Synthesis, Characterization and Toxic Metal-Binding Ability of Poly(γ-glutamic acid)-coated Superparamagnetic Nanoparticles

B.H. Chen, B.S. Inbaraj
Fu Jen University, TW

Keywords: iron oxide nanoparticles, superparamagnetic, poly(gamma-glutamic acid), coating material, metal binding, detoxification therapy


Superparamagnetic iron oxide nanoparticles (SPIONPs) coated with a non-toxic, edible biopolymer poly(-glutamic acid) (PGA-coated SPIONs) were synthesized by co-precipitation method, characterized and evaluated for their possible toxic metal-binding ability in the treatment of metal intoxication in human. The as-synthesized nanoparticles were characterized by FTIR, TEM, VSM and XRD to be superparamagnetic magnetite nanocrystals with the mean particle size of 11.8 and 14 nm as well as saturation magnetization value of 71.2 and 61.7 emu/g for bare SPIONs and PGA-coated SPIONs, respectively. In vitro binding of toxic metals lead and cadmium by PGA-coated SPIONs in batch-mode showed rapid uptake achieving >90% binding within 1 min. A maximum binding occurred in the pH 4–7, corresponding to gastrointestinal pH values except for stomach. Binding isotherms were well predicted by the Langmuir model and the maximum binding capacity was 98.70 mg/g for lead and 31.13 mg/g for cadmium. Incorporation of essential metals did not show any marked influence on lead binding, but significantly reduced the binding of cadmium. The high selectivity of lead by PGA-coated SPIONs towards lead without causing deficiency of essential metals should be an advantage and thus can be used as a potential agent for chelation therapy in biomedical applications.