Beetroot-pigment-derived colorimetric sensor for detection of calcium dipicolinate in bacterial spores.

In this proof-of-concept study, we describe the use of the main red beet pigment betanin for the quantification of calcium dipicolinate in bacterial spores, including Bacillus anthracis. In the presence of europium(III) ions, betanin is converted to a water-soluble, non-luminescent orange 1∶1 complex with a stability constant of 1.4 × 10(5) L mol(-1).

Quantum dot FRET-based probes in thin films grown in microfluidic channels.

This paper describes the development of new fluorescence resonance energy transfer (FRET)-based quantum dot probes for proteolytic activity. The CdSe/ZnS quantum dots are incorporated into a thin polymeric film, which is prepared by layer-by-layer deposition of alternately charged polyelectrolytes. The quantum dots, which serve as fluorescent donors, are separated from rhodamine acceptor molecules, which are covalently attached to the film surface by a varying number of polyelectrolyte layers.