Ccomplished by 30 min incubation in the activity of 30 MBq [99mTc]Tc/nmol DB15 with Tc-99m for preclinical testing (molecular radiolabel99m Tc]Tc/nmol peptide) was 200 MBq [mixture, containing DB15, [99maccomplished by 30 citrate anions, atof the radiing reaction Tc]TcO4-, SnCl2 and min incubation pH 11 and olabeling reaction mixture, containing DB15, [99m Tc]TcO4 – , SnCl2 and citrate to reachat at room temperature. For clinical testing, the labeling reaction was modified anions, a pH 11 molecular activity (greater than 50 MBq [99mTc]Tc/nmol peptide). was modified to labeling reaction larger and at space temperature. For clinical testing, the 99m reach a both circumstances, high-quality manage of your radiolabeled solution Glycol chitosan Protocol involved ITLC and HPLC larger molecular activity (greater than 50 MBq [ Tc]Tc/nmol peptide). In In both situations, high-quality control from the radiolabeled item involved ITLC and HPLC methods (Supplementary File). Practically quantitative radiochemical yields (98 ) had been esmethods (Supplementary File). Practically quantitative radiochemical yields (98 ) have been 99m tablished with significantly less than 2 of total radiochemical impurities ([99mTc]TcO4-, [- Tc]Tc-citestablished with much less than two of total radiochemical impurities ([99m Tc]TcO4 , [99m Tc]Tc99mTc]TcO2 nH2O) present, whereas HPLC revealed the formation of a single price and [ 99m citrate and [ Tc]TcO nH2 O) present, whereas HPLC revealed the formation of a single 99m radiochemical species2 (Figures S1 and S2; Supplementary File). Hence, [99mTc]Tc-D15 radiochemical species (Figures S1 and S2; Supplementary File). Thus, [ Tc]Tc-D15 was employed devoid of further radiochemical purification [35]. was employed devoid of additional radiochemical purification [35]. 3.2. Binding Biotin-azide Purity affinity of DB15 for the Human GRPR 3.2. Binding Affinity of DB15 for the Human GRPR 125 4 As shown in Figure 2, DB15 displaced the [125 I]I-[Tyr4]BBN radioligand from PC-3 As shown in Figure 2, DB15 displaced the [ I]I-[Tyr ]BBN radioligand from PC-3 cell membranes within a monophasic and dose-dependent way, displaying a higher binding cell membranes inside a monophasic and dose-dependent way, displaying a larger binding four affinity for the human GRPR (IC 50 = 0.37 0.03 nM, n = 3) compared using the [Tyr4 ]BBN affinity for the human GRPR (IC = 0.37 0.03 nM, n = 3) compared with the [Tyr ]BBN 50 reference (IC50 = 1.33 0.09 nM, n = three). reference (IC = 1.33 0.09 nM, n = three).distinct binding75 50 25 0 10 -13 10 -12 10 -11 ten -10 10 -9 10 -8 10 -7 ten -[peptide] (M)Figure 2. Displacement of [125of [125 I]I-[Tyrby growing concentrations of DB15 (, ICDB15 ( 2. Displacement I]I-[Tyr4]BBN four ]BBN by growing concentrations of 50 = 0.37 0.03 nM) or0.03 nM) ( reference, 1.33 reference, 1.33 0.09cell membrane homogenates; benefits [Tyr4]BBN or [Tyr4 ]BBN ( 0.09 nM) from PC-3 nM) from PC-3 cell membrane hoIC50 = 0.37 represent typical values SD of three experiments performed in triplicate. mogenates; benefits represent average values SD of three experiments performed in triplicate.3.three. GRPR-Specific Uptake of [99m Tc]Tc- DB15 by PC-3 and T-47D Cells Time-dependent cell association curves of [99m Tc]Tc-DB15 in PC-3 and T-47D cells are shown in Figure 3. High and specific uptake was observed in the course of 30 min incubation of [99m Tc]Tc-DB15 in PC-3 (13.1 0.1 ) and T-47D cells (24.2 0.7 ) at 37 C. The majority of radioactivity was linked using the cell-membrane using a smaller sized portion (six ) located within the cells, as expected for any GRPR-radioantagonist [20,35,41]. Cel.
