Synthesis of Ag@Pd Nanocubes and Pd-based Nanoframes via One-shot Injection of a Halide-free Precursor for Continuous Production in a Flow Reactor.

Noble-metal open nanostructures have remarkable catalytic capabilities toward a wide range of reactions. In particular, Pd-based open nanostructures have been synthesized and validated for superior catalytic performance toward formic acid oxidation. However, most of the syntheses are based on dropwise addition, making it challenging to increase the production volume.

Ultrasound and Photoacoustic Imaging of Nanoparticle-Engineered T Cells and Post-Treatment Assessment to Guide Adoptive Cell Immunotherapy.

Despite great promise, adoptive cell therapy (ACT) continues to fail at treating a majority of cancers, especially solid tumors. To inform development and expedite the translation of more potent cellular immunotherapies, advanced immunoimaging tools are needed to better understand the requirements for generating a robust immune response. Even methods to evaluate the delivery, location, and status of transferred T cells at the tumor target are lacking.

Rational Fabrication of Functionally-Graded Surfaces for Biological and Biomedical Applications.

As a ubiquitous feature of the biological world, gradation, in either composition or structure, is essential to many functions and processes. Taking protein gradation as an example, it plays a pivotal role in the development and evolution of human bodies, including stimulation and direction of the outgrowth of peripheral nerves in a developing fetus. It is also critically involved in wound healing by attracting and guiding immune cells to the site of injury or infection.

Continuous-Flow and Scalable Synthesis of Pd@Pt Core-Shell Nanocrystals with Enhanced Activity toward Oxygen Reduction.

We report a scalable method based on continuous-flow reactors for conformally coating the surfaces of facet-controlled Pd nanocrystals with uniform, ultrathin shells made of Pt. The key to the success of such an approach is the identification of a proper polyol to generate the Pt atoms at a relatively slow rate to ensure adequate surface diffusion and thus the formation of uniform shells in a layer-by-layer fashion. We first demonstrate the concept using the production of Pd@Pt (n = 2-5) core-shell icosahedral nanocrystals and then have the strategy successfully extended to the syntheses of Pd@Pt cubic and octahedral nanocrystals.

Nanocarriers Made of Natural Fatty Acids: Modulation of Their Release Profiles through Photo-Crosslinking.

Natural fatty acids are attractive carrier materials for drug delivery, but their rapid dissolution and degradation in vivo calls for new strategies to enhance their stability. Here we report a simple and versatile method capable of photo-crosslinking carriers made of natural fatty acids for drug delivery under controlled release. By optimizing the crosslinking density, the nanoscale carriers show a high drug loading efficiency, together with a stable network structure for minimal degradation in a body fluid mimic.

Facile Synthesis of Rhodium-Based Nanocrystals in a Metastable Phase and Evaluation of Their Thermal and Catalytic Properties.

Controlling the polymorphism of metal nanocrystals is a promising strategy for enhancing properties and discovering new phenomena. However, previous studies on Rh nanocrystals have focused on their thermodynamically stable face-centered-cubic (fcc) phase. Herein, a facile synthesis of Rh-based nanocrystals featuring the metastable hexagonal close-packed (hcp) phase is reported by using Ru seeds in their native hcp phase to template the deposition of Rh atoms.

Reliable Fabrication of Mineral-Graded Scaffolds by Spin-Coating and Laser Machining for Use in Tendon-to-Bone Insertion Repair.

A reliable method for fabricating biomimetic scaffolds with a controllable mineral gradient to facilitate the surgical repair of tendon-to-bone injuries and the regeneration of the enthesis is reported. The gradient in mineral content is created by sequentially spin-coating with hydroxyapatite/poly(ε-caprolactone) suspensions containing hydroxyapatite nanoparticles in decreasing concentrations. To produce pores and facilitate cell infiltration, the spin-coated film is released and patterned with an array of funnel-shaped microchannels by laser machining.

Bipyramidal Nanocrystals of Noble Metals: From Synthesis to Applications.

Shape control has been a major theme of nanocrystal research in terms of synthesis, property tailoring, and optimization of performance in a variety of applications. Among the possible shapes, bipyramids are unique owing to their symmetry, planar defects, and exposed facets. In this article, we focus on the colloidal synthesis of noble-metal nanocrystals featuring a triangular bipyramidal shape, together with highlights of their properties and applications.

A Multi-functional Hybrid System Comprised of Polydopamine Nanobottles and Biological Effectors for Cartilage Repair.

Biological effectors play critical roles in augmenting the repair of cartilage injuries, but it remains a challenge to control their release in a programmable, stepwise fashion. Herein, a hybrid system consisting of polydopamine (PDA) nanobottles embedded in a hydrogel matrix to manage the release of biological effectors for use in cartilage repair is reported. Specifically, a homing effector is load in the hydrogel matrix, together with the encapsulation of a cartilage effector in PDA nanobottles filled with phase-change material.

Plasmon-Induced Hot Electrons in Nanostructured Materials: Generation, Collection, and Application to Photochemistry.

Plasmon refers to the coherent oscillation of all conduction-band electrons in a nanostructure made of a metal or a heavily doped semiconductor. Upon excitation, the plasmon can decay through different channels, including nonradiative Landau damping for the generation of plasmon-induced energetic carriers, the so-called hot electrons and holes. The energetic carriers can be collected by transferring to a functional material situated next to the plasmonic component in a hybrid configuration to facilitate a range of photochemical processes for energy or chemical conversion.

Robust, Reproducible, and Scalable Synthesis of Silver Nanocubes.

It remains a challenge to accomplish colloidal synthesis of noble-metal nanocrystals marked by high quality, large quantity, and batch-to-batch consistency. Here we report a self-airtight setup for achieving robust, reproducible, and scalable production of Ag nanocubes with uniform and controlled sizes from 18 to 60 nm. Different from the conventional open-to-air setup, the self-airtight system makes it practical to stabilize the reaction condition by minimizing the loss of volatile reagents.

Seeing is believing: what is on the surface of silver nanocrystals suspended in their original reaction solution.

Colloidal synthesis of inorganic nanocrystals always involves a multitude of ionic and molecular species. How the chemical species affect the evolution of nanocrystals remains a black box. As an essential ingredient in the polyol synthesis of Ag nanocubes, Cl has been proposed to co-adsorb on the surface with poly(vinyl pyrrolidone) (PVP) to facilitate shape evolution.

Elucidating the Role of Reduction Kinetics in the Phase-Controlled Growth on Preformed Nanocrystal Seeds: A Case Study of Ru.

This study demonstrates the crucial role of reduction kinetics in phase-controlled synthesis of noble-metal nanocrystals using Ru nanocrystals as a case study. We found that the reduction kinetics played a more important role than the templating effect from the preformed seed in dictating the crystal structure of the deposited overlayers despite their intertwined effects on successful epitaxial growth. By employing two different polyols, a series of Ru nanocrystals with tunable sizes of 3-7 nm and distinct patterns of crystal phase were synthesized by incorporating different types of Ru seeds.

Putting Hybrid Nanomaterials to Work for Biomedical Applications.

Hybrid nanomaterials have found use in many biomedical applications. This article provides a comprehensive review of the principles, techniques, and recent advancements in the design and fabrication of hybrid nanomaterials for biomedicine. We begin with an introduction to the general concept of material hybridization, followed by a discussion of how this approach leads to materials with additional functionality and enhanced performance.

Rh@Au Core-Shell Nanocrystals with the Core in Tensile Strain and the Shell in Compressive Strain.

Bimetallic nanocrystals provide a versatile platform for utilizing the desired characteristics of two different elements within one particle. Core-shell nanocrystals, in particular, have found widespread use in catalysis by providing an ability to leverage the strains arising from the lattice mismatch between the core and the shell. However, large (>5%) lattice mismatch tends to result in nonepitaxial growth and lattice defects in an effort to release the strain.

Extraordinary Thermal Stability and Sinter Resistance of Sub-2 nm Platinum Nanoparticles Anchored to a Carbon Support by Selenium.

Nanoparticle sintering has long been a major challenge in developing catalytic systems for use at elevated temperatures. Here we report an electron microscopy study of the extraordinary sinter resistance of a catalytic system comprised of sub-2 nm Pt nanoparticles on a Se-decorated carbon support. When heated to 700 °C, the average size of the Pt nanoparticles only increased from 1.

Thermal Stability of Au Rhombic Dodecahedral Nanocrystals Can Be Greatly Enhanced by Coating Their Surface with an Ultrathin Shell of Pt.

Rhombic dodecahedral nanocrystals have been considered particularly difficult to synthesize because they are enclosed by {110}, a low-index facet with the greatest surface energy. Recently, we demonstrated the use of seed-mediated growth for the facile and robust synthesis of Au rhombic dodecahedral nanocrystals (AuRD). While the unique shape and surface structure of AuRD are desirable for potential applications in plasmonics and catalysis, respectively, their high surface energy makes them highly susceptible to thermal degradation.

Single-Atom Catalysts for Selective Oxygen Reduction: Transition Metals in Uniform Carbon Nanospheres with High Loadings.

Transition metal single-atom catalysts (SACs) in uniform carbon nanospheres have gained tremendous interest as electrocatalysts owing to their low cost, high activity, and excellent selectivity. However, their preparation typically involves complicated multistep processes that are not practical for industrial use. Herein, we report a facile one-pot method to produce atomically isolated metal atoms with high loadings in uniform carbon nanospheres without any templates or postsynthesis modifications.

Slowly Removing Surface Ligand by Aging Enhances the Stability of Pd Nanosheets toward Electron Beam Irradiation and Electrocatalysis.

Surface ligands play an important role in shape-controlled growth and stabilization of colloidal nanocrystals. Their quick removal tends to cause structural deformation and/or aggregation to the nanocrystals. Herein, we demonstrate that the surface ligand based on poly(vinylpyrrolidone) (PVP) can be slowly removed from Pd nanosheets (NSs, 0.

Development of Highly-Active Catalysts toward Oxygen Reduction by Controlling the Shape and Composition of Pt-Ni Nanocrystals.

Electrocatalysts comprised of Pt-Ni alloy nanocrystals have garnered substantial attention due to their outstanding performance in catalyzing the oxygen reduction reaction (ORR). Herein, we present the synthesis of Pt-Ni nanocrystals with a variety of controlled shapes and compositions in an effort to investigate the impact of the Ni content on the formation of {111} facets and thereby the ORR activity. By completely excluding O from the reaction system, we could prevent the generation of Ni(OH) on the surface of the nanocrystals and thereby achieve a linear relationship between the atomic ratio of Pt to Ni in the nanocrystals and the feeding ratio of the precursors.

Nanomaterial-Enabled Photothermal Heating and Its Use for Cancer Therapy via Localized Hyperthermia.

Photothermal therapy (PTT), which employs nanoscale transducers delivered into a tumor to locally generate heat upon irradiation with near-infrared light, shows great potential in killing cancer cells through hyperthermia. The efficacy of such a treatment is determined by a number of factors, including the amount, distribution, and dissipation of the generated heat, as well as the type of cancer cell involved. The amount of heat generated is largely controlled by the number of transducers accumulated inside the tumor, the absorption coefficient and photothermal conversion efficiency of the transducer, and the irradiance of the light.

Facile Synthesis of Ru Nanoboxes with a Hexagonal Close-Packed Structure by Templating with Ag Nanocubes and Their Catalytic Properties.

Noble-metal nanoboxes offer an attractive form of nanomaterials for catalytic applications owing to their open structure and highly efficient use of atoms. Herein, we report the facile synthesis of Ag-Ru core-shell nanocubes and then Ru nanoboxes with a hexagonal close-packed (hcp) structure, as well as evaluation of their catalytic activity toward a model hydrogenation reaction. By adding a solution of Ru(acac) in ethylene glycol (EG) dropwise to a suspension of silver nanocubes in EG at 170 °C, Ru atoms are generated and deposited onto the entire surface of a nanocube.

Deterministic Synthesis of Pd Nanocrystals Enclosed by High-Index Facets and Their Enhanced Activity toward Formic Acid Oxidation.

Noble-metal nanocrystals enclosed by high-index facets are of growing interest due to their enhanced catalytic performance in a variety of reactions. Herein, we report the deterministic synthesis of Pd nanocrystals encased by high-index facets by controlling the rate of deposition () relative to that of surface diffusion (). For octahedral seeds with truncated corners, a reduction rate (and thus deposition rate) faster than that of surface diffusion (i.