PSS Deposition Research Articles

Assembly of β-glucosidase multilayers on spherical colloidal particles and their use as active catalysts

β-glucosidase (β-GLS) layers of the enzyme, each separated by oppositely charged polyelectrolyte (poly(styrenesulfonate), PSS), were deposited onto polystyrene (PS) latex particles using the layer-by-layer adsorption technique. Electrophoretic mobility (EPM) and single-particle light scattering (SPLS) measurements revealed regular and step-wise assembly of β-GLS/PSS multilayers on the colloidal particles. Alternating positive and negative ζ-potentials were observed for β-GLS and PSS deposition, respectively. An average thickness of 3.5±0.6 nm was calculated for each β-GLS/PSS layer pair from SPLS data. The immobilized catalyst (in the form of an enzyme multilayer film on particles) proved to be active in the glucosidation of dodecanol, yielding dodecyl-β- d-glucopyranoside. The product yield increased with increasing enzyme layer number for β-GLS multilayer-coated PS particles when the outermost layer was polyelectrolyte.

2. Assembly of Alternating Polyelectrolyte and Protein Multilayer Films for Immunosensing

Alternating polyelectrolyte films constructed by the sequential adsorption of poly(allylamine hydrochloride) (PAH) and poly(styrenesulfonate) (PSS) have been used as substrates for the immobilization of immunoglobulin G (IgG) and anti-IgG. Anti-IgG has also been immobilized in multilayer films by the alternate deposition of PSS and anti-IgG. The assembly process of the multilayer films was monitored using a quartz crystal microbalance (QCM) and surface plasmon resonance (SPR). Film growth was achieved up to at least nine (5 anti-IgG and 4 PSS) layers. The utility of these films for immunosensing has been investigated via their subsequent interaction with IgG. The alternating polyelectrolyte/protein layers were constructed in order to increase the binding layer capacity (i.e. sensitivity) of the thin film with respect to IgG detection. The sensitivity, determined using IgG mass uptake data from quartz crystal microgravimetry, was found to be linearly dependent on the number of anti-IgG layers (and hence th...