Rakesh P. Chaudhary

Fe Core–Carbon Shell Nanoparticles as Advanced MRI Contrast Enhancer

The aim of this study is to fabricate a hybrid composite of iron (Fe) core–carbon (C) shell nanoparticles with enhanced magnetic properties for contrast enhancement in magnetic resonance imaging (MRI). These new classes of magnetic core–shell nanoparticles are synthesized using a one-step top–down approach through the electric plasma discharge generated in the cavitation field in organic solvents by an ultrasonic horn. Transmission electron microscopy (TEM) observations revealed the core–shell nanoparticles with 10–85 nm in diameter with excellent dispersibility in water without any agglomeration. TEM showed the structural confirmation of Fe nanoparticles with body centered cubic (bcc) crystal structure. Magnetic multi-functional hybrid composites of Fe core–C shell nanoparticles were then evaluated as negative MRI contrast agents, displaying remarkably high transverse relaxivity (r2) of 70 mM−1·S−1 at 7 T. This simple one-step synthesis procedure is highly versatile and produces desired nanoparticles with high efficacy as MRI contrast agents and potential utility in other biomedical applications.

One-step hydrogen extraction and storage in plasma generated palladium nanoparticles

This study demonstrates a novel way of hydrogen extraction from toluene and direct storage in plasma generated palladium (Pd) nanoparticles in one-step. Monodispersed Pd nanoparticles with a narrow particle-size distribution have been successfully synthesized, for the first time, by a plasma discharge between Pd electrodes in the cavitation field of toluene. The resulting well-dispersed Pd nanoparticles embedded in carbon are stabilized against agglomeration. The effect of experiment time on the particle size and the expansion of lattice spacing due to hydrogen are investigated by experimental and computational studies using density functional theory (DFT). Using X-ray diffraction and high-resolution transmission electron microscopy measurements, it was found that particle size and lattice expansion increases with experiment time. Pd nanoparticle synthesis for in situ hydrogen storage in one step using plasma discharge in an appropriate solvent emphasizes the importance of adopting this methodology which offers several advantages. These include rapid reaction rate, ability to form very small nanoparticles with narrow size distribution and hydrogen extraction from the solvent for direct storage in the Pd nanoparticle lattice.

Fluorescent carbon nanoparticles synthesized from benzene by electric plasma discharge

Various allotropes of Carbon nanoparticles (CNP) are emerging as very important building blocks for nanotechnology and biomedical applications due to their unique electronic, optical, mechanical and thermal properties. We report synthesis of crystalline CNPs from benzene using electric plasma discharge method under controlled laboratory environment. With varied electric field, different allotropes of carbon were synthesized as observed under high resolution electron microscope and selected area electron diffraction, optical spectroscopic studies revealed distinct differences between these CNPs. Raman spectroscopy of these CNPs showed a distinct peak at 1330 cm-1 (characteristic of defect band) and another peak at 1600 cm-1 (graphitic band). The ratio of defect to graphitic band was found to increase with increasing voltage between Fe-electrodes. Further, the ratio was altered when CNPs were formed using graphite-electrodes. Fluorescence spectroscopic measurements showed evident blue fluorescence exhibited by CNPs formed at relatively higher voltage between two Fe-electrodes. This was attributed to the increasing Fe-content, as measured by Energy dispersive X-ray analysis (EDX) and vibrating sample magnetometer (VSM). Addition of exogenous dyes in benzene during synthesis of CNPs using electric plasma discharge led to formation of fluorescent nanotubes. These fluorescent CNPs can be functionalized to target cancer cells for both imaging and targeted photothermal therapy using near-IR laser beam.