A molecular beacon that incorporates components of an artificially expanded genetic information system (Aegis) in its stem is shown not to be opened by unwanted stem invasion by adventitious standard DNA; this should improve the "darkness" of the beacon in real-world applications.
Department of Chemistry and UF Genetics Institute, Shands Cancer Center, Center for Research at Bio/nano Interface and McKnight Brain Institute, University of Florida, Gainesville, FL 32611-7200, USA.
