Single-domain-antibody self-assembled nanoparticles for molecular imaging of oral cancers

Objectives: Gene expression profile of cancers is known to be highly associated with clinical behavior, drug resistamce and prognosis. The unique surface markers have also been used as the primary target of functional nanoparticles to improve cancer diagnosis and therapy. This study developed a platform of modularly designed targeting nanoparticles for cancer theranostics. Methods: M13 phage display system engineered with humanized single domain antibody (SdAb) were engineered to tag 6-His peptide. The cancer targeting ligand showed high stability upon pH and thermal challenges and are of low immunogenic activity. The single domain antibody has a size about one tenth of a normal IgG. Hydroxy terminated polyester dendrons were synthesized from the chain-ends of linear PEG and 2,2-bis(hydroxymethyl)propionic acid. DTPA was selectively activated to attach to the dendrimers. The gadolinium complexed dendrimers were synthesized by addition of gadolinium salt. Fe3O4 nanoparticles weer engineered with Ni-NTA on the surface through crosslinking amino groups of NTA to the nanoparticle surface. Results: both types of nanoparticles presented satisfactory biocompatibility. The dendrimer showed positive MR contrast while the magnetite nanoparticle presented negative contrast effect. The antibody formed self-assembly monolayer on nanoparticle surface with improved targeting. The in-vitro MRI imaging showed a successful contrast imaging of oral cancer cells overexpress the target molecule, while the control HNOK cells were negative. Conclusion: In the current study, we have demonstrated the platform of modularly designed targeting functional nanoparticles through molecular recognition of 6-His peptide tag and Ni-NTA. These nnoparticle contrasts presented capability of MR molecular imaging in vitro. Future development of in vivo functional imaging is warranted.