177Lu-labeled amidoxime-functionalized biodegradable microspheres for transarterial radioembolization of hepatocellular carcinoma

Purpose Transarterial radioembolization (TARE) is an important locoregional therapy for hepatocellular carcinoma (HCC). However, clinically used yttrium-90 ( 90 Y) microspheres are non-biodegradable and provide limited imaging capability, while biodegradable polymeric microspheres prepared using conventional radiolabeling strategies often exhibit poor radionuclide stability. Experimental design We designed a biodegradable radiometal-chelating microsphere based on amidoxime-functionalized polylactic acid microspheres (PLA-g-PAO-Ms) engineered via electron beam-induced graft polymerization. Results The PLA-g-PAO-Ms exhibited a high Lu 3+ loading capacity (33.83 mg g −1 ) and underwent controlled biodegradation in vitro after approximately 20 d. Cell Counting Kit-8 (CCK-8) assays confirmed favorable cytocompatibility, with both LO2 and HepG2 cell viabilities exceeding 90% after 72 h, showing no significant difference from the control group ( p > 0.05); by contrast, free Lu 3+ (50 mg·L −1 ) significantly reduced HepG2 viability to 51.4% ( p < 0.001). In a rat orthotopic liver tumor model, the intra-arterial administration of 177 Lu-labeled PLA-g-PAO-Ms ( 177 Lu-PLA-g-PAO-Ms) resulted in pronounced tumor suppression with sustained in vivo radionuclide retention for at least 14 d. Biodistribution analysis revealed selective tumor accumulation of 8.79 ± 1.74 %ID g −1 , significantly higher than that in normal liver ( 1 ± 0.54 %ID g −1 ) and other organs ( P < 0.001 ), whereas free 177 LuCl 3 showed minimal tumor uptake ( 0.30 ± 0.28 %ID g −1 ) with predominant non-target organ accumulation. Conclusion These findings suggest that PLA-g-PAO-Ms provide a biodegradable microsphere system capable of stable radiometal incorporation and effective tumor suppression following intra-arterial administration, offering a promising approach for interventional radionuclide therapy for HCC.