Cholesterol-linked fluorescent molecular beacons with enhanced cell permeability

We appended pyrene units covalently onto adenosine (forming A(P) units) and then incorporated them into oligonucleotides such that they were positioned in complementary locations in opposite strands in the middle positions of hairpin stems. System 1 (A(P)A(P)) behaves as an effective molecular beacon (MB) that changes color from green to blue upon duplex formation. In addition, we attached a cholesterol unit to a free terminus of one of these hairpins; this approach enhanced the cellular delivery of the modified MB relative to those encountered when using conventional transfection methods. These structurally simple cholesterol-based MB systems, which can be synthesized very efficiently, have good potential for opening up new and exciting opportunities in the field of in vivo biosensors.