Research On Plant Nutrition Process And New Tumor Probes Based On PET/CT Imaging

Positron emission tomography(PET)is an important molecular imaging technique,it has been used in many areas of life science,with high sensitivity and specificity,which can reveal the physiological and biochemical changes non-invasively,quantitatively and dynamically inside the body at a molecular level.PET has been widely used in life science researches,and used in engineering processes also.PET broadens the horizons of human cognition,as a powerful tool,it should be used in analytical chemistry of life science.We introduced PET technology in analytical chemistry of life processes,and done imaging investigations in living subjects.This dissertation consists of five chapters,PET principle and related applications was summarized in the first chapter.The research reports in this dissertation are describes as follows:(1)Preparation of 13NO3-molecular imaging probe13NO3-is a molecular probes suit for nitrate-sourced nitrogen research in plants.Preparation 13NO3-vary widely between different equipment and different target.13NO3-preparation methods was researched systematically to ensure the needs in vivo imaging.Radionuclide was prepared via the 16O(p,?)13N nuclear reaction,the target materials after irradiation was purified to obtain I3NO3-solution.Changed the beam current,bombarding time and target materials,preparation method was confirmed by measuring radioactivity and calculating the yield.The product activity did not meet the demand for PET imaging by using H2160 as a target material.Added 0.5%H216O2 in H2160 as the target material,15 ?A beam current,5 min bombarding,the integrated beam current was 1.3 ?Ah,removed 13NH4+,48V by pass through SCX solid phase extraction column,absorbed 18F-by using a Al2O3 solid phase extraction column,added 0.5 mL 0.5 mol/L H2SO4 solution and boiled 1.5 min,then added 0.75 mL 0.5 mol/L K2CO3 solution,got 13NO3-4514MBq,the yield was 3472 MBq/?Ah,it can been used as a imaging probe for plant nitrate-sourced nitrogen uptake and distribution.(2)PET/CT imaging nitrate-sourced nitrogen uptake and distribution in growing kohlrabi plantThe plant is at a very important stage of the nitrogen cycle,nitrate-sourced nitrogen is an important part of the nitrogen cycle.Nitrate-sourced nitrogen metabolism of plant is closely related to the ecosystem and the food crisis,therefore the research on plant nitrate-sourced nitrogen metabolism is of great significance.PET imaging do not disturb plants.PET/CT was employed for study the nitrate-sourced nitrogen uptake and distribution in plant,and established protocols for application.Administered 13NO3-to plant for PET/CT imaging,it was prepared after purification the cyclotron bombarding target materials.CT images showed the internal structure of living intact plants clearly,and can be used to mark the plants using metal wiring,so that can easily contrast PET/CT images to true plant.PET quantitative analysis showed that,13NO3-transported to the target tissue along the shortest distance route,transport velocity was about 1.0 cm/min,strong growth tissue used 13N take precedence over others.This method is simple,real-time,under physiological state,quantificational,visualized,it can be used for higher plants physiological and biochemical study with other probes.(3)PET/CT imaging of nitrate uptake and transportation under the stress condition in growing intact kohlrabi plant.Most researches on nitrogen metabolism process of plants is an isolated part of whole or based on some tissues,however,which have been influenced by research means and other factors for a long term.Study of growing plants with PET/CT is a non-invasive method without significant physiological disturbance for it.Investigated in nitrate-sourced nitrogen uptake and transportation of kohlrabi plant with PET/CT under glutamine environment,MSX and vanadate stress conditions.Leaf NO3-uptake was significantly reduced,axillary bud depressed 41.7%,corm at the junction with root declined 4.5%under 1 mM glutamine growing condition.The 13N transport to leaves was almost undetectable,axillary bud and corm at the junction with root were inhibited 95.4%,40.6%respectively under 1 mM MSX stress.Lateral bud under the corm showed the fast recovery,the recovery rate was 30%,axillary bud showed the slow recovery,recovery rate was 6%under recovery 3 h after MSX stress condition,but it showed whole metabolism contrast to MSX stress,the leaves was beginning to metabolize.Axillary bud and corm at the junction with root were inhibited 79.8%,94.5%respectively under 2 mM Na3V04 stress growing 2 h.(4)Foundational research on positron emission radionuclide doped cancer probeCancer are a tremendous threat to human health,early diagnosis malignant tumors has become a key issue to increase the cure rate and improve the prognosis.Disadvantages of active targeting to tumors nanoplatform probe for PET in vivo diagnosis,are low quantity radioactivity carried and easy leak.We constructed 68Ga doped superparamagnetic iron oxide nanoparticles,it can overcome the disadvantages.Investigated in synthetic methods of 68Ga doped SPIO nanoparticles and employed PET/CT imaging for evaluate the probe in vivo with animal preliminary.Bulk synthesis of SPIO and gallium doped SPIO via coprecipitation,particle size was 10-20 nm,it had good magnetic response.Ga is doped successfully in crystal lattice.nanoparticles/68Ga = 1000/1 SPIO was synthesized by microsynthesis and applied to rabbit imaging.Employed liver clearance of nanoparticles for simulating active targeting to cancer.The T/NT was 2239,T/NT of the control probe was 4-11,it is stable in vivo and no leakage.68Ga doped SPIO can carry a large amount of radioactivity,it improve the contrast of image(with high sensitivity)significantly and no leakage in vivo,we hope that the surface will be modified with active targeting to cancer molecule,and apply to cancer early diagnosis.