A new biocompatible coating for bioanalytical devices based on PSI (polysuccinimide)
Protein chips need to immobilize proteins that retain their native structures. Polymer coatings can be used to build up nanostructures on a protein-chip. This is generally done by synthesizing the polymer with a series of steps. Polymer coatings reported in this dissertation were prefabricated in solution as small polymers and then assembled into a coating in a single, or a small number of steps. This reduces the time and the complexity required for device fabrication such as microfluidic systems.
Prefabricated polysuccinimide (PSI) coatings were developed as a new generation of biocompatible coatings for microfabricated analytical systems. These coatings were developed for gold and/or glass BioCD discs. Linear and branched PSIs were characterized with NMR, elemental analysis (EA), size exclusion chromatography (SEC), and AFM. These methods established that PSI coatings deposited on surfaces were usually 2-5 nm thick and very hydrophobic. This prevents non-specific binding of proteins from the surface physically and chemically.
Proteins were immobilized on inorganic surfaces in three ways: PSI coatings with biotin, protein G, or direct binding to IgG on immunological assays. Antibody immobilization and antigen detection were measured using AFM, ellipsometry (ELS), fluorescence microscopy, and interferometry. The nonspecific binding of sample proteins from the blocking coatings was confirmed to be very low through SEC development.