College of Physics and Photoelectric Engineering, Harbin Engineering University, Harbin, 150001, China; Key Lab of In-fiber Integrated Optics, Ministry Education of China, Harbin Engineering University, Harbin, 150001, PR China.
Department of Physics and Optical Science, University of North Carolina at Charlotte, Charlotte, NC, 28223-0001, USA.
Talanta. 2020 Mar 1;209:120513. doi: 10.1016/j.talanta.2019.120513. Epub 2019 Oct 31.
In this study, we demonstrate a novel nematic liquid crystal (LC) 4-cyano-4'-pentylbiphenyl (5CB) microdroplet-based biosensor for real-time, quantitative and sensitive detection of urea by whispering gallery mode (WGM) lasing technology. The single stearic acid-doped 5CB microdroplet is taken as both optical resonator and sensing reactor. To the best of our knowledge, this work is the first report of urea detection with WGM lasing. The enzymatic reaction between urea and urease produces hydroxide ions. Deprotonation and self-assembly of stearic acid occur at the aqueous/LC interface with increased pH value, promoting the reorientation of LC molecules. The detectable shift of WGM lasing spectra related to the configuration transition of LC microdroplets can be used as an indicator of enzymatic reaction, and this allows detection of urea molecules by the sensor at a concentration of only 0.1 mM. The proposed sensor also demonstrated the ability to detect urea in real urine samples. Compared with conventional POM observations, monitoring and identification of lasing spectra from LC microdroplets as a versatile method allow for more quantitative and sensitive detection of analyte reactions and can be expected to replace POM imaging technology for current LC-based biosensor systems.
在这项研究中，我们展示了一种基于向列相液晶（LC）4-氰基-4'-戊基联苯（5CB）微滴的新型生物传感器，用于通过 whispering gallery mode（WGM）激光技术实时、定量和灵敏地检测尿素。单个硬脂酸掺杂的 5CB 微滴既是光学谐振器又是传感反应器。据我们所知，这是首次使用 WGM 激光报告尿素检测的工作。尿素和脲酶之间的酶反应产生氢氧根离子。随着 pH 值的升高，硬脂酸在水/LC 界面上发生去质子化和自组装，促进 LC 分子的重排。与 LC 微滴构型转变相关的 WGM 激光光谱的可检测位移可用作酶反应的指示剂，这使得传感器能够以低至 0.1 mM 的浓度检测尿素分子。该传感器还展示了在真实尿液样本中检测尿素的能力。与传统的 POM 观察相比，监测和识别 LC 微滴中的激光光谱作为一种通用方法，可以更定量和灵敏地检测分析物反应，并有望取代 POM 成像技术，用于当前基于 LC 的生物传感器系统。
