Adaptive interferometry of protein on a BioCD.
Adaptive spinning-disk interferometry is capable of measuring surface profiles of a thin biolayer with subnanometer longitudinal resolution. High-speed phase modulation in the signal beam arises from the moving surface height profile on the spinning disk and is detected as a homodyne signal via dynamic two-wave mixing. A photorefractive quantum-well device performs as an adaptive mixer that compensates disk wobble and vibration while it phase-locks the signal and reference waves in the phase quadrature condition (pi/2 relative phase between the signal and local oscillator). We performed biosensing of immobilized monolayers of antibodies on the disk in both transmission and reflection detection modes. Single- and dual-analyte adaptive spinning-disk immunoassays were demonstrated with good specificity and without observable cross-reactivity. Reflection-mode detection enhances the biosensing sensitivity to one-twentieth of a protein monolayer, creates a topographic map of the protein layer, and can differentiate monolayers of different species by their effective optical thicknesses.
Peng
Leilei
L
Department of Physics, Purdue University, 525 Northwestern Avenue, West Lafayette, Indiana 47907, USA. lpeng1@partners.org
Varma
Manoj M
MM
Cho
Wonryeon
W
Regnier
Fred E
FE
Nolte
David D
DD
D000818:Animals; D015374:Biosensing Techniques; D004867:Equipment Design; D006801:Humans; D007118:Immunoassay / Q000295:instrumentation* / Q000379:methods*; D007074:Immunoglobulin G / Q000737:chemistry; D007368:Interferometry / Q000379:methods*; D008027:Light; D051379:Mice; D015233:Models, Statistical; D055095:Optics and Photonics; D009991:Oscillometry; D011506:Proteins / Q000032:analysis*; D011817:Rabbits; D012680:Sensitivity and Specificity
D007074:Immunoglobulin G; D011506:Proteins