Radiation-induced synthesis and characterization of ruthenium/carboxymethylated-chitosan nanocomposites

Carboxymethylated chitosan (CMCts) protected ruthenium nanoparticles (RuNPs) were synthesized by γ-radiation-induced reduction of metal ions at room temperature. The characteristics of RuNPs/CMCts composites prepared under different experimental conditions have been investigated by means of TEM, XPS and TGA. The results indicated that the average size of RuNPs increases as the concentration of precursor decreases. Narrowly distributed nanocomposites have been obtained when low molecular weight CMCts (LM-CMCts, Mn = 4400 Da) was utilized as stabilizer. The TEM images demonstrated the RuNPs prepared in a wide pH range of 4.5–12.3 can be dispersed uniformly in the alkalic CMCts solution for more than 2 months with the average particle sizes of 1.0–3.0 nm. XPS spectrum confirmed the ruthenium ions have been reduced to metal atoms by irradiation. TGA curves indicated that RuNPs/CMCts composites exhibited good thermal stability at temperature less than 200 °C and strong interactions existed between the metal nanoparticles and stabilizer molecules.

► Biocompatible RuNPs were successfully produced by γ-irradiation for the first time.
► RuNPs in a pH range of 4.5–12.3 dispersed uniformly with the sizes of 1.0–3.0 nm.
► Narrowly distributed RuNPs have been obtained when LM-CMCts was used as stabilizer.
► TGA curves suggested the carboxymethyl group in CMCts can stabilize RuNPs.