Open AccessDetection of heavy metal ions using whispering gallery mode lasing in functionalized liquid crystal microdroplets
Author(s) -
Rui Duan,
Yanzeng Li,
Hanyang Li,
Jun Yang
Publication year - 2019
Publication title -
biomedical optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.362
H-Index - 86
ISSN - 2156-7085
DOI - 10.1364/boe.10.006073
Subject(s) - whispering gallery wave , lasing threshold , materials science , liquid crystal , metal ions in aqueous solution , biosensor , ion , detection limit , optics , laser , doping , optoelectronics , stearic acid , metal , nanotechnology , chemistry , resonator , chromatography , physics , wavelength , organic chemistry , metallurgy , composite material
We demonstrate a detection method for heavy metal (HM) ions based on whispering gallery mode (WGM) lasing in a liquid crystal (LC) microdroplet biosensor. By doping with stearic acid, nematic LC 4-cyano-4'-pentylbiphenyl (5CB) microdroplets are biochemically functionalized and used as both optical microresonators and sensing elements. Typical WGM lasing emission is observed in stearic acid-doped 5CB microdroplets under a pulse laser pump. Our results show that quantitative spectral shift of WGMs can serve as a real-time indicator of the adsorption of HM ions on the microdroplet surface. The detection limit of our sensor is as low as 40 pM for Cu(II) ions, six orders of magnitude better than the exposure threshold defined by the World Health Organization. Furthermore, this sensing system has an ability to discriminate between heavy and light metal ions. We believe that this novel biosensor has great application potential for environmental monitoring and drinking water quality testing.