Quantitative analysis of palladacycle-tagged PLGA nanoparticle biodistribution in rat organs by means of atomic absorption spectrometry and inductively coupled plasma mass spectrometry

Abstract

In the present study, the biodistribution of PLGA nanoparticles labelled with Pd in the form of a dimeric cyclopalladated derivative of N,N-dimethyldiphenylmethylamine (PLGA/Pd NPs) was investigated in rats using graphite furnace atomic absorption spectrometry (GFAAS) and inductively coupled plasma mass spectrometry (ICP-MS). Sample preparation conditions were selected for complete degradation (microwave digestion) of biological samples and Pd dissolution for further study by the GFAAS and ICP-MS techniques. The detection limits (LODs) were 0.7 ng mL⁻¹ (GFAAS) and 0.05 ng mL⁻¹ (ICP-MS). The PLGA/Pd NPs obtained by ultrasonication had an average size of ∼189.0 nm; the Pd content was 18.2 μg mg⁻¹ PLGA. The Pd label was stably retained in the palladacycle-loaded PLGA nanoparticles with only 0.7% of Pd released within 4 h of incubation in the model medium (PBS, 37 °C). The Pd content in rat organs was evaluated 2 h post intravenous administration of the PLGA/Pd NPs after complete degradation of biological samples and Pd dissolution for further analysis by the GFAAS and ICP-MS techniques. The biodistribution profile of the Pd characterized by typical for the NP accumulation in the RES organs (liver: 70% of the dose, spleen: 26% of the dose) with minor uptake (<1%) in the lungs, kidneys, brain, and heart suggests that poorly soluble cyclopalladated complexes may serve as suitable labels for evaluation of the NP biodistribution.