Biodistribution of nanostructured lipid carriers: A tomographic study

•Radiolabelled lipid nanoparticles for biodistribution study are obtained.•99mTc-DBODC2 included in nanoparticle does not affect their morphology and dimension.•SPECT technique evaluates nanoparticle biodistribution, by high-quality images.•It was possible to detect the lipid nanoparticle presence in brown fat tissue.

This study describes the preparation, characterization, and biodistribution of radiolabelled nanostructured lipid carriers (NLCs) especially designed for in vivo tomographic study.A preliminary formulative study was conducted in order to incorporate 99mTc based tracer in NLCs. At this aim a 99mTc complex containing a terminal 99mTcN multiple bond ([99mTc]N-DBODC2) has been synthesized and included in NLCs produced by a stirring and ultrasonication method.The morphological and dimensional characteristics of the produced NLCs have been accurately investigated by a number of specific techniques, including: cryogenic transmission electron microscopy, X-ray, photon correlation spectroscopy and sedimentation field flow fractionation. The obtained NLCs were employed for achieving in vivo tomographic images of the rat body by small-animal SPECT scanner that enabled the investigation of NLC biodistribution after intraperitoneal, intravenous, intranasal and oral administration. NLC production protocol allowed to firmly encapsulate the radiotracer within the nanoparticles. In vivo studies evidenced that NLC remained stable in vivo, suggesting their suitability as controlled release system for drugs and radiochemical for therapeutic and diagnostic purposes.Moreover the high resolution images obtained by the SPECT technique allowed to detect NLC presence in brown fat tissue, suggesting NLC therapeutic application for treating human obesity and related metabolic disorders.

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