Impact of dose and surface features on plasmatic and liver concentrations of biodegradable polymeric nanocapsules

Abstract

The effect of polymeric nanocapsule dose on plasmatic and liver concentrations 20min after intravenous administration in mice was evaluated. Nanocapsules were prepared with different polymers, namely, poly(D,L-lactide) (PLA), polyethylene glycol-block-poly(D,L-lactide) (PLA-PEG), and PLA with chitosan (PLA-Cs) and compared with a nanoemulsion. These formulations were labelled with a phthalocyanine dye for fluorescent detection. The nanostructures had narrow size distributions upon separation by asymmetric flow field flow fractionation with static and dynamic light scattering detection, with average hydrodynamic diameters in the 130-300nm range, negative zeta potentials, except PLA-Cs nanocapsules, which had a positive zeta potential. Flow cytometry revealed uptake mostly by monocytes and neutrophils in mice and human blood. PLA nanocapsules and the nanoemulsion showed dose-dependent plasma concentrations, where the percentage of plasmatic fluorescence increased with increasing administered dose. In contrast, PLA-PEG nanocapsules led to a dose-independent plasmatic profile. PLA-Cs nanocapsules showed the lowest plasmatic and liver levels of fluorescence at all administered doses and significant intravenous toxicity in mice. This work demonstrates the importance of considering the nanocarrier dose when evaluating pharmacokinetic and biodistribution data and emphasizes the role of surface features in determining the plasmatic and liver concentrations of a poorly soluble lipophilic encapsulated compound.

Keywords: AlClPc; Chitosan; Chitosan (75–85% deacetylated, low molecular weight, Pubchem CID 71853); Field flow fractionation; Nanocapsules; PLA-PEG; Phthalocyanine; Pluronic® F68 (Pubchem CID 24751); Poly(D,L-lactide) (PLA Mw 75,000–120,000g/mol, Pubchem SID 135022784); Polyethylene glycol-block-poly(D,L-lactide) (PLA-PEG, Pubchem CID 125226); Polymer dose; Soy lecithin (Epikuron™ 170, Pubchem CID 57369748); ZnPc [zinc(II) phthalocyanine] (Pubchem CID 2735172); [chloro(29H,31H-phthalocyaninato)aluminium (Pubchem CID 123667).