Detection of known mutations for medical diagnostics by FRET spectroscopy

Detection of DNA Sequence with Enhanced Sensitivity and Higher FRET Efficiency Using a Light-Emitting Polymer, Peptide Nucleic Acid Probe and Anionic Surfactant System

An improved strategy has been developed for detection of DNA sequence by using water-soluble cationic conjugated polymer (PFP)/single-strand (ss) DNA and peptide nucleic acid labeled with fluorescent dye (PNAC*), where an anionic surfactant (sodium dodecyl sulphate, SDS) system has been used to improve the sensitivity of the sensor. The method of detection is simple to use, fast and cost-effective. This method uses the phenomenon of Forester Resonance Energy Transfer (FRET). The detection sensitivity of the biosensor has been improved by about ten times by using the anionic surfactant. It is observed that the effect of surfactant is to increase the photoluminescence (PL) intensity of the PNAC* when the sequence of the DNA is complementary (to that of PNA probe). On the other hand when the two sequences are non-complementary, the PL intensity of the PNAC* is further reduced as compared to the case when surfactant was absent.

Strength in numbers: effects of acceptor abundance on FRET efficiency

Fluorescence resonance energy transfer (FRET) is a strongly distance-dependent process between a donor and an acceptor molecule, which can be used for sensitive distance measurements and characterization of molecular interactions at the nanometer level. The original mathematical description of this process, however, is only valid for the interaction of one donor with one acceptor. This criterion is not always met, especially in biological systems, where multiple structures can interact simultaneously, often making distance estimations based on transfer efficiency values error-prone. Herein we investigate how the interaction of multiple acceptors and donors influences the transfer efficiency value in an intramolecular cellular FRET system by manipulating the fluorophore/protein ratio of the fluorophore-conjugated antibodies. We show that the labeling ratio of the acceptor has the largest influence on measured transfer efficiency and decreasing or increasing the acceptor labeling ratio can be utilized to manipulate the FRET response of the acceptor-donor pair and therefore is a tool for optimizing sensitivity of FRET measurements.