Nanogold amplified electrochemiluminescence/electrochemistry in bipolar silica nanochannel array for ultrasensitive detection of SARS-CoV-2 pseudoviruses.

The prompt and accurate point-of-care test (POCT) for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in infected persons or virus-containing environmental samples is of great importance. The present work reports a highly integrated electrochemiluminescence/electrochemical (ECL/EC) sensor for determination of SARS-CoV-2 pseudoviruses, in which bio-recognition element (SARS-CoV-2 IgG antibody), bifunctional probe (tris (2,2'-bipyridyl) ruthenium (Ru(bpy) ₃ ²⁺ )), and amplification material (gold nanoparticles (Au NPs)) are designed into bipolar silica nanochannel array (bp-SNA). bp-SNA consisting of homogeneous two-layer mesoporous silica films bears inner silanol groups and outer amino groups, generating a solid "electrostatic nanocage" for stable confinement of Ru(bpy) ₃ ²⁺ and Au NPs inside the nanochannels and further providing functional sites for covalent modification of SARS-CoV-2 IgG antibody. Owing to the preconcentration capacity of bp-SNA and amplified effect of Au NPs, ECL or EC signals of Ru(bpy) ₃ ²⁺ can be remarkably promoted and thereby increase the analytical performance, which can be diminished by immunorecognization of target SARS-CoV-2 pseudoviruses on the sensing interface. The developed integrated ECL/EC sensor based on Ru@AuNPs/bp-SNA modified solid indium tin oxide electrode enables the sensitive analysis of SARS-CoV-2 pseudoviruses by ECL mode with a linear range of 50 TU mL ^-1 -5000 TU mL ^-1 , as well as the EC mode with a linear range of 100 TU mL ^-1 -5000 TU mL ^-1 . Moreover, the designed sensor showed satisfactory results in the analyses of saliva and pond water samples. When flexible electrode substate (polyethylene terephthalate) is employed, Ru@AuNPs/bp-SNA has great potential to integrate with KN95 face masks for direct detection of SARS-CoV-2 pseudoviruses produced from breathing, talking and coughing processes, which could provide an efficient platform for POCT diagnosis.
Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
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