Magnetic nanoparticle-mediated non-invasive imaging and eradication of lymph nodes

Regional lymph node (LN) dissection is often used for the treatment of deep LNs in tumour surgery; however, the method is prone to incomplete LN dissection, trauma, complications, and other side effects. LN tracers make it easier to visualise and remove LNs. However, the current common LN tracers only have a single function or have radiation hazards related to their use. Therefore, the use of multi-functional LN tracers to improve the efficiency of deep LN eradication and reduce trauma and complications is currently a major challenge to be addressed. This study aimed to develop a multi-functional citrate-coated magnetite nanoparticle (CMNP) that could specifically drain to and accumulate in LNs. The CMNPs can be used as photoacoustic imaging contrast agents and magnetic resonance imaging contrast agents to image LNs. When an alternating magnetic field is applied, the CMNP can generate heat and raise the temperature of LNs, which is sufficient to coagulate and necrotise the LNs, thereby achieving LN inactivation. Eradication of LNs by magnetic hyperthermia is not limited by depth, and only LNs are specifically heated. Moreover, the method is less invasive and accurate for deep LNs.