The pairing of donors and acceptors at a molecular level is a unique approach to increasing the energy at the donor-acceptor interface. This approach has led to the development of a novel chemo-sensor that uses nitro-benzo-furazan (NBD) to detect Tryptophan (Trp) with excellent selectivity. This sensor employs an intermolecular Förster Resonance Energy Transfer (FRET) and dis-aggregation effect that causes a change in the solution's fluorescence from orange to green. The sensor has a fast response time of 30 sec and can distinguish Trp from 19 other essential amino acids with a limit of detection of 16.81 ppb. The research is focused on proving the fluorescence detection mechanism through various analytical and theoretical methods. It confirmed the feasibility of creating a portable detection kit through a test paper experiment. The study also used mung bean (Vigna radiata) seedlings as a model to detect Trp in plants via fluorescence imaging. This research established effective techniques for monitoring Trp in environmental samples and living plant systems.