Development Of Multi-layer Microfluidic Nuclear Magnetic Resonance Probe For Rapid Detection Of Tumor Markers

Recently,malignant tumors have become the primary factor that endangers public health and causes cancer patients to die.Detection of tumor markers is of great meaningful for disease diagnosis and prognosis evaluation.For the detection of tumor markers,Nuclear magnetic resonance technology has good clinical application prospects.In this paper,a multi-layer microfluidic nuclear magnetic resonance probe was designed and manufactured.Combined with immunomagnetic nanoparticle biosensing technology,a miniature nuclear magnetic resonance diagnostic instrument was developed to achieve rapid and accurate detection of tumor markers.The main achievements of this dissertation are as follows.(1)Research of micro-NMR probe design theoretical.Based on the NMR signals detection mechanism and simulation,comparing the electromagnetic field distribution of the solenoidtype micro-coil and the planar-type micro-coil,the simulation results showed that the solenoid radiofrequency coil has higher strength and uniformity.At the same time,the simulation also pointed out that the current density in the solenoid coil wire is affected by the skin effect and the proximity effect.The relative sensitivity and quality factor were analyzed and optimized to obtain the optimal coil size parameters.Then the accuracy and limitation of the existing theory were verified.(2)Design and manufacture of multi-layer microfluidic NMR probe.According to the performance requirements of the probe,the multi-layer microfluidic NMR probe chip consists of four layers which integrated micro-channel and detection module.For batch manufacture,the individual layers were processed by 3D printing and sealed using a double-sided acrylic transparent tape.The probe produced through sheet processing,coil winding,sealing bonding and overall assembly,and then optimized the process of sheet layer printing and coil winding.Compared with the conventional capillary glass tube probe and embedded PDMS probe,the probe designed in this paper not only has advantages in structure and function,but also has better comprehensive performance in signal acquisition.(3)Set up the miniature nuclear magnetic resonance diagnostic apparatus and carry out research on detection of tumor markers.According to the platform requirement,choose the miniature magnet and the electronic control system.Based on the u DMR,the gradient concentration of magnetic nanoparticle solution of particle size in 30 nm,100nm,180 nm,250nm and 600 nm was measured.The measurement results show that the relaxation parameters were related to solution concentration and particle size,which explain the working mechanism of the magnetic nanoparticle sensor.Then,synthesis immunomagnetic nanoparticles by covalent bonding the antibody in the particle surfaces.Based on the u DMR apparatus and magnetic relaxation mechanism,detected tumor marker protein MUC1 and breast tumor cell MCF-7.By optimizing the synthesis process,mixing concentration and mixing time of immunomagnetic nanoparticles,established the value curve between the concentration of MCF-7 and the change rate of relaxation parameter.Finally,the detection limit of MCF-7 was reduced to 500 cell / m L.Compared with other detection methods,the u DMR developed in this paper has higher sensitivity and convenience for the detection of tumor markers,and the instrument cost is lower and the sample pretreatment time is shorter,which has a good application prospect.