Publications by authors named "Kavita Chandra"

5 Publications

  • Page 1 of 1

Label Free Particle-by-Particle Quantification of DNA Loading on Sorted Gold Nanostars.

Anal Chem 2019 05 11;91(9):5566-5572. Epub 2019 Apr 11.

Department of Chemistry , Texas A&M University , College Station , Texas 77843 , United States.

This paper describes a label free technique for determining ligand loading on metal nanoparticles using a variant of secondary ion mass spectrometry. Au clusters bombard DNA-functionalized anisotropic gold nanostars and isotropic nanospheres with similar surface areas to determine ligand density. For each projectile impact, co-localized molecules within the emission area of a single impact (diameter of 10-15 nm) were examined for each particle. Individual nanoparticle analysis allows for determination of the relationship between particle geometry and DNA loading. We found that branched particles exhibited increased ligand density versus nanospheres and determined that positive and neutral curvature could facilitate additional loading. This methodology can be applied to optimize loading for any ligand-core interaction independent of nanoparticle core, ligand, or attachment chemistry.
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http://dx.doi.org/10.1021/acs.analchem.8b03715DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6896788PMC
May 2019

Detecting and Visualizing Reaction Intermediates of Anisotropic Nanoparticle Growth.

J Am Chem Soc 2018 03 26;140(9):3219-3222. Epub 2018 Feb 26.

This paper describes a correlative approach to detect, visualize, and characterize intermediate species during a seedless, anisotropic nanoparticle synthesis. Changes in radical concentration as a function of time were correlated in situ to the optical properties and morphology of the particles. Depending on type and concentration of reaction precursors, either one or two increases in radical production occurred, corresponding to initial particle formation and increased branch length, respectively. Thus, changes in radical intensity can be considered as an indicator of nanoparticle structure and properties.
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http://dx.doi.org/10.1021/jacs.8b00124DOI Listing
March 2018

Separation of Stabilized MOPS Gold Nanostars by Density Gradient Centrifugation.

ACS Omega 2017 Aug 23;2(8):4878-4884. Epub 2017 Aug 23.

Department of Materials Science and Engineering and Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States.

This article describes the stabilization and postsynthetic separation of gold nanostars (AuNS) synthesized with a morpholine-based Good's buffer, 3-(-morpholino)propanesulfonic acid. Resuspension of AuNS in ultrapure water improved the shape stability of the particles over 30 days. We demonstrated the sorting of nanostars via rate-zonal centrifugation through a linear sucrose gradient based on branch length and number. We determined that one round of centrifugation was sufficient for separation. Also, we improved the structural homogeneity and stability of the nanoparticles through the optimization of the storage conditions and established a robust method to sort AuNS based on size and shape.
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http://dx.doi.org/10.1021/acsomega.7b00871DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6641882PMC
August 2017

Shape-Dependent Nonlinear Optical Properties of Anisotropic Gold Nanoparticles.

J Phys Chem Lett 2015 Dec 25;6(24):4904-8. Epub 2015 Nov 25.

Center for Nanoscale Materials, Argonne National Laboratory , Argonne, Illinois 60439, United States.

This Letter reports the shape-dependent third-order nonlinear optical properties of anisotropic gold nanoparticles. We characterized the nonlinear absorption coefficients of nanorods, nanostars, and nanoshells using femtosecond Z-scan measurements. By comparing nanoparticle solutions with a similar linear extinction at the laser excitation wavelength, we separated shape effects from that of the localized surface plasmon wavelength. We found that the nonlinear response depended on particle shape. Using pump-probe spectroscopy, we measured the ultrafast transient response of nanoparticles, which supported the strong saturable absorption observed in nanorods and weak nonlinear response in nanoshells. We found that the magnitude of saturable absorption as well as the ultrafast spectral responses of nanoparticles were affected by the linear absorption of the nanoparticles.
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http://dx.doi.org/10.1021/acs.jpclett.5b02263DOI Listing
December 2015

Biodistribution and in vivo toxicity of aptamer-loaded gold nanostars.

Nanomedicine 2015 Apr 18;11(3):671-9. Epub 2014 Nov 18.

Department of Chemistry, Northwestern University, Evanston, IL, USA; Department of Materials Science and Engineering, Northwestern University, Evanston, IL, USA. Electronic address:

This paper reports an in vivo evaluation of toxicology and biodistribution of a highly anisotropic Au nanoconstruct composed of a gold nanostar (AuNS) core and a ligand shell of a G-quadruplex DNA aptamer AS1411 (Apt) supporting both targeting and therapy capabilities. We examined the toxicity of the nanoconstructs (Apt-AuNS) at four different injected concentrations. At the highest dose tested (48 mg/kg), maximal tolerated dose was not reached. Clinical pathology showed no apparent signs of acute toxicity. Interestingly, the nanoconstructs circulated longer in female rats compared to male rats. In two different tumor models, the biodistribution of Apt-AuNS, especially tumor accumulation, was different. Accumulation of Apt-AuNS was 5 times higher in invasive breast cancer tumors compared to fibrosarcoma tumors. These results provide insight on identifying a tumor model and nanoconstruct for in vivo studies, especially when an in vitro therapeutic response is observed in multiple cancer cell lines. From the clinical editor: This study investigated the toxicity and distribution of aptamer loaded gold nanostars in a rodent model of invasive breast cancer and fibrosarcoma. Acute toxicity was not identified even in the highest studied doses. Fivefold accumulation was demonstrated in the breast cancer model compared to the fibrosarcoma model. Studies like this are critically important in further clarifying the potential therapeutic use of these nanoconstructs, especially when ex vivo effects are clearly demonstrated.
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http://dx.doi.org/10.1016/j.nano.2014.10.005DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4385396PMC
April 2015