Functional Carbon Nanotubes And Its Tissue Distribution And Metabolism In Vivo Preliminary Study

ObjectiveTo synthesis amino functionalized multi-walled carbon nanotubes(MWNT) and then used to investigate its vivo metabolism and biodistribution.Method1.Amino-functionalized MWNT (MWNT-NH2) was prepared by reacting acyl chloride contained MWNT with Para-phenylenediamine in the presence of pyridine.The resulting MWNT -NH₂ was analysed by infrared spectrum and Raman spectrum.2.The MWNT-NH₂ was reacted with dianhydride form of diethylenetriaminepentaacetic acid (DTPA) in different proportions. The production was tested by both scanning and transmission electron microscope (SEM,TEM), thermo gravimetric analysis(TGA) and nuclear magnetic resonance(NMR).3.In the presence of SnCl2, 99mTc was used to chelated with MWNT–DTPA and was analysed by TEM and element spectrum.4.DTPA ampule was use as control group, MWNT-DTPA-99mTc was iv administered to rabbits, then scanned by single photon emission computed tomography (SPECT). In the end, urine was collected then received TEM and element spectrum analysis.5. A total of 20 rabbits were used, 5 in each 4 time point. Rabbits were iv administered 1ml MWNT-DTPA-99mTc which contained 0.5mCi of 99mTc activity. At 30min, 1h, 2h and 3h after injection, 5 rabbits per group were killed. Lung, heart, liver, spleen, kidney and bladder(urine included) were collected. Each organ was then weighted and samples were analyzed for 99mTc activity using a well-typeγcounter. Finally, the percentage of radioactivity in each organ was calculated. Statistics was done using SPSS13.0 software.Result1.Amide and N-H absorption band showed up at 1580cm-1 and 3413cm-1 in infrared spectrum which means MWNT-NH₂ was successfully prepared. Raman spectrum showed that the structure of MWNT was remaining. The solubility of MWNT increased after this reaction.2.TGA curve showed that MWNT–DTPA contains 25% of DTPA and its weight loss increased following the material proportion added. NMR illustrated that the DTPA molecular attached on MWNT is much stable than pure DTPA. TEM demonstrated that the MWNT was totally coated by DTPA.3.Under TEM we could see clearly the black metal particles attaching on MWNT-DTPA surface, Tc and Sn was detected in the particles through element spectrum analysis. 4.Compared with the control group, the MWNT-DTPA-99mTc administered rabbit group continuously visualized mainly in heart, liver, spleen and kidney, but their brightness gradually decreased during 54min, the time-radioactive curve of each organ also descended as time prolonged. TEM and element spectrum analysis of urine samples indicated the abundant presence of prototype MWNT which contains Tc on its surface.5. Quantitative study showed that the radioactivity in 6 collected organs takes 80% of injected dose, and highly in liver(≈21%) and kidney(≈23%), but lower in lung(≈4%), heart(≈10%) and spleen(≈9%), in bladder the number was about 11%. The number above decreased rapidly in all collected organs as time flows. For example, lung , heart and spleen nearly vanished when liver and kidney remains 8% until 3h after injection. At the same time the bladder takes almost half of the injected dose.Conclusion1.MWNT-NH₂ and MWNT-DTPA were successfully synthesized. The solubility of MWNT increased after this functionalization.2.MWNT-DTPA could be successfully chelated with 99mTc.3.The iv administered MWNT-DTPA-99mTc mainly distributed in heart, liver, spleen and kidney, but could be cleared from systemic metabolism, for its appearance in urine, the most possible mechanism might be renal excretion route.4. Quantitative study proved that iv administered MWNT-DTPA-99mTc mainly distributed in lung, heart, liver, spleen and kidney, and decreased as time flows. We also found the radioactivity finally accumulated in bladder which demonstrated that the 99mTc labeled MWNT could be eliminated through renal excretion.