Self-assembled chromogen-loaded polymeric cocoon for respiratory virus detection

Inspired by the self-assembly approach, in this work, the chromogen, 3,3 ',5,5 '-tetramethylbenzidine (TMB), was successfully co-precipitated in aqueous solution to form collective nanoparticles (NPs) of signal molecules (TMB-NPs). Utilizing poly(lactide-co-glycolide) (PLGA) in the molecular delivery approach, the formed emulsion nanovesicle (TMB-NPs@PLGA) exhibits an enrichment of the collective signal molecules in a single antibody-antigen conjugation. A specific antibody-conjugated TMB-NPs@PLGA forms an immunocomplex sandwich structure upon the addition of influenza virus (IV)/A. The addition of dimethyl sulfoxide (DMSO) dissolves the PLGA nanovesicles, releasing the encapsulated TMB-NPs. Sequentially, the TMB-NPs release TMB molecules upon the addition of DMSO. The released TMB is catalytically oxidized by H2O2 with self-assembled protein-inorganic nanoflowers, where copper nanoflowers (CuNFs) acted as the nanozyme. The developed immunoassay demonstrates high sensitivity for IV/A with a limit of detection (LOD) as low as 32.37 fg mL(-1) and 54.97 fg mL(-1) in buffer and serum, respectively. For practical needs, a clinically isolated IV/A/H3N2 and spike protein of SARS-CoV-2 were detected with the LODs of 17 pfu mL(-1) and 143 fg mL(-1), respectively. These results show the applicability of the advanced TMB-NPs@PLGA-based colorimetric sensor for the highly sensitive detection of airborne respiratory viruses.

Automated summary

By co-precipitating the chromogen TMB in aqueous solution, collective nanoparticles TMB-NPs were formed and enriched in PLGA nanovesicles using a molecular delivery approach. The developed colorimetric sensor demonstrated high sensitivity in detecting influenza virus and other respiratory viruses, showcasing practical applications for airborne virus detection.