Green Synthetic Approach to Nanoparticles & Carbon Dots

Biosynthesis of nanoparticles has gained significant interest as an emerging technology to reduce the toxicity of nanoparticles commonly associated with conventional chemical synthetic approaches. We have synthesized metal and metal oxide nanoparticles using various plant extracts, which acts as reducing and stabilizing agents. In addition, the incorporation of these plant extracts highly augment the characteristics of these nanoparticles. The biosynthesized nanoparticles act as efficient catalysts for the organic transformations and other practical applications.

Carbon dots (CDs) are known as an excellent candidate for diverse applications such as optoelectronics, detection of transition metal ions, fluorescent inks, photo-catalysis and cellular imaging because of their strong photoluminescence, high photostability, good water-solubility, low cytotoxicity, excellent biocompatibility and eco-friendliness. We have synthesized a facile, economical, and highly durable fluorescent nitrogen-doped carbon dots (FNCDs) by utilizing plant extract and aqueous ammonia as the carbon and nitrogen sources, respectively. Thus, biosynthesized FNCDs shows diverse applications such as label-free sensitive and selective detection of Fe3+, fluorescent ink and cellular imaging with good biocompatibility and low cytotoxicity.

Selected works on the green synthesis of nanoparticles and carbon dots 

Biosynthesis of Fe, Pd, and Fe–Pd bimetdenyic nanoparticles and their application as recyclable catalysts for [3 + 2] cycloaddition reaction: a comparative approach
(Catal. Sci. Technol., 2015, 5, 2612-2621)

TEM images of Fe-PdNPs at (a) 100 nm, (b) 50 nm . STEM-EDS elemental maps of
(c) Fe-PdNPs, (d) Fe Kα shell,  and (e) Pd Lα shell

Proposed mechanism for the formation of  naphtho[1,2-b]furan-3-carboxamides

AuFeAg hybrid nanoparticles as an efficient recyclable catalyst for the synthesis of α,β- and β,β-dichloroenones
(Applied Catalysis, A: General 2015, 506, 180-187)

TEM images of AuFeAg-NPs at (a) 100 nm, (b) 50 nm (c) HRTEM image with d-spacing STEM image of
(d) AuFeAg-NPs, along with the EDS elemental maps of (e) Au Lα shell, (f) FeLα shell, and (g) Ag Lα shell.

AuFeAg-NPs catalyzed synthesis of a variety of α,β-dichloroenones

Enhanced catalytic performance of magnetic Fe3O4-MnO2 nanocomposites for the decolorization of rhodamine B, reduction of 4-nitroaniline, and sp3 C-H functionalization of 2-methylpyridines to isatins
(Journal of Catalysis, 2016, 344, 273-285)

(a) SEM image of Fe3O4-MnO2 NCs at 500 nm. (b) TEM image of a portion of fig (e),
(c, d) HRTEM at 5 nm showing the lattice fringes, (f) SAED pattern

Highly fluorescent nitrogen-doped carbon dots derived Phyllanthus acidus utilized as a fluorescent probe for label-free selective detection of Fe3+ ions, live cell imaging and fluorescent ink
(Biosensors & Bioelectronics, 2018, 99, 303-311)