Review Article
An Elegant Biosensor Molecular Beacon Probe: Challenges and Recent Solutions
Table 1
Variations of 5′-X- and 3′-Y-terminal attachments to increase signal-to-noise (S/N) ratio of an MB probe.*
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| | X | Y | Comments | S/N | LOD | Ref. |
| 1 | FAM* | Gold nanoparticle (GNP) | 1.4 nm GNP | 76–100 | N/D | [74] [75] | 2 | DABCYL | FAM | | 14 | N/D | [75] | 3 | 2 DABCYL | FAM | | ~80 | N/D | [75] | 4 | 3 DABCYL | FAM | Multiple DABCYL groups increase stem melting temperature by ~5°C | 320 | N/D | [75] | 5 | Poly(phenylene ethynylene)s (PPEs) | DABCYL | | N/D | N/D | [76] | 6 | FAM | Coumarin | Dynamic range was found to be 1–100 nM | 4 () | 0.17 nM | [77] | 7 | Metallophthalocyanine (PC) | Metallo-phthalocyanine (PC) | Two PCs form nonfluorescent H-dimers in the closed MB conformation | 59 | N/D | [78] | 8 | Lanthanide-based luminescent complex | BHQ2 | Time-resolved acquisition of the luminescent signal | >400 | <1 pM | [79] | 9 | Eu3+ complex of chlorosulfonylated tetradentate -diketone | BHQ-2 | LOD was determined in a cell medium. Time-resolved acquisition of the luminescent signal. | >200 | 0.5 nM | [80] | 10 | Pyrene | Pyrene | Detection based on the excimer formation | ~100 / | 1 nM | [81] | 11 | 1 to 4 pyrene residues | DABCYL | MB containing two pyrene residues MB demonstrated the best performance | 1–29 | <1 nM | [82] [83] |
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N/D: not determined; FAM: fluorescein; DABCYL: 4-((4-(dimethylamino)phenyl)azo)benzoic acid; BHQ2: blackhole quencher 2; LOD: limit of detection; S/N: signal-to-noise ratio.
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