Nanoparticles adsorbed protein layers

A particularly useful ECL pathway for detecting low concentrations of proteins by immunosensors is initiated by oxidation at 0.9 V vs SCE of the sacrificial reductant TprA, whose products react in a complex pathway with RuCbpy) " to yield RuCbpy) ". We developed an immunosensor on a SWCNT forest platform for PSA in serum utilizing this approach with Ru(bpy)3Lsilica nanoparticles attached to secondary antibodies (RuBPY-silica-Ab2) as labels [99]. Addition of surfactants increases the hydrophobicity of the sensor surface via an adsorbed surfactant layer, which facilitates oxidation of TprA [1(X)]. Including Triton X-100 and Tween 20 in the electrolyte solution containing TPrA improved PSA sensitivity tenfold compared to TprA in surfactant-free solutions [99]. Surface... 

Responsive polymer bmshes are not only investigated on planar substrates, but can also be used to decorate nanoparticles (Figure 5.13). Here, the key biomedical application is the accommodation (immobilize) of biofunctional moieties such as proteins or enzymes (Wittemann Ballauff, 2006 Wittemann, Haupt, BaUauff, 2003). If there is sufficient attraction between a protein and a polymer brush to overcome excluded volume effects (the antifouling properties of the brush), much larger amounts of protein can accumulate inside a brnsh layer than can be adsorbed onto just the particles surface. The role of the attached polymer chains is thus to strongly increase the available surface area. In Fignre 5.13, we schematically show a spherical polymer brush filled with adsorbed nanoparticles. Because, protein molecules inunobilized by polymers are found to be relatively weakly bound, they keep their conformation and (enzymatic)... 

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