SnS₂ QDs@MXene Ohmic Junction-Based Surface Plasmon Coupling ECL Sensor to Detect Saliva Exosome for the Diagnosis of Childhood Asthma

This study represents a novel surface plasmon coupling electrochemiluminescence (SPC-ECL) method for detecting salivary exosomes and the diagnosis of childhood asthma. First, SnS₂ QDs@MXene Ohmic junctions was developed as efficient ECL emitters. The Ohmic junction provided a low resistance to reduce the contact resistance and improve charge injection efficiency, which enhanced the ECL signal by 2.76 times. Furthermore, the self-assembled surface plasmonic Bi@SiO₂ array was prepared. When the ECL of SnS₂ QDs@MXene resonated with the electronic oscillations in the Bi@SiO₂ NPs array, the luminescence intensity was enhanced and regulated into the directionally polarized signal by the SPC-ECL effect. Remarkably, the detection of CD9-exosomes in saliva was achieved successfully based on the above sensing system, which can be used to analysis the acute exacerbation and chronic persistence of childhood asthma.