消逝波激励的光流控激光器及其在生物传感中的应用研究

A bare quartz fiber will be implanted in a PDMS microfluidic channel filled with dye gain media containing donor-to-acceptor pairs linked by DNA sequences and longitudinally pumped by evanescent wave along the fiber axis, then Whispering-gallery-mode (WGM) lasing emission based on fluorescence resonance energy transfer (FRET) will emit out from the channel. We will first intend to acquire the key factors of which will affect the highly efficient resonant energy transfer, and how to achieve monolayer gain lasing emission. We will then utilize the specificity of molecular beacons (MBs) of identifying nucleic acid sequences to develop a novel probe based on optofluidic FRET lasing, and offer a new method for highly sensitive detection of DNA target sequences and explore single molecule detection by using MBs lasing under the condition of evanescent wave pump. Furthermore, based on the unique feature of long WGM lasing produced length, we will fill multicolor MBs in different microfluidic channels along the fiber axis and develop an experimental platform for multi-parameter synchronous and parallel measurement in multi-sample channels under a single wavelength pump light. If the project will be supported and carried out successfully, it will lay a good theoretical and experimental foundation for the potential bio-sensing applications of the optofluidic lasers based on evanescent wave pump.

将石英光纤植入由DNA序列连接的供体和受体对染料增益介质微流道中，采用沿光纤轴向消逝波激励方式，在微流道中产生基于荧光共振能量转移（FRET）机制的回音壁模式（WGM）激光辐射，同时寻求获得实现高效FRET激光辐射及单层增益介质激光辐射的关键因素。利用分子信标（MBs）的特异性，在微流道中发展基于光流控FRET激光的新型探针，探讨利用MBs激光实现对DNA靶序列高灵敏度探测的新方法；在消逝波激励条件下，开展利用MBs激光实现单分子探测的探索。本课题将利用消逝波激励的WGM激光沿光纤轴向具有较长激光产生长度的独特优势，沿光纤轴向不同样品沟槽中填入多种MBs，在单一波长激励条件下，开发多样品通道中实现多参数同步并行检测的实验平台。本项目研究将为消逝波激励的光流控激光器在生物传感中的应用奠定良好的实验和理论基础。

利用化学交联的方法在光纤表面实现单分子层的增益介质，采用沿光纤轴向消逝波激励的方式，实现了高效的单分子层回音壁(Whispering Gallery Modes, WGMs)模式激光辐射。利用消逝波激励的激光具有较长激光产生长度及低阈值的特性，在不改变抽运光波长的情况下，结合染料分子间的荧光共振能量转移(FRET)机制，实现了波长调谐范围为240 nm的激光辐射。以荧光素钠(DSF)水溶液作为光纤的增益包层介质及传感探针，采用沿光纤轴向消逝波光激励方式，在水相条件下实现了低阈值光纤光流控激光（FOFL）辐射。在pH值6.51-8.13范围内，激光辐射强度与pH值显示出良好的线性关系，激光传感的灵敏度比荧光传感的灵敏度提高了两个数量级。提出的FOFL激光传感器具有出色的鲁棒性和低样品消耗，在实时和原位动态药物检测及危险、有毒有害、易挥发的溶液传感方面具有巨大潜力。利用表面活性剂能够防止染料分子在水溶液中的缔合从而提高其量子效率的特性，通过添加十二烷基苯磺酸钠(SDBS)的罗丹明B（RhB）水溶液作为光纤的增益包层介质。采用沿光纤轴向消逝波光激励方式，在水相条件下实现了SDBS增溶RhB的低阈值WGM激光辐射。实验结果表明：当SDBS的浓度为7-10 mM时，染料聚集体被分离并溶解在胶束中，引起RhB的量子效率快速增大，激光阈值降低。当SDBS的浓度大于10 mM，所有染料分子被吸附到胶束中形成单体分子，RhB的量子效率缓慢增加并趋于稳定，因此激光阈值趋于不变。采用沿光纤轴向激励包层溶液分方式，在PDMS微流道中实现了均匀的荧光辐射，结合染料分子之间FRET机制，实现了受体分子的荧光辐射。在不改变抽运光波长及不更换包层溶液的情况下，同时实现微流芯片上多色可调谐的荧光辐射。