Dual colorimetric and luminescent assay for dipicolinate, a biomarker of bacterial spores

A binary mixture of Tb(3+) and pyrocatechol violet (PV) forms a 1 : 1 Tb(3+)/PV complex that can be used in a dye displacement assay. Addition of dipicolinate (DPA) to the Tb(3+)/DPA complex simultaneously produces a PV color change from blue to yellow and luminescence emission from the newly formed Tb(3+)/DPA complex.