*2.3. In Vitro Studies*

#### *2.3. In Vitro Studies* 2.3.1. Serum Stability of the <sup>225</sup>Ac-rHDL System

2.3.1. Serum Stability of the 225Ac-rHDL System The 225Ac-rHDL was incubated in fresh human serum at 37 °C for 10 d. During the analysis of the samples at 24, 72, 144, and 240 h, the radioactivity associated with the rHDL system remained greater than 99%. It is important to mention that, according to what has previously been reported [11,12], the 225Ac daughters (alpha emitters) can escape from the carrier vehicle and irradiate non-target tissues. However, the successful 225Ac-DOTAbenzene-p-SCN encapsulation into the hydrophobic vesicle of rHDL allowed the retention The <sup>225</sup>Ac-rHDL was incubated in fresh human serum at 37 ◦C for 10 d. During the analysis of the samples at 24, 72, 144, and 240 h, the radioactivity associated with the rHDL system remained greater than 99%. It is important to mention that, according to what has previously been reported [11,12], the <sup>225</sup>Ac daughters (alpha emitters) can escape from the carrier vehicle and irradiate non-target tissues. However, the successful <sup>225</sup>Ac-DOTAbenzene-p-SCN encapsulation into the hydrophobic vesicle of rHDL allowed the retention of <sup>225</sup>Ac and its progeny within the nanosystem.
