Synthesis and characterization of Gd-DTPA/fucoidan/peptide complex nanoparticle and in vitro magnetic resonance imaging of inflamed endothelial cells

P-selectin overexpressed on activated endothelial cells and platelets is a new target for treatment of cancers and cardiovascular diseases such as atherosclerosis and thrombosis. In this study, depolymerized low molecular weight fucoidan (LMWF₈₇₇₅) and a thermolysin-hydrolyzed protamine peptide (TPP₁₈₈₀) were prepared. TPP₁₈₈₀ and LMWF₈₇₇₅ were able to form self-assembled complex nanoparticles (CNPs). The formation of TPP₁₈₈₀/LMWF₈₇₇₅ CNPs was characterized by Fourier-transform infrared spectra, circular dichroism spectra and isothermal titration calorimetry. The CNPs selectively targeted PMA-stimulated, inflamed endothelial cells (HUVECs) with high expression of P-selectin. Gd-DTPA MRI contrast agent was successfully loaded in the CNPs with better T₁ relaxivity and selectively accumulated in the activated HUVECs with increased MRI intensity and reduced cytotoxicity as compared to free Gd-DTPA. Our results suggest that the TPP₁₈₈₀/LMWF₈₇₇₅ CNPs may have potential in future for early diagnosis of cardiovascular diseases and cancers in which the endothelium is inflamed or activated.