Research

Our group is principally focused on establishing a highly interdisciplinary research program based on analytical chemistry and materials science of metallic and semiconductor nanoparticles. Due to the continuous growth in energy storage demands for both consumer products as well as global infrastructure, our goal is to develop materials for efficient energy conversion, charge storage devices, and fabrication of advanced nanosensor substrates. In all applications, understanding the fundamental physics and chemistry of the material is essential to properly tailor material properties for eventual device design. A broad range of techniques is utilized for particle development including analytical chemistry and macroscale materials science. Of particular interest is the development of semiconductor nanoparticles, commonly known as quantum dots (QDs). Here we are principally focused on controlling particle composition thru novel synthetic techniques and verification with a variety of analytical methods.

Analytically define semiconductor nanoparticle composition: 

Semiconductor nanoparticles are an important class of materials due to tunable optical and electronic properties as a function of size and composition, which can make essential nanomaterials for various potential applications including the use as probes for biomolecules detection, making modern electronic devices, and fabricating solar cells for photocurrent generation. Such properties can be further modulated through chemical composition, enabled by implementing precise protecting ligands on the particle surface. This part of the research focuses to define the QDs composition and also to understand the surface ligand exchange chemistry.

Electrochemical behavior of redox-labeled QD films: 

The semiconductor nanoparticle’s surface will be functionalized by various redox functionalities with the aim of incorporating permanent charge on the particles. The highly charged film of the resultant material will be prepared on the solid surface via electrochemical methods. The ion-transfer process (ITIES) of such polyelectrolyte type nanoparticle films will be examined under various conditions. This research provides a mechanism for understanding charged transport across QD-liquid interfaces which is critical to efficient energy storage material development.

Fabrication of advanced nanosensor substrates: 

Metallic nanoparticles such as gold and silver display size and shape dependent optical properties known as localized surface plasmon resonance (LSPR). The LSPR signature can be exploited for high resolution, high sensitivity molecular spectroscopy, biological sensors and plasmon waveguides. This component of our research program aims to develop substrates functionalized with mono- and polydisperse nanoparticles, of arbitrary geometry, for advanced sensing applications.

Educational Goals: 

The synthesis and characterization of nanoparticle systems would be beneficial for the students as it provides a gateway for learning how chemistry is intimately coupled with the fundamentals of nanoparticle photoluminescence. Additionally, this project offers the opportunity to operate a wide range of instruments such as NMR, TGA, FTIR, SEM, TEM, AFM and electrochemical instrumentation.

Education

• Ph.D. The Graduate Center, City University of New York, 2006
• Faculty Intern, University of Utah, 2006-2008
• Postdoctoral Fellow, University of North Carolina at Chapel Hill, 2008-2010

Publications & Professional Activity

*(^#signifies undergraduate research student, ^$signifies high-school student)

Indiana University Purdue University Indianapolis

1.  Investigating the control by quantum confinement and surface ligand coating of photocatalytic efficiency in chalcopyrite copper indium diselenide nanocrystals. Jana, A.; Lawrence, K. N.; Teunis, M. B.; Mandal, M.; Kumbhar, A.;*Sardar, R. Chem. Mater. 2016, 28, 1107-1120. (A.J. and K.N.L. contributed equally to this work).
2. Label-free nanoplasmonic-based short noncoding RNA sensing at attomolar concentration allows for quantitative assay of microRNA-10b in biological fluids and circulating exosomes. Joshi, G. K.; Deitz-McElyea, S.; Liyanage, T.; Lawrence, K. N.; $Mali, S.; *Sardar, R. *Korc, M.; ACS Nano. 2015, 9, 11075-11089. Most-accessed paper (no. 16), October-December, 2015.
3. Solvent-like ligand-coated ultrasmall cadmium selenide nanocrystals: Strong electronic coupling in a self-organized assembly. Lawrence, K. L.; Johnson, M. A.; Dolai, S.; Kumbhar, A.; *Sardar, R. Nanoscale 2015, 7, 11667-11677.
4. Mechanistic study of the formation of bright white light-emitting ultrasmall CdSe nanocrystals: Role of phosphine free selenium precursors. Dolai, S.; Dutta, P.; Muhoberac, B. B.; #Irving, C. D.; *Sardar, R. Chem. Mater. 2015, 27, 1057-1070.
5. 5.   Molecule-like CdSe nanoclusters passivated with strongly interacting ligands: Energy level alignment and photoinduced ultrafast charge transfer processes. Xie, Y.; Teunis, M. B.; Pandit, B.; *Sardar, R.; *Liu, J. J. Phys. Chem. C 2015, 119, 2813-2821.
6. Highly specific plasmonic biosensors for ultrasensitive microRNA detection in plasma from pancreatic cancer patients. Joshi, G. K.; Deitz-McElyea, S.; Johnson, M. A.; $Mali, S.; *Korc, M.; *Sardar, R. Nano Lett. 2014, 14, 6955-6963.
7. Enhancing the physicochemical and photophysical properties of small (<2.0 nm) CdSe nanoclusters for intracellular imaging applications. Lawrence, K. L.; Dolai, S.; Lin, Y,-H.; Dass, A.; *Sardar, R. RSC Advances 2014, 4, 30742-30753.
8. Effects of surface passivating ligands and ultrasmall CdSe nanocrystal size on delocalization of exciton confinement. Teunis, M. B.; Dolai, S.; *Sardar. R. Langmuir 2014, 30, 7851-7858.
9. Novel pH-responsive nanoplasmonic sensor: Controlling polymer structural change to modulate localized surface plasmon resonance response. Joshi, G. K.; Johnson, M. A.; *Sardar, R. RSC Advances 2014, 4, 15807-15815.
10.  Ultrasensitive photoreversible molecular sensors of azobenzene-functionalized plasmonic nanoantennas. Joshi, G. K.; #Blodgett, K. N.; Muhoberac, B. B.; Johnson, M. A.; #Smith, K. A.; *Sardar, R. Nano Lett. 2014, 14, 532-540.
11.   Isolation of bright blue light-emitting CdSe nanocrystals with 6.5 kDa core in gram scale: High photoluminescence efficiency controlled by surface ligand chemistry. Dolai, S.; Nimmala, P. R.; Mandal, M.; Muhoberac, B. B.; Dria, K.; Dass, A.; *Sardar, R. Chem. Mater. 2014, 26, 1278-1285.
12.  Correlated optical spectroscopy and electron microscopy studies of the slow Ostwald-ripening growth of silver nanoparticles under controlled reducing conditions. #Dennis, N. W.; Muhoberac, B. B.; #Newton, J. C.; Kumbhar, A. *Sardar, R. Plasmonics 2014, 9, 111-120.
13. Temperature-controlled reversible localized surface plasmon resonance response of polymer-functionalized gold nanoprisms in the solid state. Joshi, G. K.; #Smith, K. A.; Johnson, M. A.; *Sardar, R. J. Phys. Chem. C 2013, 117, 26228-26237.
14. Photophysical and redox properties of molecule-like CdSe nanoclusters. Dolai, S.; Dass, A.; *Sardar, R. Langmuir 2013, 29, 6187-6193.
15. Designing efficient localized surface Plasmon resonance-based sensing platforms: Optimization of sensor response by controlling the edge length of gold nanoprisms. Joshi, G. K.; #McClory, P.; Muhoberac, b. B.; Kumbhar, A.; #Smith, K. A.; *Sardar, R. J. Phys. Chem. C 2012, 116, 20990-21000.
16. Improved localized surface plasmon resonance biosensing sensitivity using chemically synthesized gold nanoprisms as plasmonic transducers. Joshi, G. K.; #McClory, P.; Dolai, S.; *Sardar, R. J. Mater. Chem. 2012, 22, 923-931.
17. Low temperature synthesis of magic-sized CdSe nanoclusters: Influence of ligands on photophysical properties. #Newton, J. C.; Ramasamy, K.; Mandal, M.; Joshi, G. K.; Kumbhar, A.; *Sardar, R.  J. Phys. Chem. C 2012, 116, 4380-4389.

Selected Doctoral and Postdoctoral Publications

1. Soft ligand stabilized gold nanoparticles: Incorporation of bipyridyls and two-dimensional assembly. Shem, P. M.; Sardar, R.; Shumaker-Parry, J. S. J. Colloid Interface Science 2014, 426, 107.
2. 3D-Addressable redox: Modifying porous carbon electrodes with ferrocenated 2 nm gold nanoparticles. Chow, K, F.; Sardar, R.; Sassin, M. B.; Wallace, J. M.; Feldberg, S. W.; Rolison, D. R.; Long, J. W.; *Murray, R. W. J. Phys. Chem. C 2012, 116, 9283.
3. Spectroscopic and microscopic investigation of gold nanoparticle formation: Ligand and temperature effects on rate and particle size. Sardar, R.; *Shumaker-Parry, J. S. J. Am. Chem. Soc. 2011, 133, 8179. Most-read paper (no. 11), June-July, 2011.
4.  Persistent multilayer electrode adsorption of poly-cationic Au nanoparticles. Beasley, C. A.; Sardar, R.; #Barnes, N. M.; *Murray, R. W. J. Phys. Chem. C. 2010, 114, 18384.
5. Single-step generation of fluorophore-encapsulated gold nanoparticle core-shell materials. Sardar, R.; Shem, P. M.; #Pecchia-Bekkum, C.; #Bjorge, N. S; *Shumaker-Parry, J. S. Nanotechnology 2010, 21, 345603. Cover Highlights, Vol. 21, No. 34 August 2010.
6. Interfacial Ion transfers between a monolayer phase of cationaic Au nanoparticles and contacting organic solvent. Sardar, R.; Beasley, C. A.; *Murray, R. W. J. Am. Chem. Soc. 2010, 132, 2058.
7. One-Step Synthesis of Phosphine-Stabilized Gold Nanoparticles Using the Mild Reducing Agent 9-BBN. Shem, P. M.; Sardar, R.; *Shumaker-Parry, J. S. Langmuir 2009, 25, 13279. Most-read paper (no. 13), November-December, 2009.
8. Gold nanoparticles: Past, present, and future. Sardar, R.; Funston, A. M.; *Mulvaney, P.; *Murray, R. W. Langmuir (Perspective) 2009, 25, 13840. Most-read paper (no. 3), in last 12 months, 2009-2010.
9. 1. Gold nanoparticles: Past, present, and future. Sardar, R.; Funston, A. M.; *Mulvaney, P.; *Murray, R. W. Langmuir (Perspective) 2009, 25, 13840. Most-read paper (no. 3), in last 12 months, 2009-2010.
10. Electrospray ionization mass spectrometry of intrinsically cationized nanoparticles, [Au144/146{SC11H22N(CH2CH3)3}x{S(CH2)5CH3}y]+. Fields-Zinna, C. A.; Sardar, R.; Beasley, C. A.; *Murray, R. W. J. Am. Chem. Soc. 2009, 131, 16266.
11. Ferrocenated Au nanoparticle monolayer adsorption on self-assembled monolayer coated electrodes. Sardar, R.; Beasley, C. A.; *Murray, R. W. Anal. Chem. 2009, 81, 6960.
12. 9-BBN induced synthesis of nearly monodisperse w–functionalized alkylthiol stabilized nanoparticles.  Sardar, R.; *Shumaker-Parry, J. S. Chem. Mater. 2009, 21, 1167-1169.
13. pH-controlled assemblies of polymeric amine-stabilized gold nanoparticles. Sardar, R.; #Bjorge, N. S; *Shumaker-Parry, J. S. Macromolecules 2008, 41, 4347.
14. Asymmetrically functionalized gold nanoparticles organized in one-dimensional chains. Sardar, R.; *Shumaker-Parry, J. S. Nano Lett. 2008, 8, 731.
15. Polymer induced synthesis of stable gold and silver nanoparticles and subsequent ligand exchange in water. Sardar, R.; Park, J,-W.; *Shumaker-Parry, J. S. Langmuir 2007, 23, 11883. Most-accessed paper (no. 15), October-December, 2007.
16. Versatile solid phase synthesis of gold nanoparticle dimers using an asymmetric functionalization approach. Sardar, R.; #Heap, T. B; *Shumaker-Parry, J. S. J. Am. Chem. Soc. 2007, 129, 5356.
17. Self-assembled stable silver nanoclusters and nanonecklaces formation: Polymethylhydrosiloxane mediated one-pot route to organosols. *Chauhan, B. P. S.; Sardar, R. Macromolecules 2004, 37, 5136 Cover Highlights, Vol. 38, No. 1 January 11, 2005.