Sensitive SERS detection of trace methamphetamine in complex samples through sharp-spiked gold nanostructure.

Taking a massive overdose of methamphetamine (MAMP), which is one of the most prevalent illicit drugs in the world, will stimulate central nervous system, impair both physical and mental health and even lead to death. Therefore, the rapid quantitative testing in the field of MAMP is of great importance to law enforcement agencies. In this study, a branched, sharp-spiked gold nanostructure, named AuNS@4-MBA, is successfully synthesized at room temperature. The quantitative detection of MAMP is achieved through surface-enhanced Raman scattering (SERS) using the AuNS@4-MBA substrate. Due to the unique morphology of the nanostructure, numerous "hot spots" are formed, providing optimal conditions for sensitive detection. Upon activation of the system using EDC/NHS, the SERS signal intensity at 1080 cm-1 exhibits a gradual decrease as the MAMP concentration increases. This reduction can be attributed to the formation of amide compounds in the vicinity of 4-MBA, which not only interferes with the 4-MBA signal but also suppresses the aggregation of gold nanostars. Under optimized experimental conditions, the detection limit for MAMP was determined to be 1.3 × 10-8 M (1.96 ng/mL), with a linear detection range spanning from 5 × 10-8 M to 5 × 10-4 M. Kinetic and isotherm analyses revealed that the capture of MAMP onto the AuNS@4-MBA surface follows pseudo-second-order kinetics and adheres to the Langmuir model. Furthermore, this highly accurate detection method demonstrates exceptional efficacy in complex biological and environmental matrices. Its universal applicability extends to the detection of illicit drugs containing amine groups, underscoring its potential as a robust tool for forensic analysis and rapid on-site drug screening at crime scenes.