Probing DNA hybridization in homogeneous solution and at interfaces via measurement of the intrinsic fluorescence decay time of a single label.

The hybridization of DNA oligomers including molecular beacons can be detected by measurement of either the decay time or the intensity of a single fluorescent label attached to the end of the respective oligonucleotide. The method works both in solution and solid phase and can distinguish between fully complementary and mismatch sequences as demonstrated for a 15-mer oligonucleotide and a 25-mer molecular beacon. The fluorescence lifetime method is advantageous in (a) requiring a single label (and therefore a single labeling step) only; and (b), being based on measurement of a self-referenced magnitude that is hardly affected by parameters such as fluctuations in light intensity that make measurement of intensity more prone to interferences.

Synthesis and characterization of the first fluorescent nonpeptide NPY Y1 receptor antagonist.

Cyanine-5-labelled neuropeptide Y (NPY) was demonstrated to be an ideal universal fluorescent ligand for the combined investigation of NPY Y(1), Y(2) and Y(5) receptors. With respect to improved stability, detection of receptor subtypes in cells and tissues, and prevention of receptor internalization, small nonpeptidic fluorescent antagonists should be superior. Here we present a set of four fluorescent nonpeptide NPY Y(1) receptor (Y(1)R) antagonists.

Screening scheme based on measurement of fluorescence lifetime in the nanosecond domain.

The authors demonstrate that the fluorescence lifetime of certain fluorescent labels is a useful parameter to detect affinity binding between biotin and streptavidin, as well as between biotinylated bovine serum albumin and streptavidin. The assay is performed in a microplate format, and lifetimes are determined using dye laser-induced fluorescence. Four fluorescent labels are presented that undergo a significant change in their lifetime upon affinity binding.

Novel type of general protein assay using a chromogenic and fluorogenic amine-reactive probe.

We report on a new and simple one-reagent method for general protein assay. It makes use of one of two new reactive labeling reagents presented here (and referred to as pyrylium [Py] labels). These can be applied for both photometric and fluorometric protein assays at near neutral pHs at room temperature.