With the rapid development of protein and gene research, increasing advanced technologies appear to meet the need of highly sensitive and specific detections. Molecular beacons (MBs), a class of novel fluorescent probes, are designed based on the fluorescence resonance energy transfer (FRET) and the complementary pairing principles. Since it was first established in 1996 by Tyagi et al., MBs have been widely used in biological and clinical research as well as the detection and diagnosis of genetic diseases.
As shown in Figure 1, a classical molecular beacon DNA probe is a hairpin-like oligonucleotide composed of two parts: (a) a loop portion responsible for binding to targets and (b) a stem portion attaching a fluorophore and a quencher at both ends. In terms of the signal transduction mechanism, MBs act like "switches" that normally turn fluorescence "off" in free state, where the fluorophore and quencher are in close distance of approximately 7-10 nm. While when the loop targets nucleic acid molecules complementarily, the fluorophore and the quencher are separated, consequently turning fluorescence "on".
Figure 1. Mechanism of MB DNA probe operation. (Fang X, et al., 2000)
One of the best-known advantages is that MB DNA probes can function without removing the unhybridized or unbounded probes, which is an essential requirement for in vitro detection. Besides, the fluorescence intensities of MB DNA probes could be optimized up to 200-fold higher over other linear DNA probes which makes DNA molecule imaging and hybridization process monitoring achievable. More importantly, MBs can recognize DNA/RNA quite specifically, even the target sequences differ by only one single nucleotide. In addition, MBs are commercially available and easy to synthesize. And probes with different colors can be produced by using MBs with DABCYL (a most commonly used quenching agent). Together, these excellent properties make MBs widely used in real-time monitoring of living cells.
MB DNA probes have been successfully employed not only in basic medicine but in clinical medicine. The major applications in basic medicine include the detections of nucleic acid, proteins, the double-stranded DNA, biochips and biosensors probe, gene mutation, SNP (single nucleotide polymorphism), allele and multi-determination; dynamic nuclear acid detection in vivo as well as qRT-PCR detection of target. In addition, it has been reported that MB technologies can also be used in clinical medicine, such as the intact tumor detection; SARS virus and hepatitis B virus (HBV) detection.
Creative Biogene can provide all kinds of MB DNA probes. The detailed information is shown below:
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