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. Various monodispersed nanostructures with well-defined mesoporous shape and large mesopores (≈ 40 nm) are successfully synthesized from mono- (Au, Pd, and Pt), bi- (AuPd, AuPt, AuRh, PtRh, and PdPt), and tri-noble metals (AuPdRh, AuPtRh, and AuPdPt). Along with a successful demonstration of its effectiveness in synthesis of various mesoporous nanostructures, the possible mechanism of liposome-guided formation of such nanostructures via time sectioning of the synthesis process (monitoring time-resolved growth of mesoporous structures) and computational quantum molecular modeling (analyzing chemical interaction energy between metallic cations and liposomes at the enthalpy level) is also revealed. These mesoporous metallic nanostructures exhibit a strong photothermal effect in the near-infrared region, effective catalytic activities in hydrogen peroxide decomposition reaction, and high drug loading capacity. Thus, the liposome-templated method provides an inspiring and robust avenue to synthesize mesoporous noble metal-based nanostructures for versatile biomedical applications.

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, i.e., porous Au@Pt core-shell nanostructures, is particularly developed to reduce the multidrug resistance by oxygenating the tumor along with synergistic chemo-photothermal therapy for efficient tumor eradication. The porous platinum (Pt) shell was able to catalyze oxygen generation from endogenous hydrogen peroxide in the tumor, reducing the exocytosis of doxorubicin (DOX) via suppressed expression of hypoxia-inducible factor-1α, multidrug resistance gene 1, and P-glycoprotein. The strong absorbance of Au@Pt nanostructures in NIR window II enabled NIR-II photothermal therapy. Further incorporation of DOX into the mesopores of Au@Pt nanostructures with the assistance of phase change materials (PCM) led to the formulation of Au@Pt-DOX-PCM-PEG nanotherapeutics for NIR-II-activated chemotherapy. This work presents an efficient H2O2-driven oxygenerator for enhanced hypoxia-dampened chemotherapy and NIR-II photothermal therapy.

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. We have applied cryo-SEM imaging and spatially resolved EDS to collect new information characterizing polyelectrolyte microgels. These are charged gel particles with dimensions in the range of 0.1-100 µm. Perhaps most notable is the fact that the high hydration levels-the samples are mostly water-allow robust calibration curves to be generated using frozen-hydrated buffers with known salt and/or hydrocarbon compositions. Such calibration curves enable quantitative composition measurements in the low-concentration extremes associated with high-swelling hydrogels. We use an experimentally derived carbon calibration curve to determine the microgel swell ratio, Q. The swell ratio, arguably, is the single most important gel characteristic because it is directly related to the mesh size of the networked polymer, which in turn determines many of the gel's mechanical and transport properties. While Q can be experimentally measured in macroscopic gels based on weight measurements in the dry and hydrated states, it is very difficult to measure in a microgel, and the fact that EDS in a cryo-SEM can determine Q from a single X-ray spectrum is significant. Furthermore, because of the electrostatic charge distributed along the polymer chains, the presence and concentration of counter-ions play a critical role in polyelectrolyte systems. While conceptually understood for decades, experimental measurements of counter-ion concentrations have been largely limited to a relatively small set of materials that involve macroscopic samples. By developing calibration curves from frozen-hydrated buffer of known ionic strength, we measure the concentration of Na counter-ions in microgels of poly(acrylic acid) (PAA) with a limit of detection of ∼0.014 M. Such measurements may help resolve some long-standing questions in polyelectrolyte science concerning counter-ion condensation. Even in the absence of a calibration curve, we show that spatially resolved X-ray spectroscopy can map the spatial distribution of a cationic oligopeptide complexed within a hydrated PAA microgel because of the nitrogen fingerprint that, albeit at very low concentration, is unique to the peptide. We look specifically at the case of a microgel with a so-called core-shell structure, where, again, the underlying polyelectrolyte science responsible for core-shell formation remains incompletely understood. These examples highlight how a modern cryo-SEM can be exploited to quantitatively characterize hydrated soft matter. The approach is almost certain to continue its development and impact as the base of experienced practitioners, the accessibility to well-configured microscopes, and the abundance of challenging problems involving hydrated soft matter all continue to grow.

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 via MCM coating and mitochondria targeting afforded a synergistic efficacy for tumor eradication with limited side effects. The demonstrated biocompatibility, multi-imaging capability, and high therapeutic efficiency under NIR laser irradiation indicate the potentials of this multifunctional nanotheranostic platform for clinical utility in cancer therapy.

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. For m = n systems, native crystal growth habits were preserved while the crystal orientation in n = m direction(s) was dictated by the geometry of the scaffold. For n≠m systems, on the other hand, orientation control was restricted within a single plane, either parallel or perpendicular to the substrate surface. Intriguingly, control over crystal shape was also observed for perylene crystals grown in cylindrical nanopores (n > m). Within the nanopores, crystal growth was restricted along a single direction to form a needle-like morphology. Once growth proceeded above the scaffold surface, the crystals adopted their native growth habit to form asymmetric T-shaped single crystals with concave corners. These findings suggest that nanoporous scaffolds with spatially-varying dimensionalities can be used to grow single crystals of complex shapes.

Mechanistic Study of Pb(II) Removal by TiO2 and Effect of PO4.

As a commercial adsorbent, TiO2 shows a high adsorption capacity for lead (Pb(II)). However, the molecular structure of Pb(II) adsorption on TiO2 is still unknown. Meanwhile, as a widely used corrosion inhibitor, phosphate (PO4) is usually added into drinking water, and its influential mechanism on Pb(II) removal by TiO2 remains unknown. Here, the mechanisms of Pb(II) adsorption on TiO2 and the effect of PO4 were systematically investigated using a combination of spectroscopic analyses and surface complexation modeling. The adsorption structure of Pb(II) on TiO2 was revealed as a tridentate mononuclear configuration by the extended X-ray absorption fine structure (EXAFS) analysis. In the presence of 0.1-5 mg/L PO4, Pb(II) was removed mainly by adsorption on TiO2 rather than precipitation. Ternary complexation between Pb(II) and PO4 on TiO2 surfaces was found based on EXAFS and in situ Fourier transform infrared characterizations. These complexation structures were used to build a surface complexation model to accurately simulate and predict Pb(II) removal under different conditions. This study provides essential information about the mechanisms of Pb(II) removal by TiO2 and develops a model to predict adsorption behaviors, especially in the presence of PO4.

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.g., -57 °C for a silicon surface with a native oxide), the impacting water droplet spontaneously delaminates from the substrate and freezes radially outward in a horizontal plane, as opposed to the typical upward freezing shown on a warmer surface. The self-delamination phenomenon is suppressed or reinstated by the combination of thermal and hydrophobic modifications of the surface, which can be taken advantage of for effective deicing schemes for icephobic surface applications.

A Porous Au@Rh Bimetallic Core-Shell Nanostructure as an H2 O2 -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. Coating Au@Rh nanostructures with tumor cell membrane (CM) enables tumor targeting via homologous binding. As a result of the large pores of Rh shells and the trapping ability of CM, the photosensitizer indocyanine green (ICG) is successfully loaded and retained in the cavity of Au@Rh-CM. Au@Rh-ICG-CM shows good biocompatibility, high tumor accumulation, and superior fluorescence and photoacoustic imaging properties. Both in vitro and in vivo results demonstrate that Au@Rh-ICG-CM is able to effectively convert endogenous hydrogen peroxide into oxygen and then elevate the production of tumor-toxic singlet oxygen to significantly enhance PDT. As noted, the mild photothermal effect of Au@Rh-ICG-CM also improves PDT efficacy. By integrating the superiorities of hypoxia regulation function, tumor accumulation capacity, bimodal imaging, and moderate photothermal effect into a single nanosystem, Au@Rh-ICG-CM can readily serve as a promising nanoplatform for enhanced cancer PDT.

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. Functionalization of AuNFs with hyaluronic acid (HA) endows the targeting capacity for CD44-overexpressed tumor cells while gatekeeping doxorubicin (DOX) loaded into mesopores. Conjugation of Raman reporter 4-aminothiophenol (4-ATP) onto AuNFs yields a surface-enhanced Raman scattering (SERS) fingerprint for Raman spectroscopy/imaging. In vivo evaluation of HA-4-ATP-AuNFs-DOX on tumor-bearing xenografts demonstrates its high efficacy in eradication of solid tumors in NIR-II under PA-Raman dual image-guided photo-chemotherapy. Thus, current AuNFs offer versatile capabilities for phototheranostics.

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. We use cryo-scanning electron microscopy (SEM) with X-ray microanalysis to confirm this understanding. We study poly(acrylic acid) (PAA) microgels which form a core-shell structure when complexed with a small cationic antimicrobial peptide (L5). We follow the spatial distribution of polymer, water, Na counterions, and peptide based on the characteristic X-ray intensities of C, O, Na, and N, respectively. Frozen-hydrated microgel suspensions include buffers of known composition from which calibration curves can be generated and used to quantify both the microgel water and sodium concentrations, the latter with a minimum quantifiable concentration less than 0.048 M. We find that as-synthesized PAA microgels are enriched in Na relative to the surrounding buffer as anticipated from established ideas of counterion shielding of electrostatic charge. The shell in L5-complexed microgels is depleted in Na and enriched in peptide and contains relatively little water. Our measurements furthermore show that shell/core interface is diffuse over a length scale of a few micrometers. Within the limits of detection, the core Na concentration is the same as that in as-synthesized microgels, and the core is free of peptide. The core has a slightly lower water concentration than as-synthesized controls, consistent with the hypothesis that the core is under compression from the 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. By further tuning the ion-dose and energy, various nanostructure configurations can be realized, thus extending its horizon to new functional 3D-nanostructures. It has been revealed that at higher-energies (∼30 kV), the nanostructures can exhibit two-stage bidirectional-bending in contrast to the bending towards the incident-ions at lower-energies (∼16), implying an effective transfer of kinetic-energy. Computational studies show that the spatial-distribution of implanted-ions, dislocated silicon atoms, has potentially contributed to the local development of stresses. Nanocharacterization confirms the formation of two distinguishable ion-irradiated and un-irradiated regions, while the smoothened morphology of the irradiated-surface suggested that the bending is also coupled with sputtering at higher ion-doses. The bending effects associated with local ion irradiation in contrast to global ion irradiation are presented, with the mechanism elucidated. Finally, weaving of nanostructures is demonstrated through strain-engineering for new nanoscale artefacts such as ultra-long fully-bent nanowires, nano-hooks, and nano-meshes. The aligned growth of bacterial-cells is observed on the fabricated nanowires, and a mesh based "bacterial-trap" for site-specific capture of bacterial cells is demonstrated emphasizing the versatile nature of the current approach.

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). A computational framework was developed to provide additional insights, with the detailed nanoindentation process on graphene modelled based on the finite element method. The model was first validated by calibration with polymer materials of known properties, and the contribution of graphene was then studied and corrected to determine the actual moduli of the encapsulated hydrated sample. Application of the proposed approach was performed on hydrated bacterial cells (Klebsiella pneumoniae) to correlate the structural and mechanical information. EM and energy-dispersive x-ray spectroscopy imaging confirmed that the cells in their near-native stage can be studied inside the miniaturised environment enabled with graphene encapsulation. The actual moduli of the encapsulated hydrated cells were determined based on the developed computational model in parallel, with results comparable with those acquired with wet AFM. It is expected that the successful establishment of controlled graphene encapsulation offers a new route for probing liquid/live cells with scanning probe microscopy, as well as correlative imaging of hydrated samples for both biological and material sciences.

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 (EG3) and 1-dodecanethiol (CH3). The FIB-SEM technique enables a direct measurement of the contact area between individual bacteria and the substrate. The area of adhesion is effectively zero on the EG3 substrate. It is nonzero on all of the other substrates and increases with increasing hydrophobicity. The fact that the contact area is highest on the unmodified gold, however, indicates that other forces beyond hydrophobicity are significant. The magnitude of bacterial deformation suggests that the adhesive forces are on the order of a few nN, consistent with AFM force measurements reported in the literature. The resolution afforded by electron microscopy furthermore enables us to probe changes in the cell-envelope thickness, which decreases within and near the contact area relative to other parts of the same bacterium. This finding supports the idea that mechanosensing due to stress-induced membrane thinning plays a role in the planktonic-to-biofilm transition associated with bacterial adhesion.

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. While conventional MWCNTs have great axial strength, they have weak radial compressive strength, and do not bond well to one another or to other materials. In contrast, BHCNTs are shown to be up to 31% stiffer and 233% stronger than conventional MWCNTs in radial compression and have excellent mechanical properties at elevated temperatures. The corrugated surface of BHCNTs enables them to bond easily to themselves and other materials, in contrast to carbon nanotubes (CNTs). BHCNTs can, therefore, be used to make nanocomposites, nanopaper sheets, and bundles that are stronger than those made with CNTs.

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. The capsules can spontaneously coat silica particles, and be reversibly removed by varying pH. Furthermore, the capsule walls can be photo-cross-linked to preserve their integrity over the entire pH scale, resulting in pH-triggered "breathing" containers or responsive coatings on silica particles useful for encapsulation and controlled release.

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. Combination of positive surface charge with mitochondria-targeting domain onto Au NPs allowed their accumulation in the mitochondria of breast cancer cells to significantly elevate reactive oxygen species formation in 5-aminolevulinic-acid-enabled photodynamic therapy and improve selective destruction of 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. In order of increasing cooling effectiveness these are: (1) drying in air; (2) plunging in liquid nitrogen; (3) plunging in liquid ethane; and (4) high pressure freezing with liquid nitrogen. These different methods give rise to markedly different biofilm morphologies, which are revealed by cryo-SEM imaging. Significantly, high-pressure frozen biofilms exhibit a rich network of nanoscale ECM fibers surrounding individual bacteria throughout the biofilm thickness. This structure is entirely lost when similar biofilms are dried in air, and it is substantially modified when these biofilms are plunged into liquid nitrogen or liquid ethane.

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., poly(methacrylic acid) (PMAA), poly(2-ethylacrylic acid) (PEAA), poly(2-n-propylacrylic acid) (PPAA) and poly(2-n-butylacrylic acid) (PBAA). When deposited at a micropillar-patterned silicon substrate, hydrophilic PMAA LbL hydrogels supported complete surface wetting (contact angle, CA, of 0°), whereas PEAA, PPAA, and PBAA ultrathin coatings supported large-amplitude wetting transitions, with CA changes from 110 to 125° at acidic to 0° at basic pH values, and the transition pH increasing from 6.2 to 8.4 with increased polyacid hydrophobicity. At acidic pHs, droplets showed a large hysteresis in CA (a "sticky droplet" behavior), and remained in the Wenzel state. The fact that CA changes for wetting-nonwetting transitions occurred at values close to physiologic pH makes these coatings promising for controlling flow and bioadhesion using external stimuli. Finally, we show that the surface wettability transitions can be used to detect positively charged analytes (such as gentamicin) in solution via large changes in CA associated with adsorption of analytes within the hydrogels.

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. Our results show that decreasing coalescence increased the solvent evaporation rate, supersaturation of the solutes, and nucleation density of the precipitating organic crystals. This phenomenon was utilized to tailor the average size of pentaerythritol tetranitrate (PETN) crystals dispersed in an adhesive binder matrix from ~0.2 to upwards of 100 µm. The results suggest that controlling the extent of droplet coalescence can be used as an effective means to tailor the composite morphology of printed organic materials at the nanoscale.

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.