Hongyou Fan, Sandia National Laboratories
Feng Bai, Henan University
Mei Cai, General Motors Company
Yu Han, King Abdullah University of Science and Technology
Angstrom Thin Film Technologies LLC
MilliporeSigma (Sigma-Aldrich Materials Science)
NM05.01: Session I
Monday PM, April 02, 2018
PCC North, 200 Level, Room 229 B
8:00 AM - NM05.01.01
Aminolated and Thiolated PEG-Covered Gold Nanostructures with High Stability and Anti-Aggregation for Lateral Flow Devices
Purdue University1Show Abstract
The few lateral flow assays (LFAs) established for detecting the endocrine disrupting chemical (EDC) bisphenol A (BPA) have employed citrate-stabilized gold nanoparticles (GNPs), which have inevitable limitations and instability issues. To address these limitations, we developed more stable sensitive lateral flow assay by designing strategies for modifying the surfaces of gold nanostructures with polyethylene glycol and then testing their effectiveness and sensitivity toward BPA in an LFA.
To further enhance detection, the work was extended to the incorporation of gold nannostructures into the design of a surface-enhanced Raman scattering lateral flow assay (SERS-LFA). The assay includes high-SERS-performance gold nanoparticles, i.e., 40 nm gold nanostars (GNSs), and 4-aminothiolphenol (4-ATP) as a Raman reporter. To demonstrate the performance of this SERS-LFA kit toward BPA detection, we tested BPA stock solutions with concentrations ranging from 0 to 32 ppb. Without the application of any enhancement strategy, this modified BPA LFA can achieve a naked-eye limit of detection (LOD) of 0.8 ng/mL, which is 12.5 times better than the LOD of other reported BPA LFAs, and a quantitative LOD of 0.472 ng/mL. The limit of detection for the SERS signals was 0.074, which was 202 and 8 times more sensitive than those of visual intensity and color intensity quantification, respectively. The range of quantification of the SERS signals doubled compared to that of color intensity quantification.
8:30 AM - NM05.01.02
Colloidal Nanoparticles for Ultrasensitive Biosensing
Imperial College London1Show Abstract
This talk will provide an overview of our recent developments in the design of nanomaterials for ultrasensitive biosensing. Bio-responsive nanomaterials are of growing importance with potential applications including drug delivery, diagnostics and tissue engineering (1). Using enzyme-mediated signal readouts we have developed a suite of nanoparticle based ultrasensitive biosensing approaches as well as a cell/tissue-interfacing nanoneedle platform (2). We are applying these biosensing approaches both in high throughput drug screening and to diagnose diseases ranging from cancer to global health applications.
 Stevens MM, George JH, Exploring and engineering the cell surface interface., Science, 2005, Vol:310, Pages:1135-1138.
 Howes PD, Chandrawati R, Stevens MM, 2014, Colloidal nanoparticles as advanced biological sensors, Science, 2013, Vol:346, DOI: 10.1126/science.1247390.
9:00 AM - NM05.01.03
Synthesis of Octahedral PtNiCu Ternary Alloy Nanostructure as Efficient Electrochemical Catalyst
University of California, Los Angeles1Show Abstract
Platinum-nickel (Pt-Ni) octahedral based nanomaterials represent an emerging class of highly active electrochemical catalysts, but can not meet the increasing activity demand for broad application and suffer from stability issue. We introduced Cu into octahedral Pt-Ni with controlled morphology. The octahedral Pt-Ni-Cu shows significantly enhanced activity and stability compared to octahedral Pt-Ni catalysts for cathode oxygen reduction reaction (ORR) , which is demonstrated to be a potential electrochemical catalyst. Computational simulation confirmed that the presence of Cu can improve the transition metal (Ni and Cu) retention thus improve both activity and stability.
9:15 AM - NM05.01.04
Synthesis and Chemical Transformation of Ni Nanoparticles Embedded in Silica
Joseph Tracy1,Brian Lynch1,Bryan Anderson1,2,3,W. Kennedy3
North Carolina State University1,Universal Technology Corporation2,Air Force Research Laboratory3Show Abstract
Ni nanoparticles (NPs) catalyze many chemical reactions, in which they can become contaminated or agglomerate, resulting in poorer performance. We report deposition of silica (SiO2) onto Ni NPs from tetraethyl orthysilicate (TEOS) through a reverse microemulsion approach, which is accompanied by an unexpected etching process. Ni NPs with an initial average diameter of 27 nm were embedded in composite SiO2-overcoated Ni NPs (SiO2-Ni NPs) with an average diameter of 30 nm. Each SiO2-Ni NP contained a ~7-nm oxidized Ni core and numerous smaller oxidized Ni NPs with diameters of ~2 nm distributed throughout the SiO2 shell. Etching of the Ni NPs is attributed to use of ammonium hydroxide as a catalyst for deposition of SiO2. Aliquots acquired during the deposition and etching process reveal agglomeration of SiO2 and Ni NPs, followed by dissociation into highly uniform SiO2-Ni NPs. This etching and embedding process may also be extended to other core materials. The stability of SiO2-Ni NPs was also investigated under high-temperature oxidizing and reducing environments. The structure of the SiO2-Ni NPs remained significantly unchanged after both oxidation and reduction, which suggests structural durability when used for catalysis.
9:30 AM - NM05.01.05
Biocompatible, Radiotherapeutic Hafnium Oxide Nanoparticle Imaging Probes Prepared Using a Novel Templated Synthesis
Prakash Nallathamby1,Viktoriya Sokolova2,Oleg Prymak2,Matthias Epple2,Ryan Roeder1
University of Notre Dame1,University of Duisburg-Essen2Show Abstract
Hafnium oxide (HfO2) with a k-edge of 50 keV is being explored as a clinical X-ray contrast agent. HfO2 NPs are also in clinical trials as radiosensitizers that induce immune action against tumor sites. However, the unpredictable stability of commercially available HfO2 makes it hard to predict their pharmacokinetics and their size range of ((50-100 nm) results in zero clearance from an in vivo system. Therefore, in this study we have executed a modular approach for the design and scalable synthesis of novel, non-sintered, 4-8 nm metal oxide nanoparticles (e.g. Hafnium oxide, Gadolinium oxide) with 40-60 fold higher X-ray attenuation cross-sections than the NPs diameter. Contrast-enhanced computed tomography (CT) and spectral (color) X-ray CT with the aid of these new class of probes have the potential to enable targeted image guided therapeutics with CT as a lower cost and higher resolution alternative to PET and MRI.
Amorphous HfO2 seed NPs, ~1.5 nm in size, embedded in a polycationic mesh and immobilized inside a silica template, were prepared by the simultaneous reduction and stabilization of tetrakis dimethyl amido hafnium by oleylamine at >250°C in a polyol solvent. Seed NPs were subsequently subjected to high-temperature calcination (>650°C), followed by alkaline digestion of the silica template, to prepare crystalline HfO2 NPs. As-prepared HfO2 NPs were surface functionalized with a monolayer of fluorescent silane to enable fluorescence imaging. The hydrodynamic diameter and zeta potential were measured using dynamic light scattering. In vitro cytocompatibility was characterized using established methods which included Live/Dead assay and confocal laser scanning microscopy after incubating NPs with HeLa cancer cells and THP-1 macrophage cells at 25-200 mg NPs/100,000 cells
We achieved >95% efficient conversion of the amorphous seed NPs to crystalline orthorhombic-HfO2 NPs. HfO2 NPs were ~4-5 nm in diameter and formed non-sintered flocculants, 220-290 nm in diameter. As-prepared CY5 tagged-HfO2 NPs exhibited simultaneous X-ray contrast and fluorescence in multispectral imaging. Both HfO2 and CY5 tagged-HfO2 NPs remained well-dispersed over 24 h. The measured zeta potential was -13 to -16 mV. Encapsulating the HfO2 NPs in a SiO2 shell reduced the hydrodynamic diameter to ~30 nm and inhibited the formation of flocculants. MTT and Live/Dead assays confirmed that the HfO2 NPs were neither cytotoxic nor pro-inflammatory. Confocal microscopy confirmed highly efficient uptake of Cy5-HfO2 NPs by HeLa cells and THP-1 cells.
HfO2 NPs were prepared using a novel templated synthesis resulting in crystalline NPs, ~4-5 nm in diameter, which flocculate into 220-290 nm clusters. Therefore, these NPs provide both long blood circulation and eventual renal clearance through phagocytic breakdown after delivery as radiographic imaging probe or radiosensitizer.
9:45 AM - NM05.01.06
Brightness-Equalized Indium Phosphide Quantum Shells Tunable Through Visible and NIR
Boston University1Show Abstract
The future of semiconductor quantum dots (QDs) in biomedical imaging lies not with well-established CdSe-based materials that raise issues of toxicity and limited tissue penetration depths, but rather with heavy metal-free compositions that emit in the near infrared (NIR) and short wave infrared (SWIR) in addition to visible wavelength ranges. With this motivation, we have developed semiconductor quantum shells (QSs) comprising non-toxic constituents. These ZnSe/InP/ZnS core/shell/shell structures are dubbed QSs because their Inverted-Type I bandgap structure yields quantum confinement-based emission from the InP shell. The excitonic emission from the QSs is tunable from the visible through the NIR with shell thickness, yielding emission peaks ranging from 515 – 850 nm. This tunablility range is wider than that seen for Type I InP QDs, particularly expanding emission deeper in the first optical tissue window, which spans from 650 – 950 nm. In this talk, I will detail the synthetic control of these heterostructured nanomaterials. In depth photophysical characterization has elucidated the structure/function relationship, enabling the concerted design of these emitters. Of particular note is our ability to match the brightness of emitters of various colors by tuning both the core size and shell thickness. The presentation will include early nanotoxicity and animal imaging results.
10:30 AM - NM05.01.07
Crystal Phase-Controlled Synthesis of Novel Noble Matel Nanomaterials
Nanyang Technological University1Show Abstract
In this talk, I will summarize the recent research on the crystal phase-engineering of novel nanomaterials in my group. It includes the first-time synthesis of hexagonal-close packed (hcp) Au nanosheets (AuSSs) on graphene oxide, surface-induced phase transformation of AuSSs from hcp to face-centered cubic (fcc) structures, the first-time synthesis of 4H hexagonal phase Au nanoribbons (NRBs) and their phase transformation to fcc Au RNBs, and the epitaxial growth of 4H Ag, Pt, Pd, PtAg, PdAg, PtPdAg, Rh, Ir, Ru, Os and Cu on 4H Au NRBs. Importantly, the concept of crystal-phase heterostructure is proposed.
11:00 AM - NM05.01.08
Tuning Nanoparticle Sizes and Properties Through Continuous Growth
Sandia National Laboratories1Show Abstract
Traditional approaches to nanoparticle size control generally attempt to control size by controlling the nucleation step and varying the number of nuclei formed. I will present several approaches to nanoparticle size control and systematic variation that seeks to control and systematically vary nanoparticle size using identical nucleation events, but varying the nanoparticle growth. The approaches have in common the constant addition of nanoparticle precursor that leads to a steady state reaction. This method, referred to as the Extended LaMer mechanism, leads to a linear increase in nanoparticle volume with time. The reaction can be extended for as long as the nanoparticles remain colloidally stable, allowing for systematic variation of nanoparticle sized through a wide range. The approach is general and can be applied to a range of synthetic systems to produce nanoparticles with exceptional reproducibility in size. One can also take advantage of the loss in colloidal stability to design a reaction that precipitates at a desired size. Since this loss of solubility is essentially a phase transition, the nanoparticle size is controlled by thermodynamics and not kinetics. This improve the ease of reproducibility of nanoparticle size with or without careful control of the reaction kinetics. A continuous reaction using this precipitation approach in magnetic nanoparticles will be discussed as will scale up and applications of these nanoparticles. This work was performed, in part, at the Center for Integrated Nanotechnologies, an Office of Science User Facility operated for the U.S. Department of Energy (DOE) Office of Science. Sandia National Laboratories is a multi-mission laboratory managed and operated by National Technology and Engineering Solutions of Sandia, LLC., a wholly owned subsidiary of Honeywell International, Inc., for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-NA-0003525.
11:30 AM - NM05.01.09
In Situ Studies of Organometallic ZnO Nanoparticle Synthesis for Applications in CO2 Reduction Catalysis
Milo Shaffer1,Sebastian Pike1,Andres Trenco2,1,Charlotte Williams2,1
Imperial College London1,University of Oxford2Show Abstract
Well-defined, organically-modified ZnO nanoparticles were prepared via an efficient hydrolysis route, without the need for surfactant co-ligands, washing or size-selection steps. The products have a narrow size distribution and are soluble in organic solvents. The synthesis involves reacting a mixture of alkylzinc carboxylate complex and excess diethylzinc with water to yield carboxylate-capped ZnO nanoparticles. Varying the ratio of the different organometallic species enables control of either size or degree of surface modification.
The bottom-up synthesis of ligand-stabilized functional nanoparticles from molecular precursors is widely applied but is difficult to study mechanistically. In this organometallic system, which avoids excess ligand, 31P NMR spectroscopy can be used to follow the trajectory of phosphinate ligands during the synthesis. Initially, we established the structures of a range of ligated zinc oxo clusters, containing 4, 6 and 11 zinc atoms, showing that the clusters interconvert rapidly and self-assemble in solution based on thermodynamic equilibria rather than nucleation kinetics. Subsequently, we identified these clusters in situ during the synthesis of phosphinate-capped zinc oxide nanoparticles. Unexpectedly, the ligand is sequestered to a stable Zn11 cluster during the majority of the synthesis and only becomes coordinated to the nanoparticle surface, in the final step. In addition to a versatile and accessible route to (optionally doped) zinc clusters, the findings provide an understanding of the role of well-defined molecular precursors during the synthesis of small (2–4 nm) nanoparticles.
These stabilised ZnO nanoparticles can be combined with copper nanoparticles to form colloidal catalysts. In a slurry phase reactor, these systems have proven to be highly active in methanol synthesis compared to the analogue heterogeneous Cu/ZnO/Al2O3. The increased catalytic activity appears to correlate with a higher exposed surface area and with the selection of the capping ligand, which plays a role in supporting re-structuring and stability.
11:45 AM - NM05.01.10
Determination of the Inherent Electrical Transport Properties in Individual Colloidal Semiconductor Nanocrystals of SnS
Adam Biacchi1,Son Le1,Brian Alberding1,Joseph Hagmann1,Curt Richter1,Edwin Heilweil1,Angela Hight Walker1
National Institute of Standards and Technology1Show Abstract
Colloidal-based solution syntheses offer a scalable and cost-efficient means of producing nanoscale semiconductors in high yield. While much progress has been made towards the controlled and tailorable synthesis of semiconductor nanocrystals in solution, it remains a substantial challenge to fully characterize the products’ inherent carrier transport properties. This is often due to their irregular morphology or small dimensions, which usually demand the formation of colloidal assemblies or films as a prerequisite to performing electrical measurements. Here, we report a novel means for obtaining a comprehensive analyses of the electronic transport properties of individual colloidal semiconductor nanocrystals. First, we present the development of a novel solution chemistry-based synthetic approach to produce nearly monodisperse µm-scale 2D tin(II) sulfide (SnS) nanoribbons and square nanosheets using a one-pot, one-step, easily-scalable synthetic route. These syntheses represent a rare example in this size regime of essentially uniform, single-crystalline, 2D nanocrystals produced using colloidal chemistry. Next, we detail the structural characterization of these SnS materials, and describe how they are processed from solution to fabricate back-gated, top-contact solid-state devices from individual colloidal crystals. Finally, we interrogate their electronic transport properties by a combination of multi-point contact probe electrical transport measurements and time-resolved terahertz spectroscopy. These studies allow for the determination of carrier concentration, carrier mobility, conductivity, and the majority carrier type within an individual 2D colloidal nanocrystal. Our findings illustrate that minor manipulation of solution chemistries may afford products with substantively disparate charge carrier parameters, which are challenging to extract using common experimental practices, and underpins that this metrological strategy represents a significant and valuable advancement in the characterization of colloidally-synthesized semiconductors.
NM05.02: Session II
Monday PM, April 02, 2018
PCC North, 200 Level, Room 229 B
1:30 PM - NM05.02.01
Tunable Emissive Fluorescent Carbon Dots and Their Application
Zaicheng Sun1,Dan Qu1
Beijing University of Technology1Show Abstract
Carbon dots, as a rising fluorescent materials have attracted continuously attention for potential applications in LED, solar cells, sensor, bioimaging and photocatalyst. However, its photo luminescent quantum yield (PL QY) is still quite low, especially emission in long wavelength region like red light. Herein, we proposed increasing the PL QY by doped carbon dots with N or S, N. The PL QY of carbon dots dramatically rises up after doping with N. It can reach over 90%. The carbon dots prepared via bottom-up route show excitation independent emission. In order to extend the absorption in the visible light region, S element is further introduced into the carbon dots to form S, N co-doped carbon dots. Due to the introduction of S and N, there is another S state was introduced into the band gap. That results in the new emission at red light region. Blue, green and red light emissions were obtained from carbon dots. Due to the excellent biocompatibility and low cytotoxicity, we further conjugated the cisplatin with carbon dots to obtain the theranostic agent. We explored to adding more function onto the carbon dots, like self-targeting and therapeutic function to construct the nanomedicine integrating with targeting, bio-imaing and therapy function together.
2:00 PM - NM05.02.02
Quantitative Prediction of Position and Orientation for Platonic Nanoparticles at Liquid/Liquid Interfaces
Shuzhou Li1,Wenxiong Shi1
Nanyang Technological University1Show Abstract
Platonic particles are promising materials with nanoscale light-matter interactions in plasmonics and biosensing, due to their unique structure caused by vertices, edges and facets. The position and orientation of Platonic particles play a crucial role in determining the resultant assembled structures at a liquid/liquid interface. Therefore, it is desirable to develop a reliable theory that can predict the interfacial configuration of an isolated Platonic nanoparticle from nanoparticle-solvent interactions and solvent-solvent interactions. Here, we numerically explored all possible orientations of a Platonic nanoparticle, including three specific orientations: vertex up, edge up, and facet up orientations. We found that a specific orientation is more preferred than random orientations. We also demonstrated that the free energy change theory could quantitatively predict the position and orientation of an isolated Platonic nanoparticles at a liquid/liquid interface, where the surface wettability of the nanoparticle determined the most stable position and the preferred orientation. Molecular dynamics simulations were used to test our theory where the surface wettability of a Platonic solid was adjusted from extremely hydrophobic to extremely hydrophilic by changing the charge amount on the Ag surface. The molecular dynamics simulation results were in excellent agreement with our theoretical prediction for an isolated Ag Platonic nanoparticle at a hexane/water interface. Our proposed theory bridges molecular-level simulations and assembly structure of Platonic nanoparticles in experiments, in which the insights from nanoparticle wettability in solvents can be used to predict macroscopic superlattice structure in experiments. This work advances our ability to precisely predict the final structures of the Platonic nanoparticle assemblies at a liquid/liquid interface.
3:00 PM - NM05.02.03
Impact of Anionic Ligands on Photophysics of CdSe and CdS Nanocrystals
Svetlana Kilina1,Levi Lystrom1
North Dakota State University1Show Abstract
Significance of the surface passivation of II-VI colloidal quantum dots (QDs) on their photophysical properties is discussed. Optically forbidden nature of surface-associated states makes their direct measurements challenging. Our DFT-based simulations of CdSe QDs ligated by anionic ligands, such as carboxylates, thiolates, and hydrides, provide insights into the role the acidic ligands play during synthesis and ligand exchange, as well as in manipulating QD’s optical response. Thus, our calculations reveal much more complicated exchange mechanism of the native surface ligands of CdSe QDs with phenyl-dithiocarbamates (PTCs) as it was thought before. PTCs decompose during exchange with native ligands, while only a small portion of deprotonated PTCs covalently bounds to the Cd-enriched surface. Our calculations also reveal that attachment of the hydride to Se sites results in strong distortions of Cd-Se bounds leading to ‘cleaning’ out of extra Se ions from the QD surface (in a form of SeH2 gas) and eliminating Se-associated trap states. On the other hand, adsorption of H- on Cd, when the surface is enriched by metal ions, results in blue-shifted lower-energy transitions with very high oscillator strength, which likely responsible for experimentally observed emission enhancement of CdSe QDs treated by hydrides. The calculated results allow for explanations of experimental trends and observables sensitive to surface defects and ligand passivation and offering guidance for controlling the optical response of II-VI nanostructures by means of surface ligand engineering.
3:15 PM - NM05.02.04
Site-Specific Polymer Nanoreactors for Studying Complex Nanoparticles Using Correlative Electron Microscopy
Jingshan Du1,Pengcheng Chen1,Vinayak Dravid1,Chad Mirkin1
Northwestern University1Show Abstract
Complex nanoparticles, which contain multiple elements, crystal structures, and architectures, are useful for elucidating principles of fundamental thermodynamics and can be applied in fields spanning catalysis to plasmonics. However, the combinations of elements that have been explored thus far in these systems are limited by a lack of combinatorial methods for preparing multiplexed nanoparticle systems. In this presentation, we will discuss how correlative electron microscopy can be used to study the structures and dynamics of complex nanoparticles generated in scanning probe-deposited polymer nanoreactors. Metal, oxide, and hybrid metal-oxide nanoparticles of a variety of compositions and structures can be rapidly generated on electron-transparent substrates with exquisite site-specificity. These particles can then be easily relocated multiple times, enabling repeated, correlated characterization at the individual nanoparticle level. Moreover, polymer nanoreactors provide a viable platform for studying coarsening and solvent-particle interactions at the nanoscale and can be analyzed using in situ electron microscopy. This work demonstrates how polymer nanoreactors, when combined with advanced electron microscopy techniques, can be used as a versatile methodology for understanding the structure–function relationships as well as