Nanosurface-induced cooperativity in self-assembled maghemite nano-catalysts with esterase-like activity

ORGN 270

Yong Gao, ygao@chem.siu.edu and Yan Zheng, tjuzhengyan@hotmail.com. Department of Chemistry and Biochemistry, Southern Illinois University, 224 Neckers Hall, Carbondale, IL 62901
We have recently designed, synthesized and tested a small library of magnetic biomimetic nano-catalysts for the hydrolysis of organophosphates and ester compounds. These nano-catalysts are composed of a 12-nm maghemite nanocrystals core surrounded by a layer of mixed amino acid derivatives. We subjected these nano-catalysts to the hydrolysis reactions of paraoxon and 4-nitrophenyl acetate in neutral water at ambient temperature. From this small library, we identified a triad of amino acids (Glu-His-Cys) that demonstrated highest catalytic hydrolysis activity in both systems. Interestingly, the catalytic activity dropped significantly if maghemite nanoparticles coated with only one or two amino acids of the triad are employed in the hydrolysis reactions. Without a maghemite nanoparticle support, the mixture of Glu, His, and Cys did not show catalytic activity at all. We believe that the enhanced catalytic activity of the triad was due to collaborative effects induced by the unique surface structures of the nanoparticle carriers. Our systems offer opportunities in neutralizing chemical warfare agents and environmental pesticide contaminants. They could also be utilized as novel magnetically recoverable “esterases” in numerous chemical transformations.
 

Molecular Recognition and Self-Assembly
8:00 AM-12:00 PM, Tuesday, 28 March 2006 Georgia World Congress Center -- C302, Oral

Division of Organic Chemistry

The 231st ACS National Meeting, Atlanta, GA, March 26-30, 2006