Research On Key Technologies For Real-time On-site Detection Of Radiation Biomarkers

For long-term space flight and deep space exploration missions,it is of great significance to monitor radiation biomarkers in real time in orbit to assess space radiation damage and its risks.These biomarkers can be detected by immunofluorescently labeling of CD4+ cells to assess the extent of cell radiation damage.However,conventional methods for biomarker detection are time-and labor-intensive,and require professionals and a variety of equipments.This type of research currently focuses on the utilization of microfluidic technology,but there are still many key technologies to be overcome for previous studies,such as fluid manipulation and efficiency of multi-step mixing as well as multi-target detection under microgravity conditions,degree of microdevice integration,etc.On the basis of our previous work,this project has studied the technologies that could be employed under the microgravity environment,enabling microfluidic chip-based liquid storage and automatic control,as well as parallel processing of multiple samples and efficienctly mixing of multiple steps based on immunomagnetic beads.After that,a prototype of portable microfluidic device was designed and preliminarily constructed.The main research work and related results are as follows:1)Aiming at the fluid control problem of the microfluidic chip for multi-target detection,this work studied the method of microchamber isolation through an array of plungers on the multi-channel/multi-chamber chip,as well as the approach of automatic fluid control over the multi-channel/single-chamber chip.By using fluid simulation and experimental verification,the multi-channel/single-chamber chip was proved to be feasible for automatic fluid control and multi-target analysis;2)For the first time,this study proposed a microfluidic technology of three-dimensional(3D)mixing of magnetic beads in parallel with multiple steps,resulting from the reciprocating movement of two plates embeded with vertically staggered magnets and the mode of magnetic bead immobilization-solution replacement.Through magnetic field simulation and experimental verification,this work investigated the structure parameters of the 3D magnetic field and the conditions of magnetic beads3 D mixing.The magnets used were cylindrical(6 mm for diameter,10 mm for length),which were arranged in an "S" shape and staggered vertically on the upper and lower plates.The spacings of magnets in vertical and horizontal directions were 6 mm and 3.48 mm,respectively.When the ratio of immunomagnetic beads/CD4+ cells was 100:1 and the 3D mixing time was 15 min,the capture efficiency of cells reached 88.3% with good reproducibility;3)Considering the structure of the multi-channel/single-chamber chip and the technology of magnetic beads 3D mixing in parallel with multiple steps,a prototype of the portable microdevice for biomarker detection was designed and constructed.It was preliminarily verified for its basic function and the feasibility of parallel processing of multiple cell samples.This work presented the technology of magnetic beads 3D mixing in parallel with multiple steps based on the multi-channel/single-chamber chip,which enables reagent prestorage and automatic fluid control,parallel processing of multiple cell samples and efficient mixing/reaction with multiple steps based on immunomagnetic beads,as well as construction of the portable microdevice for biomarker detection.The microdevice requires no professionals to operate and holds great potentials for use under microgravity environment.It is expected to be utilized for automated and high-efficiency processing of cell damage biomarkers as well as rapid detection of multiple targets.It could provide effective technical solutions for real-time on-site detection of radiation biomarkers and makes it possible for on-orbit applications.