Biocompatible Dendrimer-Encapsulated Palladium Nanoparticles for Oxidation of Morin

Development of highly efficient catalysts to expedite the degradation of organic dyes has been drawing great attention. The aggregation of catalysts reduces the accessibility of catalytic centers for organic dyes and therefore decreases their catalytic ability. Herein, we report a facile method to prepare highly biocompatible and stable dendrimer-encapsulated palladium nanoparticles (Pd-n-G5MCI NPs), which exhibit high catalytic efficiency for oxidation of morin. The biocompatible dendrimers were prepared via surface modification of G5 polyamidoamine (G5 PAMAM) dendrimers using maleic anhydride and L-cysteine. Then, they were incubated with disodium tetrachloropalladate, followed by reduction using sodium borohydride to generate Pd-n-G5MCI NPs. Transmission electron microscopy results demonstrated that palladium nanoparticles (Pd NPs) inside Pd-n-G5MCI had small diameters (1.77-2.35 nm) and monodisperse states. Dynamic light scattering results confirmed that Pd-n-G5MCI NPs had good dispersion and high stability in water. Furthermore, MTT results demonstrated that Pd-n-G5MCI NPs had high biocompatibility. More importantly, Pd-n-G5MCI NPs successfully catalyzed the decomposition of H2O2 to the hydroxyl radical ((OH)-O-center dot), and the generated (OH)-O-center dot quickly oxidized morin. This reaction kinetics followed pseudo-first-order kinetics. Apparent rate constant (k(app)) is an important criterion for evaluating the catalytic rate. The concentrations of Pd-n-G5MCI NPs and H2O2 were positively correlated with k(app), whereas the correlation between the concentration of morin and k(app) was negative. The prepared Pd-n-G5MCI NPs have great potential to catalyze the degradation of organic dyes in bio-related systems in the future.