The Uptake and Translocation of Latex Nanospheres and Microspheres after Oral Administration to Rats

Abstract

Non-ionic and carboxylated fluorescent polystyrene microspheres (100, 500 nm, 1 and 3 microns in diameter), were fed by gavage (2.5% w/v; 1.25 mg kg-1) daily for 10 days to female Sprague Dawley rats. Peyer's patches, villi, liver, lymph nodes and spleen of animals fed the non-ionic microspheres from 100 nm to 1 micron showed unequivocal evidence of uptake and translocation of the particles. Heart, kidney and lung showed no evidence of the presence of microspheres. Carboxylated microspheres were taken up to a lesser degree than the non-ionised particles. Experiments with 125I radiolabelled 100 nm and 1 micron particles showed a higher uptake of the smaller particles, which were concentrated in GI tissue and liver. Particles were not distributed randomly in the tissues, but were concentrated at the serosal side of the Peyer's patches and could be seen traversing the mesentery lymph vessels towards the lymph nodes. The results demonstrate a need to re-examine the possibilities of particulate oral delivery, as well as the potential toxicity of ingested particulates.

Phototoxicity and cytotoxicity of fullerol in human lens epithelial cells

“…Intravenous injection of a polar C 60 derivative to rats led to accumulation of the compound in many animal organs including the brain and the eye (Jensen et al, 1996). The use of nanosized (colloid) carriers for drug delivery is described and particles have been found months after dosing in the eye (Amrite and Kompella, 2005;Bourges et al, 2003;Jani et al, 1989).…”

Correlating gastric emptying of amphotericin B and paracetamol solid lipid nanoparticles with changes in particle surface chemistry

“…The aforementioned results suggest that, in SGF+SIF, the drug-free particles retained their integrity as regards size and surface charge, which are critical features needed to augment 185 absorption via endocytosis and subsequent lymphatic transport (Jani et al, 1989(Jani et al, , 1994Shakweh et al, 2005). The increase in size observed after exposure of the particles to the media may be a result of either aggregation or ingress of the dissolution media into the particles or both.…”

Nanoparticle Formulation Increases Oral Bioavailability of Poorly Soluble Drugs: Approaches, Experimental Evidences and Theory

“…Within, the time of the experiment (30 min) none of the particles was endocytosed by the enterocytes despite the fact that the latex nanoparticles preferentially bound the cell surface more strongly than the mucus. After a longer time window (oral gavage for several days) a sparse accumulation of charged particulates in the lamina propria (connective tissue under the epithelia) was found compared to uncharged latex nanoparticles in the same size range [23].…”

“…Charged particles, such as carboxylated polystyrene nanoparticles [23] or those composed of positively charged polymers exhibit poor oral bioavailability through electrostatic repulsion and mucus entrapment. Szentkuti [28] determined the rate of particle diffusion across the mucus layer to the enterocyte surface with respect to both size and surface charge of the particles, and found that cationic nanometer-sized latex particles became entrapped in the negatively charged mucus, whereas repulsive carboxylated fluorescent latex nanoparticles were able to diffuse across this layer.…”

“…Initially it was assumed that the Peyer's patches did not discriminate clearly in the type and size of the absorbed particles. Later it was recognized that modified characteristics, such as particle size [22] the surface charge of particles [23], attachment of ligands [24,25] or coating with surfactants [26], offers possibilities of sitespecific targeting to different regions of the gastrointestinal tract, including the Peyer's patches [27].…”