Intrinsically 64Cu-labeled TCPP-PEG nanoparticles. (a–d) Thin-layer chromatography (TLC) plates of TCPP-PEG nanoparticles at various time points after mixing 64Cu with TCPP-PEG nanoparticles: a) TCPP-PEG2K, b) TCPP-PEG5K, c) TCPP-PEG10K, and d) TCPP-PEG30K. (e–h) Quantified labeling yield of 64Cu on TCPP-PEG nanoparticles at various time points after incubation (n = 3): e) TCPP-PEG2K, f) TCPP-PEG5K, g) TCPP-PEG10K, and h) TCPP-PEG30K.(i–l) Stability test of 64Cu labeling on TCPP-PEG nanoparticles after incubation in serum with or without NOTA competitive reaction at 37 °C for different periods of time: i) TCPP-PEG2K, j) TCPP-PEG5K, k) TCPP-PEG10K, and l) TCPP-PEG30K.