Dr. Dhiraj Kumar, PhD - University of Minnesota - Postdoctoral Associate

Dr. Dhiraj Kumar

PhD

University of Minnesota

Postdoctoral Associate

Minneapolis, MN | United States

Main Specialties: Biology, Chemistry

Additional Specialties: Nanomaterials, Nanoparticles, Synthesis and modifcation, Biomedical applications

ORCID logohttps://orcid.org/0000-0002-1008-8638

Dr. Dhiraj Kumar, PhD - University of Minnesota - Postdoctoral Associate

Dr. Dhiraj Kumar

PhD

Introduction

I am a material scientist with interest in developing nano-materials/bio-materials for various biomedical applications. In past, My research interested have been on multi-functional nanoparticles for ovarian cancer targeting and MARS spectral imaging and developing gold nanoparticles based formulation for drug delivery. The current research focus is on dental biomaterials and phospholipid liposome.

Primary Affiliation: University of Minnesota - Minneapolis, MN , United States

Specialties:

Additional Specialties:

Research Interests:

Education

Sep 2009 - Oct 2012
University of Ulster at Jordanstown
PhD Nanomedicine
NIBEC
Jul 2007 - Jul 2009
Amity University
M.Tech. Nanobiotechnology
Amity Institute of Nanotechnology
Jul 2004 - May 2006
University of Delhi Department of Chemistry
M.Sc. Physical Chemistry
Chemistry
Jul 2001 - May 2004
Hindu College New Delhi
B.Sc. [Honors] Chemistry
University of Delhi

Experience

Jan 2014 - Jun 2018
University of Otago
Research fellow
Obstetrics and gynaecology
Jun 2013 - May 2015
University of Canterbury
Postdoc (Visiting) Fellow
Oct 2012 - Mar 2013
University of Ulster at Jordanstown
Postdoctoral Fellow
NIBEC
Oct 2018
University of Minnesota
Postdoctoral Fellow

Publications

10Publications

16Reads

2Profile Views

1PubMed Central Citations

Self-assembly dynamics and antimicrobial activity of all l- and d-amino acid enantiomers of a designer peptide.

Nanoscale 2018 Dec;11(1):266-275

MDRCBB, Minnesota Dental Research Center for Biomaterials and Biomechanics, University of Minnesota, Minneapolis, Minnesota 55455, USA.

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http://dx.doi.org/10.1039/c8nr07334aDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6319268PMC
December 2018
5 Reads
7.394 Impact Factor

Seed mediated synthesis of highly mono-dispersed gold nanoparticles in presence of hydroquinone

Dhiraj Kumar et al 2016 Nanotechnology 27 (35) 355601

Nanotechnology

Gold nanoparticles (AuNPs) are being studied for several biomedical applications, including drug delivery, biomedical imaging, contrast agents and tumor targeting. The synthesis of nanoparticles with a narrow size distribution is critical for these applications. We report the synthesis of highly mono-dispersed AuNPs by a seed mediated approach, in the presence of tri-sodium citrate and hydroquinone (HQ). AuNPs with an average size of 18 nm were used for the synthesis of highly mono-dispersed nanocrystals of an average size 40 nm, 60 nm, 80 nm and ~100 nm; but the protocol is not limited to these sizes. The colloidal gold was subjected to UV–vis absorbance spectroscopy, showing a red shift in lambda max wavelength, peaks at 518.47 nm, 526.37 nm, 535.73 nm, 546.03 nm and 556.50 nm for AuNPs seed (18 nm), 40 nm, 60 nm, 80 nm and ~100 nm respectively. The analysis was consistent with dynamic light scattering and electron microscopy. Hydrodynamic diameters measured were 17.6 nm, 40.8 nm, 59.8 nm, 74.1 nm, and 91.4 nm (size by dynamic light scattering—volume %); with an average poly dispersity index value of 0.088, suggesting mono-dispersity in the size distribution, which was also confirmed by transmission electron microscopy analysis. The advantage of a seed mediated approach is a multi-step growth of nanoparticle size that enables us to control the number of nanoparticles in the suspension, for size ranging from 24.5 nm to 95.8 nm. In addition, the HQ-based synthesis of colloidal nanocrystals allowed control of the particle size and size distribution by tailoring either the number of seeds, amount of gold precursor or reducing agent (HQ) in the final reaction mixture.

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July 2016
15 Reads

Current Density Enhancement in Inverted Nano-pyramid Textured Crystalline Silicon Solar Cell using Gold Nanoparticles

Micro/Nano Materials, Devices, and Systems, SPIE Proceeding

The surface plasmon resonances induced light coupling is widely recognized as a promising way of enhancing the light absorption in photovoltic devices. This is achieved by enhanced localized electromagnetic field in the vicinity of metal surface or the strong light scattering effects from metal nanoparticles integrated on the front surface of as-fabricated solar cells. In this paper, the colloidal gold nanoparticles(Au NPs), synthesized by modified Turkevich and Frens method, were integrated onto the inverted nanopyramid silicon solar cell via a dip coating method. A 7% increase in short-circuit current density of solar cell was observed for 15 minutes dip coating. As a result, a 4.6% increase in overall efficiency was achieved. However,the dense surface coverage of Au NPs resulted in decreased fill factor.

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December 2013
16 Reads

Glutathione-mediated release of Bodipy® from PEG cofunctionalized gold nanoparticles.

Int J Nanomedicine 2012 25;7:4007-22. Epub 2012 Jul 25.

Nanotechnology and Integrated BioEngineering Centre, University of Ulster, Belfast, Northern Ireland.

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Source
http://dx.doi.org/10.2147/IJN.S33726DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3418179PMC
March 2013
11 Reads
1 Citation

Polyethylene Glycol Functionalised Gold Nanoparticles: The Influence of capping density on stability in various media

Gold Bulletin

Thiol-terminated polyethylene glycol (PEG) is commonly used to functionalize the surface of gold nanoparticles (AuNPs) in order to improve their in vivo stability and to avoid uptake by the reticular endothelial system. Although it has been reported that AuNPs functionalized with tethered PEG are stable in biological media, the influence of chain density remains unclear. This study investigates the influence of PEG capping density on the stability of washed and dried AuNPs in: water, phosphate-buffered saline solution (PBS), phosphate-buffered saline solution containing bovine serum albumin (PBS/BSA), and dichloromethane (DCM). PEG coating had a dramatic effect on stability enabling stable suspensions to be produced in all the media studied. A linear relationship was observed between capping density and stability in water and DCM with a somewhat lower stability observed in PBS and PBS/BSA. A maximum PEG loading level of ∼14 wt.% was achieved, equivalent to a PEG surface density of ∼1.13 chains/nm2.

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April 2011
14 Reads

Top co-authors

Brian J Meenan
Brian J Meenan

School of Engineering

1
Dorian Dixon
Dorian Dixon

School of Engineering

1
Conrado Aparicio
Conrado Aparicio

University of Minnesota School of Dentistry

1
Ting Sang
Ting Sang

Stomatological Hospital of Nanchang University

1
Xiao Zhu
Xiao Zhu

Zhejiang University

1
Zhou Ye
Zhou Ye

Zhejiang University School of Medicine

1

Following

Brian Meenan
Brian Meenan

University of Ulster