Metformin salts with oxidized multiwalled carbon nanotubes: In vitro biological activity and inhibition of CNT internalization

The increasing attention for metformin as anticancer drug, combined with its high doses necessary to exploit its action, makes interesting the preparation of carbon nanotubes (CNT) derivatives decorated with this drug. In this work, the preparation of metformin salt with oxidized CNT is described together with viability test in three different cell lines. Although the tests were performed at concentration 500 times lower than that used with free metformin, a dose dependent effect was evidenced. However, cytofluorimetric experiments revealed, unexpectedly, that metformin-CNT salts do not pass the cell membranes of all the six model cancer cell lines studied.