Luminescence sensing of narcotic drugs by a BSA protein stabilized AuAgCd trimetallic nanocluster

A luminescent trimetiallic nanocluster (NCs) stabilized by BSA protein (AuAgCd-BSA) was synthesized along with its mono and bimetallic counterparts (Au-BSA and AuAg-BSA). The detail characterization and comparative luminescence sensing performance for narcotic drugs and psychotropic substance (amphetamine, morphine) were performed for these three clusters. It was revealed that the trimetallic cluster can detect amphetamine and morphine drugs through turn on luminescence response. The calculated binding constants are found to be K_a = 5.86× 10³ M⁻¹ for Amphetamine and 3.75× 10³ M⁻¹ for Morphine by using Benesi-Hildebrand equation. The trimetallic cluster also showed selective turn off luminescence response in presence of mercury (Hg²⁺) ions. The origin of the enhanced PL responses in presence of amphetamine and morphine was further investigated by exploring the PL lifetime decay studies, which reveals that larger excited state lifetime (in μs timescale) value of pristine cluster remain unchanged upon incremental addition of drugs leading to longer interaction time with the analytes. Thus, the present work undoubtedly establishes the superior drug sensing behaviour of AuAgCd-BSA tri-metallic NCs as compared to its mono-metallic and bi-metallic counterparts and open further emphasis on exploring luminescence-based sensing of narcotic drugs which has great forensic relevance.