Synthesis and properties of Polycaprolactone-graft-Poly(2-(dimethylamino)ethyl methacrylate-co-methoxy polyethylene glycol monomethacrylate) as non-viral gene vector
Polycaprolactone-graft-Poly(2-(dimethylamino)ethyl methacrylate-co-methoxy polyethylene glycol monomethacrylate) (PCL-graft-P(DMAEMA-co-mPEGMMA)) was synthesized by combination of ring-opening polymerization (ROP) and atom transfer radical polymerization (ATRP). PCL-graft-P(DMAEMA-co-mPEGMMA) was characterized by FTIR, 1H NMR, and GPC. PCL-graft-P(DMAEMA-co-mPEGMMA) with expected composition and structure was achieved. pH- and thermo-sensitive properties of the PCL-graft-P(DMAEMA-co-mPEGMMA) nanoparticles prepared by the nanoprecipitation method were investigated by TEM and DLS. With increase in the temperature, the size of PCL-graft-P(DMAEMA-co-mPEGMMA) nanoparticles is decreased under base environment. Furthermore, in vitro transfection and toxicity assays were tested in 293T cells. The results indicate that PCL-graft-P(DMAEMA-co-PEGMMA) has lower cytotoxicity at N/P ratios less than 10 with transfection efficiency concomitantly reducing at N/P ratios less than 20 compared to PCL-graft-PDMAEMA as the control. However, PCL-graft-P(DMAEMA-co-PEGMMA) presents higher transfection efficiency at N/P ratios more than 20 compared to PCL-graft-PDMAEMA. Copyright © 2010 John Wiley & Sons, Ltd.
Available from: Jianhua Zhang
- "2. Experimental section 2.1. Materials c-(2-Bromo-2-methylpropionate)-e-caprolactone (BMPCL) was synthesized by methods reported previously    "
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ABSTRACT: Nanoparticles (NPs) assembled from amphiphilic polycations has been certificated as potential carriers for gene delivery. Structural modification on polycation moieties may be an efficient route to further enhance gene delivery efficiency. In this study, two electroneutral monomers with different hydrophobicity, 2-hydroxyethyl methacrylate (HEMA) and 2-hydroxyethyl acrylate (HEA), are respectively incorporated into the cationic PDMAEMA side chains of amphiphilic poly(ε-caprolactone)-graft-poly(dimethylamino ethylmethacrylate) (PCD) by random copolymerization, to obtain poly(ε-caprolactone)-graft-poly(dimethylamino ethyl methacrylate-co-2-hydroxyethyl methacrylate) (PCD-HEMA) and poly(ε-caprolactone)-graft-poly(dimethylamino ethyl methacrylate-co-2-hydroxyethyl acrylate) (PCD-HEA). Minimal HEA or HEMA moieties in PDMAEMA do not lead to statistically significant changes in particle size, zeta potential, DNA condensation properties and buffering capacity of the naked NPs. But the incorporation of HEMA and HEA respectively leads to reduction and increase in the surface hydrophilicity of the naked NPs and NPs/DNA complexes which is confirmed by water contact angles assay. These simple modifications on PDMAEMA by HEA and HEMA moieties significantly affect the gene transfection efficiency on HeLa cells in vitro: PCD-HEMA NPs/DNA complexes show much higher transfection efficiency than PCD NPs/DNA complexes, while PCD-HEA NPs/DNA complexes show lower transfection efficiency than PCD NPs/DNA complexes. Fluorescence activated cell sorter and confocal laser scanning microscope results indicate that the incorporation of hydrophobic HEMA moieties facilitates the enhancement in both cellular uptake and endosomal/lysosomal escape, leading to the higher transfection efficiency. Moreover, the process of endosomal/lysosomal escape is confirmed in our research that the PCD and its derivatives do not just rely on the proton sponge mechanism, but the membranous damage owing to polycation chains, especially the hydrophobic modified ones. Hence, it is proved that hydrophobic modification of cationic side chains is a crucial route to improve gene transfection mediated by polycation NPs.
Available from: Paul C Wang
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ABSTRACT: A group of amphiphilic cationic polymers, methoxy polyethylene glycol-block-(polycaprolactone-graft-poly(2-(dimethylamino)ethyl methacrylate)) (PECD), were synthesized by combining ring-opening polymerization (ROP) and atom transfer radical polymerization (ATRP) methods to form nanoparticles (NPs). The structures of these amphiphilic cationic polymers were characterized by (1)H NMR measurement. The PECD NPs have hydrophobic cores covered with hydrophilic PEG and cationic PDMAEMA chains. These self-assembly nanoparticles were characterized by dynamic light scattering (DLS) technique. PECD NPs can effectively condense DNA to form compact complexes of the size 65-160 nm suitable for gene delivery. The in vitro gene transfection studies of HeLa and HepG2 cells show that PECD NPs have better transfection efficiency compared to polyethylenimine (PEI) and Lipofectamine 2000 at low dose (N/P = 5). The cytotoxicity result shows that PECD NPs/DNA complexes at the optimal N/P ratio for transfection have comparable toxicity with PEI and Lipofectamine. These results indicate that PECD NPs have a great potential to be used as efficient polymeric carriers for gene transfection.
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ABSTRACT: Binary complexes of cationic polymers and DNA were used commonly for DNA delivery, whereas, the excess cationic charge of the binary complexes mainly leads to high toxicity and unstability in vivo. In this paper, ternary complexes by coating polyglutamic acid-graft-poly(ethylene glycol)(PGA-g-mPEG) onto binary complexes of polycaprolactone-graft-poly(N,N-dimethylaminoethyl methacrylate) (PCL-g-PDMAEMA) nanoparticles (NPs)/DNA were firstly developed for effective and targeted gene delivery. The coating of PGA-g-mPEG was able to decrease the zeta potential of the nano-sized DNA complexes nearly to electroneutrality without interferring with DNA condensation ability. As a result, the stability, the escape ability from endosomes and the transfection efficiency of the complexes were enhanced. The ternary complexes of PCL-g-PDMAEMA NPs/DNA/PGA-g-mPEG demonstrated lower cytotoxicity in CCK-8 measurements and higher gene transfection efficiency than the binary complexes in vitro. In addition, Lactate dehydrogenase (LDH) assay was performed to quantify the membrane-damaging effects of the complexes, which is consistent with the conclusion of CCK-8 measurement for cytotoxicity assay. The in vivo imaging measurement and histochemical analysis of tumor sessions confirmed that the intravenous administration of the ternary complexes with red fluorescent protein (RFP) as payload led to protein expression in tumor, which was further enhanced by the targeted coating of PGA-g-PEG-folate.
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