Fig. 6.

The ¹¹¹In-DTPA-AHNP-PEG preparation and stability assay. a The flowchart of ¹¹¹In-DTPA-AHNP-PEG synthesis was illustrated, where AHNP-PEG was conjugated with DTPA for indium-111 labeling. b The molecular weight assay for PEG, AHNP-PEG, and DTPA-AHNP-PEG. The molecular weights of PEG, AHNP-PEG and DTPA-AHNP-PEG were detected by using mass spectrometry. c The labeling efficiency of ¹¹¹In-DTPA-AHNP-PEG. The DTPA-AHNP-PEG was labeled with indium-111 in PBS for 1 h. ITLC was performed to analyze the radio-labeling efficiency. d The stability of ¹¹¹In-DTPA-AHNP-PEG in various pH buffers. The DTPA-AHNP-PEG was incubated at different buffer conditions (pH 6.0, 7.4, and 8.0) for 6 days at 37 °C and detected by HPLC. The results indicated that the levels of DTPA-AHNP-PEG was preserved more than 98% for 6 days. Data are presented as mean ± SEM (n = 5). *P < 0.05, versus day 0. e The stability of ¹¹¹In-DTPA-AHNP-PEG in human, fetal bovine and mouse serum. The radioactivity of ¹¹¹In-DTPA-AHNP-PEG was estimated in human, fetal bovine, and mouse serum for 144 h at 37 °C. The radioactivity was determined by ITLC. Data are presented as mean ± SEM (n = 5)