Study On Fiber-Based Microfluid Technology For Trace Detection Of Aggregation Induced Emission Molecules

Optical detection methods for some specific enzymes are very effective for early diagnosis of tumors.Aggregation induced emission(AIE)molecules play an important role in the detection of biological macromolecules such as enzymes because of their photostability.Optical fiber sensors can carry out in-situ detection with compact structure and superior biocompatibility.Optical fiber sensors for fluorescence detection have developed rapidly.Microstructured fibers have been employed to construct liquid core waveguides.In such waveguides,the exciting light and the emitting fluorescence are both constrained and the sensitivity of fluorescence detection can be improved.However,when detecting AIE molecules,the air hole of the microstructure fiber is blocked frequently by the aggregated molecular clusters.One of the solutions is to make the waveguide by Teflon material.Due to the low surface energy,the microfluid channels made by Teflon allow the sample solution flowing freely.However,the sensitivity is insufficient for nanomole level detection,eg.trace detection of cancer marker in in situ diagnose.Tapered fiber can excite and collect fluorescence efficiently because of its large evanescent field and small size.Fluorescence detectors based on Teflon capillary and tapered fiber with microlens are expected to find wide applications in biomedicine and other fields.The main research content of this paper is the study on a microfluid fiber for trace detection of aggregation induced emission m olecules,including:1.The physical properties of AIE molecules were studied.The absorptionemission spectra make the excitation light source need to be selected at 340 nm.The size of its aggregation state makes it necessary to select the liquid core waveguide with large diameter.The influence of temperature on luminescence requires the experiment to be carried out at a constant temperature of 20 ℃.The experimental system was built and the parameters were optimized.The concentration response of the fluorescent solution was measured by the prepared microfluid detector.The minimum detectable concentration of TPE-COOH solution was 0.005 m M and the device length was 2 cm.2.The optical fiber sensing end was optimized.The UV multimode fiber was tapered,and a microlens was integrated at the tip of the tapered fiber probe.Experiments showed that microlens can significantly improve the coupling efficiency of fluorescence.It was also proved that the tapered fiber probe with longer tapered length,thinner waist and larger microlens would have higher efficiency in fluorescence collection.In the fabrication process,the shape of the sensor can be well controlled and the repeatability is ensured.3.The microfluid fiber device for trace detection of aggregation induced emission molecules was fabrication by the optimized tapered fiber and 2 cm Teflon capillary.The tapered fiber simultaneously excited and collected fluorescence.Using this structure,the AIE detection device with small sample volume(0.649 μL)and low LOD(0.316 μM)was fabricated.In order to explore the application of the sensor in practice,the repeatability and stability of the proposed sensor were studied.In the circulating detection of fluorescent solution and water,the relative standard deviation(RSD)of the TPE-COOH photoluminescence(PL)peak intensity was only 2.31%.The microfluidic velocity was set from 50 μL/min to 250 μL/min at an interval of 50 μL/min,the average PL peak intensity increased by only3.91%.