(415e) Bioconjugated Magnetic Nanoparticles for Non-Invasive Diagnosis of Inflammatory Bowel Disease

Superparamagnetic iron oxide nanoparticles (SPIONs) have emerged as versatile tools in biomedical research, promising innovative solutions for disease treatment, diagnosis, and monitoring. SPIONs are suitable as contrast agents for magnetic resonance imaging (MRI). However, their potential for targeted diagnosis of gastrointestinal (GI) diseases such as inflammatory bowel disease (IBD) has so far been limited. In this study, we have investigated the targeting capability of bioconjugated SPIONs towards inflamed intestinal tissue and developed a protocol for their in vivo administration and subsequent ex vivo evaluation using imaging techniques. We synthesize and successively modify silica-coated SPIONs with organic moieties to enable click chemistry-based bioconjugation with anti-ICAM1 and anti-CEACAM1 antibodies. These antibodies target proteins that are upregulated on the epithelial cell surface during inflammation in the GI tract.¹ Thermogravimetric analysis and Fourier transform infrared spectroscopy confirm successful functionalization of SPIONs following each modification step. Assessment of cell viability indicates no adverse toxic effects of the bioconjugated particles.

Our functionalization approach facilitates the controlled orientation of the ligand on the particle surface, exposing the antigen-binding site to enable particle binding to target sites. Quantitative analysis reveals a significantly higher concentration of iron in inflamed Caco-2 cells upon exposure to ICAM1-modified particles compared to non-conjugated counterparts. Furthermore, laser scanning confocal microscopy of inflammation-induced Caco-2 cells suggests surface interaction and internalization of the bioconjugated SPIONs, highlighting their potential for targeted imaging in inflammatory diseases. Further, we designed an experimental protocol for incubating bioconjugated nanoparticles in the colon of mice in vivo. Inflammation was chemically induced in the GI tract of the mice prior to nanoparticle administration to resemble ulcerative colitis in humans. Our findings suggest that rectal administration can be an effective approach for nanoparticle delivery to the colon. The developed experimental procedure enabled exploration of the targeting potential of the bioconjugated SPIONs using laser scanning confocal microscopy and MRI. Confocal micrographs showed preferential accumulation of Ceacam1-conjugated SPIONs in severely inflamed regions, while particles in moderately damaged areas were primarily localized above the epithelial layer, hindered by the presence of the mucus barrier. This spatial distribution indicates the utility of targeted nanoparticles for characterizing the degree and severity of the active inflammation. Overall, our findings demonstrate the potential of SPION-based systems for precise imaging and therapeutic interventions in GI diseases.

Acknowledgement:

This project has received funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (grant agreement No. 101002582). The authors also acknowledge financial support from the Science for Life Laboratory.

References:

1. Asad, S., C. Wegler, D. Ahl, C.A.S. Bergström, M. Phillipson, P. Artursson, and A. Teleki, “Proteomics-informed identification of luminal targets for in situ diagnosis of inflammatory bowel disease,” J. Pharm. Sci. 110, 239 (2021).