title: Generation 9 polyamidoamine dendrimer encapsulated platinum nanoparticle mimics catalase size, shape, and catalytic activity.
abstract: Poly(amidoamine) (PAMAM) encapsulated platinum nanoparticles were synthesized and used as catalase mimics. Acetylated generation 9 (Ac-G9) PAMAM dendrimer with a molecular size around 10 nm was used as a template to synthesize platinum nanoparticles. The feeding molar ratio of Pt(4+) and Ac-G9 is 2048, and the synthesized platinum nanoparticle (Ac-G9/Pt NP) has an average size of 3.3 nm. Ac-G9/Pt NP has a similar molecular size and globular shape with catalase (~11 nm). The catalytic activity of Ac-G9/Pt NP on the decomposition of H2O2 is approaching that of catalase at 37 °C. Ac-G9/Pt NP shows differential response to the changes of pH and temperature compared with catalase, which can be explained by different catalytic mechanisms of Ac-G9/Pt NP and catalase. Ac-G9/Pt NP also shows horseradish peroxidase activity and is able to scavenge free radicals such as di(phenyl)-(2,4,6-trinitrophenyl)iminoazanium (DPPH). Furthermore, Ac-G9/Pt NP shows excellent biocompatibility on different cell lines and can down-regulate H2O2-induced intracellular reactive oxygen species (ROS) in these cells. These results suggest that dendrimers are promising mimics of proteins with different sizes and Ac-G9/Pt NP can be used as an alternative candidate of catalase to decrease oxidation stress in cells.
authors.affiliation: Shanghai Key Laboratory of Regulatory Biology, School of Life Sciences, East China Normal University, Shanghai 200062, People's Republic of China.
authors.forename: Xinyu
authors.initials: X
authors.lastname: Wang
authors.forename: Yincong
authors.initials: Y
authors.lastname: Zhang
authors.forename: Tianfu
authors.initials: T
authors.lastname: Li
authors.forename: Wende
authors.initials: W
authors.lastname: Tian
authors.forename: Qiang
authors.initials: Q
authors.lastname: Zhang
authors.forename: Yiyun
authors.initials: Y
authors.lastname: Cheng
mesh_terms: D055162:Biocatalysis; D002374:Catalase / Q000737:chemistry* / Q000378:metabolism; D050091:Dendrimers / Q000737:chemistry / Q000378:metabolism*; D053768:Metal Nanoparticles / Q000737:chemistry*; D010316:Particle Size; D010984:Platinum / Q000737:chemistry / Q000378:metabolism*; D011073:Polyamines / Q000737:chemistry / Q000378:metabolism*; D013499:Surface Properties
chemical_list: D050091:Dendrimers; C531249:Poly(amidoamine); D011073:Polyamines; D010984:Platinum; D002374:Catalase