State Key Laboratory for Mesoscopic Physics, School of Physics, Peking University, Beijing 100871, China.
Frontiers Science Center for Nano-optoelectronics, Peking University, Beijing 100871, China.
Proc Natl Acad Sci U S A. 2022 Feb 8;119(6). doi: 10.1073/pnas.2108678119.
Label-free sensors are highly desirable for biological analysis and early-stage disease diagnosis. Optical evanescent sensors have shown extraordinary ability in label-free detection, but their potentials have not been fully exploited because of the weak evanescent field tails at the sensing surfaces. Here, we report an ultrasensitive optofluidic biosensor with interface whispering gallery modes in a microbubble cavity. The interface modes feature both the peak of electromagnetic-field intensity at the sensing surface and high- factors even in a small-sized cavity, enabling a detection limit as low as 0.3 pg/cm The sample consumption can be pushed down to 10 pL due to the intrinsically integrated microfluidic channel. Furthermore, detection of single DNA with 8 kDa molecular weight is realized by the plasmonic-enhanced interface mode.
无标记传感器在生物分析和早期疾病诊断中非常理想。光消逝传感器在无标记检测方面表现出了非凡的能力，但由于在传感表面的消逝场尾部较弱，其潜力尚未得到充分利用。在这里，我们报告了一种超灵敏的光流体生物传感器，它在微泡腔内具有界面 whispering gallery 模式。界面模式具有传感表面处电磁场强度的峰值和高 Q 因子，即使在小尺寸腔中也是如此，从而实现了低至 0.3 pg/cm 的检测限。由于固有集成的微流道，样品消耗可降低至 10 pL。此外，通过等离子体增强的界面模式实现了对 8 kDa 分子量的单 DNA 的检测。
