AVS 52nd International Symposium
    Biomaterial Interfaces Thursday Sessions
       Session BI-ThA

Paper BI-ThA2
Impact of Composite Shell Thickness on Stability of Single Enzyme Nanoparticles

Thursday, November 3, 2005, 2:20 pm, Room 311

Session: Bionanotechnology
Presenter: A.S. Lea, Pacific Northwest National Laboratory
Authors: A.S. Lea, Pacific Northwest National Laboratory
J.B. Kim, Pacific Northwest National Laboratory
J.W. Grate, Pacific Northwest National Laboratory
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Single-enzyme nanoparticles (SENs), comprised of individual alpha-chymotrypsin molecules surrounded by a porous organic/inorganic composite network less than a few nanometers thick, have been developed. The synthetic procedure, entailing enzyme modification and two orthogonal polymerization steps, yields nanoparticles containing a single enzyme. In stability experiments, the incorporation of these enzymes into the nanostructure dramatically increased its enzymatic stability. Furthermore, the nanoscale structure around the enzyme is sufficiently thin and porous that it does not impose a significant mass transfer limitation on the substrate. We have used tapping mode AFM (TM-AFM) to characterize single enzyme nanoparticles containing alpha-chymotrypsin (SEN-CT). Compared to transmission electron microscopy (TEM), TM-AFM resulted in much quicker and more accurate characterization of SENs since they are still in a hydrated state. We can tailor the thickness of the composite shell during the orthogonal polymerization steps in the synthesis of the SENs. The measured size-distribution of the different preparations was used to relate enzyme stability to the thickness of the porous composite shell. We will discuss this relationship in detail.