Utilizing Deep Eutectic Solvent in Microemulsion for Eco‐Friendly Synthesis of Fluorescent Carbon Nanoparticles and their Highly Sensitive Sensing of Antibiotics and Nitroaromatic Compounds

Abstract Microemulsions (MEs) comprising of cholinium dodecylbenzene sulphonate Cho[DBS], a bio‐based ionic liquid surfactant as an emulsifier, hydrophobic deep eutectic solvent (HDES) as nonpolar phase, and water as a polar component are constructed. Negative value of ∆G estimated from isothermal titration calorimetry (ITC) plots indicate spontaneous aggregation of Cho[DBS] both in water and HDES. The aggregates of Cho[DBS] in HDES and water show the critical micellar concentration (cmc) of ≈4.26 and ≈2.4 mMm, respectively. Cho[DBS] shows a better emulsifying capacity with a high monophasic region in the ternary phase diagram. MEs are utilized as nanoreactors for the sustainable synthesis of nano‐sized fluorescent carbon nanoparticles (FCNPs) with precise control over size and morphology. FCNPs are characterized using PXRD, Raman, XPS, HR‐TEM, UV–vis, and Fluorescence spectroscopic techniques. FCNPs exhibited remarkable properties viz. adjustable luminescence, good solubility, and biocompatibility. FCNPs are applied for fluorometric sensing of nitroaromatic compounds (NACs) and antibiotics through a quenching response originating from the inner filter effect, with a fast response nanomolar detection, and are found highly selective toward TNP (NAC), NFT, and NZF (antibiotics).