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Biomed Opt Express. 2018 Jan 2;9(2):373-386. doi: 10.1364/BOE.9.000373. eCollection 2018 Feb 1.

Extreme sensitive metasensor for targeted biomarkers identification using colloidal nanoparticles-integrated plasmonic unit cells.

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Department of Electrical and Computer Engineering, Florida International University, 10555 W Flagler St., Miami, FL 33174, USA.
Center for Personalized NanoMedicine, Institute of Neurolmmune Pharmacology, Department of Immunology, Herbert Wertheim College of Medicine, Florida International University, Miami, FL 33199, USA.
Bio-MEMS and Microsystems Laboratory, Department of Electrical and Computer Engineering, Florida International University, 10555 W Flagler St., Miami, FL 33174, USA.
Electrodics and Electrocatalysis Division, CSIR-Central Electrochemical Research Institute, Karaikudi, 630 006, Tamil Nadu, India.


Engineered terahertz (THz) plasmonic metamaterials have emerged as promising platforms for quick infection diagnosis, cost-effective and real-time pharmacology applications owing to their non-destructive and harmless interaction with biological tissues in both in vivo and in vitro assays. As a recent member of THz metamaterials family, toroidal metamaterials have been demonstrated to be supporting high-quality sharp resonance modes. Here we introduce a THz metasensor based on a plasmonic surface consisting of metamolecules that support ultra-narrow toroidal resonances excited by the incident radiation and demonstrate detection of an ultralow concertation targeted biomarker. The toroidal plasmonic metasurface was designed and optimized through extensive numerical studies and fabricated by standard microfabrication techniques. The surface then functionalized by immobilizing the antibody for virus-envelope proteins (ZIKV-EPs) for selective sensing. We sensed and quantified the ZIKV-EP in the assays by measuring the spectral shifts of the toroidal resonances while varying the concentration. In an improved protocol, we introduced gold nanoparticles (GNPs) decorated with the same antibodies onto the metamolecules and monitored the resonance shifts for the same concentrations. Our studies verified that the presence of GNPs enhances capturing of biomarker molecules in the surrounding medium of the metamaterial. By measuring the shift of the toroidal dipolar momentum (up to Δω~0.35 cm-1) for different concentrations of the biomarker proteins, we analyzed the sensitivity, repeatability, and limit of detection (LoD) of the proposed toroidal THz metasensor. The results show that up to 100-fold sensitivity enhancement can be obtained by utilizing plasmonic nanoparticles-integrated toroidal metamolecules in comparison to analogous devices. This approach allows for detection of low molecular-weight biomolecules (≈13 kDa) in diluted solutions using toroidal THz plasmonic unit cells.


(040.2235) Far infrared or terahertz; (250.5403) Plasmonics; (280.1415) Biological sensing and sensors; (300.6495) Spectroscopy, terahertz

Conflict of interest statement

The authors declare that there are no conflicts of interest related to this article.

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