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FIGURE 1. (A) "Import-export" model showing bidirectional movement of 8D3 mAb to TfR. Bidirectional movement of PNA-8D3 conjugate across either BBB or BCM is possible because of ability of 8D3 mAb to access endogenous transport pathways for transferrin, which exist at both cellular barriers. Access to TfR pathways allows PNA radiopharmaceutical to move between blood and intracellular compartment of target cell. (B) Conjugation of PNA to 8D3 mAb to TfR creates bifunctional molecule that both accesses TfR for transport between tissue compartments and binds to target mRNA based on sequence specificity of nucleotide residues of PNA radiopharmaceutical. PNA has biotin moiety at amino terminus to allow for capture by conjugate of 8D3 mAb and SA and has carboxyl terminal tyrosine (Tyr) or lysine (Lys) residues to allow for radiolabeling with 125I or 111In, respectively.
