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 population.

Sensitive SARS-CoV-2 detection in wastewaters using a carbon nanodot-amplified electrochemiluminescence immunosensor.

Given the great utility that having fast, efficient and cost-effective methods for the detection of SARS-CoV-2 in wastewater can have in controlling the pandemic caused by this virus, the development of new dependable and specific SARS-CoV-2 coronavirus sensing devices to be applied to wastewater is essential to promote public health interventions. Therefore, herein we propose a new method to detect SARS-CoV-2 in wastewater based on a carbon nanodots-amplified electrochemiluminescence immunosensor for the determination of the SARS-CoV-2 Spike S1 protein. For the construction of the immunosensor, N-rich carbon nanodots have been synthetized with a double function: to contribute as amplifiers of the electrochemiluminescent signal in presence of [Ru(bpy)3]2+ and as antibody supports by providing functional groups capable of covalently interacting with the SARS-CoV-2 Spike S1 antibody. The proposed ECL immunosensor has demonstrated a high specificity in presence of other virus-related proteins and responded linearly to SARS-CoV-2 Spike S1 concentration over a wide range with a limit of detection of 1.2 pg/mL. The immunosensor has an excellent stability and achieved the detection of SARS-CoV-2 Spike S1 in river and urban wastewater, which supplies a feasible and reliable sensing platform for early virus detection and therefore to protect the population. The detection of SARS-CoV-2 Spike S1 in urban wastewater can be used as a tool to measure the circulation of the virus in the population and to detect a possible resurgence of COVID-19.