Inflammation imaging by silica nanoparticles with antibodies orientedly immobilized

The objective of this study is to design fluorescent nanoprobes for inflammation imaging. An antibody against CD11b expressed on the surfaces of mouse macrophages (anti-CD11b), was fluorescently labeled. Protein G, which has an ability to bind the Fc region of antibody, was conjugated onto the surface of silica nanoparticles (SiNP). Then, the fluorescent-labeled anti-CD11b was orientedly immobilized to the SiNP surface through the specific protein G-antibody interaction. After the intravenous injection of anti-CD11b orientedly immobilized SiNP to the mouse model of acute interstitial nephritis, unilateral ureteral obstruction (UUO) of one kidney, the fluorescent intensity at the UUO and non-treated, normal kidneys was assessed. The anti-CD11b orientedly immobilized SiNP were accumulated in the UUO kidney to a significantly great extent compared with the normal, non-inflamed kidney. The fluorescence intensity of inflamed kidney 6 and 12 h after injection of the anti-CD11b orientedly immobilized SiNP were significantly higher than that of anti-CD11b randomly immobilized SiNP or free anti-CD11b injection. Histological experiments revealed that the anti-CD11b orientedly immobilized SiNP were associated with macrophages infiltrated into the inflammation site. It is concluded that the anti-CD11b orientedly immobilized SiNP are promising nanoprobes to image the inflammation site at a high intensity.