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. 2021 Oct 15;12(2):867–875. doi: 10.1016/j.apsb.2021.09.032

Figure 3.

Figure 3

Binding affinity and cellular uptake. (A) The SPR assay determined binding kinetics constants (KD) between non-radioactive reference standards (NOTA-P-FAPI, NOTA-FAPI-42, and DOTA-FAPI-04) and human recombinant FAP proteins. (B) Binding of [18F]AlF-P-FAPI and [18F]FAPI-42 to different cell lines, including cell lines transfected with human FAP, after 60 min of incubation. (C) Uptake of [18F]AlF-P-FAPI in A549-FAP cells after incubation for 5–120 min, with and without blocking using DOTA-FAPI-04 as competitor. (D) Internalization of [18F]AlF-P-FAPI and [18F]FAPI-42 into A549-FAP cells after a 60 min incubation period. (E) Efflux kinetics of [18F]AlF-P-FAPI and [18F]FAPI-42 after 60 min of incubation of A549-FAP cells with radiolabeled compounds, followed by incubation with compound-free medium for 5–120 min. The % ID/1 mio cells represents the percentage of total applied dose normalized to 1 million cells. Data were represented as mean ± SD (n = 4), ∗P < 0.05; ∗∗∗P < 0.001.