Gold Nanoparticle-Based Terahertz Metamaterial Sensors: Mechanisms and Applications

Terahertz (THz) waves, especially those assisted by THz metamaterials, have great potential for detecting trace amounts of sensing targets. Some nanomaterials, such as gold nanoparticles (AuNPs), also show promising characteristics; however, their application in this context is hindered by a lack of plasmonic activity in the THz region. This study is the first to introduce AuNPs into THz metamaterial applications as a new tool for improving the sensitivity of protein detection. We demonstrate the mechanism of THz metamaterial detection through sensing different targets by using metamaterials with distinct resonance peaks. Furthermore, we used an AuNP-based THz metamaterial sensing method to detect avidin. The limit of detection of conjugated avidin-AuNPs reached 7.8 fmol, presenting greater than a 1000-fold sensitivity improvement compared with that of avidin alone. Our present work illustrates the feasibility of AuNP-based protein sensing, which may lay a foundation for the development of numerous metallic nanoparticle-based THz metamaterial biosensors.