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Label-Free Bioanalytical Detection Using Membrane-Coated Silica Nanoparticles

Michael M. Baksh, Esther M. Winter, Nathan G. Clack and Jay T. Groves: University of California, Berkeley and Lawrence Berkeley National Lab

  • Membrane-coated silica particles exhibit colloidal phase transitions that are governed by membrane surface interactions.
  • Collective phase behavior of the beads serves as a cooperative amplifier; a readily detectable response from small numbers of microscopic binding events between ligands and membrane-bound protein(s) of interest alters the structure of the colloidal dispersion in measurable ways.
  • Further statistical analysis of bead pair distribution functions enables quantitative determination of binding affinities.
  • This technology has already been patented, and is currently being licensed by NuvoMetrix Inc. for commercialization.

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Silica microbeads are coated with synthetic or natural membranes containing ligand of interest.
Beads are allowed to settle to the bottom of a well.

Label-Free Bioanalytical Detection.jpg

Beads spontaneously form two-dimensional structures.

Label-Free Bioanalytical Detection.jpg

Radial distribution function (to measure changes in colloidal structure) varies continuously with the concentration of ligand bound to the bead surface.

Baksh, Jaros, & Groves, Nature 427:p.139-141 (2004)
Winter & Groves, Anal, Chem 78:p. 174-180 (2006)