You can try immunoprecipitation

You might be able to monitor intrinsic fluorescence of the antibody, since it should be the only protein in the reaction (assuming you are purifying your DNA).  Two possibilities:  1.)  Binding of the antibody might alter the intrinsic fluorescence of the antibody a bit, if one or more the tryptophans in the antibody happen to be even slightly altered upon binding.  2.)  Polarization of the antibody's intrinsic fluorecence almost surely has to increase when binding to a nice long DNA molecule.  In either case, you'd have to test and see.  Thinking about it, the most likely failure mode is whether or not you have enough antibody concentration to easily detect intrinsic fluoresence at steady state, without fancy high-sensitivity fluorometers.  If you can fluorescently label the antibody, you'll have a much better shot at such an approach.

Just do a dotblot.