Nathan D Burrows

All Publications

• Metagenomic analysis of microbial communities yields insight into impacts of nanoparticle design NATURE NANOTECHNOLOGY Metch, J. W., Burrows, N. D., Murphy, C. J., Pruden, A., Vikesland, P. J. 2018; 13 (3): 253-+

  Abstract

  Next-generation DNA sequencing and metagenomic analysis provide powerful tools for the environmentally friendly design of nanoparticles. Herein we demonstrate this approach using a model community of environmental microbes (that is, wastewater-activated sludge) dosed with gold nanoparticles of varying surface coatings and morphologies. Metagenomic analysis was highly sensitive in detecting the microbial community response to gold nanospheres and nanorods with either cetyltrimethylammonium bromide or polyacrylic acid surface coatings. We observed that the gold-nanoparticle morphology imposes a stronger force in shaping the microbial community structure than does the surface coating. Trends were consistent in terms of the compositions of both taxonomic and functional genes, which include antibiotic resistance genes, metal resistance genes and gene-transfer elements associated with cell stress that are relevant to public health. Given that nanoparticle morphology remained constant, the potential influence of gold dissolution was minimal. Surface coating governed the nanoparticle partitioning between the bioparticulate and aqueous phases.

  View details for DOI 10.1038/s41565-017-0029-3

  View details for Web of Science ID 000427009000020

  View details for PubMedID 29335567

• Understanding the Seed-Mediated Growth of Gold Nanorods through a Fractional Factorial Design of Experiments LANGMUIR Burrows, N. D., Harvey, S., Idesis, F. A., Murphy, C. J. 2017; 33 (8): 1891-1907

  Abstract

  Since the development of simple, aqueous protocols for the synthesis of anisotropic metal nanoparticles, research into many promising, valuable applications of gold nanorods has grown considerably, but a number of challenges remain, including gold-particle yield, robustness to minor impurities, and precise control of gold nanorod surface chemistry. Herein we present the results of a composite fractional factorial series of experiments designed to screen seven additional potential avenues of control and to understand the seed-mediated silver-assisted synthesis of gold nanorods. These synthesis variables are the amount of sodium borohydride used and the rate of stirring when producing seed nanoparticles, the age of and the amount of seeds added, the reaction temperature, the amounts of silver nitrate and ascorbic acid added, and the age of the reduced growth solution before seed nanoparticles are added to initiate rod formation. This statistical experimental design and analysis method, besides determining which experimental variables are important and which are not when synthesizing gold nanorods (and quantifying their effects), gives further insight into the mechanism of growth by measuring the degree to which variables interact with each other by mapping out their mechanistic connections. This work demonstrates that when forming gold nanorods by the reduction of auric ions by ascorbic acid onto seed nanoparticles, ascorbic acid determines how much gold is reduced, and the amount of seeds determine how it is divided, yet both influence the intrinsic growth rates, in both width and length, of the forming nanorods. Furthermore, this work shows that the reduction of gold proceeds via direct reduction on the surface of seeds and not through a disproportionation reaction. Further control over the length of gold nanorods can be achieved by tuning the amount of silver nitrate or the reaction temperature. This work shows that silver does not directly influence rod length or width, and a new primary role for silver is proposed as a catalyst promoting the reduction of gold on the ends of forming nanorods. Furthermore, this silver catalyst is removed from the reaction by adsorption onto the surface of the growing nanorod. This work also demonstrates the importance of freshly prepared silver nitrate and ascorbic acid solutions, free from even a few hours of photodegradation, in preparing gold nanorods with high shape purity and gold yield.

  View details for DOI 10.1021/acs.langmuir.6b03606

  View details for Web of Science ID 000395360800018

  View details for PubMedID 27983861

• Sulfate-Mediated End-to-End Assembly of Gold Nanorods LANGMUIR Abtahi, S. H., Burrows, N. D., Idesis, F. A., Murphy, C. J., Saleh, N. B., Vikesland, P. J. 2017; 33 (6): 1486-1495

  Abstract

  There is interest in the controlled aggregation of gold nanorods (GNRs) for the production of extended nanoassemblies. Prior studies have relied upon chemical modification of the GNR surface to achieve a desired final aggregate structure. Herein we illustrate that control of electrolyte composition can facilitate end-to-end assembly of cetyltrimethylammonium-bromide-coated (CTAB) GNRs. By adjusting either the sulfate anion concentration or the exposure time it is possible to connect GNRs in chain-like assemblies. In contrast, end-to-end assembly was not observed in control experiments using monovalent chloride salts. We attribute the end-to-end assembly to the localized association of sulfate with exposed quaternary ammonium head groups of CTAB at the nanorod tip. To quantify the assembly kinetics, visible-near-infrared extinction spectra were collected over a predetermined time period, and the colloidal behavior of the GNR suspensions was interpreted using plasmon band analysis. Transmission electron microscopy and atomic force microscopy results support the conclusions reached via plasmon band analysis, and the colloidal behavior is consistent with Derjaguin-Landau-Verwey-Overbeek theory.

  View details for DOI 10.1021/acs.langmuir.6b04114

  View details for Web of Science ID 000394411100020

  View details for PubMedID 28098460

• Surface Chemistry of Gold Nanorods LANGMUIR Burrows, N. D., Lin, W., Hinman, J. G., Dennison, J. M., Vartanian, A. M., Abadeer, N. S., Grzincic, E. M., Jacob, L. M., Li, J., Murphy, C. J. 2016; 32 (39): 9905-9921

  Abstract

  Gold nanorods have garnered a great deal of scientific interest because of their unique optical properties, and they have the potential to greatly impact many areas of science and technology. Understanding the structure and chemical makeup of their surfaces as well as how to tailor them is of paramount importance in the development of their successful applications. This Feature Article reviews the current understanding of the surface chemistry of as-synthesized gold nanorods, methods of tailoring the surface chemistry of gold nanorods with various inorganic and organic coatings/ligands, and the techniques employed to characterize ligands on the surface of gold nanorods as well as the associated measurement challenges. Specifically, we address the challenges of determining how thick the ligand shell is, how many ligands per nanorod are present on the surface, and where the ligands are located in regiospecific and mixed-ligand systems. We conclude with an outlook on the development of the surface chemistry of gold nanorods leading to the development of a synthetic nanoparticle surface chemistry toolbox analogous to that of synthetic organic chemistry and natural product synthesis.

  View details for DOI 10.1021/acs.langmuir.6b02706

  View details for Web of Science ID 000384842000001

  View details for PubMedID 27568788

• Thermal Transport across Surfactant Layers on Gold Nanorods in Aqueous Solution ACS APPLIED MATERIALS & INTERFACES Wu, X., Ni, Y., Zhu, J., Burrows, N. D., Murphy, C. J., Dumitrica, T., Wang, X. 2016; 8 (16): 10581-10589

  Abstract

  Ultrafast transient absorption experiments and molecular dynamics simulations are utilized to investigate the thermal transport between aqueous solutions and cetyltrimethylammonium bromide (CTAB)- or polyethylene glycol (PEG)-functionalized gold nanorods (GNRs). The transient absorption measurement data are interpreted with a multiscale heat diffusion model, which incorporates the interfacial thermal conductances predicted by molecular dynamics. According to our observations, the effective thermal conductance of the GNR/PEG/water system is higher than that of the GNR/CTAB/water system with a surfactant layer of the same length. We attribute the enhancement of thermal transport to the larger thermal conductance at the GNR/PEG interface as compared with that at the GNR/CTAB interface, in addition to the water penetration into the hydrophilic PEG layer. Our results highlight the role of the GNR/polymer thermal interfaces in designing biological and composite-based heat transfer applications of GNRs, and the importance of multiscale analysis in interpreting transient absorption data in systems consisting of low interfacial thermal conductances.

  View details for DOI 10.1021/acsami.5b12163

  View details for Web of Science ID 000375245100059

  View details for PubMedID 26938771

• Anisotropic Nanoparticles and Anisotropic Surface Chemistry JOURNAL OF PHYSICAL CHEMISTRY LETTERS Burrows, N. D., Vartanian, A. M., Abadeer, N. S., Grzincic, E. M., Jacob, L. M., Lin, W., Li, J., Dennison, J. M., Hinman, J. G., Murphy, C. J. 2016; 7 (4): 632-641

  Abstract

  Anisotropic nanoparticles are powerful building blocks for materials engineering. Unusual properties emerge with added anisotropy-often to an extraordinary degree-enabling countless new applications. For bottom-up assembly, anisotropy is crucial for programmability; isotropic particles lack directional interactions and can self-assemble only by basic packing rules. Anisotropic particles have long fascinated scientists, and their properties and assembly behavior have been the subjects of many theoretical studies over the years. However, only recently has experiment caught up with theory. We have begun to witness tremendous diversity in the synthesis of nanoparticles with controlled anisotropy. In this Perspective, we highlight the synthetic achievements that have galvanized the field, presenting a comprehensive discussion of the mechanisms and products of both seed-mediated and alternative growth methods. We also address recent breakthroughs and challenges in regiospecific functionalization, which is the next frontier in exploiting nanoparticle anisotropy.

  View details for DOI 10.1021/acs.jpclett.5b02205

  View details for Web of Science ID 000370765700007

  View details for PubMedID 26817922

• In solution SERS sensing using mesoporous silica-coated gold nanorods ANALYST Gao, Z., Burrows, N. D., Valley, N. A., Schatz, G. C., Murphy, C. J., Haynes, C. L. 2016; 141 (17): 5088-5095

  Abstract

  Mesoporous silica-coated gold nanorods (AuNR@MS) act as a colloidally stable Raman sensing platform with a built-in analyte size cutoff. Herein, these core-shell plasmonic nanostructures were presented with a range of thiolated Raman-active molecules to probe the limits of this platform for SERS sensing. The experimental results show generally, that the transport of molecules through the mesopores is highly dependent on the size of the molecule and specifically, that AuNR@MS with pores of ∼4 nm diameter are able to sense analytes with molecular dimensions smaller than 1.5 nm. This sensing platform will likely find broad use, performing well even in complex media based on the high colloidal stability imbued by the mesoporous silica shell.

  View details for DOI 10.1039/c6an01159d

  View details for Web of Science ID 000382111100012

  View details for PubMedID 27396950

• Anisotropic Noble Metal Nanocrystal Growth: The Role of Halides CHEMISTRY OF MATERIALS Lohse, S. E., Burrows, N. D., Scarabelli, L., Liz-Marzan, L. M., Murphy, C. J. 2014; 26 (1): 34-43

  View details for DOI 10.1021/cm402384j

  View details for Web of Science ID 000330416900005

• Crystalline nanoparticle aggregation in non-aqueous solvents CRYSTENGCOMM Burrows, N. D., Kesselman, E., Sabyrov, K., Stemig, A., Talmon, Y., Penn, R. 2014; 16 (8): 1472-1481

  View details for DOI 10.1039/c3ce41584h

  View details for Web of Science ID 000330781000010

• Microfluidic-SERS devices for one shot limit-of-detection ANALYST Kim, D., Campos, A. R., Datt, A., Gao, Z., Rycenga, M., Burrows, N. D., Greeneltch, N. G., Mirkin, C. A., Murphy, C. J., Van Duyne, R. P., Haynes, C. L. 2014; 139 (13): 3227-3234

  Abstract

  Microfluidic sensing platforms facilitate parallel, low sample volume detection using various optical signal transduction mechanisms. Herein, we introduce a simple mixing microfluidic device, enabling serial dilution of introduced analyte solution that terminates in five discrete sensing elements. We demonstrate the utility of this device with on-chip fluorescence and surface-enhanced Raman scattering (SERS) detection of analytes, and we demonstrate device use both when combined with a traditional inflexible SERS substrate and with SERS-active nanoparticles that are directly incorporated into microfluidic channels to create a flexible SERS platform. The results indicate, with varying sensitivities, that either flexible or inflexible devices can be easily used to create a calibration curve and perform a limit of detection study with a single experiment.

  View details for DOI 10.1039/c4an00357h

  View details for Web of Science ID 000337125600004

  View details for PubMedID 24756225

  View details for PubMedCentralID PMC4067008

• Cryogenic Transmission Electron Microscopy: Aqueous Suspensions of Nanoscale Objects MICROSCOPY AND MICROANALYSIS Burrows, N. D., Penn, R. 2013; 19 (6): 1542-1553

  Abstract

  Direct imaging of nanoscale objects suspended in liquid media can be accomplished using cryogenic transmission electron microscopy (cryo-TEM). Cryo-TEM has been used with particular success in microbiology and other biological fields. Samples are prepared by plunging a thin film of sample into an appropriate cryogen, which essentially produces a snapshot of the suspended objects in their liquid medium. With successful sample preparation, cryo-TEM images can facilitate elucidation of aggregation and self-assembly, as well as provide detailed information about cells and viruses. This work provides an explanation of sample preparation, detailed examples of the many artifacts found in cryo-TEM of aqueous samples, and other key considerations for successful cryo-TEM imaging.

  View details for DOI 10.1017/S1431927613013354

  View details for Web of Science ID 000330344800019

  View details for PubMedID 24001937

• Effect of pH on the Kinetics of Crystal Growth by Oriented Aggregation CRYSTAL GROWTH & DESIGN Burrows, N. D., Hale, C. H., Penn, R. 2013; 13 (8): 3396-3403

  View details for DOI 10.1021/cg4001939

  View details for Web of Science ID 000323020000017

• Size-Dependent Anatase to Rutile Phase Transformation and Particle Growth CHEMISTRY OF MATERIALS Sabyrov, K., Burrows, N. D., Penn, R. 2013; 25 (8): 1408-1415

  View details for DOI 10.1021/cm302129a

  View details for Web of Science ID 000318144000025

• Effect of Ionic Strength on the Kinetics of Crystal Growth by Oriented Aggregation CRYSTAL GROWTH & DESIGN Burrows, N. D., Hale, C. H., Penn, R. 2012; 12 (10): 4787-4797

  View details for DOI 10.1021/cg3004849

  View details for Web of Science ID 000309493300018

• Aggregation of ferrihydrite nanoparticles in aqueous systems FARADAY DISCUSSIONS Yuwono, V. M., Burrows, N. D., Soltis, J. A., Tram Anh Do, Penn, R. 2012; 159: 235-245

  View details for DOI 10.1039/c2fd20115a

  View details for Web of Science ID 000310281600012

• Oriented Aggregation: Formation and Transformation of Mesocrystal Intermediates Revealed JOURNAL OF THE AMERICAN CHEMICAL SOCIETY Yuwono, V. M., Burrows, N. D., Soltis, J. A., Penn, R. 2010; 132 (7): 2163-+

  Abstract

  Oriented aggregation is a special case of aggregation in which nanocrystals self-assemble and form new secondary single crystals. This process has been suggested to proceed via an intermediate state known as the mesocrystal, in which the nanocrystals have parallel crystallographic alignment but are spatially separated. We present the first direct observations of mesocrystals with size and shape similar to product oriented aggregates by employing cryo-TEM to directly image the particles in aqueous suspension. The cryo-TEM images reveal that mesocrystals not only form but also transform to the final single crystal product while in the dispersed state. Further, high-resolution cryo-TEM images demonstrate that the mesocrystals are composed of spatially separated and crystallographically aligned nanocrystals.

  View details for DOI 10.1021/ja909769a

  View details for Web of Science ID 000275085100028

  View details for PubMedID 20112897

• Quantifying the Kinetics of Crystal Growth by Oriented Aggregation MRS BULLETIN Burrows, N. D., Yuwono, V. M., Penn, R. 2010; 35 (2): 133-137

  View details for DOI 10.1557/mrs2010.633

  View details for Web of Science ID 000274676800014