Biodegradable Poly(2-Dimethylamino Ethylamino)Phosphazene for In Vivo Gene Delivery to Tumor Cells. Effect of Polymer Molecular Weight

Abstract

Purpose. Previously, we have shown that complexes of plasmid DNA with the biodegradable polymer poly(2-dimethylamino ethylamino)phosphazene (p(DMAEA)-ppz) mediated tumor selective gene expression after intravenous administration in mice. In this study, we investigated the effect of p(DMAEA)-ppz molecular weight on both in vitro and in vivo tumor transfection, as well as on complex induced toxicity. Materials and Methods. p(DMAEA)-ppz with a broad molar mass distribution was fractionated by preparative size exclusion chromatography. Polyplexes consisting of plasmid DNA and the collected polymer fractions were tested for biophysical properties, (cyto)toxicity and transfection activity. Results. Four p(DMAEA)-ppz fractions were collected with weight average molecular weights ranging from 130 to 950 kDa, and with narrow molecular mass distributions (M w /M n from 1.1 to 1.3). At polymer-to-DNA (N/P) ratios above 6, polyplexes based on these polymers were all positively charged (zeta potential 25-29 mV), and had a size of 80-90 nm. The in vitro cytotoxicity of the polyplexes positively correlated with polymer molecular weight. The in vitro transfection activity of the different polyplexes depended on their N/P ratio, and was affected by the degree of cytotoxicity, as well as the colloidal stability of the different polyplexes. Intravenous administration of polyplexes based on the high molecular weight polymers led to apparent toxicity, as a result of polyplex-induced erythrocyte aggregation. On the other hand, administration of polyplexes based on low molecular weight p(DMAEA)-ppz_s (M w 130 kDa) did not show signs of toxicity and resulted in tumor selective gene expression. Conclusion. Polymer molecular weight fractionation enabled us to optimize the transfection efficiency/ toxicity ratio of p(DMAEA)-ppz polyplexes for in vitro and in vivo tumor transfection.

Investigation of nucleophilic substitution pathway for the reactions of 1,4-benzodioxan-6-amine with chlorocyclophosphazenes

“…1,4-Benzodioxan-6-amino substituted cyclotriphosphazene derivatives (1)(2)(3)(4)(5) were synthesized from the reactions of trimer with 1,4-benzodioxan-6-amine in the presence of triethylamine as a hydrogen chloride acceptor in THF in four stoichiometries (1:1, 1:2, 1:4 and 1:6) at room temperature under an argon atmosphere (Fig. 2).…”

“…Aminocyclophosphazenes use a variety of applications in science and technology including anti-cancer reagents [1][2][3][4], tumor growth inhibitors [5,6], biologically and biomedically active molecules [7], flame retardants [8], antimicrobial reagents [9], multisite coordination ligands [10][11][12][13] and supramolecular chemistry [14]. Although the reactions of hexachlorocyclotriphosphazatriene (N 3 P 3 Cl 6 , trimer) with primary aliphatic [15,16] and aromatic [8b, [17][18][19] amines have been studied in great detail [20][21][22][23], there are limited studies about the reactions of octachlorocyclotetraphosphazatetraene (N 4 P 4 Cl 8 , tetramer), with a number of especially primary aromatic amines in the literature [13b, 22,[24][25][26][27].…”

Multifunctioning pH‐responsive nanoparticles from hierarchical self‐assembly of polymer brush for cancer drug delivery

“…A lower molecular weight polymer has a lower toxicity. 54 To further decrease its toxicity, the molecular weight of PDEA was kept low, 2.5 KDa.…”

Poly‐ and Cyclophosphazenes as Drug Carriers for Anticancer Therapy

“…Targeting properties can be afforded by introducing a targeting group such as folate or galactosamine, as mentioned earlier. Luten et al (2003) and de Wolf et al, 2005de Wolf et al, , 2007 have recently performed pioneering work on gene delivery using cationic polyphosphazenes. Polyphosphazenes bearing cationic moieties were synthesized by nucleophilic substitution of poly(dichlorophosphazene) with either 2-dimethylaminoethanol (DMAE) or 2-dimethylaminoethylamine (DMAEA), to obtain cationic polyphosphazene derivatives (pDMAE and pDMAEA).…”

“…In particular, since polymeric drug delivery systems have attracted much attention recently as a major emerging nanobiotechnology for polymer therapy, extensive studies have been directed at new drug delivery systems from polyphosphazenes by many research groups in various fields. For example, polyphosphazene micelles Chang et al, 2002Chang et al, , 2005Zhang et al, 2005aZhang et al, , b, 2006 and hydrogels (Allcock and Ambrosio, 1996;Allcock and Pucher, 1991;Kang et al, 2006a, b;Lee et al, 2002;Seong et al, 2005) were prepared for sustained release of hydrophobic and small-molecular drugs, biodegradable microspheres, and matrices (Andrianov, 2006;Andrianov and Payne, 1998;Andrianov et al, 2004a, b;Caliceti et al, 2000;Kumbar et al, 2006;Lakshmi et al, 2003;Nair et al, 2004;Veronese et al, 1998) for protein and vaccine delivery, cationic polyphosphazenes for gene delivery (de Wolf et al, 2005(de Wolf et al, , 2007Luten et al, 2003), and thermosensitive poly and cyclophosphazenes (Jun et al, 2006;Kim, J.I. et al, 2004;Lee et al, 1999a, b;Song et al, 1999;Toti et al, 2007) for controlled release of anticancer drugs.…”