Abstract
The first object of this work is the preparation of novel multi-functional bio-carrier. To improve the low drug loading efficiency of traditional bio-carrier, this study used a rising star in carbon-based nanomaterials, graphene. Among these Graphene-based nanomaterials, graphene oxide (GO) has been proposed as the most promising bio-carriers due to its ultrahigh specific surface area and extraordinary chemical capability. i. The application of superoxide scavenging by using graphene-based material 1. To increase dispersibility of bio-carrier in water, this study used modified Hummers method to prepare graphene oxide (GO) graphite powder. The graphene oxide was further modified by grafting poly acrylic acid(PAA) to increase its stability and biocompatibility in physiological solutions. 2. PAA-g-GOs was incubated with GL261 tumor cells. PAA-g-GOs would scavenge the fluorescent by using DCFH-DA method that confirmed the superoxide scavenge ability of PAA-g-GOs. 3. By in vitro and in vivo experiment, the growth of tumor cells would be inhibited due to the superoxide scavenging ability of PAA-g-GOs. These results indicated that PAA-g-GOs is a promising candidate for novel multi-functional bio-carrier of clinical tumor treatment. ii. The application of biodistribution by using graphene-based material 1. The effects of various dimensions of GO on the organ distribution have been investigated in this work. The GO with three different dimensions can be fabricated by ultrasonication, centrifugation, and filtration method. The stability and biocompatibility of GO in physiological solutions were increased by grafting PEG on GO surface. 2. PEG-g-GOs was incubated with neutrophil cells to investigate its toxicity and inflammation. It was found that both GO and PEG-g-GOs will not apparently cause damage to neutrophil. However, GO will cause the mutually aggregation of neutrophil and dose-dependent stimulation inducing the induction of the free radicles while PEG-g-GOs will not, this represents that PEG-g-GOs can effectively avoid phagocytosis by neutrophil, moreover, it verifies the high biocompatibility and stability of PEG-g-GOs. 3. The radioactivity element Tc-99m was absorbed on PEG-g-GOs to form 99mTc-PEG-g-GOs that was tracked by Nanospect/CT and Autoradiography method to observe the biodistribution in vivo. The results of Nanospect/CT and Autoradiography showed that the dimension of GO is a major factor to control the biodistribution. PEG-g-GOs (<200nm) were mainly accumulated in spleen; PEG-g-GOs (400-1000nm) were mainly accumulated in liver; PEG-g-GOs (>1000nm) were mainly accumulated in lung. We can do the passive targeting as the treatment by the distribution of bio-carrier. Moreover, we are capable of discovering which material is the best in cycle ability and provide a probability of active targeting bio-carrier in the future. The most important thing is that in the long-term biodistribution result suggests the gradual clearance of PEG-g-GOs from mice. It means PEG-g-GOs would not residual in vivo for long time. Nevertheless, our results are highly encouraging and pave the way for future graphene based in vivo biomedical research.