| Hypersensitive cardiac troponin(hs-cTn)is an important basis for the diagnosis of myocardial infarction and risk stratification of acute coronary syndrome(ACS).Clinically,the detection turnaround time of hs-cTn is preferably controlled within 30 minutes,and POCT(Point-of-care Testing)detection is recommended.The POCT chemiluminescent enzyme immunoassay is currently the only bedside hs-cTn detection method that meets the double standard requirements of the guidelines.The most critical module of the chemiluminescence detection system is the immunomagnetic separation.However,the existing magnetic separation cleaning methods generally have the disadvantages,such as long magnetic particle capture time,low recovery rate and poor cleaning effect.In this work,we utilize the magnetic pole alternating reverse laminated permanent magnet as the magnetic source of the capture zone,and propose to inject the cleaning liquid in the non-magnetic field,and realize the non-contact magnetic stirring function by using the interactive magnetic field,and design a fast non-destructive high purity,Finally,design a rapid and non-destructive high-purity immunomagnetic particles separation method and structure.The details of this work are described as following three aspects:1.In this work,we propose the use of a permanent magnet with alternating magnetic poles of multiple magnets as the magnetic source of the capture zone.Firstly,we establish the dynamic model of magnetic particles under the action of flow field and magnetic field.Based on the finite element analysis method,we study deeply the spatial magnetic field distribution of different laminated permanent magnets and its influence on magnetic particle capture efficiency.The simulation and experimental results show that the uniform strong magnetic force of the three-layer permanent magnet can greatly improve the capture efficiency compared with the single magnet.For the magnetic particles with a radius of 1um,the recovery time is only 18 s,and the shortening is nearly 2 times.2.In this work,we suggest to inject liquid in the non-magnetic field and use the interactive magnetic field to realize the non-contact magnetic stirring function.By establishing the shear stress model of the magnetic particle chain,combined with the Monte Carlo particle chain simulation and finite element simulation,we analyse deeply the effect of the particle chaining law and the magnetic field strength component gradient on the magnetic particles.Furthermore,we constructe the physical structure of the alternating magnetic field.The experimental results show that the non-magnetic field injection and the increase of the magnetic stirring process can make the cleaning effect better and the separation purity higher,compared to the fixed magnetic field cleaning.3.In this work,we successfully construct an immunomagnetic separation cleaning detection system,and carry out repeated experiments and analysis on the system's dark noise,background noise,magnetic particle loss rate and cleaning effect.Finally,we evaluate the performance of the system based on the detection of cardiac troponin.The results showed that the system has a very wide linear range of detection(0-100000 pg/mL)and a CV of 4.26% at the concentration of 6.4 pg/mL.The lower limit of detection and imprecision are far less than the hs-cTn detection requirement of CV ? 10% at the 99 th percentile(20 ~ 40 pg/mL)of the general healthy population,which lay the foundation for further realizing POCT chemiluminescence immunoassay system for hs-cTn assay. |
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