<p>Affibody-Modified Gd@C-Dots with Efficient Renal Clearance for Enhanced MRI of EGFR Expression in Non-Small-Cell Lung Cancer</p>

Purpose: Gd-encapsulated carbonaceous dots ( [email protected] ) have excellent stability and magnetic properties without free Gd leakage, therefore they can be considered as a safe alternative T1 contrast agent to commonly used Gd complexes. To improve their potential for cancer diagnosis and treatment, affibody-modified [email protected] targeting non-small-cell lung cancer (NSCLC) EGFR-positive tumors with enhanced renal clearance were developed and synthesized. Materials and Methods: [email protected] were developed and modified with Ac-Cys-Z EGFR:1907 through EDC/NHS. The size, morphology, and optical properties of the [email protected] and [email protected] EGFR:1907 were characterized. Targeting ability was evaluated by in vitro and in vivo experiments, respectively. Residual gadolinium concentration in major organs was detected with confocal imaging and inductively coupled plasma mass spectrometry (ICP-MS) ex vivo. H&E staining was used to assess the morphology of these organs. Results: [email protected] with nearly 20 nm in diameter were developed and modified with Ac-Cys-Z EGFR:1907 . EGFR expression in HCC827 cells was higher than NCI-H520. In cell uptake assays, EGFR-expressing HCC827 cells exhibited significant MR T1WI signal enhancement when compared to NCI-H520 cells. Cellular uptake of [email protected] EGFR:1907 was reduced, when Ac-Cys-Z EGFR:1907 was added. In vivo targeting experiments showed that the probe signal was significantly higher in HCC827 than NCI-H520 xenografts at 1 h after injection. In contrast to [email protected] , [email protected] EGFR:1907 nanoparticles can be efficiently excreted through renal clearance. No morphological changes were observed by H&E staining in the major organs after injection of [email protected] EGFR:1907 . Conclusion: [email protected] EGFR:1907 is a high-affinity EGFR-targeting probe with efficient renal clearance and is therefore a promising contrast agent for clinical applications such as diagnosis and treatment of NSCLC EGFR-positive malignant tumors. Keywords: [email protected] , EGFR, MRI, nanoparticles, efficient renal clearance