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The present study focuses on the green synthesis of nitrogen-doped carbon dots (C.dots) from sesame seeds using microwave pyrolysis method. The C.dots obtained were characterized and extensively studied using transmission electron microscopy (TEM), UV/ visible spectroscopy, fluorescence spectroscopy and Fourier transform infra-red spectroscopy (FTIR) techniques. The results indicated the presence of highly fluorescent, aqueous soluble and significantly photostable C.dots with a quantum yield of 8.02%. The average size distributions of C.dots were found to be 5 nm. These C.dots were effectively applied as a selective sensor for Fe(III) as the fluorescence intensity was significantly quenched with increasing metal concentrations. The limit of detection (LOD) was found to be 2.56 M of Fe(III). This study demonstrates a low cost, environmental friendly and waste recyclable synthetic method for preparation of C.dots and its application as a selective Fe(III) sensor.Keywords: Carbon dots, fluorescence, sesame seeds, microwave pyrolysis, metal ions, quenching.CARBON DOTS (C.dots) are gaining increasing attention within the carbon nanomaterial family due to their varied applications in biological, sensing, optical and electrical fields 1-3 . They are swiftly replacing the conventional semiconductor nanoparticles (Q.dots) which have raised serious health and environmental concerns because of the presence of heavy metals in it 4 . C.dots are spherical, oxygenous carbon nanoparticles with size below 10 nm. C.dots akin to Q.dots show several interesting properties such as excitation-dependent emission, chemical and photostability, enhanced fluorescence quantum yields and the possibility of fine-tuning the sensing properties by surface modification [5][6][7][8][9][10][11] In order to improve the photophysical and photochemical properties of C.dots, hetero-atom doped C.dots are synthesized by different ways. Among them, nitrogendoped C.dots received much attention because of their good biocompatibility and the related broad applications in the areas of bio-imaging, electrocatalysis and sensors 25,26 . However, most of the synthesis methods reported so far have either a long reaction time or a need of extra chemicals for doping. Thus, synthesizing Ndoped C.dots in a cost effective and ecofriendly manner and using them for sensing applications, especially for biologically active and environmentally hazardous metal ions will be highly beneficial.Iron is an essential element for many biological processes 27 . The presence of iron in body either at higher levels or at lower levels can lead to several problems which eventually disturbs the lipid metabolism and glucose levels 28 . Therefore, quantitative determination of bioactive iron is an important health care challenge. Some studies have already been reported in this direction; Qian et al. 29 used the N-doped C.dots for detection of Fe(III). Wang et al. 30 used a wide variety of green carbonaceous precursors like milk, silk, honey, hair, lemon, etc. to detect Fe(III).The pre...