The Iodine-125 Labelling And The Biodistribution On Rats Of The Single-walled Carbon Nanotubes

Background:Carbon nanotubes(CNTs) is a typical nano-material .Because of its unique structure, the unique electrical properties and chemical stability and the higher mechanical properties, CNTs arouse the worldwide scientist, including physicist, chemist and material scientists'the greatest interest, raise a upsurge of Carbon nanotubes(CNTs) research.Carbon Nanotubes(CNTs) include Multi-walled Carbon Nanotubes (MWCNTs) and Single-walled Carbon Nanotubes (SWCNTs). SWCNTs is a jointless and fistular carbon circular cylinder,coiled by monostratum graphite, its diameter is from 0.4nm to 6nm and its length commonly range from dozens of nm to micron. SWCNTs possess many features, for example, large length-diameter ratio,few structural defects,small tip radius of curvature and so on,so they have unique mechanical, electronical ,chemical and magnetics properties,thereby at materisl enhance, nanometer molecule devices, the microscope pinpoint of probe, modified electrode et al. numerous regions have potential applications prospects.At the same time ,owing to SWCNTs'nanometer-scale fistular channel, they are considered a very potential material for storing up hydrogen and other gases.CNTs possess huge specific surface areas, so either organic or inorganic molecules could covalently or noncovalently bind to the surface of CNTs, modify or functionalize on the CNTs surface. The surface modification could increase CNTs'dispersibility in structure composite materials and improve its optical properties on optics composite materials, and so on.So we can prepare bioprobe and molecule devices et al. that based on CNTs. The oxygenization of CNTs in the process of CNTs'surface modification have got quite important role. Oxidation not only etched on the side wall of CNTs ,forming the defects or hole, and CNTs can be interrupted, formed port, generated a variety of active groups. The introduction of active groups have not only improved the hydrophilicity of CNTs, made them more easily soluble in water and other polar solvents, but also provided the conditions for reaction between Carbon nanotubes and other substances or groups , which can further modification on the surface of CNTs. Moreover, the carboxyl groups generating in the process of oxidation can reduce the van der Waals force between CNTs, which effectively solve the problem of the winding aggregation between the CNTs. The hydroxyl, carboxyl functional groups generated during the oxidation can also make CNTs further reacted with other chemical reagents, obtaining functionalized CNTs that can be used as chemical probes and the additives of structure composite,and so on.Meanwhile,in recent years more and more researches showed that CNTs could cause a variety of animal organ tissues damage and bring cytotoxic effects. Therefore,no mater in application advanced development of drug carrier, vaccinum,et al, or the biological safety research and evaluation, we need to learn how to interact between CNTs and life system and such act how to affect life system . CNTs enter life system and subsequently absorption, distribution, metabolism, excretion ,et al. in organism were the important foundation on studying their interaction and bring correlative biological effects. Radioisotope tracer technique, because of its simple means, easy to detect, high detect sensitivity, and the reliable result and almost free from outside interference, especially could detect CNTs which in complicated biotic tissues, so it is a sort of effective technology to detect and quantitative analysis CNTs in life system. Therefore,we could use radionuclide to label CNTs, trace radionuclide track way to detect the location and the law of movement of the CNTs in the biosystem.In this paper,we use simple violet acid oxidation combine ultrasonic to treat SWCNTs. At the precondition that do not change their fundamental characteristics,we use Iodogen oxidative method to react between the SWCNTs and sodium iodide, and then ude transmission electron microscopy and X-ray photoelectron spectroscopy to detect the covalent binding between SWCNTs and sodium iodide.After ascertain SWCNTs and sodium iodide be able to covalently bind,then we adopt the same Iodogen oxidative method to prepare radioactive Iodine-125 labeled SWCNTs. After exposed Iodine-125 labelled SWCNTs to rats by intratracheal instillate, detected the biodistribution of the labeled products in vivo, supply important reference for SWCNTs ulterior biomedicine and pharmacology application and safety evaluation studies .Objective: In this paper, we aimed to:(1) Study the effects of SWCNTs structure and morphous via violet acid's oxydation combine ultrasonic treatment,explored weather the treatment can produce defects, holes and hydroxyl, carboxyl groups on the SWCNTs;(2)Study the formation of the C-I covalent bond between the Single-wall carbon nanotubes and sodium iodide , provided detailed reference for the follow-up radioactive Iodine-125 labelled SWCNTs experiments; (3) To expore the biodistribution of the Iodine-125 labeled SWCNTs in rats exposed by tracheae instillation, supply important reference for SWCNTs ulterior biomedicine and pharmacology application and the biological safety sdudy .Methods:(1)Adopted concentrated nitric acid / concentrated sulfuric acid's oxidation combine ultrasonic to treat SWCNTs , then detect and analyze the fore-and-after treated samples with transmission electron microscope(TEM), Fourier transform infrared spectrometer(FT-IR) and microzone Raman spectrometer(.2)Iodogen oxidative method was used to synthesize iodinated Single-walled carbon nanotubes (I-SWCNTs). The covalent bind between carbon and iodine and the formation of C-I covalent bond were detected and exosyndrome with transmission electron microscope(TEM)and X-ray photoelectron spectroscopy(XPS)(.3)To use violet acid's oxidation combine ultrasonic to treat the SWCNTs,then adopt Iodogen oxidative method labeled the SWCNTs by Iodine-125,generated radioiodinated Single-wall carbon nanotubes(¹²⁵I-SWCNTs). To purify the labelled productions with ultrafiltrate centrifugation,and then exposed to health male Wistar rats by intratracheal instillation,to get the blood and urine, and then sacrificed them by cervical vertebrae dislocation, dissected them to get and weigh the heart, liver, spleen, lung, kidney, tracheae, blood vessel, brain ,et al. main organ tissues at 2h, 4h, 8h, 24h and 72h intervals post dosing of each group rats,detect their radioactivity,calculated uptake rate of each tissues.The uptake rate was represented by the percent of the injected dose per gram of tissue or per milliliter body fluid(%ID/g or %ID/ml),which was observed the biodistribution of ¹²⁵I-SWCNTs in vivo .Results:(1)The result of SWCNTs that treated by the violet acid's oxidation combined ultrasonic,TEM imaging and component analysis shown that,in contrast with untreated SWCNTs, the treated SWCNTs'wall is clean,graphite-like debris, metal catalyst particles and other impurities have been better remove .The wall of SWCNTs formed more defects. Fourier transform infrared spectrometer and microzone Raman spectrometer detection found that SWCNTs form more hydroxyl and carboxyl functional group, and did not change their essential characteristics .(2)The result of iodinated Single-wall carbon nanotubes(I- SWCNTs) that were prepared by Iodogen oxidative method . The imaging of the Transmission electron microscope show that, compared with the untreated SWCNTs , the iodinated productions covalent bind the iodine , the walls of tubes are no longer smooth and had gaps. The component analysis also shown that the iodinated productions labeled with the iodine. XPS spectra shown that the iodine electron binding energy on I-SWCNTs is analogous to that on iodonitrobenzene that have C-I covalent bond. So we can conclude that the C-I covalent bond was formed between the iodine and SWCNTs.(3)The radiolabelled rate of Iodine-125 labelled SWCNTs is 46.14%,the radiochemical purity is 98.95%. In order of total radioactivity concentration in mian organs /tissues and body fluids for ¹²⁵I-SWCNTs, it showed that trachea>urine>stomach>small intestine>serum>bladder>blood vessel>kidney>liver>lung>adrenal>femoral head>spleen>spermary>thymus>thyroid>heart>fat>muscle>brain. The distribution of radioactivity in the tissues and body fluids of the rats[use the percent of the injected dose per gram of tissue or per milliliter body fluid (%ID/g or %ID/ml) to show] can reach each tissue. However, the highest radioactive distribution is in the trachea, which was significantly higher than other tissues. Compared with 2h group,24h group's radioactivity distribution raised up significantly(P﹤0.05),to 72h post dosing without obviously step down(compared with 24h group,P﹥0.05. Distribution of radioactivity in the urine followed with trachea, radioactivity decreased gradually along with the time extending. Bladder also have a higher distribution of radioactivity. The distribution of radioactivity in serum and blood vessle increased rapidly in 2h post dosing, within 8h post dosing no significantly decreased (P> 0.05), but decreased after 24h post dosing (P <0.05). The distribution of radioactivity in lung, liver and kidney did not significantly decrease within 8h post dosing, but decreased rapidly after 8h post dosing.Compared with the 2h group, 24h and 72h groups were significantly step down (P <0.05).Conclusion: The total results show that violet acid's oxidation combine ultrasonic treatment are able to make SWCNTs form more gaps and hydroxyl and carboxyl functional groups, which provide the binding site for SWCNTs'iodine modification. The treated SWCNTs by violet acid and ultrasonic can react with sodium iodide by Iodogen oxidative method.The result of the reaction is to form C-I covalent bond which provide a reliable experimental evidence for the follow-up SWCNTs'radioactive labeled by Iodine-125. So we use the same Iodogen oxidative method to labell SWCNTs by radioactive Iodine-125. The radiochemical purity of the labeled product (¹²⁵I-SWCNTs) is 98.95%, whivh indicate that ¹²⁵I-SWCNTs could stand for SWCNTs' biology behavior in vivo. ¹²⁵I-SWCNTs are exposed to rats by intratracheal instillation. And the total administered radioactivity of the ¹²⁵I-SWCNTs distribute mostly in the trachea. After administer, the ¹²⁵I-SWCNTs are absorbed quickly and accumulated gradually at tunica mucosa tracheae, to 72h post dosing have got higher accumulation which indicate that the most of ¹²⁵I-SWCNTs are difficult to through air-blood barrier. The radioactive distribution in serum and blood vessel from 2h to 8h post dosing are higher,and the distribution step down distinctly after 24h post dosing,which prompt that part of ¹²⁵I-SWCNTs can be transported and distribute via blood, and they can be cleared off quickly from blood circulation. The higher radioactive distribution of ¹²⁵I-SWCNTs in digestive system, bladder and urine which prompt that they excrete mostly through feces and urine forms; but they decreased significantly after 24h pose dosing showed that they are cleared off quickly. The lowest distribution in fat and brain suggested that it was difficult for ¹²⁵I-SWCNTs to cross the blood- brain barrier.The ratioactive biodistribution in lung, liver and kidney without step down distinctly within 8h post dosing, but cut down quickly after 8h post dosing, showed that the ¹²⁵I-SWCNTs could be phagocytized by the reticuloendothelial system (RES) that in these tissues and accumulated transiently in them.