| Technetium-99 (99mTc) was used as an isotope tracer to study the biodistribution of oxidized multi-walled carbon nanotubes (oMWCNTs) and/orgraphene oxide nanoplatelets (GONP) after intravenous administration (i.v.). The authors also investigated the histological impact of non-radiolabeled oMWCNT or GONP as they passed through systemic circulation and their excretion pathways in comparison to co-exposure groups of both (oMWCNTs and GONP). Results indicated that oMWCNTs were mainly excreted through feces rather than urine. From the blood, oMWCNTs first entered the stomach, then intestines via chyme, and were finally excreted in feces. GONP also followed this pathway, but could also be excreted through urine when co-exposed with oMWCNTs. In summary, the biodistribution patterns and excretion rates of the nanomaterials in vivo depended on their composition and chemical modifications. A new mechanism is proposed to explain how chemical modification groups affect the behavior of nanomaterials in vivo. The behavior and fate of GONP depended strongly on oMWCNTs in mice in vivo, but the GONP did not affect deeply biodistribution and excretion pattern of oMWCNTs in co-exposure.The effects of cadmium (Cd (Ⅱ)) on absorption, excretion, and distribution of nickel (Ni (Ⅱ)) were studied in rats using 63Ni-NiCl2 as radiotracer in the presence and absence of CdCl2, through intraperitoneal injection (i.p.). The time-concentration curves in the blood were fitted with a two-compartment model. The peak time (t (peak)) is 0.31 h in the absence of Cd (Ⅱ), and it is 5.5 h in the presence of Cd (Ⅱ). The levels of nickels were higher at 3 h and lower (close to zero) at 24 h in all organs of interest, except kidneys, in the absence of Cd (Ⅱ). There still residue Ni (Ⅱ) at 72 h post-injection in the presence of Cd (Ⅱ). The Cd (Ⅱ) did effect the total Ni (Ⅱ) excretion 24 h post-injection. Our study showed that cadmium has a competitive effect on the absorption of nickel and an inhibitory effect on the elimination of it, so cadmium may induce the bioaccumulation of nickel in the body. Therefore,The influence of cadmium on nickel induced synthesis of metallothionein in liver of adult female rats was studied post injected intraperitoneally with nickel and cadmium either alone or in co-injection (1 mg/kg body weight/8 days), and the nickel elimination from five organs was also investigated post injected intraperitoneally with nickel and cadmium for long time using 63Ni-NiCl2 as radiotracer. The metallothionein can be induced synthesis in liver post injected intraperitoneally with nickel alone, but nickel is not bonded to metallothionein. The cadmium can induce metallothionein synthesis in liver, but nickel can also be not linked to metallothionein induced by cadmium post co-injection with cadmium and nickel. Therefore, because nickel cannot be combined with protein for forming stable nickel-metallothionein, although cadmium can lead to nickel elimination lags from various organs, the nickel can be removed completely from tissues for long time after injected intraperitoneally with nickel and cadmium.After making model of gastric functional disorder (FD), part of model mice were injected intravenously (i.v.) with oxide multi-walled carbon nanotubes (oMWCNTs) to investigate effect of carbon nanotubes on gastric emptying. The results showed that NO content in stomach, compared with model group, was decreased significantly and close to normal level post-injection with oMWCNTs (500 and 800μg/mouse). In contrast to FD or normal groups, the content of acetylcholine (Ach) in stomach was increased obviously in injection group with 500 or 800μg/mouse of oMWCNTs. The kinetic curve of emptying was fitted to calculate gastric motility factor k; the results showed that the k of injection group was much higher than FD and normal. In other words, the gastric motility of FD mice was enhanced via injection with oMWCNTs. In certain dosage, oMWCNTs could improve gastric emptying and motility.The magnetic nano-materials, Co/graphitic carbon (GC)-shell nanocrystals, were synthesized via chemical vapour deposition (CVD) method, and then the 60Co-Co/GC nanocrystals were injected intravenously (i.v) to investigate biodistribution in mice in vivo. The results showed that most of nanocrystals were accumulated in lung, liver and spleen over an extended period of time post injected i.v. with 60Co-Co/GC nanocrystals. The nanoparticles were cleared rapidly from blood and closed-to background level within 10 min. The 60Co-Co/GC nanocrystals were eliminated slowly from body in 24 h,6.09% of Co-Co/GC nanocrystals were excreted by urine, 1.85% by feces in 24 h, and total excretion was less than 10%.
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