Patterning materials with nanoscale features opens many research opportunities ranging from fundamental science to technological applications. However, current nanofabrication methods are ill-suited for sub-5 nm patterning and pattern transfer. We demonstrate the use of colloidal lithography to transfer an anisotropic pattern of discrete features into substrates with a critical dimension below 5 nm.
View Article and Find Full Text PDFSelf-assembly is an increasingly popular approach to systematically control the formation of complex, multicomponent materials with structural features orders of magnitude larger than the constituent colloidal nanocrystals. Common approaches often involve templating prefabricated patterns to control particle organization- or programming-specific interactions between individual building blocks. While effective, such fabrication methods suffer from major bottlenecks due to the complexity required in mask creation for patterning or surface modification techniques needed to program directed interactions between particles.
View Article and Find Full Text PDFThe use of nanocrystal (NC) building blocks to create metamaterials is a powerful approach to access emergent materials. Given the immense library of materials choices, progress in this area for anisotropic NCs is limited by the lack of co-assembly design principles. Here, we use a rational design approach to guide the co-assembly of two such anisotropic systems.
View Article and Find Full Text PDFA variety of available terminal sire lines makes the choice of terminal sire line complex for the pig producer. Higher birth weights are important for subsequent growth performance and selection for this trait is also necessary in sire lines. The aim was to investigate the effect of sire line, birth weight and gender on growth performance, carcass traits and meat quality.
View Article and Find Full Text PDFInvestigation of charge transfer in quantum dot (QD) systems is an area of great interest. Specifically, the relationship between capping ligand and rate of charge transfer has been studied as a means to optimize these materials. To investigate the role of ligand interaction on the QD surface for electron transfer, we designed and synthesized a series of ligands containing an electron accepting moiety, naphthalene bisimide (NBI).
View Article and Find Full Text PDFMany studies on nanocrystal (NC) self-assembly into ordered superlattices have focused mainly on attractive forces between the NCs, whereas the role of organic ligands on anisotropic NCs is only in its infancy. Herein, we report the use of a series of dendrimer ligands to direct the assembly of nanoplates into 2D and 3D geometries. It was found that the dendrimer-nanoplates consistently form a directionally offset architecture in 3D films.
View Article and Find Full Text PDFSubstitutional doping is a potentially powerful technique to control the properties of nanocrystal (NC) superlattices (SLs). However, not every NC can be substituted into any lattice, as the NCs have to be close in size and shape, limiting the application of substitutional doping. Here we show that this limitation can be overcome by employing ligands of various size.
View Article and Find Full Text PDFNanoparticle (NP) stability is imperative for commercialization of nanotechnology. In this study, we compare the stability of Au NPs with surfaces functionalized with oleylamine, dodecanethiol, and two dendritic ligands of different generations. Dendrimer ligands provide a significant increase in the chemical stability of Au NPs when analyzed by cyanide-induced NP decomposition as well as an investigation into their colloidal stability at ambient conditions.
View Article and Find Full Text PDFAn optically active metallo-polymer assembly is demonstrated via conjugation of a genetically engineered elastin-like polypeptide (ELP) and a ruthenium(II) polypyridyl complex. By taking advantage of the phase transition of ELPs in water, photophysical properties of the resultant conjugate are investigated for both phases, below and above the critical transition temperature. Upon coacervation, the luminescence of the metallo-ELP is greatly enhanced as a consequence of local effects on the metal-ligand luminophore.
View Article and Find Full Text PDFRare-earth nanocrystals (RE NCs) are a valuable class of nanomaterials due to their ability to bring the attractive properties of rare earth bulk crystals to biomedical applications and solution-processable engineering. Of the bottom-up synthesis approaches, solvothermal methods yield highly crystalline and monodisperse RE NCs. Herein, we report a polycatenar ligand controlled synthesis of RE NCs using a semi-combinatorial approach with a microreactor setup that enables the investigation of the influences of several reaction parameters on the growth of the RE NCs.
View Article and Find Full Text PDFThe use of ethionamide (ETH) in treating multidrug-resistant tuberculosis is limited by severe side effects. ETH disposition after pulmonary administration in spray-dried particles might minimize systemic exposure and side effects. To explore this hypothesis, spray-dried ETH particles were optimized for performance in a dry powder aerosol generator and exposure chamber.
View Article and Find Full Text PDFInorganic-organic hybrid materials such as organically templated metal oxides, metal-organic frameworks (MOFs) and organohalide perovskites have been studied for decades, and hydrothermal and (non-aqueous) solvothermal syntheses have produced thousands of new materials that collectively contain nearly all the metals in the periodic table. Nevertheless, the formation of these compounds is not fully understood, and development of new compounds relies primarily on exploratory syntheses. Simulation- and data-driven approaches (promoted by efforts such as the Materials Genome Initiative) provide an alternative to experimental trial-and-error.
View Article and Find Full Text PDFTuberculosis (TB) is a life-threatening infection that requires a lengthy treatment process that is often associated with adverse effects. Pulmonary delivery of anti-TB drugs has the potential to increase efficacy of treatment by increasing drug concentrations at the lungs, the primary site of infection. The aim of the present study is to evaluate the disposition of rifampicin (RIF) after its pulmonary administration as porous particles (PPs) to guinea pigs and contrast it to that after oral administration.
View Article and Find Full Text PDFWe describe the design and synthesis of a new graphene ribbon architecture that consists of perylenediimide (PDI) subunits fused together by ethylene bridges. We created a prototype series of oligomers consisting of the dimer, trimer, and tetramer. The steric congestion at the fusion point between the PDI units creates helical junctions, and longer oligomers form helical ribbons.
View Article and Find Full Text PDFThe Wnt/β-catenin pathway plays multiple and diverse roles in development by regulating gene expression via T-cell factor/Lymphoid enhancer-binding factor (Tcf/Lef) DNA binding factors. Misregulation of this pathway is thought to initiate colon adenoma formation. It is controversial whether Tcf4 (Tcf7L2) functions as an oncogene or tumor suppressor gene in colon carcinogenesis.
View Article and Find Full Text PDFAntimicrob Agents Chemother
April 2010
Novel treatments for multidrug-resistant tuberculosis (MDR-TB), extensively drug-resistant tuberculosis (XDR-TB), or latent TB are needed urgently. Recently, we reported the formulation and characterization of the nitroimidazo-oxazine PA-824 for efficient aerosol delivery as dry powder porous particles and the subsequent disposition in guinea pigs after pulmonary administration. The objective of the present study was to evaluate the effects of these PA-824 therapeutic aerosols on the extent of TB infection in the low-inoculum aerosol infection guinea pig model.
View Article and Find Full Text PDFPurpose: To formulate rifampicin, an anti-tuberculosis antibiotic, for aerosol delivery in a dry powder 'porous nanoparticle-aggregate particle' (PNAP) form suited for shelf stability, effective dispersibility and extended release with local lung and systemic drug delivery.
Methods: Rifampicin was encapsulated in PLGA nanoparticles by a solvent evaporation process, spray dried into PNAPs containing varying amounts of nanoparticles, and characterized for physical and aerosol properties. Pharmacokinetic studies were performed with formulations delivered to guinea pigs by intratracheal insufflation and compared to oral and intravenous delivery of rifampicin.
Antimicrob Agents Chemother
April 2009
We formulated PA-824, a nitroimidazopyran with promise for the treatment of tuberculosis, for efficient aerosol delivery to the lungs in a dry powder porous particle form. The objectives of this study were to prepare and characterize a particulate form of PA-824, assess the stability of this aerosol formulation under different environmental conditions, and determine the pharmacokinetic parameters for the powder after pulmonary administration. The drug was spray dried into porous particles containing a high drug load and possessing desirable aerosol properties for efficient deposition in the lungs.
View Article and Find Full Text PDFBy manufacturing a single-particle system in two particulate forms (i.e., micrometer size and nanometer size), we have designed a bacterial vaccine form that exhibits improved efficacy of immunization.
View Article and Find Full Text PDFPurpose: To develop an aerosol system for efficient local lung delivery of a tuberculostatic drug.
Methods: The antibiotic, capreomycin sulfate, was spray dried to form a dry powder aerosol. The chemical content and physical properties of resulting particles were assessed under various storage conditions.
Antimicrob Agents Chemother
August 2007
Purpose: To characterize organic cation (OC) transport in primary cultured rabbit alveolar epithelial cell monolayers, using [14C]-guanidine as a model substrate.
Methods: Type II alveolar epithelial cells from the rabbit lung were isolated by elastase digestion and cultured on permeable filters precoated with fibronectin and collagen. Uptake and transport studies of [14C]-guanidine were conducted in cell monolayers of 5 to 6 days in culture.
Purpose: To develop a cell culture model of human alveolar epithelial cells in primary culture for the in vitro study of pulmonary absorption and transport.
Methods: Type II pneumocytes isolated from normal human distal lung tissue by enzyme treatment and subsequent purification were plated on fibronectin/collagen coated polyester filter inserts, and cultured using a low-serum growth medium. Characterization of the cell culture was achieved by bioelectric measurements, cell-specific lectin binding, immunohistochemical detection of cell junctions, and by assessment of transepithelial transport of dextrans of varying molecular weights.
Objective: To evaluate whether the family system variables of adults with diabetes relate to the adequacy of metabolic control or the psychosocial adaptation to the illness.
Research Design And Methods: A total of 150 insulin-requiring adults were assessed on a single occasion. They completed two family system measures (the Family Environment Scale [FES] and the Diabetes Family Behavior Checklist [DFBC]), two quality-of-life measures (the Diabetes Quality of Life Scale and the Medical Outcomes Study Health Survey-36), and one measure of cognitive appraisal (the Appraisal of Diabetes Scale).