Small amine-functionalized diesel soot-derived onion-like nanocarbon for selective sensing of glutamic acid and imaging application†

Black carbon (BC) generated from vehicle engine exhaust is a global environmental concern and a freely available carbon source. Herein, onion-like nanocarbon (ONC) isolated from diesel soot (DS) has been surface-functionalized with a small amine named ethylenediamine (en). The amine-functionalized ONC designated as f-en-ONC shows maximum emission at 430 nm under excitation at 350 nm. The aqueous solution of f-en-ONC emits a blue color on UV-light illumination and displays a quantum yield of ∼18%. Among the different tested biomolecules, f-en-ONC selectively detects glutamic acid (GLA) through fluorescence-based quenching. The limit of detection for GLA was found to be ∼ 17.3 μM. Based on spectral overlap studies, UV-visible spectra, and the Stern–Volmer plot, the dynamic quenching mechanism was suggested for the fluorescence-based sensing of GLA. Further, the water-soluble f-en-ONC was used as a bioimaging probe for cancer cells.