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The investigation of protein A and Salmonella antibody adsorption onto biosensor surfaces by atomic force microscopy
Author(s) -
Lee Kyoung G.,
Pillai Shreekumar R.,
Singh Shree R.,
Willing Gerold A.
Publication year - 2008
Publication title -
biotechnology and bioengineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.136
H-Index - 189
eISSN - 1097-0290
pISSN - 0006-3592
DOI - 10.1002/bit.21644
Subject(s) - biosensor , quartz crystal microbalance , adsorption , chemistry , protein a , protein crystallization , protein adsorption , layer (electronics) , s layer , scanning electron microscope , analytical chemistry (journal) , nanotechnology , crystallography , materials science , antibody , chromatography , biochemistry , biology , crystallization , organic chemistry , gene , immunology , composite material
The investigation of Protein A and antibody adsorption on surfaces in a biological environment is an important and fundamental step for increasing biosensor sensitivity and specificity. The atomic force microscope (AFM) is a powerful tool that is frequently used to characterize surfaces coated with a variety of molecules. We used AFM in conjunction with scanning electron microscopy to characterize the attachment of protein A and its subsequent binding to the antibody and Salmonella bacteria using a gold quartz crystal. The rms roughness of the base gold surface was determined to be approximately 1.30 nm. The average step height change between the solid gold and protein A layer was approximately 3.0 ± 1.0 nm, while the average step height of the protein A with attached antibody was approximately 6.0 ± 1.0 nm. We found that the antibodies did not completely cover the protein A layer, instead the attachment follows an island model. Salt crystals and water trapped under the protein A layer were also observed. The uneven adsorption of antibodies onto the biosensor surface might have led to a decrease in the sensitivity of the biosensor. The presence of salt crystals and water under the protein A layer may deteriorate the sensor specificity. In this report, we have discussed the application and characterization of protein A bound to antibodies which can be used to detect bacterial and viral pathogens. Biotechnol. Bioeng. 2008;99: 949–959. © 2007 Wiley Periodicals, Inc.