Adarsh D. Radadia, Courtney J. Stavis, Rogan Carr, Hongjun Zeng, William P.
King, John A. Carlisle, Aleksei Aksimentiev, Robert J. Hamers, and Rashid
Bashir.
Control of nanoscale environment to improve stability of immobilized
proteins on diamond surfaces.
Advanced Functional Materials, 21:1040-1050, 2011.
RADA2011-AA
Immunoassays for detection of bacterial pathogens rely on the selectivity and stability of
bio-recognition elements such as antibodies tethered to sensor surfaces. The search for
novel surfaces that improve the stability of biomolecules and assay performance has been
pursued for a long time. However, the anticipated improvements in stability have not been
realized in practice under physiological conditions because the surface functionalization
layers on commonly used substrates, silica and gold, are themselves unstable on time
scales of days. In this paper, we show that covalent linking of antibodies to diamond
surfaces leads to substantial improvements in biological activity of proteins as measured
by the ability to selectively capture cells of the pathogenic bacterium E scherichia coli
O157:H7 even after exposure to buffer solutions at 37 ºC for extended periods of
time, approaching 2 weeks. Our results from ELISA, XPS, fluorescence microscopy, and MD
simulations suggest that by using highly stable surface chemistry and controlling the
nanoscale organization of the antibodies on the surface, it is possible to achieve significant
improvements in biological activity and stability. Our findings can be easily extended to
functionalization of micro and nanodimensional sensors and structures of biomedical
diagnostic and therapeutic interest.
