Rui Duan,Yanzeng Li,Bojian Shi,Hanyang Li,Jun Yang
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.
Li Zhonghao,Cai Zhihan,Wang Yuhan,Liu Yuliang,Li Guifeng,Yang Xi,Deng Ming,Chen Yu-Cheng,Yang Jichun,Luo Yang,Gong Chaoyang,Zhu Tao
The mechanical properties of biological fluids serve as early indicators of disease, offering valuable insights into complex physiological and pathological processes. However, the existing technologies struggle to achieve high-throughput measurement, limiting their widespread applications in disease diagnosis. Here, we propose laser-emission vibrational microscopy of microdroplets for high-throughput measurement of the intrinsic mechanical properties of fluids. The microdroplet array supporting high Q-factor (10 4 ) whispering gallery modes (WGM) lasing was massively fabricated on a superhydrophobic surface with inkjet printing. Ultrasound was employed to actuate the mechanical vibrations of the microdroplets, and the vibration amplitude was quantified using time-resolved laser spectra. We found that the stimulus-response of the laser emission is strongly dependent on the liquid viscosity. Fast mapping of the microdroplets’ viscosities was achieved by stage scanning. High-throughput screening of hyperlipidemia disease was also demonstrated by performing over 2000 measurements within 25 min. Thanks to the small volume of the microdroplets, a single drop of blood can support over seven million measurements. The high-throughput ability and small sample consumption make it a promising tool for clinical diagnoses based on mechanical properties.
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