SERS fingerprinting of β₂-agonists for anti-doping based on Au-COF substrate

β₂-agonists, also known as β₂-adrenoceptor agonists, are secreted by the adrenal medulla of the animal body and have a characteristic catecholamine structure. When inhaled, the drug rapidly relaxes the smooth muscles of the airways in asthma patients, improves ventilation, and temporarily increases alertness during exercise and helps relieve fatigue. However, the use of β₂-agonists to improve physical performance in a short period of time can lead to extreme dependence and irritation, and there are still many unknown hazards. They are now on the World Anti-Doping Organization (WADA) prohibited list.

Surface-enhanced Raman spectroscopy (SERS) can directly detect the characteristic peaks associated with β₂-agonist compounds in a fast and sensitive manner. This study is the first to utilize a direct Raman detection technique, achieving successful acquisition of the fingerprint spectra of three target analytes (vilanterol, fenoterol, bambuterol) as well as the establishment of a corresponding fingerprint spectral analysis method. To further improve its performance, in this study, gold nanoparticles were synthesized via redox methods and integrated with covalent organic framework (COF) to construct a novel highly sensitive detection platform for β₂-agonists. The Au-COF composite exhibits high adsorption performance and can significantly enhance the SERS signal of the target, thereby achieving low detection limits, including 9.25 × 10^-6 g ·mL^-1 for bambuterol, 9.76 × 10^-6 g mL^-1 for vilanterol, and 7.54 × 10^-6 g·mL^-1 for fenoterol, which makes it promising for improving the overall sensitivity of β₂-agonist detection.

This study develops a novel analytical method utilizing Au-COF composites for highly sensitive SERS detection. It pioneers the application of this strategy in the qualitative and quantitative analysis of trace β₂-agonists. The research not only significantly expands the scope of Au-COF composites but also provides a technologically promising approach with substantial practical value for ensuring medical safety through clinical medication monitoring and for detecting banned substances in sports.