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.
Department of Physics, Purdue University, 525 Northwestern Avenue, West Lafayette, Indiana 47907, USA. lpeng1@partners.org
Leilei
L
Peng
Manoj M
MM
Varma
Wonryeon
W
Cho
Fred E
FE
Regnier
David D
DD
Nolte
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