System Development And Experimental Studies On The Optical Fiber-based In Vivo Flow Cytometry

Traditional methods of examining circulating tumor cells(CTCs)are sampling and optical examination.Sampling examination,also known as invasive examination,can only measure a small amount of blood samples.However,many studies have also revealed that the release of CTCs may be intermittent.Other non-invasive optical detection approaches cannot quantify in vivo circulating cells.These problems can be overcome and solved by the usage of an Optical Fiber-based in vivo Flow Cytometry(OF-IVFC).The in vivo Flow Cytometry(IVFC)is a newly developed optical technique for quantitative analysis of circulating cells in biomedical applications.Nowadays,the IVFC has been employed for tracking specific cells which are dyed by fluorescent dyes in circulatory system.The fluorescent cells can be continuously detected and counted in small living animals.The IVFC technique can be very helpful in early tumor diagnosis,rapid evaluation of chemotherapeutic drugs and detection of tumor recurrence.It has been extensively studied,in particular,the biomedical fields.The OF-IVFC is to place the end face of an imaging optical fiber on the animal skin.Compared to the invasive methods,the OF-IVFC can quantify circulating cells without changing characteristics of the living cells and their living environment.The ultimate goal of this work is to achieve in vivo,real-time,continuous,dynamic and non-invasive detection of the CTCs,assisting the early detection and treatment of tumors.This work is aimed at developing an OF-IVFC system and system performance validation.This core idea of the system is to combine the confocal system with IVFC,and employing an imaging fiber to guide light.The OF-IVFC system is consisted of laser excitation source,optical imaging fiber,fluorescence detection optics,and data acquisition card.During the past decade,the fluorescence-based IVFC is limited to visible region.However,in recent years,it has been found that the near-infrared(NIR)fluorescent dyes have some advantages,e.g.,deeper penetration,less absorption and less scattering.Therefore,IVFC has extended to the near-infrared region,demonstrating a great potential in biomedical applications.In this work,a 782 nm laser is used to excite the NIR fluorescent dyes,and a 458 nm laser is used to excite visible fluorescent.The IR-780 and green fluorescent protein(GFP)signals from dual labeled cells can be simultaneously detected.Mice are used as experimental subjects.Preliminary experimental results are demonstrated in this thesis.