TABLE 2.
Summary of current rG4 structure imaging studies
| Name | Target rG4 | Ex. | Em. | Biophysical approaches | Biological system | Applications | References |
|---|---|---|---|---|---|---|---|
| Small molecules | |||||||
| QUMA-1 | rG4s in cells | 555 | 660 | Fluorescence spectroscopy, competition assay, CD, NMR, HPLC, MS | Cell line: HeLa | General rG4 dynamic | Chen et al. 2018b |
| ThT-NE | HCV RNA CG2a | 461 | 495 | Fluorescence spectroscopy: 1693-fold in vitro, CD, UV-Vis spectroscopy, gel electrophoresis, NMR | Cell line: Huh7, FCA1, GG2, GG2-G4Mut and HLCZ01 | Hepatitis C virus (HCV) infection | Luo et al. 2019 |
| NIR-2 | HCV RNA CG2a | 591 | 689 | Fluorescence spectroscopy, CD, NMR, HRMS | Cell line: Huh7, FCA1, GG2-G4-Mut and GG2 Organ: Huh7 or GG2 cell xenograft mice 3.4-fold ex vivo |
HCV infection | Zhang et al. 2021 |
| ThT-NA | rG4s in cells | 510 | 610 | Fluorescence spectroscopy, CD, NMR | Cell line: HepG2 and HeLa Tissue: HeLa cell xenograft mice |
Cancer | Lu et al. 2022 |
| TCB-1 | Abnormal NOP56 RNA | 490 | 526 | Fluorescence spectroscopy: 150 to 438-fold with dG4/rG4 in vitro, UV-Vis spectroscopy, NMR, MS | Cell line: HeLa and MCF-7, 8-Fold | Autosomal dominant spinocerebellar ataxia 36 (SCA36) | Sun et al. 2023 |
| TOR-G4 | rG4s in cells | 467 | 540 | Fluorescence spectroscopy, UV-Vis spectroscopy, NMR, MS | Cell line: U2OS | Fluorescent lifetime-based imaging | Robinson et al. 2024 |
| NIRG-2 | dG4s and rG4s | 850 | 940 | Fluorescence spectroscopy, CD, NMR | Cell line: 4T1, HEK293, A549, MCF-7, LX-2, and L929 Tissue: chicken breast Tumor: 4T1 subcutaneous xenograft mice: 47-fold in vivo |
Cancer lymphatic metastasis | Wang et al. 2024 |
| SCY-5 | Parallel dG4s and rG4s | 575 | / | Fluorescence spectroscopy, UV-vis spectroscopy, native gel electrophoresis, NMR | Cell line: HUVECs, MCF-10A, MCF-7, HeLa, A549, and SMMC7721, >3.5-fold in tumor cells, twofold in normal cells Blood: greater than twofold for cancer patient, twofold for normal patient |
Cancer | Sun et al. 2024 |
| 4S-2TO-4a | dG4s and rG4s | 498 | 680 | Fluorescence spectroscopy, CD, UV-Vis spectroscopy, native gel electrophoresis, NMR, HRMS | Cell line: HeLa | General G4 imaging | Parveen et al. 2024 |
| ThT | dG4s and rG4s | 404 | 490 | Fluorescence spectroscopy, TCSPC time-resolved decays, UV-Vis spectroscopy, | Cell line: U2OS | General G4 imaging | Bradford et al. 2024 |
| TzN-TASQ | dG4s and rG4s | 286 | 414 | Fluorescence spectroscopy, UV-Vis spectroscopy, NMR, molecular dynamics simulations | General G4 detection | Ledvinka et al. 2024 | |
| Small molecule + antibody | |||||||
| 5-BrdU PDC + antibody | rG4s in cells | / | 450 | G4-FID, click reaction | Cell line: A549 and A2780 | General G4 imaging | Masson et al. 2021 |
| Small molecule + antisense | |||||||
| ISCH-app | APP rG4 | 570 | 650 | Fluorescence spectroscopy, CD, UV-Vis spectroscopy, RTS assay, SHALiPE assays | Cell line: HEK293T and HeLa, 28–50-fold in cells | Alzheimer's Disease (AD) | Lyu et al. 2019 |
| MAMPA | BCL2 rG4 | 488 | 520 | Fluorescence spectroscopy, MS | Cell line: HeLa, MCF 10A, MDA-kb2, MCF-7, BT-474, SK-BR3, MDA-MB-231, mESC, and 293FT | Proto-oncogene | Dai et al. 2022 |
| Aptamer | |||||||
| L-Apt.1-1_Pepper | APP rG4 | 485 | 530 | Fluorescence spectroscopy: 44.5 ± 1.4-fold in vitro, CD, native gel electrophoresis | Cell line: HEK293T and HeLa | AD | Lau et al. 2024 |
