Research On Ultrasensitive Fiber Microcavity Laser And Its Application In Disease Immunodiagnosis

Highly sensitive,efficient and disposable tests play an important role in disease diagnosis.Highly sensitive detection enables early disease diagnosis,leading in more effective and timely medical intervention,better treatment outcomes,and lower mortality rates.High-efficiency detection can be achieved by decreasing the assay time and enhancing the detection multiplexing,enabling for disease screening on a large scale and providing more detailed pathology information to help understand disease processes.The disposable test can avoid pollution produced by repeated usage,and its low cost and inherent safety make it suitable for mass screening and early disease diagnosis.Optical fiber laser combines the advantages of optical fiber with laser and shows great potential for applications in disease diagnosis.Based on the technology of ultra-sensitive optical fiber microcavity,this dissertation overcomes the difficulty of repetitively preparing ultrasensitive microcavities by using common single-mode fibers that can be prepared at a low cost and in large quantities,and combines a variety of sensing schemes and sensitization mechanisms to achieve highly sensitive,efficient,and disposable biomarker detection,providing a high-performance sensing platform for disease diagnosis.The main research contents are as follows:(1)A highly sensitive and efficient detection platform based on ultrasensitive microcavities is proposed.First,a multicolor optical fiber biolaser is achieved by crosslinking different dyes on the optical fiber’s outer surface with the advantage of the fiber’s continuous and uniform axial distribution.Utilizing the narrow linewidth and the small size of optical fiber lasers,the integration of wavelength-division multiplexing and spacedivision multiplexing is achieved,with the potential for high-throughput sensing.Furthermore,a cavity-sensitized homogeneous immunolaser combined with a timedivision multiplexing sensing technique enables the simultaneous detection of two biomarkers,cardiac troponin Ⅰ and immunoglobulin G,with limits of detection(LOD)of 26.55 fM and 7.35 fM,respectively.The protocol’s broad applicability was demonstrated by sensing disease biomarkers.(2)To meet the demand for disposable,highly sensitive detection,a sub-monolayer biomagnification laser based on a communication fiber is presented.Cross-linking gain molecules on the surface of the optical fiber causes all gain molecules to participate in laser emission,reducing fluorescence background noise and achieving highly sensitivity sensing.A biomagnification based on the sub-monolayer scheme enhances the laser signal while lowering the quantity of biomolecules on the fiber surface,hence increasing sensitivity.The biomagnification technique demonstrated highly sensitive avidin detection with a detection limit of 373 aM,which was four orders of magnitude lower than the saturated monolayer laser,demonstrating the biomagnification method’s sensitizing effect.Finally,combined with double-antibody sandwich immunosensing,resulted in a sensitive immunoassay with a detection range of 3.2 pg/mL to 10000 pg/mL,for programmed cell death-ligand 1(PD-L1),a cancer biomarker,is achieved.This technology represents a significant step toward highly sensitive,disposable fiber-optic sensor sensing,as well as a novel solution for the production of simple quantitative biosensors.(3)To address the issue that traditional organic dyes are prone to photobleaching,which affects laser output and deteriorates sensing performance,quantum dots are employed as the gain material to build a high-stability laser,and its stability is exploited to optimize sensing performance.First,the quantum dots are chemically crosslinked to the surface of the optical fiber in order to create a highly stable laser.The laser’s signal is then amplified by optimizing the pumping method,and the laser threshold concentration is reduced,resulting in fewer biotin sites on the fiber surface and more sensitive sensing.Ultra-sensitive sensing(100 aM)of avidin is achieved by competitive sensing of avidin and streptavidin.Furthermore,due to the fiber laser’s high stability and small size,it can be used as a probe for sensing biological processes and states,as demonstrated by the sensing of hydrogen peroxide,horseradish peroxidase,and recognition gold nanoparticles,showing a wide application prospect of quantum dot optical fiber lasers in biosensing.