| Objective:Due to the unique physical-chemical properties and mechanical properties, carbon nanotubes(CNTs) have been widely applied in a great variety of fields, including electronics, nanocomposites, biological and chemical fields. CNTs have successfully encapsulated biological moleculars, such as chemotherapeutic drugs and anti-inflammatory agents. At present drug encapsulation using CNT has two main problem to solve. One is the inner diameter of common CNTs is small, which induces the low drug loading efficiency. The other is how to block the entry/exit paths of encapsulated drug and obtain the sustained release. In the study, we used the unique superiority in the structure and properties of CNTs to prepare a targeting antitumor drug delivery system using large-inner-diameter multi-walled carbon nanotubes(LID-MWCNTs) for sustained release and to study its properties, and creat a new treatment to the targeting and multiple tumor therapy. Methods:LID-MWCNTs were purificated and oxidated under multi-steps procedure, which includes calcination, HCl washing, mixed acid reflux and length selection, to obtain the nanocarriers with the entry/exit paths of drug and ultrashort oxidized LID-MWCNTs(USTs) as homologous blockers. 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-[amino(polyethylene glycol)-2000](DSPE-PEG2000-NH2) was loaded onto the surface of LID-MWCNT carriers, and folic acid(FA) was conjugated through amidation. The LID-MWCNTs were labeled with fluorescent moleculars to trace their distribution in vitro. Cisplatin(CDDP) was encapsulated and USTs were employed to block the drug entry/exit paths. The microscopic observation of O-LID-MWCNTs was detected by scanning electron microscope. The groups conjugated onto the surface of modified LID-MWCNTs were characterized by Fourier transform infrared spectroscopy. The conjugation of FA was confirmed by ultraviolet-visible spectrophotometer. The morphology of CDDP@UST-FA-LID-MWCNTs was observed by SEM and transmission electron microscope. The elementary composition of encapsulated particles was analysised by energy dispersive x-ray analysis. The drug loading efficiency and drug release profile in vitro were determined by inductively coupled plasma optical emission spectrometry. The targeting property was evaluated through intracellular tracking of CDDP@UST-FA-LID-MWCNTs in vitro using inverted phase contrast fluorescence microscope. And CCK-8 assay was employed to test the cytotoxicity of CDDP@UST-FA-LID-MWCNTs on CAL-27 and MCF-7 cells. Results:Targeting anti-tumor drug delivery system using LID-MWCNTs for sustained release was established. The drug loading efficiency was as high as 70.97%. CDDP@UST-FA-LID-MWCNTs showed a typical biphasic sustained release pattern. The accumulating release time was 18 h. The CDDP@UST-FA-LID-MWCNTs exhibited a targeting property. Fluorescent observation demonstrated more drugs were delivered into tumor cells by CDDP@UST-FA-LID-MWCNTs compared to its counterpart without FA conjugation. CCK-8 experiment revealed that CDDP@UST-FA-LID-MWCNTs inhibited the proliferation of tumor cells with a dose-dependent pattern. Conclusion:1. Through a multi-steps of purification and oxidation, amorphous carbon and metal catalyst particles were removed from the surface of tubes, defects on the side wall were emerged, the tubes were cut, and the ends were open. Meantime, a large number of carboxyl groups were introduced onto the open ends and side wall defects. Finally, the carriers with drug entry/exit and homologous blockers USTs were obtained at the same time through length choose.2. The obtained FA conjugated LID-MWCNT carriers through amidation made the foundation for achieving targeting drug delivery system.3. CDDP@UST-FA-LID-MWCNT drug delivery system exhibited an improved drug loading efficiency and a sustained drug release profile. It could specifically target the tumor cells and exhibited an advantage of significant antitumor effect. |
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