Externally sensitized deprotection of PPG-masked carbonyls as a spatial proximity probe in photoamplified detection of binding events.

Externally sensitized electron-transfer fragmentation in dithiane PPG (photoremovable protecting group)-protected carbonyls is adopted for detection and amplification of molecular recognition events. The new methodology allows for detection of as low as 50 attomoles of avidin utilizing an imager based on a low sensitivity mass-produced consumer CCD camera. Numeric modelling is carried out to demonstrate the intrinsic limitations of 2D amplification on surfaces and the advantages of unconstrained amplification in a compartmentalized volume of spatially addressable 3D solutions.