Table 2. PET imaging agents.
| Imaging modality | Dye/contrast agent | Means of incorporation | Polymer components | Responsive size change | Responsive imaging property | Formulation method a | Size (nm) | Targeting group | Cells/in vivo work | Therapeutics | Ref. |
| PET | 99mTc labeled 1-hexylcarbamoyl-5-fluorouracil (HCFU) | Encapsulation | Poly-(NIPAAM-co-VP) crosslinked by MBA; coated with h polysorbate 80 | N/A | N/A | A | 50 | N/A | Biodistribution imaging of rabbits | HCFU | 91 |
| PET + UV fluorescence | 68Ga-NODAGA Alexa Fluor 488 | Conjugation Conjugation | Star-shaped PEG crosslinked by disulfide bond | Reducing environment | N/A | B | 290 | N/A | Uptake in monocytes | N/A | 92 |
| PET | 64Cu-NOTA | As crosslinker | PAA chemically crosslinked with NOTA crosslinkers | N/A | N/A | A | 63 | N/A | Imaging of 4T1 tumor and metastasis of mice | N/A | 93 |
| PET | [18F]-labelled BoHc/A | Conjugation to encapsulated drugs | Amino group- and cholesteryl-group-bearing pullulan (cCHP) | N/A | N/A | C | 40 | N/A | Imaging delivery to nasal mucosa of mice | BoHc/A | 84 |
| PET + visible light | 68Ga-DOTA NaYF4:Yb/Er/Tm UCNP | Conjugation As core from wit polymer was build on | PEI (coated on UCNP), conjugated with PEG | N/A | N/A | E | 136 | RGD | Imaging of M21 tumor bearing mice | N/A | 94 |
| PET + NIR | 64 Cu-DOTA Cy5.5 | Conjugation Conjugation | 5β-Cholanic acid and azide groups modified glycol chitosan | N/A | NIR turned ON upon cleavage of MMP-sensitive peptide | C | ∼300 | MMP-sensitive peptide | Imaging of A549 tumor in mice | N/A | 95 |
| PET + NIR | 124I-labeled chlorophyll-a cyanine dye | Encapsulation Conjugation | PAA | N/A | — | A | 18–25 | N/A | Imaging of Colon26 tumors in mice | Chlorophyll-a (PDT) | 96 |
a Formulation methods: refer to Fig. 1.