Trimethyl and carboxymethyl chitosan carriers for bio-active polymer–inorganic nanocomposites

The carrier properties of carboxymethyl chitosan (CMC) and trimethyl chitosan (TMC) in combination with polyoxometalates (POMs) as inorganic drug prototypes are compared with respect to the influence of polymer matrix charge and structure on the emerging composites. A direct crosslinking approach with TMC and K6H2[CoW11TiO40]·13H2O ({CoW11TiO40}) as a representative anticancer POM affords nanocomposites with a size range of 50–90 nm. The obtained POM–chitosan composites are characterized with a wide range of analytical methods, and POM encapsulation into positively charged TMC brings forward different nanocomposite morphologies and properties than CMC as a carrier material. Furthermore, uptake of fluorescein isothiocyanate (FITC) labeled POM–CMC and POM–TMC by HeLa cells was monitored, and the influence of chlorpromazine (CP) as inhibitor of the clathrin mediated pathway revealed different cellular uptake behavior of composites and pristine carriers. TMC/{CoW11TiO40} nanocomposites are taken up by HeLa cells after short incubation times around 30 min at low concentrations. The anticancer activity of pristine {CoW11TiO40} and its TMC-nanocomposites was investigated in vitro with MTT assays and compared to a reference POM.