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.

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

Beads spontaneously form two-dimensional structures.

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)