A Hollow Core Photonics Crystal Fiber Based Miniaturized Sensor For Detection Of Aggregation-induced Emission Molecules

The discovery of aggregation-induced luminescence?AIE?molecules is a major breakthrough in bioluminescence detection research in recent years.It overcomes the problem of traditional fluorescence molecule aggregation-induced quenching and exhibits strong fluorescence in the aggregate state.The fiber-based fluorescence detection has the advantages of high signal-to-noise ratio and high sensitivity.The coupling efficiency of molecular emission fluorescence and fiber conduction mode becomes the key to detection.A miniature sensor for detection of aggregation-induced emission molecule is proposed in this work.The sensing head is fabricated by use of hollow core photonic crystal fiber with a core diameter of about 4.8?M.The cladding holes are sealed by fusion splicing technique while the central hole remains open to allow the filtration of solution with AIE molecules.In this paper,the steps and processes of fabricating the sensing unit by the fusion splicer's discharge collapse technique and filling the central air hole of the hollow photonic crystal fiber by the pressure difference method are described in detail.When the solution is excited by ultraviolet lamp,the fluorescence light is received by a fiber optic spectrometer.The fluorescence intensity is associated with the concentration of AIE molecules and the infiltrated core length.In the whole process of the experiments,the output peak wavelength is stable which indicates that the existing forms of AIE particles are stable and the fluorescence reabsorption can be neglected.The experimental results obtained are in accordance with the traditional microplate spectrophotometer methods.The most exciting result is the amount of sample measured can be as low as 0.36 nL,the limit of detection is calculated to be 7.27?M.In addition,the miniature sensor was successfully applied to detect an AIE-based bio-probe for evaluating the activity of dipeptidyl-peptidase 4?DPP-4?inhibitor sitagliptin with IC₅₀ of 59.80±3.06 nM.The advantage of small device size and nanoliter scale sample volume suggested the proposed sensor is promising in many biosensing applications.