Effect of mixed acid reflux time on purification and biocompatibility of large-inner-diameter multi-walled carbon nanotubes / 中国组织工程研究

ABSTRACT

BACKGROUND:A mass of debris particles that can lead to cytotoxicity exist in commercial large-inner-diameter multi-walled carbon nanotubes (LID-MWCNTs).Because of the high hydrophobicity on the surface of the tube wall,the carbon tubes can be twisted and agglomerated,resulting in the low dispersion and poor biocompatibility.Therefore,to explore the effective methods of purifying and modifying LID-MWCNTs is the primary problem to develop its potency in the biomedical application.OBJECTIVE:To explore the effects of different mixed acid reflux time on LID-MWCNTs purification and biocompatibility.METHODS:After pretreatment with high temperature calcinations and hydrochloric acid pickling,LID-MWCNTs were purified under different time of mixed acid reflux time (1,2,4 hours).The mixed acid reflux time for best purification was chosen based on surface morphology and dispersibility,so as to optimize preparation technology and observe the characterization.The L929 cells and CAL-27 cells were treated with different concentrations of raw LID-MWCNTs (5,10,20,40,80 mg/L) and purified LID-MWCNTs by mixed acid reflux (5,10,20,40,80 mg/L).After 72 hours,cell counting kit-8 assay was employed to test the proliferation of L929 cells and CAL-27 cells.RESULTS AND CONCLUSION:(1) With the time of mixed acid reflux,the length of LID-MWCNTs was decreased,and the dispersion was improved.However,the external surface of the tubes after mixed acid reflux 2 and 4 hours were destroyed obviously.Especially after mixed acid reflux 4 hours,the tubes were destroyed seriously and the diameter of tubes was not uniform.However,after mixed acid reflux 1 hour,the fundamental structure and morphology of the tubes were not changed,the debris particles were undetected on the tube wall surface,and the tubes had the good dispersion.(2) Under the same concentration,the survival rate of L929 cells in the raw LID-MWCNTs group was lower than that in the purified LID-MWCNTs group.At the concentration of 10-80 mg/L,the survival rate of L929 cells in the group of mixed acids reflux 1 hour was up to 90％,higher than that in the other groups (P ＜ 0.05).(3) Under the same concentration,the survival rate of CAL-27 cells in the raw LID-MWCNTs group was lower than that in the purified LID-MWCNTs.At the concentration of 20-80 mg/L,the survival rate of CAL-27 cells in the group of mixed acids reflux 1 hour was up to 90％,higher than that in the other groups (P ＜ 0.05).These results revealed that the raw LID-MWCNTs were purified effectively after mixed acid reflux 1 hour,and the cytotoxicity was decreased.