A comparative analysis of polyurethane hydrogel for immobilization of IgG on chips

Hydrogels are considered an optimum material for protein chip surfaces, since they provide a quasi-liquid environment which allows protein activity to be maintained and shows good spot morphology as well as excellent immobilization capacity. In the following, we present a polyurethane (PU) chip that electrostatically binds IgG. The PU surface is optimized with regard to layer thickness (similar to 200 nm), hydrogel (2%) and immobilized antibody concentration (0.5 mg mL(-1); 0.3 ng spot(-1)), pH and ionic strength of the print buffer as well as to blocking solution. Evaluation is done in a direct IgG immunoassay using the Nexterion slide H as a reference. It is shown that higher IgG loading is achieved on the PU chip than on slide H, no matter whether I x PBS (pH 7.2), Sorensen (pH 5.8) or Nexterion buffer was used as a spotting solution. Moreover, the crossreactivity with goat IgG, human IgG and monoclonal anti-CRP spotted in Nexterion buffer was as low as <= 0.74% (slide H: <= 3.34%). (C) 2007 Elsevier B.V. All rights reserved.