Click Chemistry-Based Bioconjugation of Iron Oxide Nanoparticles

Superparamagnetic iron oxide nanoparticles (SPIONs) exhibit unique properties for diverse biomedical applications, including drug delivery and diagnostic imaging. Actively targeted SPIONs enhance delivery to diseased sites, reducing side effects and enhancing treatment efficacy. However, the development of reproducible functionalization protocols is challenged by the erratic behavior of nanoparticles in suspensions, such as agglomeration and sedimentation. In this study, a functionalization method is developed and systematically optimized to attach the Fc-region of antibodies onto silica-coated SPIONs via click chemistry, ensuring controlled ligand orientation on the particle surface. The synthesis and successive modifications of silica-coated SPIONs with organic moieties are presented resulting in the final click conjugation with antibodies targeting intercellular adhesion molecule 1 (ICAM1). This protein is upregulated on epithelial cell surfaces during gastrointestinal inflammation. Thermogravimetric analysis and infrared spectroscopy confirm successful SPION functionalization after each modification step. Cell viability assessment indicates no adverse effects of bioconjugated particles. Quantitative elemental analysis reveals significantly higher iron concentration in inflammation-induced Caco-2 cells exposed to ICAM1-modified particles compared to non-conjugated counterparts. Furthermore, laser scanning confocal microscopy of these cells suggests surface interaction and internalization of bioconjugated SPIONs, underscoring their potential for targeted imaging and therapy in inflammatory diseases.