FLUORESCENCE NEWS ARTICLE A Novel Technique of Synthesis of Highly Fluorescent Carbon Nanoparticles from Broth Constituent and In-vivo Bioimaging of C. elegans A. Pramanik 1 & A. K. Kole 1,2 & R. N. Krishnaraj 3 & S. Biswas 1 & C. S. Tiwary 4 & P. Varalakshmi 5 & S. K. Rai 5 & B. A. Kumar 6 & P. Kumbhakar 1 Received: 24 January 2016 /Accepted: 14 June 2016 # Springer Science+Business Media New York 2016 Abstract Here we have demonstrated a novel single step technique of synthesis of highly fluorescent carbon nanopar- ticles (CNPs) from broth constituent and in vivo bioimaging of Caenorhabditis elegans (C. elegans) with the synthesized CNPs has been presented. The synthesized CNPs has been characterized by the UV-visible (UV-Vis) absorption spectros- copy, transmission electron microscopy (TEM) and Raman studies. The sp 2 cluster size of the synthesized samples has been determined from the measured Raman spectra by fitting it with the theoretical skew Lorentzian (Breit-Wigner- Fano (BWF)) line shape. The synthesised materials are showing excitation wavelength dependent tunable photoluminescence (PL) emission characteristics with a high quantum yield (QY) of 3 % at a very low concentration of CNPs. A remarkable increase in the intensity of PL emission from 16 % to 39 % in C. elegans has also been observed when the feeding concen- tration of CNPs to C. elegans is increased from 0.025 % to 0.1 % (w/v). The non-toxicity and water solubility of the syn- thesized material makes it ideal candidate for bioimaging. Keywords Carbon nanoparticles . Broth constituents . Quantum yield . C. elegans . Bioimaging Introduction Carbon based materials have been in the fore-front of research studies since after the first discovery of carbon nanotubes and its interesting properties [1]. Recently carbon nanoparticles (CNPs) have attracted renewed attention of the scientists due to its unique fluorescent property, excellent biocompatibility, nontoxic nature and low cost synthesis techniques. It has been observed that CNPs upon irradiation exhibit intense light emission which can be tuned from ultraviolet (UV) to infrared (IR) region by tailoring its size and shape and this is making CNPs a potential candidate for bioimaging, and other opto- electronic applications [2–5]. To achieve a high fluorescence from CNPs, careful modifications of its size and surface are required. A wide variety of synthesis techniques, like laser ablation technique [2], arc discharge [3], plasma treatment [4], and combustion route [5] have already been used to syn- thesize CNPs. However, all these synthesis techniques require complex experimental setup which is a major disadvantage. Thus easy, economical and the large scale production of high- ly fluorescent CNPs still remains a great challenge to the re- searchers. Hydrothermal method, on the other hand, is a sim- ple low cost technique and by this technique one can tune the shape and size of the synthesized CNPs. Also it is possible to easily functionalize the CNPs just by varying the experimental conditions. Sadhanala et al. [6] have synthesized boron doped carbon nanoparticles with size independent colour tunability from blue to red. Tong et al. [ 7] have reported facile * P. Kumbhakar nitdgpkumbhakar@yahoo.com; pathik.kumbhakar@phy.nitdgp.ac.in 1 Nanoscience Laboratory, Department of Physics, National Institute of Technology Durgapur, Durgapur 713209, India 2 Present address: Department of Physics, School of Applied Sciences, KIIT University, Bhubaneswar, Odisha -751024, India 3 National Institute of Technology Durgapur, Durgapur 713209, India 4 Department of Material Science and Nano-Engineering, Rice University, Houston, TX 77005, USA 5 Department of Molecular Microbiology, School of Biotechnology, Madurai Kamaraj University, Madurai, India 6 Department of Genetic Engineering, School of Biotechnology, Madurai Kamaraj University, Madurai, India J Fluoresc DOI 10.1007/s10895-016-1854-8