ORIGINAL ARTICLE Biogenic Synthesis of Fluorescent Carbon Dots at Ambient Temperature Using Azadirachta indica (Neem) gum Chinmay Phadke 1 & Ashmi Mewada 1 & Roopa Dharmatti 1 & Mukeshchand Thakur 1 & Sunil Pandey 1 & Madhuri Sharon 1,2 Received: 4 March 2015 /Accepted: 15 June 2015 # Springer Science+Business Media New York 2015 Abstract Synthesis of fluorescent Carbon Dots (CDs) from various carbonaceous materials apparently has acquired lots of interest amongst researchers as the corollary of the proper- ties of CDs; which are subsequently getting unveiled. In this study we report the use of Azadirachta indica (Neem) Gum as a novel natural pre-cursor for synthesis of CDs at room tem- perature. Water soluble CDs of around 5–8 nm were obtained after treatment of the gum with ethanol and NaOH. These CDs exhibited green fluorescence in UV-light (λ = 365 nm). These CDs were found to be stable, having many bio-linkers at- tached on their surface, making it suitable for drug attachment and hence can serve as potential candidates for applications like drug delivery vehicles as well as for biosensors. Keywords Azadirachta indica . Carbon-dots . Carbon materials . FTIR . Nanoparticles Introduction The word quantum dots (QD) usually implies to quantum dots of metals like CdSe, CdS etc. Usually they are synthesized by chemical methods [1, 2], which accounts for presence of heavy metals in QDs making them unfavourable to be used for Bioimaging. Moreover, such QDs are found to have high cytotoxicity [3, 4]. After the discovery of Carbon Dots (CDs) in 2004 [5], it has fetched lot of attention because of its properties like small size, photoluminescence, biocompatibility, water solubility and excellent stability. Till date these properties of CDs have been explored in various fields like drug delivery [6], gene delivery [7], bio-imaging [8], biosensors [9] etc. Biogenically synthesized CDs have been proved to be worthy over chem- ically synthesized CDs [10], as it overcomes several draw- backs of Quantum Dots (QDs). There are many reports that focus on the low toxicity of CDs and excellent Photoluminescence properties of biogenic CDs, which are idyllic for imaging application [10–12]. Till date, many studies have reported synthesis of CDs by Physical, Biological as well as Chemical approach using var- ious methods e.g. Combustion/Microwave assisted synthesis [13], Laser ablation/Passivation [14], supported synthesis [15] and electrochemical oxidation [12]. However, these method- ologies require use of expensive instruments, chemicals and rigorous experimental conditions as well as these produce a low yield of CDs which makes them tedious and unfavourable. Additionally, many of the chemicals used are environmentally detrimental and hence additional precautions are needed to be taken. Ample of studies reported CDs syn- thesis at higher temperature using above mentioned methods [13–15] however, so far only our lab has reported CDs syn- thesis at room temperature [16]. Of late, natural pre-cursors like Sugar cane juice [16], Orange juice [17], Watermelon peel [18], Trapa bispinosa peel [19], Bread [20], Rice husk [21] have been used for production of eco-friendly CDs because of their high carbon content. These CDs get coated with natural linkers onto whom Chinmay Phadke and Ashmi Mewada have equal contribution. Electronic supplementary material The online version of this article (doi:10.1007/s10895-015-1598-x) contains supplementary material, which is available to authorized users. * Madhuri Sharon sharonmadhuri@gmail.com 1 N. S. N. Research Centre for Nanotechnology & Bio-Nanotechnology, Ambernath, MS, India 2 Monad Nanotech Pvt Ltd, A-702 Bhavani Towers, Powai, Mumbai, MS, India J Fluoresc DOI 10.1007/s10895-015-1598-x