Biodistribution of Tc-99m-Labeled Solid Lipid Nanoparticles and Evaluation of Their Possibility as a Radiopharmaceutical

TL;DR

This study explores using radiolabeled solid lipid nanoparticles for imaging, showing they target the liver and spleen in rabbits.

Contribution

The study demonstrates the potential of 99mTc-labeled SLNs as a novel radiopharmaceutical for liver–spleen imaging.

Findings

99mTc-labeled SLNs showed high radiolabeling efficiency (>95%) and were taken up mainly by the liver and spleen.

Ex vivo analysis confirmed the in vivo findings, showing significant uptake in RES organs.

Confocal microscopy supported the biodistribution results in liver and spleen tissues.

Abstract

Solid lipid nanoparticles (SLNs) are submicron colloidal systems widely investigated as drug carriers; however, their intrinsic biodistribution properties are also critical when SLNs are considered for diagnostic imaging. In the present proof-of-concept study, drug-free SLNs were evaluated exclusively as a radiolabeled imaging agent rather than as a drug delivery system. SLNs were radiolabeled with Technetium-99m (99mTc), and their in vivo biodistribution was investigated using gamma camera imaging, ex vivo organ counting, and confocal microscopy. SLNs were prepared by a microemulsion–low-temperature solidification method and characterized by dynamic light scattering (DLS), scanning electron microscopy (SEM), and differential scanning calorimetry (DSC). Radiolabeling efficiency was determined by instant thin-layer chromatography (ITLC) and exceeded 95%. Following intravenous administration in a rabbit model, dynamic scintigraphic imaging demonstrated predominant uptake in the liver and spleen. These findings were quantitatively confirmed by ex vivo biodistribution analysis at 4 h post-injection and qualitatively supported by confocal microscopy of liver and spleen tissues. The results indicate that 99mTc-labeled SLNs behave as RES-targeting radiocolloids and may serve as potential agents for liver–spleen scintigraphy.

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