photodynamic cancer therapy. Besides, the nanoparticles can also present the magnetic resonance and computer tomography imaging effects due to the Gd³⁺ and Yb³⁺ ions in the UCNPs. Furthermore, due to the photodynamic and the photothermal effects, the nanoparticles possess efficient in vivo tumor growth inhibition under the single irradiation of 808 nm light. The multifunctional cancer therapy platform with multimode imaging effects realizes a true sense of light‐induced imaging‐guided cancer therapy.     

Plasmonic Janus‐Composite Photocatalyst Comprising Au and C–TiO2 for Enhanced Aerobic Oxidation over a Broad Visible‐Light Range

Asymmetric Janus nanostructures containing a gold nanocage (NC) and a carbon–titania hybrid nanocrystal (AuNC/(C–TiO₂)) are prepared using a novel and facile microemulsion‐based approach that involves the assistance of ethanol. The localized surface plasmon resonance of the Au NC with a hollow interior and porous walls induce broadband visible‐light harvesting in the Janus AuNC/(C–TiO₂). An acetone evolution rate of 6.3 μmol h^?1 g^?1 is obtained when the Janus nanostructure is used for the photocatalytic aerobic oxidation of iso‐propanol under visible light (λ = 480–910 nm); the rate is 3.2 times the value of that obtained with C–TiO₂, and in photo‐electrochemical investigations an approximately fivefold enhancement is obtained. Moreover, when compared with the core–shell structure (AuNC@(C–TiO₂) and a gold–carbon–titania system where Au sphere nanoparticles act as light‐harvesting antenna, Janus AuNC/(C–TiO₂) exhibit superior plasmonic enhancement. Electromagnetic field simulation and electron paramagnetic resonance results suggest that the plasmon–photon coupling effect is dramatically amplified at the interface between the Au NC and C–TiO₂, leading to enhanced generation of energetic hot electrons for photocatalysis.     

Chemical Bonding Assembly of Multifunctional Oxide Nanocomposites

The synthesis, functionalization and assembly of metal oxide nanoparticles BaTiO₃ and CoFe₂O₄ is presented. The ferroelectric (BaTiO₃) and ferromagnetic (CoFe₂O₄) oxide nanoparticle surfaces are directly functionalized via the anchoring of phosphonic acid and aminosilane molecules that engender the nanoparticles with terminal carboxylic acid and amine functional groups, respectively. These promote the electrostatic self‐assembly of the particles in non‐polar solvents and permit the synthesis of more chemically robust assemblies linked by the covalent amide bond via the addition of the chemical coupling agent N‐N′‐dicyclohexylcarbodiimide. This functionalization and assembly procedure is applied to two systems: the first comprised of 50 nm BaTiO₃ and 10 nm CoFe₂O₄ particles and the second of 200 nm BaTiO₃ and 12.5 nm CoFe₂O₄ particles. The latter composites possess magnetoelectric properties when processed into dense ceramics and, as a direct result of the assembly performed in solution, have a high degree of homogeneity between the ferroelectric and ferromagnetic phases. The developed functionalization and assembly procedure is considered to be adaptable to the preparation of other hybrid oxide nanomaterials with different property combinations.     

Chiral AuCuAu Heterogeneous Nanorods with Tailored Optical Activity

Here, a facile wet‐chemistry route for the selective growth of crystalline copper (Cu) along the sides of gold nanorods (Au NRs) in the presence of a hexadecylamine (HDA) is reported. The resulting heterostructures feature part etching of copper by galvanic replacement reaction and form crystalline AuCu alloy metal on one side of the Au NRs. By virtue of the dipeptide (cysteine‐phenylalanine, Cys‐Phe) ligand used during synthesis, the AuCuAu heteronanorods (HNRs) exhibit strong circular dichroism (CD) in the wavelength range of 400–1000 nm. The plasmonic chirality can be tailored by increasing the length of the Au NRs, the scale of Cu nanocrystals on the Au NRs, and the amount of gold chloride for postgrowth, resulting in an anisotropy factor (g factor) as high as 0.57 × 10^?2. The strong CD signals are attributed to the local electromagnetic field. Under circular polarized light (CPL) illumination, the chiral plasmonic AuCuAu nanostructure exhibits high efficiency for light polarization dependent reactive oxygen species (¹O₂) that is 22.31 times that of Au NRs. The results of this study demonstrate that the chiral enantiomer provides a chirality dependent avenue for highly efficient phototherapy.     

Highly Stable Au Nanoparticles with Tunable Spacing and Their Potential Application in Surface Plasmon Resonance Biosensors

Colloidal Au‐amplified surface plasmon resonance (SPR), like traditional SPR, is typically used to detect binding events on a thin noble metal film. The two major concerns in developing colloidal Au‐amplified SPR lie in 1) the instability, manifested as a change in morphology following immersion in organic solvents and aqueous solutions, and 2) the uncontrollable interparticle distance, determining probe spacing and inducing steric hindrance between neighboring probe molecules. This may introduce uncertainties into such detecting techniques, degrade the sensitivity, and become the barricade hampering colloidal Au‐based transducers from applications in sensing. In this paper, colloidal Au‐amplified SPR transducers are produced by using ultrathin Au/Al₂O₃ nanocomposite films via a radio frequency magnetron co‐sputtering method. Deposited Au/Al₂O₃ nanocomposite films exhibit superior stability, and average interparticle distances between Au nanoparticles with similar average sizes can be tuned by changing surface coverage. These characteristics are ascribed to the spacer function and rim confinement of dielectric Al₂O₃ and highlight their advantages for application in optimal nanoparticle‐amplified SPR, especially when the probe size is smaller than the target molecule size. This importance is demonstrated here for the binding of protein (streptavidin) targets to the probe (biotin) surface. In this case, the dielectric matrix Al₂O₃ is a main contributor, behaving as a spacer, tuning the concentration of Au nanoparticles, and manipulating the average interparticle distance, and thus guaranteeing an appropriate number of biotin molecules and expected near‐field coupling to obtain optimal sensing performance.     

Near‐Infrared SERS Nanoprobes with Plasmonic Au/Ag Hollow‐Shell Assemblies for In Vivo Multiplex Detection

For the effective application of surface‐enhanced Raman scattering (SERS) nanoprobes for in vivo targeting, the tissue transparency of the probe signals should be as high as it can be in order to increase detection sensitivity and signal reproducibility. Here, near‐infrared (NIR)‐sensitive SERS nanoprobes (NIR SERS dots) are demonstrated for in vivo multiplex detection. The NIR SERS dots consist of plasmonic Au/Ag hollow‐shell (HS) assemblies on the surface of silica nanospheres and simple aromatic Raman labels. The diameter of the HS interior is adjusted from 3 to 11 nm by varying the amount of Au³⁺ added, which results in a red‐shift of the plasmonic extinction of the Au/Ag nanoparticles toward the NIR (700–900 nm). The red‐shifted plasmonic extinction of NIR SERS dots causes enhanced SERS signals in the NIR optical window where endogenous tissue absorption coefficients are more than two orders of magnitude lower than those for ultraviolet and visible light. The signals from NIR SERS dots are detectable from 8‐mm deep in animal tissues. Three kinds of NIR SERS dots, which are injected into live animal tissues, produce strong SERS signals from deep tissues without spectral overlap, demonstrating their potential for in vivo multiplex detection of specific target molecules.     

Interfacial Modulation with Aluminum Oxide for Efficient Plasmon-Induced Water Oxidation

Plasmon-induced photocatalysts hold great promise for solar energy conversion owing to their strong light-harvesting ability and tunable optical properties. However, the complex process of interfacial extraction of hot carriers and the roles of metal/semiconductor interfaces in plasmonic photocatalysts are still not clearly understood. Herein, the manipulation of the interface between a plasmon metal (Au) and a semiconductor (rutile TiO₂) by introducing an interfacial metal oxide (Al₂O₃) is reported. The resulting Au/Al₂O₃/TiO₂ exhibits remarkable enhancement in photocatalytic water oxidation activity compared with Au/TiO₂, giving an apparent quantum efficiency exceeding 1.3% at 520 nm for photocatalytic water oxidation. Such an interfacial modulation approach significantly prolongs the lifetime of hot carriers in the Au/TiO₂ system, which conclusively improves the utilization of hot carriers for plasmon-induced water oxidation reaction upon irradiation. This work emphasizes the essential role of the interfacial structure in plasmonic devices and provides an alternative method for designing efficient plasmonic photocatalysts for solar energy conversion.     

Wireless Manipulation of Magnetic/Piezoelectric Micromotors for Precise Neural Stem‐Like Cell Stimulation

Precise neural electrical stimulation, which is a means of promoting neuronal regeneration, is a promising solution for patients with neurotrauma and neurodegenerative diseases. In this study, wirelessly controllable targeted motion and precise stimulation at the single‐cell level using S.platensis@Fe₃O₄@tBaTiO₃ micromotors are successfully demonstrated for the first time. A highly versatile and multifunctional biohybrid soft micromotor is fabricated via the integration of S.platensis with magnetic Fe₃O₄ nanoparticles and piezoelectric BaTiO₃ nanoparticles. The results show that this micromotor system can achieve navigation in a highly controllable manner under a low‐strength rotating magnetic field. The as‐developed system can achieve single‐cell targeted motion and then precisely induce the differentiation of the targeted neural stem‐like cell by converting ultrasonic energy to an electrical signal in situ owing to the piezoelectric effect. This new approach toward the high‐precision stimulation of neural stem‐like cells opens up new applications for micromotors and has excellent potential for precise neuronal regenerative therapies.