Application of magneto-luminescent gold nanoclusters in environmental analysis with microfluidic systems

This research has led to the development of a system based on microfluidics. This system utilizes magnetic gold nanoclusters (AuMNCs) to determine the presence of tetracyclines in water samples. These AuMNCs have been modified to acquire magnetic properties to be retained in the reaction/detection zone of the microfluidic system. The first step to obtain AuMNCs was the synthesis of magnetic nanoparticles (MNPs) by the co-precipitation method and then adding an amount of MNPs to BSA as the stabilizing agent and ascorbic acid as the reducing agent. The microfluidic system favors the retention of AuMNCs in the reaction/detection zone of the system to achieve the change in the luminescent signal produced by the interaction with tetracyclines. The microfluidic reactor was incorporated into the optical pathway of a conventional spectrofluorometer, using a 3D-printed device to focus the excitation beam to the reaction zone of the microfluidic channel. The instrumental signal was obtained at a 22.5° angle from the excitation beam, which help perform measurements of reactions in the microfluidic channels. The method was compared with not retained AuMNCs and AuNCs, obtaining better results with the magnetically retained system. The system was applied to determine different tetracyclines in water samples.