Development of highly sensitive plasmonic biosensors encoded with gold nanoparticles on M13 bacteriophage networks

In this study, a novel nanoplasmonic substrate is developed for biomedical applications. In nanoplasmonic biosensors, a substrate that can induce strong hot spots by forming uniform nanogaps smaller than 10 nm is required to implement a device capable of detecting biomarkers at low concentrations. Herein, gold nanoparticles-encoded M13 bacteriophage (AuNPs@M13) substrate was developed by immobilizing 60 nm AuNPs onto the surface of an M13 bacteriophage scaffold with a network assembly structure. The plasmonic characteristics of the proposed AuNPs-M13 were evaluated by assessing the nanogap distribution, electromagnetic enhancement effects, and reproducibility of the fabricated substrate. Additionally, an immunoassay for severe acute respiratory syndrome coronavirus 2 was performed to confirm the clinical applicability of the proposed AuNPs@M13 substrate. When the AuNPs@M13 was used as a nanoplasmonic substrate, it was possible to achieve better sensitivity (limit of detection [LoD] = 1.21 PFU/mL) than that with the commercially available lateral flow assay strip (LoD = 300-500 PFU/mL) or enzyme-linked immunoassay (LoD = 48 PFU/mL). The proposed AuNPs@M13 in this study is expected to be used as an innovative biomedical device for the highsensitivity detection of various biomarkers.

Automated summary

A novel nanoplasmonic substrate was developed for biomedical applications, which showed strong hot spots for detecting biomarkers at low concentrations. The substrate, called AuNPs@M13, was made by immobilizing 60 nm gold nanoparticles onto the surface of an M13 bacteriophage scaffold. It demonstrated higher sensitivity and lower limit of detection compared to commercially available assays.