Enhanced Terahertz Specific Sensing for Alzheimer’s Marker by Metasurface-Analyte Union Modification on Microfluidic Sensor
Weinan Shi, Fei Fan, Shanshan Li, Liang Ma, Yiming Wang, Xianghui Wang, Shengjiang Chang
Abstract
Metasurface (MS)-based terahertz (THz) biosensors have attracted significant attention in the biological field due to their nondestructive and harmless interaction with biochemical samples. However, it is still challenging for specific detection in mixed samples via THz metasensors. In this work, we modified THz MS chips and target biomolecules, respectively, utilized immune binding and gold nanorods (GNRs), and achieved THz high-sensitive specific detection for Alzheimer’s marker <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{A}\beta _{\text {1-42}}$ </tex-math></inline-formula> protein via a microfluidic platform. A double-ring coupled metallic MS that can provide a strong localized field enhancement was fabricated and then modified with <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{A}\beta _{\text {1-42}}$ </tex-math></inline-formula> -antibody by covalent binding to capture <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{A}\beta _{\text {1-42}}$ </tex-math></inline-formula> . Moreover, GNRs were introduced to bind <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{A}\beta _{\text {1-42}}$ </tex-math></inline-formula> , and the sensor’s response to <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{A}\beta _{\text {1-42}}$ </tex-math></inline-formula> is greatly enhanced. Through this sensor-analytes modification, the sensitivity of the sensor can reach 240.91 GHz <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\cdot $ </tex-math></inline-formula> mL/nmol, and the limit of detection (LoD) is one order of magnitude higher than that without GNRs. In addition, the LoD for <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{A}\beta _{\text {1-42}}$ </tex-math></inline-formula> reached 0.2 pmol/mL (1 ng/mL), which is 100 times higher than other nonspecific proteins. More importantly, the biosensor can also recognize <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{A}\beta _{\text {1-42}}$ </tex-math></inline-formula> in a mixed sample with physiological limiting concentration. Our high selectivity and sensitivity nanomaterial-MS hybrid-based THz biosensor would give access to rich applications in label-free biosensing.