Susan Sharma

Publications (2)8.01 Total impact

• Source

  Available from: ncbi.nlm.nih.gov

  Article: Functional reassembly of the Escherichia coli maltose transporter following purification of a MalF-MalG subassembly.

  Susan Sharma, Johnny A Davis, Tulin Ayvaz, Beth Traxler, Amy L Davidson
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  ABSTRACT: Taking advantage of a chaperone-like function of MalK, a stable complex of MalF-MalG could be solubilized from the Escherichia coli membrane and purified in high yield in the absence of MalK. This MalF-MalG complex was competent for efficient reassembly of a functional MalFGK(2) maltose transporter complex both in detergent solution and in proteoliposomes.
  Journal of Bacteriology 05/2005; 187(8):2908-11. · 3.83 Impact Factor
• Source

  Available from: Peter R C Gascoyne

  Article: Dielectrically Addressable Microspheres Engineered Using Self-Assembled Monolayers.

  Jody Vykoukal, Daynene Mannering Vykoukal, Susan Sharma, Frederick F Becker, Peter R C Gascoyne
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  ABSTRACT: We have used self-assembled monolayer techniques to produce a new class of microspheres with specifically engineered dielectric properties to enable their dielectrophoretic manipulation and identification in microsystems. Dielectrophoresis is an electrokinetic phenomenon that exploits frequency-dependent polarizability differences between a particle and its suspending medium to drive the movement of the particle toward or away from the high-field regions of an inhomogeneous electric field. While dielectrophoretic methods have been used extensively for cell manipulation, separation, and identification, we wished to extend the applicability of dielectrophoresis to molecular analysis by developing a panel of dielectric microspheres or "handles". Dielectric shell theory was used to model the dielectrophoretic response for a biomimetic particle composed of a thin insulating shell over a conductive interior. We specifically sought to modulate the specific capacitance, and thereby the dielectric properties, of the particle by controlling the thickness of the insulating layer. Such a structure was fabricated by covering a gold-coated polystyrene core particle with self-assembled monolayers of alkanethiol and phospholipid. To test the prediction that the carbon chain length of these layers should dictate the dielectric properties of the particles, we constructed a panel of six microsphere types with shell compositions ranging from a C(9) alkanethiol monolayer to a C(32) hybrid bilayer membrane. These microsphere populations were distinguishable and manipulatable by dielectrophoresis in a characteristic, frequency-dependent manner as predicted by theory. Experimentally derived specific membrane capacitance values were inversely related to the insulating shell thickness and agreed with published capacitance values for planar layers of similar thicknesses. These proof of principle studies are the first to demonstrate that the dielectric properties of particles can be specifically engineered to allow their dielectrophoretic manipulation and are a first step toward the development of bead-based dielectrophoretic microsystems for multiplexed molecular separation and analysis.
  Langmuir 03/2003; 19(6):2425-2433. · 4.19 Impact Factor