@article{marusak_johnston-peck_wu_anderson_tracy_2017, title={Size and Composition Control of CoNi Nanoparticles and Their Conversion into Phosphides}, volume={29}, ISSN={["1520-5002"]}, url={https://doi.org/10.1021/acs.chemmater.6b04335}, DOI={10.1021/acs.chemmater.6b04335}, abstractNote={The synthesis of binary rather than unary metal nanoparticles (NPs) introduces challenges in controlling the chemistry and opportunities to tune the properties of the products. Ligand-stabilized CoNi NPs were synthesized by heating mixtures of Ni(acac)2 and Co(acac)2 (acac = acetylacetonate), oleylamine, trioctylphosphine, and trioctylphosphine oxide to 240 °C. Varying the amounts of the Co and Ni precursors allows for control over the NP size, giving diameters of 6–18 nm and compositions (XCo) of ≤0.7. The products are enriched with Ni, in comparison with the Co:Ni ratio of the precursors. Co and Ni are both dispersed throughout the NPs, while the shells are enriched with Co. The magnetic properties of CoNi NPs are between those of magnetically soft Ni and magnetically harder Co, with additional effects caused by oxidation under ambient atmosphere, which gives rise to exchange bias. When the reaction mixture for synthesizing CoNi NPs is heated to 300 °C, trioctylphosphine decomposes, and conversion into ...}, number={7}, journal={CHEMISTRY OF MATERIALS}, publisher={American Chemical Society (ACS)}, author={Marusak, Katherine E. and Johnston-Peck, Aaron C. and Wu, Wei-Chen and Anderson, Bryan D. and Tracy, Joseph B.}, year={2017}, month={Apr}, pages={2739–2747} }
 @article{anderson_wu_tracy_2016, title={Silica Overcoating of CdSe/CdS Core/Shell Quantum Dot Nanorods with Controlled Morphologies}, volume={28}, ISSN={["1520-5002"]}, url={http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000380576700010&KeyUID=WOS:000380576700010}, DOI={10.1021/acs.chemmater.6b01225}, abstractNote={CdSe/CdS core/shell quantum dot nanorods (QDNRs) exhibit anisotropic optical properties. Overcoating QDNRs with silica (SiO2) shells is desirable for protecting the surface of the inorganic core, imparting dispersibility in water, and allowing functionalization with silanes. While several methods have been developed for encapsulating spherical CdSe-based quantum dots in SiO2, extension of these approaches to QDNRs has been limited. Here, we report a reverse microemulsion approach for controlled deposition of SiO2 overcoatings with thicknesses of 2–12 nm onto CdSe/CdS QDNRs with aspect ratios of up to 19. Addition of poly(ethylene glycol) silane during SiO2 deposition terminates the reaction and allows facile control over the shell thickness, especially for thinner shells. By independently controlling the amounts of tetraethyl orthosilicate, ammonium hydroxide (NH4OH), and water, morphological control is achieved, giving uniform SiO2 shells or heterogenenous deposition onto the ends of QDNRs as lobed struc...}, number={14}, journal={CHEMISTRY OF MATERIALS}, author={Anderson, Bryan D. and Wu, Wei-Chen and Tracy, Joseph B.}, year={2016}, month={Jul}, pages={4945–4952} }
 @article{wu_tracy_2015, title={Large-Scale Silica Overcoating of Gold Nanorods with Tunable Shell Thicknesses}, volume={27}, ISSN={["1520-5002"]}, url={http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000353865800021&KeyUID=WOS:000353865800021}, DOI={10.1021/cm504764v}, abstractNote={Gold nanorods (GNRs) overcoated with SiO2 are of interest for enhancing the shape stability of GNRs during photothermal heating, for further functionalization with silanes, and for biomedical applications. While methods have recently been developed for synthesizing GNRs on a large scale, SiO2 overcoating of GNRs is still conducted on a small reaction scale. Here, we report a method for large-scale synthesis of SiO2-overcoated GNRs (SiO2-GNRs), which gives ∼190 mg of SiO2-GNRs. SiO2 is deposited onto and encapsulates the cetyltrimethylammonium bromide (CTAB) coatings that stabilize GNRs by adding tetraethoxysilane (TEOS) via syringe pump. Control over the CTAB concentration is critically important for obtaining uniform overcoatings. Optical absorbance spectra of SiO2-GNRs closely resemble those of uncoated GNRs, which indicates overcoating of single rather than multiple GNRs and confirms that they remain well dispersed. By adjusting the reaction conditions, shells as thick as ∼20 nm can be obtained. For thin shells (<10 nm), addition of poly(ethylene glycol) silane (PEG-silane) at different times during the overcoating reaction allows facile control over the shell thickness, giving shells as thin as ∼2 nm. The bulky PEG chain terminates further cross-linking and deposition of SiO2.}, number={8}, journal={CHEMISTRY OF MATERIALS}, author={Wu, Wei-Chen and Tracy, Joseph B.}, year={2015}, month={Apr}, pages={2888–2894} }
 @article{gonzalez_wu_tracy_martin_2015, title={Photochemical synthesis of size-tailored hexagonal ZnS quantum dots}, volume={51}, ISSN={["1364-548X"]}, url={http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000349324200014&KeyUID=WOS:000349324200014}, DOI={10.1039/c4cc09222h}, abstractNote={Photochemically generated ketyl radicals were employed for the synthesis of hexagonal ZnS quantum dots at room temperature.}, number={15}, journal={CHEMICAL COMMUNICATIONS}, author={Gonzalez, Carlos M. and Wu, Wei-Chen and Tracy, Joseph B. and Martin, Benjamin}, year={2015}, pages={3087–3090} }
 @article{kodumagulla_varanasi_pearce_wu_hensley_tracy_mcknight_melechko_2014, title={Aerosynthesis: Growth of Vertically-aligned Carbon Nanofibres with Air DC Plasma}, volume={4}, ISSN={["1847-9804"]}, url={http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000333365200001&KeyUID=WOS:000333365200001}, DOI={10.5772/58449}, abstractNote={ Vertically-aligned carbon nanofibres (VACNFs) have been synthesized in a mixture of acetone and air using catalytic DC plasma-enhanced chemical vapour deposition. Typically, ammonia or hydrogen is used as an etchant gas in the mixture to remove carbon that otherwise passivates the catalyst surface and impedes growth. Our demonstration of the use of air as the etchant gas opens up the possibility that ion etching could be sufficient to maintain the catalytic activity state during synthesis. It also demonstrates a path toward growing VACNFs in the open atmosphere. }, journal={NANOMATERIALS AND NANOTECHNOLOGY}, author={Kodumagulla, A. and Varanasi, V. and Pearce, R. C. and Wu, W. C. and Hensley, D. K. and Tracy, J. B. and McKnight, T. E. and Melechko, A. V.}, year={2014}, month={Mar} }
 @article{sarac_wu_tracy_2014, title={Control of Branching in Ni3C1-x Nanoparticles and Their Conversion into Ni12P5 Nanoparticles}, volume={26}, ISSN={["1520-5002"]}, url={http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000336637000006&KeyUID=WOS:000336637000006}, DOI={10.1021/cm4034353}, abstractNote={Dendritic Ni3C1–x nanoparticles (NPs) with controlled branching have been synthesized through the thermolysis (230 °C) of nickel acetylacetonate using oleylamine as a reducing agent and 1-octadecene (ODE) as the solvent. Addition of trioctylphosphine (TOP) as a ligand inhibits formation of dendritic shapes and prevents incorporation of C, resulting in spherical Ni NPs. In comparison, when using octadecane (ODA) or trioctylphosphine oxide (TOPO) as the solvent, Ni NPs are obtained at 230 °C that have fewer, larger branches than when using ODE. Higher temperatures are required for incorporation of C from ODA or TOPO into Ni NPs, resulting in Ni3C1–x NPs. Therefore, the allyl group in ODE facilitates formation of Ni3C1–x NPs at lower temperatures. Conversion of dendritic Ni3C1–x NPs into Ni12P5 NPs after adding TOP and heating to 300 °C results in the formation of multiple voids in the branches, rather than yolk-in-shell structures or unfilled single voids observed for spherical NPs.}, number={10}, journal={CHEMISTRY OF MATERIALS}, author={Sarac, Mehmet F. and Wu, Wei-Chen and Tracy, Joseph B.}, year={2014}, month={May}, pages={3057–3064} }
 @article{chhetri_blackmon_wu_hill_button_casbas-hernandez_troester_tracy_oldenburg_2014, title={Probing biological nanotopology via diffusion of weakly constrained plasmonic nanorods with optical coherence tomography}, volume={111}, ISSN={["0027-8424"]}, url={http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000342922000006&KeyUID=WOS:000342922000006}, DOI={10.1073/pnas.1409321111}, abstractNote={Significance
          Many diseases are characterized by nanostructural changes in connective fibers and soluble proteins, which can indicate or drive disease progression. Noninvasive methods sensitive to nanotopological changes in 3D tissue models can elucidate biophysical changes associated with disease progression. Nanoparticles probe their environment via their diffusion, which is impacted by the size and connectivity of pores into which they freely diffuse. Here, we show that optical coherence tomography provides depth-resolved imaging of gold nanorods (GNRs) to infer local biological nanotopology. We demonstrate the broad potential of this method by sensing changes in diffusion of GNRs in 3D models of mammary ECM and pulmonary mucus.}, number={41}, journal={PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA}, author={Chhetri, Raghav K. and Blackmon, Richard L. and Wu, Wei-Chen and Hill, David B. and Button, Brian and Casbas-Hernandez, Patricia and Troester, Melissa A. and Tracy, Joseph B. and Oldenburg, Amy L.}, year={2014}, month={Oct}, pages={E4289–E4297} }
 @article{maity_wu_xu_tracy_gundogdu_bochinski_clarke_2014, title={Spatial temperature mapping within polymer nanocomposites undergoing ultrafast photothermal heating via gold nanorods}, volume={6}, ISSN={["2040-3372"]}, url={http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000345458200080&KeyUID=WOS:000345458200080}, DOI={10.1039/c4nr05179c}, abstractNote={Polarized fluorescence temperature measurements combined with direct detection of nanorod rotation within the polymer melt regions reveal the steady-state temperature gradient on the nanoscale.}, number={24}, journal={NANOSCALE}, author={Maity, Somsubhra and Wu, Wei-Chen and Xu, Chao and Tracy, Joseph B. and Gundogdu, Kenan and Bochinski, Jason R. and Clarke, Laura I.}, year={2014}, pages={15236–15247} }
 @article{maity_kozek_wu_tracy_bochinski_clarke_2013, title={Anisotropic Thermal Processing of Polymer Nanocomposites via the Photothermal Effect of Gold Nanorods}, volume={30}, ISSN={["1521-4117"]}, url={http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000315360400010&KeyUID=WOS:000315360400010}, DOI={10.1002/ppsc.201200084}, abstractNote={By embedding metal nanoparticles within polymeric materials, selective thermal polymer processing can be accomplished via irradiation with light resonant with the nanoparticle surface plasmon resonance due to the photothermal effect of the nanoparticles which efficiently transforms light into heat. The wavelength and polarization sensitivity of photothermal heating from embedded gold nanorods is used to selectively process a collection of polymeric nanofibers, completely melting those fibers lying along a chosen direction while leaving the remaining material largely unheated and unaffected. Fluorescence‐based temperature and viscosity sensing was employed to confirm the presence of heating and melting in selected fibers and its absence in counter‐aligned fibers. Such tunable specificity in processing a subset of a sample, while the remainder is unchanged, cannot easily be achieved through conventional heating techniques.}, number={2}, journal={PARTICLE & PARTICLE SYSTEMS CHARACTERIZATION}, author={Maity, Somsubhra and Kozek, Krystian A. and Wu, Wei-Chen and Tracy, Joseph B. and Bochinski, Jason R. and Clarke, Laura I.}, year={2013}, month={Feb}, pages={193–202} }
 @article{kozek_kozek_wu_mishra_tracy_2013, title={Large-Scale Synthesis of Gold Nanorods through Continuous Secondary Growth}, volume={25}, ISSN={["1520-5002"]}, url={http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000327752500010&KeyUID=WOS:000327752500010}, DOI={10.1021/cm402277y}, abstractNote={Gold nanorods (GNRs) exhibit a tunable longitudinal surface plasmon resonance (LSPR) that depends on the GNR aspect ratio (AR). Independently controlling the AR and size of GNRs remains challenging but is important because the scattering intensity strongly depends on the GNR size. Here, we report a secondary (seeded) growth procedure, wherein continuous addition of ascorbic acid (AA) to a stirring solution of GNRs, stabilized by cetyltrimethylammonium bromide (CTAB) and synthesized by a common GNR growth procedure, deposits the remaining (~70%) of the Au precursor onto the GNRs. The growth phase of GNR synthesis is often performed without stirring, since stirring has been believed to reduce the yield of rod-shaped nanoparticles, but we report that stirring coupled with continuous addition of AA during secondary growth allows improved control over the AR and size of GNRs. After a common primary GNR growth procedure, the LSPR of GNRs is ~820 nm, which can be tuned between ~700-880 nm during secondary growth by adjusting the rate of AA addition or adding benzyldimethylhexadecylammonium chloride hydrate (BDAC). This approach for secondary growth can also be used with primary GNRs of different ARs to achieve different LSPRs and can likely be extended to nanoparticles of different shapes and other metals.}, number={22}, journal={CHEMISTRY OF MATERIALS}, author={Kozek, Krystian A. and Kozek, Klaudia M. and Wu, Wei-Chen and Mishra, Sumeet R. and Tracy, Joseph B.}, year={2013}, month={Nov}, pages={4537–4544} }
 @article{oldenburg_chhetri_cooper_wu_troester_tracy_2013, title={Motility-, autocorrelation-, and polarization-sensitive optical coherence tomography discriminates cells and gold nanorods within 3D tissue cultures}, volume={38}, ISSN={["0146-9592"]}, url={http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000322576200085&KeyUID=WOS:000322576200085}, DOI={10.1364/ol.38.002923}, abstractNote={We propose a method for differentiating classes of light scatterers based upon their temporal and polarization properties computed from time series of polarization-sensitive optical coherence tomography (PS-OCT) images. The amplitude (motility) and time scale (autocorrelation decay time) of the speckle fluctuations are combined with the cross-polarization pixel-wise to render Motility-, autocorrelation-, and polarization-sensitive (MAPS) OCT contrast images. This combination of metrics provides high specificity for discriminating diffusive gold nanorods and mammary epithelial cell spheroids within 3D tissue culture, based on their unique MAPS signature. This has implications toward highly specific contrast in molecular (nanoparticle-based) and functional (cellular activity) imaging using standard PS-OCT hardware.}, number={15}, journal={OPTICS LETTERS}, author={Oldenburg, Amy L. and Chhetri, Raghav K. and Cooper, Jason M. and Wu, Wei-Chen and Troester, Melissa A. and Tracy, Joseph B.}, year={2013}, month={Aug}, pages={2923–2926} }