Permeability of surface-modified polyamidoamine (PAMAM) dendrimers across Caco-2 cell monolayers

Abstract

Aim of this study was to prepare polyamine-conjugated PAMAM dendrimers and study their permeability across Caco-2 cell monolayers. Polyamines, namely, arginine and ornithine were conjugated to the amine terminals of the G4 PAMAM dendrimers by Fmoc synthesis. The apicalto-basolateral (AB) and basolateral-to-apical (BA) apparent permeability coefficients (P app ) for the PAMAM dendrimers increased by conjugating the dendrimers with both of the polyamines. The enhancement in permeability was dependent on the dendrimer concentration and duration of incubation. The correlation between monolayer permeability and the decrease in transepithelial electrical resistance (TEER) with both the PAMAM dendrimers and the polyamine-conjugated dendrimers suggests that paracellular transport is one of the mechanisms of transport across the epithelial cells. Cytotoxicity of the polyamine-conjugated dendrimers was evaluated in Caco-2 cells by MTT (methylthiazoletetrazolium) assay. Arginine-conjugated dendrimers were slightly more toxic than PAMAM dendrimer as well as ornithine-conjugated dendrimers. Though investigations on the possible involvement of other transport mechanisms are in progress, results of the present study suggest the potential of dendrimer-polyamine conjugates as drug carriers to increase the oral absorption of drugs.

Transport of Surface Engineered Polyamidoamine (PAMAM) Dendrimers Across IPEC-J2 Cell Monolayers

“…Based on the intestinal permeation enhancement effect of the polyamines, and their absorption by carrier-mediated transport, we validated our hypothesis that conjugation of the polyamines to the PAMAM dendrimers increases their permeability presumably because of dendrimer uptake by a combination of paracellular pathway as well as by the PAT system (Pisal 2008). Here, we report the permeability enhancement of polyamine-conjugated dendrimers in IPEC-J2, a primary cell line derived from jejunal epithelia isolated from neonatal, unsuckled piglet.…”

“…Arginine-and ornithine-conjugated PAMAM dendrimers were prepared using Fmoc synthesis (Pisal et al 2008). Briefly to 1.0 mmol of G4-NH 2 dendrimer in 3.0 mL of DMF, 70 mmol each of HOBt, HBTU, Fmoc-L-Arg(pbf)-OH, and 70 mmol of DIPEA were added.…”

“…Arginine and ornithine were coupled to the amine terminals of the PAMAM dendrimers by F-moc synthesis as reported previously (Pisal et al 2008). The surface-modified dendrimers were characterized by 1 H NMR and MALDI spectroscopic analysis.…”

Poly(amido amine) dendrimers in oral delivery

“…54,55 In both cell lines, there was no significant difference in cytotoxicity between polyamine-conjugated dendrimer and native dendrimers. Furthermore, a concentration and timedependent enhancement in permeability was observed from apical to the basolateral side for the polyamine conjugated PAMAM dendrimers.…”

“…Furthermore, a concentration and timedependent enhancement in permeability was observed from apical to the basolateral side for the polyamine conjugated PAMAM dendrimers. 54,55 Another proven strategy to improve biocompatibility and pharmacokinetics of polymeric drug carriers in vivo is PEGylation. PEGylation of anionic dendrimers G3.5-COOH and G4.5-COOH with PEG 750 kDa did not significantly alter cytotoxicity up to a concentration of 0.1 mM.…”