Microfluidic Laser Biosensing Technology For Lung Cancer Diagnosis

Lung cancer has a high morbidity and mortality rate,and its early diagnosis is a major challenge for human beings at present.Early diagnosis requires highly sensitive,rapid,accurate and multi-parameter detection.The detection of lung cancer biomarkers is an important method to assist early diagnosis of lung cancer.Immunoassay based on antigen and antibody can realize the detection of lung cancer biomarkers.Turbidimetric inhibition immunoassay(TIIA)is a label-free detection method,which has the advantages of simple detection steps and fast response,but the scope of use is limited by its sensitivity.In this thesis,optofluidic laser turbidimetric inhibition immunoassay(OFL-TIIA)technology is introduced,which combines optofluidic laser with TIIA.The biological reaction of TIIA is used to control laser loss,and the detection of low concentration of biomarkers is realized by the amplification of optical microcavity and laser effect.Then,the structure of the optical microcavity was improved to detect both carcinoembryonic antigen(CEA)and neuron-specific enolase(NSE).The experimental results show that the detection limits of CEA and NSE were reduced by four orders of magnitude and three orders of magnitude,respectively,and the simultaneous detection of two lung cancer biomarkers within 15 minutes was achieved.This work achieves a sensitive and rapid detection of two types of lung biomarkers simultaneously,providing a useful immunoassay tool for the early diagnosis of lung cancer.The main research contents and results of this paper are as follows:(1)The OFL-TIIA method is proposed,and the suspension formed by the specific binding of antigens and antibodies is used to regulate the intracavity laser loss to achieve the detection of Ig G.The double amplification of optical microcavity and laser was used to reduce the lower detection limit of Ig G to 0.179 pg/m L,and the detection range included five orders of magnitude.(2)The influence of latex particle size and pump energy of CEA and NSE on the sensing experiment was explored,and it was concluded that the suitable dilution factor corresponding to CEA latex particles was 100 times,and the suitable pumping energy was 19 μJ.The suitable dilution factor corresponding to NSE latex particles is 40 times,and the suitable pumping energy is 19 μJ.The sensing experiments of CEA and NSE were carried out,and the lower detection limit of CEA by the sensor was 0.2285 pg/m L,and the detection dynamic range reached four orders of magnitude.The lower detection limit of NSE is 80.39 pg/m L,and the detection dynamic range is two orders of magnitude,with good sensing performance.(3)A high-reflection FP cavity structure was designed and prepared,and the highreflection FP cavity can realize the vertical incidence of pump laser,thereby reducing the scattering loss and enhancing the interaction between light and matter.The sensing experiment on NSE using the highly reflective FP cavity shows that the lower detection limit of NSE is 8.039 pg/m L,and the detection dynamic range is three orders of magnitude.(4)A highly reflective dual-channel FP cavity is built to realize the detection of dual markers.The lower limit of detection for CEA was 0.2285 pg/m L,with a dynamic range of four orders of magnitude lower than the detection limit of the comparison kit.The lower limit of detection for NSE is 8.039 pg/m L,with a dynamic range of three orders of magnitude lower than the detection limit of the comparison kit,and the time required for the experiment is less than 15 minutes.