Bifunctional Chelating Supramolecular Polymer and Its Application in Downregulation of Cellular Iron Uptake

A bifunctional chelating supramolecular polymer (SP-Ch) is constructed from a brush-like macromolecule (P-Ch) through hydrogen bonds. Two kinds of norbornene derivatives are used to synthesize P-Ch in which phosphonic acid as a side-group of polynorbornene can act as a chelating group and ascorbic acid as a side-chain capper of polynorbornene can reduce Fe3+ to Fe2+. It can attach to cell membranes and form two kinds of "barriers" to hinder cells from iron uptake by virtue of phosphonic acid and ascorbic acid. Higher monomer conversion and polymerization degree of P-Ch are achieved when the ratio among M1, M2, and G2 is set as 50:10:1 and SP-Ch particles reach to submicrometer levels (mean size of 147.5 nm). The best chelating and reducing capacities of SP-Ch for Fe3+ are 0.034 and 0.047 mg/mg, respectively. After being treated with SP-Ch, the amount of iron in MCF-7 cells is reduced from 3.376 to 1.784 ng/105 cells after 48 h, which confirms that the cellular iron uptake is downregulated. As a result, iron deprivation induces growth inhibition of MCF-7 cells.