Dynamics of poly(methyl acrylate)/poly(methyl methacrylate)-grafted-FeO nanocomposites.

We investigated the dynamics of nanocomposites prepared through mixing poly(methyl methacrylate) grafted FeO nanoparticles (PMMA--FeO) with poly(methyl acrylate) (PMA). A key feature here different from previous dynamics measurements of polymer nanocomposites is the different chemistry between the matrix polymer and the polymer grafts, which introduces chemical heterogeneity. Transmission electron microscopy shows clear evidence of nanoparticle clustering due to the poor miscibility between the bulk PMA and the bulk PMMA.

Liposome-Templated Green Synthesis of Mesoporous Metal Nanostructures with Universal Composition for Biomedical Application.

Porous noble metal nanoparticles have received particular attention recently for their unique optical, thermal, and catalytic functions in biomedicine. However, limited progress has been made to synthesize such porous metallic nanostructures with large mesopores (≥25 nm). Here, a green yet facile synthesis strategy using biocompatible liposomes as templates to mediate the formation of mesoporous metallic nanostructures in a controllable fashion is reported.

A Porous Bimetallic Au@Pt Core-Shell Oxygen Generator to Enhance Hypoxia-Dampened Tumor Chemotherapy Synergized with NIR-II Photothermal Therapy.

The characteristic hypoxia of solid tumors and inadequate oxygen supply become a key causation of the resistance to chemotherapy in cancer treatment. Herein, a bimetallic oxygen nanogenerator, ..

Analytical Cryo-Scanning Electron Microscopy of Hydrated Polymers and Microgels.

Despite the fact that scanning electron microscopes (SEM) coupled with energy-dispersive X-ray microanalysis (EDS) has been commercially available for more than a half-century, SEM/EDS continues to develop and open new opportunities to study the morphology of advanced materials. This is particularly true in applications to hydrated soft matter. Developments in field-emission electron sources that enable low-voltage imaging of uncoated polymers, silicon-drift detectors that enable high-efficiency collection of X-rays characteristic of light elements, and cryogenic methods to effectively cryo-fix hydrated samples have opened new opportunities to apply techniques relatively well established in hard-materials applications to challenging new problems involving synthetic polymers.

Camouflaged Gold Nanodendrites Enable Synergistic Photodynamic Therapy and NIR Biowindow II Photothermal Therapy and Multimodal Imaging.

Gold nanodendrite (AuND)-based nanotheranostic agents with versatile capabilities were fabricated by optimizing the geometrical configurations (dendrite length and density) of AuND to achieve localized surface plasmon resonance (LSPR) in near-infrared biowindow II (NIR-II), and then subsequently functionalizing with a mitochondria-targeting compound (triphenylphosphonium, TPP), loading with an NIR-photosensitizer (indocyanine green, ICG) and coating with the macrophage cell membrane (MCM) to trap ICG within AuND and selectively interact with MDA-MB-231 cells. The novel AuND-TPP-ICG@MCM system enabled the integration of multimodal fluorescence/photoacoustic/surface-enhanced Raman imaging with synergistic therapies of NIR-II photothermal therapy and NIR-I photodynamic therapy for cancer treatment. Enhanced hyperthermia and elevated production of reactive oxygen species within the tumors MCM coating and mitochondria targeting afforded a synergistic efficacy for tumor eradication with limited side effects.

Orienting and shaping organic semiconductor single crystals through selective nanoconfinement.

For organic semiconductor crystals exhibiting anisotropic charge transport along different crystallographic directions, nanoconfinement is a powerful strategy to control crystal orientation by aligning the fast crystallographic growth direction(s) with the unconfined axis(es) of nanoconfining scaffolds. Here, design rules are presented to relate crystal morphology, scaffold geometry, and orientation control in solution-processed small-molecule crystals. Specifically, organic semiconductor triisopropylsilylethynyl pyranthrene needle-like crystals with a dimensionality of n = 1 and perylene platelike crystals with n = 2 were grown from solution within nanoconfining scaffolds comprising cylindrical nanopores with a dimensionality of m = 1, representing one unconfined dimension along the cylinder axis, and those comprising nanopillar arrays with a dimensionality of m = 2.

Mechanistic Study of Pb(II) Removal by TiO and Effect of PO.

As a commercial adsorbent, TiO shows a high adsorption capacity for lead (Pb(II)). However, the molecular structure of Pb(II) adsorption on TiO is still unknown. Meanwhile, as a widely used corrosion inhibitor, phosphate (PO) is usually added into drinking water, and its influential mechanism on Pb(II) removal by TiO remains unknown.

Spontaneous Deicing on Cold Surfaces.

Although freezing of a droplet on cold surfaces is a universal phenomenon, its mechanisms are still inadequately understood, especially on the surfaces of which the temperature is lower than -60 °C. Here, we report the unique spontaneous deicing phenomena of a water droplet impacting on cold surfaces with a temperature as low as -120 °C. As a hydrophilic surface is cooled below a critically low temperature (e.

A Porous Au@Rh Bimetallic Core-Shell Nanostructure as an H O -Driven Oxygenerator to Alleviate Tumor Hypoxia for Simultaneous Bimodal Imaging and Enhanced Photodynamic Therapy.

In treatment of hypoxic tumors, oxygen-dependent photodynamic therapy (PDT) is considerably limited. Herein, a new bimetallic and biphasic Rh-based core-shell nanosystem (Au@Rh-ICG-CM) is developed to address tumor hypoxia while achieving high PDT efficacy. Such porous Au@Rh core-shell nanostructures are expected to exhibit catalase-like activity to efficiently catalyze oxygen generation from endogenous hydrogen peroxide in tumors.

Gold Nanoframeworks with Mesopores for Raman-Photoacoustic Imaging and Photo-Chemo Tumor Therapy in the Second Near-Infrared Biowindow.

Gold-based nanostructures with tunable wavelength of localized surface plasmon resonance (LSPR) in the second near-infrared (NIR-II) biowindow receive increasing attention in phototheranostics. In view of limited progress on NIR-II gold nanostructures, a particular liposome template-guided route is explored to synthesize novel gold nanoframeworks (AuNFs) with large mesopores (≈40 nm) for multimodal imaging along with therapeutic robustness. The synthesized AuNFs exhibit strong absorbance in NIR-II region, affording their capacity of NIR-II photothermal therapy (PTT) and photoacoustic (PA) imaging for deep tumors.

Counterion Exchange in Peptide-Complexed Core-Shell Microgels.

The complexation of polyvalent macroions with oppositely charged polyelectrolyte microgels can lead to core-shell structures. The shell is believed to be highly deswollen with a high concentration of counter-macroions. The core is believed to be relatively free of macroions but under a uniform compressive stress due to the deswollen shell.

Weaving nanostructures with site-specific ion induced bidirectional bending.

Site-specific ion-irradiation is a promising tool fostering strain-engineering of freestanding nanostructures to realize 3D-configurations towards various functionalities. We first develop a novel approach of fabricating freestanding 3D silicon nanostructures by low dose ion-implantation followed by chemical-etching. The fabricated nanostructures can then be deformed bidirectionally by varying the local irradiation of kiloelectronvolt gallium ions.

Controlled graphene encapsulation: a nanoscale shield for characterising single bacterial cells in liquid.

High-resolution single-cell imaging in their native or near-native state has received considerable interest for decades. In this research, we present an innovative approach that can be employed to study both morphological and nano-mechanical properties of hydrated single bacterial cells. The proposed strategy is to encapsulate wet cells with monolayer graphene with a newly developed water membrane approach, followed by imaging with both electron microscopy (EM) and atomic force microscopy (AFM).

Substrate effects on cell-envelope deformation during early-stage Staphylococcus aureus biofilm formation.

Bacterial adhesion to a surface is the first step in biofilm formation, and adhesive forces between the surface and a bacterium are believed to give rise to planktonic-to-biofilm phenotypic changes. Here we use Focused-Ion-Beam (FIB) tomography with backscattered scanning electron microscopy (SEM) to image Staphyolococcus aureus (S. aureus) biofilms grown on Au-coated polystyrene (PS) and Au-coated PS modified by mixed thiols of triethylene glycol mono-11-mercaptoundecyl ether (EG) and 1-dodecanethiol (CH).

Boron-Filled Hybrid Carbon Nanotubes.

A unique nanoheterostructure, a boron-filled hybrid carbon nanotube (BHCNT), has been synthesized using a one-step chemical vapor deposition process. The BHCNTs can be considered to be a novel form of boron carbide consisting of boron doped, distorted multiwalled carbon nanotubes (MWCNTs) encapsulating boron nanowires. These MWCNTs were found to be insulating in spite of their graphitic layered outer structures.

Spontaneous, One-Pot Assembly of pH-Responsive Hydrogen-Bonded Polymer Capsules.

We demonstrate a facile, one-pot spontaneous assembly of hydrogen-bonded polymer containers of controllable size in aqueous solution. Electron microscopy shows that capsule formation is nucleated by a pH-induced phase separation of an amphiphilic poly(carboxylic acid), followed by binding and in-growth of polymer complexes within the phase separated droplets. The simple selection of different molecular weights of a stabilizing polymer affords a wide array of capsule sizes, including those in a submicron range, which are difficult to prepare using the alternative layer-by-layer technique.

Gold nanoparticle-enhanced photodynamic therapy: effects of surface charge and mitochondrial targeting.

Aim: The authors aimed to further improve the efficiency and selectivity of gold nanoparticle (Au NP)-assisted photodynamic therapy by modulating the surface charge of Au NPs and delivering Au NPs particularly to mitochondria of breast cancer cells.

Methods: Solid gold nanospheres (˜50 nm) with negative and positive surface charge were synthesized respectively, and mitochondria-targeting Au NPs were prepared by conjugating with triphenylphosphonium molecules.

Conclusion: Positively charged Au NPs were preferably taken up by breast cancer cells.

Extracellular matrix reorganization during cryo preparation for scanning electron microscope imaging of Staphylococcus aureus biofilms.

Biofilms are three-dimensional communities of bacteria distributed in a highly hydrated extracellular matrix (ECM). They can be visualized by scanning electron microscopy (SEM), but the requisite SEM sample preparation can modify the biofilm morphology. Here, four different approaches to prepare biofilms of hydrated Staphylococcus aureus for SEM imaging are compared.

Large-amplitude, reversible, pH-triggered wetting transitions enabled by layer-by-layer films.

We report on the use of layer-by-layer (LbL) hydrogels, composed of amphiphilic polymers that undergo reversible collapse-dissolution transition in solutions as a function of pH, to induce sharp, large-amplitude wetting transition at microstructured surfaces. Surface hydrogels were composed of poly(2-alkylacrylic acids) (PaAAs) of varied hydrophobicity, i.e.

Anisotropic nanocrystal arrays organized on protein lattices formed by recombinant clathrin fragments.

Recombinant clathrin protein fragments form assemblies that template gold nanocrystals in an array across the latticed surface. The nanocrystals exhibit unusual anisotropic morphologies with long range ordering, both of which are dependent upon the presence of a hexahistidine tag on the clathrin heavy chain fragments.

Organic nanocomposite structure tailored by controlling droplet coalescence during inkjet printing.

Inkjet printing offers a low-cost, high-throughput avenue for producing functional organic materials through rapid translation of desktop discoveries to industrial roll-to-roll processes. Here, we report a simple, but effective strategy to control droplet coalescence during inkjet printing, as a major variable, to tailor the nanoscale morphology of organic composite materials produced upon evaporation of all-liquid inks. During deposition, the spacing between ink droplets was controlled to systematically vary the extent of droplet coalescence.

Noble metal nanostructure both as a SERS nanotag and an analyte probe.

We report nanotags encapsulated in Au-Ag nanostructure that are active in surface-enhanced Raman scattering. The Au-Ag nanoshells are filled with Ag via citrate reduction, entrapping label molecules in the process. The nanotags can be used for quantitative SERS measurements with the label molecules as internal reference.

Effect of oxidation on surface-enhanced Raman scattering activity of silver nanoparticles: a quantitative correlation.

We quantitatively studied, using X-ray photoelectron spectroscopy (XPS), oxidation of substrate-immobilized silver nanoparticles (Ag NPs) in a wide range of conditions, including exposure to ambient air and controlled ozone environment under UV irradiation, and we correlated the degree of silver oxidation with surface-enhanced Raman scattering (SERS) enhancement factors (EFs). The SERS activity of pristine and oxidized Ag NPs was assessed by use of trans-1,2-bis(4-pyridyl)ethylene (BPE) and sodium thiocynate as model analytes at the excitation wavelength of 532 nm. Our study showed that the exposure of Ag NPs to parts per million (ppm) level concentrations of ozone led to the formation of Ag(2)O and orders of magnitude reduction in SERS EFs.

RDX-based nanocomposite microparticles for significantly reduced shock sensitivity.

Cyclotrimethylenetrinitramine (RDX)-based nanocomposite microparticles were produced by a simple, yet novel spray drying method. The microparticles were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and high performance liquid chromatography (HPLC), which shows that they consist of small RDX crystals (∼0.1-1 μm) uniformly and discretely dispersed in a binder.

Influence of Ca(2+) and Suwannee River Humic Acid on aggregation of silicon nanoparticles in aqueous media.

Silicon nanoparticles (NPs) have potential applications in many fields including microelectronics, biomedical imaging, and most recently energetics. Even though silicon NPs are thought to be harmless, their full impact on the environment and human health needs further investigation due to their potential increased use and recent toxicity data. Various techniques were used to characterize silicon NPs that are being considered for use in energetics.