Bifunctional Au@Pt/Au nanoparticles as electrochemiluminescence signaling probes for SARS-CoV-2 detection

A novel immunosensor based on electrochemiluminescence resonance energy transfer (ECL-RET) for the sensitive determination of N protein of the SARS-CoV-2 coronavirus is described. For this purpose, bifunctional core@shell nanoparticles composed of a Pt-coated Au core and finally decorated with small Au inlays (Au@Pt/Au NPs) have been synthesized to act as ECL acceptor, using [Ru (bpy)3]2+ as ECL donor. These nanoparticles are efficient signaling probes in the immunosensor developed. The proposed ECL-RET immunosensor has a wide linear response to the concentration of N protein of the SARS-CoV-2 coronavirus with a detection limit of 1.27 pg/mL. Moreover, it has a high stability and shows no response to other proteins related to different virus. The immunosensor has achieved the quantification of N protein of the SARS-CoV-2 coronavirus in saliva samples. Results are consistent with those provided by a commercial colorimetric ELISA kit. Therefore, the developed immunosensor provides a feasible and reliable tool for early and effective detection of the virus to protect the populationThe authors wish to express their sincere thanks to the Spanish Ministerio de Ciencia e Innovacion (MICINN) (PID2020-116728RB-I00 and PID2020-115204RB-I00) and the Comunidad Autonoma ´ de Madrid (S2018/NMT-4349 TRANSNANOAVANSENS-CM Program, SI3/PJI/ 2021–00341 and 2021-5A/BIO-20943 Talent Attraction Project) for the financial support. C. Toyos-Rodríguez acknowledges the MICINN for the award of a FPI Grant (PRE2018-084953). A. de la Escosura-Muniz ˜ also thanks the MICINN for the research founding by a “Ramon ´ y Cajal” contract (RyC-2016-20299