*2.2. Preparation of NOTA-PODS-ZEGFR:03115 and NODAGA-PODS-ZEGFR:03115*

The bifunctional chelators were conjugated to ZEGFR:03115 in a one-pot reaction using TCEP-HCl as the reducing agent (Scheme 2, Figure S6). A quantitative yield was achieved using a lower molar excess of PODS-bifunctional chelator to protein compared to a conventional maleimide-based chelator (15 vs. 35 equivalents). Being the great molar excess necessary as a consequence of the inhibition of the reactivity of maleimide-based compounds by TCEP, this result suggests that PODS is not as susceptible to TCEP as maleimides [18]. To obtain extremely pure products for the subsequent radiolabeling reaction, a single final purification of the conjugates by semi-preparative HPLC was performed (Figure 1). The pure compounds were isolated in a ca. 38% and ca. 24% yield for NOTA-PODS-ZEGFR:03115 and NODAGA-PODS-ZEGFR:03115, respectively. All products were characterized by ESI mass spectrometry (Figure S7).

**Scheme 2.** Preparation of [18F]AlF-NOTA-PODS-ZEGFR:03115 and [18F]AlF-NODAGA-PODS-ZEGFR:03115. Reaction conditions: (a) TCEP-HCl, 1 M phosphate buffer pH 7; (b) AlCl3 in sodium acetate pH 4, [18F]Faq./ethanol 1:1 (*v*/*v*), for 15 min, and at 100 ◦C.

**Figure 1.** RP–HPLC analysis of NOTA-PODS-ZEGFR:03115 (**A**), and NODAGA-PODS-ZEGFR:03115 (**B**). The absorbance was recorded at the wavelength of 280 nm. The retention time (Rt) is indicated as min:sec.
