(536o) Designing Targeted Magnetic Nanoparticles Via Click Chemistry to Diagnose Inflammatory Bowel Disease

Introduction: Superparamagnetic iron oxide nanoparticles (SPION) are promising for targeted drug delivery. They can be easily functionalized with targeting ligands, exhibit hyperthermia for triggered drug release and are active as MRI contrast agents.¹ However, due to the lack of scalable and reproducible synthesis methods, few SPION-based medicinal products have reached the clinics. Flame spray pyrolysis (FSP) is an industrially established synthesis process that allows large-scale manufacture of SPIONs. We have developed a single-step flame process for encapsulating SPION with a thin SiO₂ coating^2,3 that increases their biocompatibility and facilitates further functionalization with e.g. targeting ligands by click chemistry. We hypothesize that by functionalizing SPIONs with ligands that target overexpressed biomarkers in the intestinal tissue, we can develop MRI active biosensors for monitoring inflammatory bowel disease (IBD) progression in vivo.

Methods: Pure and manganese-doped (Mn_xFe_3-xO₄; x=0.25, 0.5, 0.75) iron oxide nanoparticles with a thin SiO₂-coating were made through flame spray pyrolysis.¹ T2 relaxivity of synthesized SPIONs was measured on a preclinical MRI system of 3T magnetic field strength. SPIONs were modified by installing an initial amine functional group through silylation reaction using 3(aminopropyl)triethoxysilane (APTES) and analyzed using Fourier Transform Infrared (FTIR) spectroscopy. Thermogravimetric analysis (TGA) was used to compare the amount of organic material on the SPION surface between different functionalization strategies. An organic linker with a terminal alkyne was synthesized through EDC-NHS cross coupling, which was confirmed by nuclear magnetic resonance (NMR). The hydrodynamic particle size was measured by dynamic light scattering (DLS) and the zeta potential by electrophoretic light scattering (ELS). SPION surface is conjugated with IBD targeting ligand via click chemistry by using SiteClick^TM Antibody Azido Modification Kit. Targeting capability of the functionalized SPIONs are evaluated in vivo in a mouse model for acute colitis where inflammation in the distal colon is induced by addition of dextran sulfate sodium in their drinking water.⁴

Results: MRI measurements demonstrated that manganese-doped SPION have moderately higher T2 relaxivity, with Mn0.5-doped particles exhibiting the highest. Successful amine-functionalization of SPION using APTES was confirmed by FTIR spectroscopy. Hydrodynamic size did not change before and after APTES-modification, however, the zeta potential changed considerably from ζ = -29,3 mV for SPION to ζ = 28,7 mV for the APTES-functionalized SPION. The linker attached on the SPION surface was obtained through EDC/NHS cross coupling reaction of 6-heptynoic acid (94 % yield), confirmed by NMR spectroscopy. Global proteomics has been used to identify ICAM-1 as a promising target luminal biomarker in in vitro and in vivo preclinical models for IBD.⁴ In our ongoing work, we are coupling the linker-modified SPIONs with antibodies for ICAM-1 and evaluating their targeting capability after oral administration to our in vivo model for IBD.

Conclusions: Local diseases in the gastrointestinal tract (GIT), such as IBD, can be targeted using functionalized iron oxide nanoparticles. The magnetic properties of the particles makes them useful for the development of an MRI-based diagnostic platform to detect and localize diseases in the GIT.

References: [1] Ling, D., Hyeon, T., Small. 9, 9-10, (2013). [2] Teleki, A., M. Suter, P.R. Kidambi, O. Ergeneman, F. Krumeich, B.J. Nelson, and S.E. Pratsinis, Chem. Mater. 21, 10, (2009). [3] Teleki, A., F.L. Haufe, A.M. Hirt, S.E. Pratsinis, and G.A. Sotiriou, RSC Adv. 6, 26, (2016). [4] Asad, S., Wegler, C., D. Ahl, C.A.S. Bergström, M. Phillipson, P. Artursson and A. Teleki, J. Pharm. Sci. 110, 1 (2021).