Sericin-based gadolinium nanoparticles as synergistically enhancing contrast agents for pH-responsive and tumor targeting magnetic resonance imaging

Abstract

It is of great significance to develop gadolinium (Gd) contrast agents (CAs) for pH-responsive and tumor targeting magnetic resonance imaging (MRI). Silkworm sericin (SS) is a natural biomacromolecule from silkworm cocoon with good biocompatibility, biodegradability, and a variety of biological activities. Here, sericin was covalently cross-linked with gadolinium acetate (GAH) via Schiff's base reaction, and then blended with gadolinium chloride (GdCl3) through electrostatic adsorption to yield [email protected]3 nanoparticles. Zeta potential showed [email protected]3 could respond pH change naturally, and freely realize the transition from negative surface potential in pH 7.5 to positive surface potential in pH 5.8. The T1 weighted MR images in solution indicated that [email protected]3 has higher T1 relaxivity in pH 5.8 than that in pH 7.4, and magnevist under 3.0 T magnetic field. Further, the T1 weighted MR images in vivo suggested that [email protected]3 could target tumors and accumulate around tumor tissues to achieve MR imaging on the tumor up to 2 h. Moreover, [email protected]3 is stable without any leakage of gadolinium ions. [email protected]3 is cytocompatible and does not cause hemolysis, inflammation, tissue damage, and the change of serum biochemical indicators and body weight in vivo. [email protected]3 has exhibited great potentials as a high-performance GdCA for pH-responsive and tumor targeting MRI.