An ultrasensitive electrochemiluminescence immunosensor for SARS-CoV-2 nucleocapsid protein detection based on signal amplification strategy of DMSN@QDs

Based on signal amplification strategy of dendritic mesoporous silica nanospheres loaded with CdSe/ZnS quantum dots (DMSN@QDs), an ultrasensitive electrochemiluminescence (ECL) immunosensor with magnetic separation was constructed for the detection of SARS-CoV-2 nucleocapsid protein (NP). DMSN, a mesoporous material with abundant radial pores, large specific surface area and high porosity, can increase the loading capacity of QDs and hinder their aggregation as the nanocarrier. DMSN@QDs with good ECL efficiency were used as signal labels to construct a sandwich immunosensor. The designed ECL immunosensor displayed a good linear relationship for NP concentrations ranging from 0.005 ng mL(-1) to 50 ng mL(-1), with a limit of detection of 3.33 pg mL(-1). The ECL immunosensor was successfully applied to detect NP in human serum samples with satisfactory recovery. This strategy provided a new method for detecting NP and expanded the application field of DMSN.

Automated summary

An ultrasensitive electrochemiluminescence (ECL) immunosensor with magnetic separation was constructed for the detection of SARS-CoV-2 nucleocapsid protein (NP) using dendritic mesoporous silica nanospheres loaded with CdSe/ZnS quantum dots (DMSN@QDs) as signal labels. The DMSN@QDs exhibited good ECL efficiency and were able to increase the loading capacity of QDs and prevent their aggregation. The ECL immunosensor showed a linear relationship for NP concentrations ranging from 0.005 ng mL(-1) to 50 ng mL(-1), with a limit of detection of 3.33 pg mL(-1). It was successfully applied to detect NP in human serum samples with satisfactory recovery, providing a new method for NP detection and expanding the application field of DMSN.