Curcumin is essentially non-fluorescent (and unstable) in water. A weak broad emission can be detected at 550 nm using 420 excitation. In a non-polar environment such as a lipid membrane or after curcumin binds to serum albumin, the fluorescence is increased and blue-shifted with a 498 nm emission maximum using 420nm excitation.Biochim Biophysics Acta, 1760, 2006,1513-1520