Expanding chiral metamaterials for retrieving fingerprints via vibrational circular dichroism  

作　　者：Cheng Xu Zhihao Ren Hong Zhou Jingkai Zhou Chong Pei Ho Nan Wang Chengkuo Lee 

机构地区：[1]Department of Electrical and Computer Engineering,National University of Singapore,Singapore 117583,Singapore [2]Center for Inteligent Sensors and MEMS(CISM),National University of Singapore,Singapore 117608,Singapore [3]institute of Microelectronics(IME),Agency for Science,Technology and Research(A*STAR),Singapore 138634,Singapore [4]NUS Graduate School for Integrative Science and Engineering Program(ISEP),National University of Singapore,Singapore 117456,Singapore

出　　处：《Light(Science & Applications)》2023年第7期1401-1414,共14页光（科学与应用)（英文版）

基　　金：supported by RIE Advanced Manufacturing and Engineering(AME)Programmatic Grant Project(Grant A18A5b0056,A18A4b0055);Advanced Research and Technology Innovation Center(ARTIC)Project(WBS:A-0005947-20-00);Ministry of Education(MOE)Tier two Project(MOE-T2EP50220-0014);NRF Competitive Research Programme(NRF-CRP15-2015-02)。

摘　　要：Circular dichroism(CD)spectroscopy has been widely demonstrated for detecting chiral molecules.However,the determination of chiral mixtures with various concentrations and enantiomeric ratios can be a challenging task.To solve this problem,we report an enhanced vibrational circular dichroism(VCD)sensing platform based on plasmonic chiral metamaterials,which presents a 6-magnitude signal enhancement with a selectivity of chiral molecules.Guided by coupled-mode theory,we leverage both in-plane and out-of-plane symmetry-breaking structures for chiral metamaterial design enabled by a two-step lithography process,which increases the near-field coupling strengths and varies the ratio between absorption and radiation loss,resulting in improved chiral light-matter interaction and enhanced molecular VCD signals.Besides,we demonstrate the thin-film sensing process of BSA andβ-lactoglobulin proteins,which contain secondary structures a-helix andβ-sheet and achieve a limit of detection down to zeptomole level.Furthermore,we also,for the first time,explore the potential of enhanced VCD spectroscopy by demonstrating a selective sensing process of chiral mixtures,where the mixing ratio can be successfully differentiated with our proposed chiral metamaterials.Our findings improve the sensing signal of molecules and expand the extractable information,paving the way toward label-free,compact,small-volume chiral molecule detection for stereochemical and clinical diagnosisapplications.

关 键 词：CHIRAL VIBRATIONAL CIRCULAR 

分 类 号：O62[理学—有机化学]