Surface-modified ^99mTc-Lactoferrin nanoparticles as tracers for sentinel lymph node mapping

We had previously examined the use of radioactive technetium-99m (Tc-99m)-labelled lactoferrin nanoparticles (LF-NPs) for sentinel lymph node (SLN) mapping. Compared with commercial tracer based on human serum albumin, LF-NPs exhibited better size uniformity and reduced batch variation. However, while in vitro tests with ^99mTc-LF-NPs in RAW 264.7 macrophages were promising, the in vivo results revealed poor accumulation in the SLNs. To improve their in vivo performance, we performed surface modification of LF-NPs with different agents, including polyethylene glycol (PEG). Characterisation studies revealed that PEGylated LF-NPs (LF-NP@PEG) were the most effective. In vitro tests revealed significantly greater cellular uptake of LF-NP@PEG than unmodified LF-NPs. In vivo evaluation in animal model demonstrated increased SLN uptake and retention, which was supported by scintigraphic imaging studies. Although further refinements are needed, these findings suggest potential application for modified LF-NPs in SLN detection.