Bismuth-213 CHX-A''-DTPA-liposome chelation site (213Bi-CHX-DTPA-liposome)

Bismuth-213 CHX-A''-DTPA-liposome chelation sites refer to the specific chemical coordination environments within a liposomal delivery system designed to carry the alpha-emitting radioisotope Bismuth-213 (213Bi). This entity is not a biological target (such as a receptor or enzyme) but is instead a component of a radiopharmaceutical complex used in Targeted Alpha Therapy (TAT). The system utilizes the bifunctional chelator CHX-A''-DTPA, which is known for its high stability and rapid kinetics in binding bismuth ions, thereby preventing the release of toxic free radiometals into the systemic circulation (Brechbiel, 2008). Liposomes serve as the primary carrier, enhancing the pharmacokinetic profile of the short-lived isotope and facilitating its delivery to tumor sites. In a clinical context, these chelation sites are critical for ensuring that the high-energy alpha radiation is localized to the intended disease site, such as micrometastases or hematological malignancies. Once the liposomes reach the target tissue, the decay of 213Bi produces alpha particles that cause irreparable damage to the DNA of cancer cells (Chang et al., 2008). Because alpha particles have a very short range in human tissue, this approach minimizes collateral damage to surrounding healthy organs. This technology represents a sophisticated intersection of nanotechnology and nuclear medicine, aimed at overcoming the limitations of conventional beta-emitting radiopharmaceuticals.

Other names

213Bi-labeled liposomesCHX-A''-DTPA-functionalized liposomesBismuth-213 liposomal chelate213Bi-CHX-A''-DTPA complex

The complex functions as a delivery vehicle for Targeted Alpha Therapy (TAT). The liposome encapsulates or presents surface-bound CHX-A''-DTPA chelators that sequester the alpha-emitting radioisotope Bismuth-213. Upon administration, the liposomes accumulate in tumor tissues via the enhanced permeability and retention (EPR) effect or active targeting. The Bismuth-213 then undergoes alpha decay, releasing high-energy alpha particles with a short path length (50-100 μm) that induce lethal double-strand DNA breaks in adjacent malignant cells while sparing distant healthy tissue (Henriksen et al., 2004; Milenic et al., 2004).