Shift of whispering-gallery modes in microspheres by protein adsorption.
Biosensors based on the shift of whispering-gallery modes in microspheres accompanying protein adsorption are described by use of a perturbation theory. For random spatial adsorption, theory predicts that the shift should be inversely proportional to microsphere radius R and proportional to protein surface density and excess polarizability. Measurements are found to be consistent with the theory, and the correspondence enables the average surface area occupied by a single protein to be estimated. These results are consistent with crystallographic data for bovine serum albumin. The theoretical shift for adsorption of a single protein is found to be extremely sensitive to the target region, with adsorption in the most sensitive region varying as 1/R(5/2). Specific parameters for single protein or virus particle detection are predicted.
Arnold
S
S
Microparticle Photophysics Lab MP3L), Polytechnic University, Brooklyn, New York 11201, USA. arnold@photon.poly.edu
Khoshsima
M
M
Teraoka
I
I
Holler
S
S
Vollmer
F
F
D000327:Adsorption; D015374:Biosensing Techniques; D008863:Microspheres; D008962:Models, Theoretical; D011506:Proteins / Q000493:pharmacokinetics; D012710:Serum Albumin, Bovine / Q000493:pharmacokinetics
D011506:Proteins; D012710:Serum Albumin, Bovine