cRGD-Functionalized Calcium Carbonate Nanoprobe for Enhanced NIR-II Fluorescence Imaging and Tumor-Targeted Navigation
Lenan Wang, Linxuan Shi, Zhaorui Song, Qifan Wu, Ziqin Chen, Feifei Cui, Wenhong Dong, Meng Meng, Zili Zhang, Qi Xin, Zhen ChengAbstract
Indocyanine green (ICG) holds promise for near-infrared-II (NIR-II) fluorescence imaging but is hindered by poor photostability, rapid clearance, and lack of targeting specificity. To address these challenges, we engineered a tumor-targeted nanoprobe (cRGD@ICN) by encapsulating ICG within a calcium carbonate (CaCO3) core, followed by surface functionalization with phospholipids and cyclic RGD (cRGD) peptides. The CaCO3 encapsulation enhanced ICG photostability and amplified NIR-II emission by 9.21-fold relative to free ICG. Meanwhile, cRGD conjugation enabled active targeting of integrin αvβ3, a receptor overexpressed on diverse tumor types. cRGD@ICN showed receptor-mediated endocytosis with specific uptake in HCT116, 4T1, and U87 cells in vitro, along with selective accumulation in human ex vivo colorectal cancer tissues. In vivo NIR-II fluorescence imaging revealed that cRGD@ICN achieved high-contrast tumor monitoring with a signal-to-background ratio (SBR) of 6.54 at 16 h postinjection in HCT116 tumor-bearing mice─markedly outperforming the nontargeted control. More importantly, it also exhibited remarkable tumor-targeting ability across other tumor models (U87, 4T1). With precise tumor imaging, we performed real-time NIR-II fluorescence-guided resection of colorectal tumors, confirmed by the absence of residual tumor in the surgical cavity by H&E analysis. Moreover, primary biosafety assessments confirmed favorable biocompatibility. This work provides a promising strategy to transform ICG into a high-performance NIR-II fluorescent nanoprobe and offers a potential approach for precision image-guided oncologic surgery.