Effect of polyelectrolytes and polyelectrolyte mixtures on the electrokinetic potential of dispersed particles. 2. Electrokinetic potential of silica particles in electrolyte, polyelectrolyte and polyelectrolyte mixtures solutions

The effect pH, ionic strength (KCl concentration), weakly and medium charged anionic and cationic polyelectrolytes (PEs) as well as their binary mixtures on the electrokinetic potential of silica particles as a function of the polyelectrolyte/mixture dose, its composition, charge density (CD) of the PE, and way of adding the polymers to the suspension has been studied. It has been shown that addition of increasing amount of anionic PEs increases the absolute value of the negative zeta-potential of particles at pH > pH isoelectric point (IEP = 2.5); this increase is stronger the charge density of the polyelectrolyte is higher. Adsorption of cationic polyelectrolytes at these pH values gives a significant decrease in the negative ζ-potential and overcharging the particles; changes in the ζ-potential are more pronounced for PE samples with higher CD. In mixtures of cationic and anionic PE at pH > pHIEP, the ζ-potential of particles is determined by the adsorbed amount of the anionic polymer independently of the CD of PEs, the mixture composition and the sequence of addition of the mixture components. Unexpectedly, the ζ-potential of silica at pH = 2.1, i.e. < pHIEP, turned out to be positive in the presence of both anionic PE and cationic + anionic PE mixtures. This is explained by formation (and adsorption onto positively charged silica surface) of pseudo-cationic PEs from anionic ones due to transfer of protons from the solution to the amino-group of the anionic polymer. Considerations about the role of coulombic and non-coulombic forces in the mechanism of PE adsorption are presented.     

侧链含咪唑取代基聚(L-天冬酰胺)高效基因载体研究

通过氨基引发聚丁二酰亚胺( PSI)开环反应,制备了系列侧链含氨乙基和咪唑丙基的聚(L-天冬酰胺)共聚物(P1 ～ P5).该系列聚合物不仅具有极低的细胞毒性,而且随侧链中咪唑取代基含量的增加,聚合物在pH 5 ～8范围内缓冲能力显著提高.通过凝胶电泳、粒径和电位分析等研究了聚合物与质粒DNA的相互作用.结果表明,所有...     

Influence of polymer backbone branching on liquid crystal mesomorphous in nonequimolar complexes of poly(ethyleneimine) and dendritic amphiphiles

Two kinds of ionic self‐assembled complexes of linear or branched poly(ethyleneimine) (lPEI or bPEI) with Percec‐type dendrons [(3,4,5)16G1‐COOH] were prepared as lPEI‐(3,4,5)16G1‐x and bPEI‐(3,4,5)16G1‐x , where x is the mole ratio of the carboxyl groups of the dendritic amphiphile to the amino groups at the PEI chain. The crystal and mesomorphous structures and thermal properties of these complexes were investigated with X‐ray diffraction (XRD), Fourier transform infrared (FTIR), differential scanning calorimetry (DSC), and polarized optical microscope (POM). Both the lPEI and bPEI complexes exhibited the same α_H crystal phase and similar lamellar mesomorphous phase, irrespective of the branching of the polymer backbone and the binding degree. The lPEI series complexes lPEI‐(3,4,5)16G1‐x , however, had more ordered lamellar stacking than that of the bPEI‐(3,4,5)16G1‐x complexes, so the thermotropic liquid crystal phase SmA was formed only in the lPEI‐(3,4,5)16G1‐x complexes beyond the melting point of the tail crystal of the dendritic amphiphile. No liquid crystalline phase was found from the bPEI‐(3,4,5)16G1‐x complexes. The results suggest that the branching of polymer backbone plays a key role to the formation of thermotropic liquid crystal in the polymer–dendritic amphiphile complex. The present finding is significant for the design of functional nanostructures based on the ionic complexation of polymers and amphiphiles. © 2011 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2011     

Effect of polyelectrolytes and polyelectrolyte mixtures on the electrokinetic potential of dispersed particles. 1. Electrokinetic potential of polystyrene particles in solutions of surfactants, polyelectrolytes and their mixtures

The effect of cationic and anionic surfactants, as well as cationic and anionic polyelectrolytes (PE), their binary mixtures on the electrokinetic potential of monodisperse carboxylated polystyrene (PS) particles as a function of the reagents dose, pH, the charge density (CD) of polymers, the surfactant/PE and binary PE mixture composition, and sequence of components addition to the suspension has been studied. It has been shown that addition of increasing amount of anionic surfactant/polyelectrolytes increases the absolute value of the negative zeta-potential of PS particles; this increase is stronger the CD of the PE and pH of the system are higher. Adsorption of cationic surfactant/polyelectrolytes leads to a significant decrease in the negative ζ-potential and to overcharging the particles; changes in the ζ-potential are more pronounced for PE samples with higher CD and for suspensions with lower pH values. In mixtures of cationic and anionic PE, in a wide range of mixture composition, the ζ-potential of particles is determined by the adsorbed amount of the anionic polymer independently of the CD of PEs and the sequence of addition of the mixture components. The isoelectric point of the surface is reached at the adsorbed amount of positive charges of PE that is approximately equal to the surface CD of particles. The laws observed were explained by features of macromolecules conformation in adsorbed mixed PE layers. Considerations about the role of coulombic and non-coulombic forces in the mechanism of anionic/cationic PE adsorption are presented.     

Poly(ethyleneimine)/arginine–glycine–aspartic acid conjugates prepared with N‐succinimidyl 3‐(2‐pyridyldithio)propionate: An investigation of peptide coupling and conjugate stability

Poly(ethylene imine) (PEI), a highly cationic polymer, is being used for deoxyribonucleic acid (DNA) complexation and delivery into cells. To enhance the cellular uptake of polymer/DNA complexes, arginine–glycine–aspartic acid (RGD) peptides have been conjugated to PEI with N‐succinimidyl 3‐(2‐pyridyldithio)propionate (SPDP). This coupling scheme creates a disulfide‐linked conjugate, the stability of which in the presence of thiols is uncertain. We have investigated the conjugation of an RGD peptide, glycine–arginine–glycine–aspartic acid–serine–proline–cysteine (GRGDSPC), to PEI with SPDP and subsequently assessed the stability of the conjugates in the presence of two thiol compounds, mercaptoethanol and cysteine. SPDP effectively controls the extent of GRGDSPC substitution on PEI. The conjugates, however, are readily cleaved in the presence of the thiols; the cleavage is rapid (～50% cleavage in 2–4 h) and inversely related to the degree of peptide substitution on the polymers. The peptide coupling is stable in the absence of thiols, and its cleavage is strongly dependent on the pH of the medium but not on the ionic strength of the medium. We conclude that RGD peptides coupled to PEI are labile in the presence of physiological concentrations of thiols, and this should be taken into account when such polymer–peptide conjugates are used for DNA delivery. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 6143–6156, 2004     

Study on the influence of cross-sectional area and zeta potential on separation for hybrid-chip-based capillary electrophoresis using 3-D simulations

Hybrid chips combing microchips with capillaries have displayed particular advantages in achieving UV-vis and mass spectroscopic detection. In this work, systematic 3-D numerical simulations have been carried out to explore the influence of junction interface cross-sectional area and ζ-potential distribution on sample band broadening in hybrid-chip electrophoresis separation. In this case, the ratio of cross-sectional area of chip to capillary channel (S(ratio) ) is used as the parameter of the variation in junction interface cross-sectional area. Theoretical simulations demonstrated that the decrease of the S(ratio) would increase the separation efficiency in the hybrid-chip-based CE with uniform ζ-potential distribution. ζ-potential distribution along the axial direction of the channel also affects mass transport in hybrid-chip-based CE. Therefore, the effect of ζ-potential distribution has been considered in the 3-D simulation. Theoretical simulation results reveal that ζ-potential distribution rather than the interface cross-sectional area variation (S(ratio) ) controls the sample band broadening and manipulates sample separation efficiency in the hybrid-chip-based CE with non-uniform ζ-potential distribution. Both the theoretical simulations and experimental results show that optimal hybrid-chip CE separation efficiency can be achieved at S(ratio) =1.     

Synthesis and Application of Low Molecular Weight PEI-Based Copolymers for siRNA Delivery with Smart Polymer Blends

Polyethylenimine (PEI) is a commonly used cationic polymer for small-interfering RNA (siRNA) delivery due to its high transfection efficiency at low commercial cost. However, high molecular weight PEI is cytotoxic and thus, its practical application is limited. In this study, different formulations of low molecular weight PEI (LMW-PEI) based copolymers polyethylenimine-g-polycaprolactone (PEI–PCL) (800 Da–40 kDa) and PEI–PCL–PEI (5–5–5 kDa) blended with or without polyethylene glycol-b-polycaprolactone (PEG–PCL) (5 kDa-4 kDa) are investigated to prepare nanoparticles via nanoprecipitation using a solvent displacement method with sizes ≈100 nm. PEG–PCL can stabilize the nanoparticles, improve their biocompatibility, and extend their circulation time in vivo. The nanoparticles composed of PEI–PCL–PEI and PEG–PCL show higher siRNA encapsulation efficiency than PEI–PCL/PEG–PCL based nanoparticles at low N/P ratios, higher cellular uptake, and a gene silencing efficiency of ≈40% as a result of the higher molecular weight PEI blocks. These results suggest that the PEI–PCL–PEI/PEG–PCL nanoparticle system could be a promising vehicle for siRNA delivery at minimal synthetic effort.     

A facile approach to construct hyaluronic acid shielding polyplexes with improved stability and reduced cytotoxicity

A facile approach for polymer gene carriers was used to construct hyaluronic acid (HA) shielding polyplexes due to the electrostatic interaction. By adding HA to PEI/DNA complexes, the ξ-potential of ternary polyplexes was changed from positive to negative. Spherical particles with diameter about 250nm were observed. Ethidium bromide exclusion assay indicated that the electrostatic complexation was loosened after addition of HA. However, DNA disassembly did not occur. The proper reason was that the intensity of negative charges was not strong enough to release DNA from the complexes in our experiment. The stability of PEI/DNA/HA polyplexes in physiological condition was improved and the cytotoxicity was reduced. Comparing with PEI/DNA polyplexes, the uptake and transfection efficiency of HA shielding polyplexes was lower for HEK293T cells probably due to the reduced adsorptive endocytosis, whereas it was higher for HepG2 cells due to HA receptor mediated endocytosis. This facile approach to constructing HA shielding polyplexes might have great potential application in non-viral gene delivery research and tumor therapy.     

Strong ionic interactions in noncovalent complexes between poly(ethylene imine), a cationic electrolyte,and Cibacron Blue,a nucleotide mimic – implications for oligonucleotide vectors

Cationic polymers can bind DNA to form polyplexes, which are noncovalent complexes used for gene delivery into the targeted cells. For more insight on such biologically relevant systems, the noncovalent complexes between the cationic polymer poly(ethylene imine) (PEI) and the nucleotide mimicking dye Cibacron Blue F3G‐A (CB) were investigated using mass spectrometry methods. Two PEIs of low molecular weight were utilized (M_n ≈ 423 and 600 Da). The different types of CB anions produced by Na⁺/H⁺ exchanges on the three sulfonic acid groups of CB and their dehydrated counterparts were responsible for complex formation with PEI. The CB anions underwent noncovalent complex formation with protonated, but not with sodiated PEI. A higher proportion of cyclic oligomers were detected in PEI423 than PEI600, but both architectures formed association products with CB. Tandem mass spectrometry studies revealed a significantly stronger noncovalent interaction between PEI and dehydrated CB than between PEI and intact CB. Copyright © 2014 John Wiley & Sons, Ltd.     

Synthesis and characterization of a hydrogel with controllable electroosmosis: a potential brain tissue surrogate for electrokinetic transport

Electroosmosis is the bulk fluid flow initiated by application of an electric field to an electrolyte solution in contact with immobile objects with a nonzero ζ-potential such as the surface of a porous medium. Electroosmosis may be used to assist analytical separations. Several gel-based systems with varying electroosmotic mobilities have been made in this context. A method was recently developed to determine the ζ-potential of organotypic hippocampal slice cultures (OHSC) as a representative model for normal brain tissue. The ζ-potential of the tissue is significant. However, determining the role of the ζ-potential in solute transport in tissue in an electric field is difficult because the tissue's ζ-potential cannot be altered. We hypothesized that mass transport properties, namely the ζ-potential and tortuosity, could be modulated by controlling the composition of a set of hydrogels. Thus, poly(acrylamide-co-acrylic acid) gels were prepared with three compositions (by monomer weight percent): acrylamide/acrylic acid 100/0, 90/10, and 75/25. The ζ-potentials of these gels at pH 7.4 are distinctly different, and in fact vary approximately linearly with the weight percent of acrylic acid. We discovered that the 25% acrylic acid gel is a respectable model for brain tissue, as its ζ-potential is comparable to the OHSC. This series of gels permits the experimental determination of the importance of electrokinetic properties in a particular experiment or protocol. Additionally, tortuosities were measured electrokinetically and by evaluating diffusion coefficients. Hydrogels with well-defined ζ-potential and tortuosity may find utility in biomaterials and analytical separations, and as a surrogate model for OHSC and living biological tissues.     

PEGylated polyethyleneimine grafted silica nanoparticles: enhanced cellular uptake and efficient siRNA delivery

The present paper reports the utilization of hybrid nanocomposite particles consisting of PEI25k-PEG5k copolymer grafted silica nanoparticles (SiO₂NPs) for enhanced cellular uptake and siRNA delivery. High-resolution transmission electron microscopy and dynamic light scattering measurements ensured the average particle size of the final hybrid component as 45 nm (core SiO₂, 28–30 nm and shell PEI25k-PEG5k, 12–15 nm). Surface morphology from atomic force microscopy analysis showed the significant relationship between the particle size and shape. ²⁹Si and ¹³C cross-polarization–magic angle spinning solid state nuclear magnetic resonance (NMR), ¹H-NMR, and Fourier transform infrared spectroscopy were used to obtain the relevant structural information (such as Q3, silanol; Q4, siloxane functional groups of SiO₂NPs; resonance shifts and bending vibrations of PEI25k, –CH₂–CH₂–NH–; and PEG5k, –CH₂–CH₂–O–) from copolymer nanoparticle. Stable complexation of siRNA and nanocomposite particle (wt.%:wt.%) was achieved from 1:5 to 1:15 ratio. Nanocomposite particle (N/P) ratio and siRNA concentration determine the stability and knockdown efficiency of the PEI25k-PEG5k-graft-SiO₂NPs–siRNA complexes. It was shown that highly positively charged (zeta potential, +66 mV) PEI25k-PEG5k-graft-SiO₂NPs result in strong affinity with negatively charged siRNA. Confocal microscopy showed intensified cellular uptake of siRNA into cytoplasm of A549 cancer cell utilized for in vitro study. In conclusion, the coherence, graft density of copolymer-SiO₂NPs, and siRNA concentration were found to strongly influence the stability, and hence determine the knockdown efficiency, of PEI25k-PEG5k-graft-SiO₂NPs–siRNA complexes.     

普鲁兰多糖为骨架的新型阳离子非病毒基因载体

通过琥珀酸酐将低分子量支化聚乙烯亚胺(PEI, 分子量1000)偶联到普鲁兰多糖(Pullulan)上, 合成了新型基因载体P-PEI. 利用 ¹H NMR、 FTIR、 粒度仪、 Zeta电位仪、 透射电镜和凝胶电泳对聚阳离子载体及其与质粒pDNA 的复合物进行了表征. 凝胶阻滞实验结果证明, 载体P-PEI在体外可以通过静电相互作用稳定结合pDNA, 并能有效抑制DNA水解酶及血清成分对pDNA的降解. 噻唑蓝(MTT)细胞毒性测试、 绿色荧光蛋白表达质粒(pGFP)及荧光素酶表达质粒(pGL3)转染实验结果表明, 载体P-PEI在N/P高达12.5时对细胞MCF-7, HeLa和COS-7的毒性低于PEI; 当N/P 为6.25时能有效将pGFP和pGL3带入Hela 细胞并表达, 最佳转染效率及荧光素酶活分别为, 比Lipo 2000[(49.13±0.61)%, (58.47±7.62)×10⁸ RLU/mg蛋白) 略低. 因此以Pullulan为骨架材料的P-PEI是一种新的有潜在应用价值的非病毒基因载体.     

Superparamagnetic nanoparticles for effective delivery of malaria DNA vaccine

Low efficiency is often observed in the delivery of DNA vaccines. The use of superparamagnetic nanoparticles (SPIONs) to deliver genes via magnetofection could improve transfection efficiency and target the vector to its desired locality. Here, magnetofection was used to enhance the delivery of a malaria DNA vaccine encoding Plasmodium yoelii merozoite surface protein MSP1(19) (VR1020-PyMSP1(19)) that plays a critical role in Plasmodium immunity. The plasmid DNA (pDNA) containing membrane associated 19-kDa carboxyl-terminal fragment of merozoite surface protein 1 (PyMSP1(19)) was conjugated with superparamagnetic nanoparticles coated with polyethyleneimine (PEI) polymer, with different molar ratio of PEI nitrogen to DNA phosphate. We reported the effects of SPIONs-PEI complexation pH values on the properties of the resulting particles, including their ability to condense DNA and the gene expression in vitro. By initially lowering the pH value of SPIONs-PEI complexes to 2.0, the size of the complexes decreased since PEI contained a large number of amino groups that became increasingly protonated under acidic condition, with the electrostatic repulsion inducing less aggregation. Further reaggregation was prevented when the pHs of the complexes were increased to 4.0 and 7.0, respectively, before DNA addition. SPIONs/PEI complexes at pH 4.0 showed better binding capability with PyMSP1(19) gene-containing pDNA than those at neutral pH, despite the negligible differences in the size and surface charge of the complexes. This study indicated that the ability to protect DNA molecules due to the structure of the polymer at acidic pH could help improve the transfection efficiency. The transfection efficiency of magnetic nanoparticle as carrier for malaria DNA vaccine in vitro into eukaryotic cells, as indicated via PyMSP1(19) expression, was significantly enhanced under the application of external magnetic field, while the cytotoxicity was comparable to the benchmark nonviral reagent (Lipofectamine 2000).     

Characterization of anionic and cationic functionalized bacterial cellulose nanofibres for controlled release applications

Bacterial cellulose (BC) is a biocompatible biopolymer synthesized by Gluconacetobacter xylinus. In this study, BC was oxidized and aminated to produce hydrogels for biomedical applications, and the products were characterized. A carboxyl (pK_a of 3.9 ± 0.1) content of 1.13 ± 0.02 mmol/g was obtained with the TEMPO-catalyzed oxidation. Epichlorohydrin-mediated amination introduced amine groups (pK_a of 11.0 ± 0.1) up to 1.74 ± 0.06 mmol/g. The oxidation of BC caused a decrease in its ζ-potential to ?103 ± 6 mV, and amination increased the ζ-potential to ?4 ± 6 mV. The fibre diameter decreased after both reactions. The high absolute value of the ζ-potential for oxidized BC led to superior colloidal stability in water, and a 390 % increase in water retention. The oxidized BC hydrogel was also found to increase in water retention fivefold from pH 1 to 7, making it a smart hydrogel. The cationic and anionic BC hydrogels described here could be used for several biomedical applications, including self-assembling drug delivery devices.     

Optimization and characterization of liposome formulation by mixture design

This study presents the application of the mixture design technique to develop an optimal liposome formulation by using the different lipids in type and percentage (DOPC, POPC and DPPC) in liposome composition. Ten lipid mixtures were generated by the simplex-centroid design technique and liposomes were prepared by the extrusion method. Liposomes were characterized with respect to size, phase transition temperature, ζ-potential, lamellarity, fluidity and efficiency in loading calcein. The results were then applied to estimate the coefficients of mixture design model and to find the optimal lipid composition with improved entrapment efficiency, size, transition temperature, fluidity and ζ-potential of liposomes. The response optimization of experiments was the liposome formulation with DOPC: 46%, POPC: 12% and DPPC: 42%. The optimal liposome formulation had an average diameter of 127.5 nm, a phase-transition temperature of 11.43 °C, a ζ-potential of -7.24 mV, fluidity (1/P)(TMA-DPH)((?)) value of 2.87 and an encapsulation efficiency of 20.24%. The experimental results of characterization of optimal liposome formulation were in good agreement with those predicted by the mixture design technique.     

Bioreducible cationic random copolymer for gene delivery

Cationic polymers have been widely investigated for gene delivery, although their low transfection efficiency and high cytotoxicity limit their application. We synthesized a bioreducible cationic random copolymer, poly(cystamine bisacylamide‐aminoethyl piperazine)‐co‐poly(cystamine bisacylamide‐histamine) (denoted as CBA‐AEP‐His) from N,N′‐cystamine bis acrylamide (CBA) with aminoethyl piperazine (AEP) and histamine (His). CBA‐AEP‐His copolymer possesses disulfide linkages that endow it with redox‐responsivity to the intracellular environment. This polymer efficiently condenses pZNF580 into complexes with the size of 160 ± 4 nm to 280 ± 5 nm and positive zeta potential of 20 ± 0.3 mV to 30 ± 0.4 mV. The gel‐retardation assay shows that CBA‐AEP‐His can retard pZNF580 even at a low mass ratio of 1/1. The gene complexes were triggered to release pZNF580 when exposed to the reducing environment of dithiothreitol (DTT). CBA‐AEP‐His random copolymer presented higher buffer capacity owing to its His moieties, which protected pZNF580 from DNase degradation. The gene transfection results reveal that CBA‐AEP‐His can efficiently deliver pZNF580 and transfect EA. Hy926 cells. The MTT assay indicates that CBA‐AEP‐His and its complexes exhibit lower cytotoxicity than PEI25KDa. These results illustrate that CBA‐AEP‐His had promising properties for gene delivery, which may provide a suitable platform for the development of a non‐viral gene carrier.     

A Serum‐Resistant Low‐Generation Polyamidoamine with PEI 423 Outer Layer for Gene Delivery Vector

A new derivative of polyamidoamine and polyethylenimine, G2.5‐PEI 423 or G1.5‐PEI 423, is prepared by an amidation reaction of PAMAM G2.5 or PAMAM G1.5 using PEI 423. The polycations show a great ability to combine with pDNA to form complexes, which protect the pDNA from nuclease degradation. The polymers display stronger buffer capacity and lower cytotoxicity. The complexes have particle sizes of 120–180 nm and zeta potentials of 20–40 mV. The G2.5‐PEI 423 complexes display much higher transfection efficiencies than PAMAM G5 and Lipo‐2k, and the G1.5‐PEI 423 complexes display higher transfection efficiencies than PAMAM G4 and PEI‐25k. The complexes possess better serum‐resistant capacity. The G2.5‐PEI 423 has a great potential to be used as a serum‐resistant gene vector.

     

Polyethylenimine-based polyplex nanoparticles and features of their behavior in cells and tissues

The design of efficient systems for the targeted delivery of nucleic acids into cells is a rapidly developing area of polymer chemistry, molecular biology, and medicine. Complexes between DNA or RNA polyanions and various polycations, which are usually called polyplexes, hold promise as such delivery systems. Polyethylenimines (PEIs) and their derivatives are often used in research for the preparation of such complexes with plasmid DNA, oligonucleotides, and small RNA. Polyplex nanoparticles are employed for the delivery of genetic material into cells in culture and for the development of methods for the treatment of genetic and cancer diseases. The properties of polyplexes depend on the size, dispersity, and hydrophilicity of the used PEI or its derivatives and the ratio of polymers in the complex, which are responsible for the size, surface charge, and hydrophilicity of the resulting nanoparticles. The efficiency of polyplexes is determined by their ability to interact with components of biological systems on the surface and inside the cells, as well as with the blood vascular walls and the extracellular matrix during systemic in vivo use.     

Effect of peroxide depolymerization of chitosan on properties of chitosan sulfate particles produced from this substance

Effect of the oxidative destruction of chitosan on the rate at which a dispersed phase is formed in its dilute solutions in the presence of sulfate ions and on the composition, size and ζ-potential of submicrometer chitosan sulfate particles being formed was studied. It was found that the particle size steadily decreases as the molecular mass of chitosan becomes smaller, and the sedimentation stability of aqueous dispersions increases in the absence of surfactants. The \(\nu _{SO_4 } :\nu _{NH_2 }\) molar ratio in chitosan sulfate particles is independent of the molecular mass of chitosan and varies within the range 0.45–0.46. A pH-dependence of the sign of the ζ-potential with isoelectric point at pH 5.0 was found for particles based on destructed chitosan.     

A degradable hyperbranched poly(ester amine) based on poloxamer diacrylate and polyethylenimine as a gene carrier

Polyethylenimine (PEI) is a well-known cationic polymer which has high transfection efficiency due to its buffering effect. However, nondegradability, cytotoxicity, aggregation, and short-circulation time in vivo still need to be overcome for a successful gene delivery. Degradable, hyperbranched poly(ester amine)s (PEAs) based on poloxamer diacrylate and low molecular weight branched PEI, were successfully synthesized and evaluated as a nonviral gene carrier. The PEAs were obtained in significant yields through Michael type addition reaction of diacrylate monomers and low molecular weight branched PEI. Analysis of degradation products by the reduction in molecular weight demonstrated that PEAs degrade in a controlled fashion. The PEA showed good DNA binding ability and the sizes of complexes under physiological condition were below 150 nm, implicating its potential for intracellular delivery. It showed lower cytotoxicity in three different cell lines (A549, 293T, and HepG2) compared with PEI 25K. PEAs showed much higher transfection efficiencies in three cell lines compared with PEI 25K and PEI 1.8K, and revealed little serum dependency in A549 cell line when the content of poloxamer in the PEA was increased up to 30%.