Layer-by-Layer Method for Immobilization of Protein Molecules on Biochip Surface

The article presents a Layer-by-Layer method to produce new biochip surfaces on gold or mica for protein binding. The chip surfaces were modified by two polyelectrolytes, poly(sodium 4-styrenesulfonate) and pory(diallyldimethylam- monium chloride), which produce negatively and positively charged surfaces, respectively. Then, the modified surfaces were used for the binding of several proteins, such as bovine serum albumine, apo-transferrine, tissue transglutaminase and SAG (sensitive to apoptosis gene) protein. The proteins were self-assembled from aqueous solution on the modified surfaces and adsorption process has been examined by Surface Plasmon Resonance and Atomic Force Microscopy. Our results suggested that negatively charged surface was preferable for the binding of four proteins, even though two surfaces could be used.