LAUSR

Abstract In the present study, a single step and template free synthesis was proposed for the preparation of heterostructured single crystalline rod like bismuth sulfide/sulfur doped graphene (SGr-Bi 2 S 3 ) nanocomposite. The structural properties and physical interactions of SGr-Bi 2 S 3 were investigated by various physicochemical techniques which provide the knowledge about growth mechanism and orientation of reactive sites. These highly oriented edge reactive sites of SGr-Bi 2 S 3 promoted the fascinating electrochemical performance towards the electrocatalysis of tryptophan (Trp). Trp is an essential biological compound it’s monitoring in human diet is quite important. Thereby, the SGr-Bi 2 S 3 modified screen printed carbon electrode (SPCE) is applied to the determination of Trp. Trp is determined by differential pulse voltammetry (DPV) which revealed an acceptable sensitivity and lowest detection limit about 1.2 µA µM −1  cm −2 and 0.004 µM, respectively. These values are highly encouraged for the real time analysis of Trp in human blood (12–13 µg/mL). Moreover, it exhibited good selectivity over the range of interfering compounds (which present in blood co-exist with Trp). Therefore, this low-cost disposable SGr-Bi 2 S 3 /SPCE can applicable for the determination of Trp in biological samples.