Highly sensitive and selective detection of tryptophan by antipyrine based fluorimetric sensor

• Antipyrine based imine molecule (AP) was synthesized by a simple condensation method with moderate yield. • The AP as a sensor is sensitive and selective towards tryptophan (TP) in neutral condition. • It can be employed for the detection of TP in human biofluids such as blood and urine samples. • Interaction between the AP and TP through hydrogen bonding was described by experimental studies and theoretical methods. • UV-Visible and fluorescence spectroscopy studies showed that the biosensor as an AP bind with TP. For the detection of tryptophan (TP), organic molecule based on antipyrine (AP) has been synthesized. UV-vis and fluorimetric study has been used to confirm the sensing mechanism of AP with TP and theoretical explanations based on DFT calculations were also employed. The presence of numerous interfering biomolecules such alanine, asparagine, ascorbic acid, creatine, creatinine, cysteine, dopamine, glutamine, histidine, leucine, phenylalanine proline and urea could be optically distinguished by the AP by a change in colour from yellow to intense yellow fluorescence. The impressive sensing performance of AP sensor exhibits rapid response, remarkable sensitivity and selectivity towards TP with excellent limit of detection, high quantum yield and binding constant of 2 × 10 −7 mol/L, 0.89 and 1.12 × 10 6 M −1 respectively.