Size |
<0.5 kDa |
0.5–2 kDa |
5–15 kDa |
150 kDa |
55 kDa |
10–100 nm |
1–4 μm |
Example |
18F-FDG |
Cyclic RGD peptide |
[99Tc]-TTA-1 |
Cetuximab-IRDye800 |
[18F]FB-T84.66 |
EGFR antibody-gold nanoparticle |
VEGFR2-targeted microbubble |
Advantage |
Easy escape vasculature. |
Easily modified. Superior selectivity. |
Inexpensive production. High diversity. |
High affinity and specificity. |
Superior tumor penetration. High tumor- to blood ratio. |
Effective delivery of signaling and therapeutic payload. |
Good safety, wide availability of contrast mode ultrasound scanner |
Drawback |
Costly development. Limited size for the signaling component. |
Rapid degradation. |
Low in vivo stability. Poor membrane passage. |
Slow clearance. Restricted in passing biological barriers. |
Accumulation in kidneys. |
Difficult extravasation due to size. |
Imaging limited to molecular targeted differentially expressed on tumor vasculature |