Guanidinated multi-arm star polyornithines with a polyethylenimine core for gene delivery

Multi-arm star polyornithines PEI-P(Orn)_n are prepared by grafting polyornithine arms onto branched polyethylenimine (PEI) with an M_w of 600 via the ring-opening polymerization of N-carboxyanhydride of benzyloxycarbonyl ornithine. To enhance gene delivery efficiency and reduce cytotoxicity, the amino side groups on the polyornithine arms are partially guanidinated that transforms the ornithine units to arginine units. Thus, the guanidinated products G-PEI-P(Orn)_n contain multiple poly(ornithine-co-arginine) arms. PEI-P(Orn)_n and G-PEI-P(Orn)₇₁ mediate the transfection of pGL3 plasmid to 293T cells almost as efficient as 25 kDa PEI in serum-free medium. Notably, in contrast to the dramatically lowered efficiency of 25 kDa PEI in the presence of serum, the efficiency of G-PEI-P(Orn)₇₁ can be retained or even enhanced in the medium containing 10% serum. The improved serum-compatibility and high efficiency of the guanidinium-modified star polyornithines make them promising for gene delivery.     

A Novel Co-polymer Based on Hydroxypropyl ��-Cyclodextrin Conjugated to Low Molecular Weight Polyethylenimine as an in Vitro Gene Delivery Vector

A novel co-polymer based on 2-hydroxypropyl-α-cyclodextrin cross-linked by low molecular weight polyethylenimine was synthesized as a gene delivery vector. The copolymer could bind and condense DNA tightly. It showed lower cytotoxicity than PEI 25kDa in SK-BR-3 cells. Transfection efficiency was increased over 5.5-fold higher than PEI 25 kDa in SK-BR-3 cells in complete serum medium. It is a potential candidate vector for gene therapy.     

Zwitterionic Modification of Polyethyleneimine for Efficient In Vitro siRNA Delivery

Polyethylenimine (PEI) has been widely used in gene delivery. However, its high cytotoxicity and undesired non-specific protein adsorption hinder the overall delivery efficacy and the practical applications of PEI-based gene delivery systems. In this study, we prepared hydrophobically modified PEIs (H-PEIs) via the reaction of octanal with 40% of primary amines in PEI_25k and PEI_10k, respectively. Two common zwitterionic molecules, 1,3-propanesultone and β-propiolactone, were then used for the modification of the resulting H-PEIs to construct polycationic gene carriers with zwitterionic properties (H-zPEIs). The siRNA delivery efficiency and cytotoxicity of these materials were evaluated in Hela-Luc and A549-Luc cell lines. Compared with their respective parental H-PEIs, different degrees of zwitterionic modification showed different effects in reducing cytotoxicity and delivery efficiency. All zwitterion-modified PEIs showed excellent siRNA binding capacity, reduced nonspecific protein adsorption, and enhanced stability upon nuclease degradation. It is concluded that zwitterionic molecular modification is an effective method to construct efficient vectors by preventing undesired interactions between polycationic carriers and biomacromolecules. It may offer insights into the modification of other cationic carriers of nucleic acid drugs.     

Graphene based gene transfection

Graphene as a star in materials research has been attracting tremendous attentions in the past few years in various fields including biomedicine. In this work, for the first time we successfully use graphene as a non-toxic nano-vehicle for efficient gene transfection. Graphene oxide (GO) is bound with cationic polymers, polyethyleneimine (PEI) with two different molecular weights at 1.2 kDa and 10 kDa, forming GO-PEI-1.2k and GO-PEG-10k complexes, respectively, both of which are stable in physiological solutions. Cellular toxicity tests reveal that our GO-PEI-10k complex exhibits significantly reduced toxicity to the treated cells compared to the bare PEI-10k polymer. The positively charged GO-PEI complexes are able to further bind with plasmid DNA (pDNA) for intracellular transfection of the enhanced green fluorescence protein (EGFP) gene in HeLa cells. While EGFP transfection with PEI-1.2k appears to be ineffective, high EGFP expression is observed using the corresponding GO-PEI-1.2k as the transfection agent. On the other hand, GO-PEI-10k shows similar EGFP transfection efficiency but lower toxicity compared with PEI-10k. Our results suggest graphene to be a novel gene delivery nano-vector with low cytotoxicity and high transfection efficiency, promising for future applications in non-viral based gene therapy.     

Development of Covalent Chitosan-Polyethylenimine Derivatives as Gene Delivery Vehicle: Synthesis,Characterization, and Evaluation

There is an increasing interest in cationic polymers as important constituents of non-viral gene delivery vectors. In the present study, we developed a versatile synthetic route for the production of covalent polymeric conjugates consisting of water-soluble depolymerized chitosan (dCS; M_W 6–9 kDa) and low molecular weight polyethylenimine (PEI; 2.5 kDa linear, 1.8 kDa branched). dCS-PEI derivatives were evaluated based on their physicochemical properties, including purity, covalent bonding, solubility in aqueous media, ability for DNA condensation, and colloidal stability of the resulting polyplexes. They were complexed with non-integrating DNA vectors coding for reporter genes by simple admixing and assessed in vitro using liver-derived HuH-7 cells for their transfection efficiency and cytotoxicity. Using a rational screening cascade, a lead compound was selected (dCS-Suc-LPEI-14) displaying the best balance of biocompatibility, cytotoxicity, and transfection efficiency. Scale-up and in vivo evaluation in wild-type mice allowed for a direct comparison with a commercially available non-viral delivery vector (in vivo-jetPEI). Hepatic expression of the reporter gene luciferase resulted in liver-specific bioluminescence, upon intrabiliary infusion of the chitosan-based polyplexes, which exceeded the signal of the in vivo jetPEI reference formulation by a factor of 10. We conclude that the novel chitosan-derivative dCS-Suc-LPEI-14 shows promise and potential as an efficient polymeric conjugate for non-viral in vivo gene therapy.     

Surface modification and PEGylation of branched polyethyleneimine for improved biocompatibility

In this article, we report the surface modification of branched polyethyleneimine (PEI) for improved biocompatibility. PEIs with different surface functionalities were synthesized via covalent modification of the PEI amines, including neutralized PEI modified with acetic anhydride, negatively charged PEI modified with succinic anhydride, hydroxylated PEI modified with glycidol, and PEI–poly(ethylene glycol) (PEG) conjugates modified with both PEG and acetic anhydride. The modified PEI derivatives were characterized with ¹H‐NMR, Fourier transform infrared spectroscopy, and ζ‐potential measurements. An in vitro cytotoxicity assay of mouse fibroblasts revealed that the biocompatibility of PEI was significantly improved after these modifications. The neutral and negatively charged PEIs were nontoxic at concentrations up to 200 μg/mL, whereas the pristine PEI was toxic to cells at concentrations as low as 10 μg/mL. The successfully modified PEIs with different surface charges and functionalities may provide a range of opportunities for various biomedical applications. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

A systemic gene vector constructed by zwitterionic polymer modified low molecular weight PEI

Good blood compatibility and long-term circulation are very important to polycationic systemic gene vectors. In this work, polysulfobetaine-modified low molecular weight polyethyleneimine (LMW PEI, 1.8k) was synthesized and investigated as a vector for gene delivery in vitro and in vivo. PHEAA-b-PMPDSAH was synthesized via atomic transfer radical polymerization method, and then LMW PEI was grafted to PHEAA-b-PMPDSAH by an amido–hydroxy reaction. Incorporation of PMPDSAH into PEI was shown to retain the uncompromised ability to condense DNA into nanocomplexes. MTT assays revealed that the cytotoxicity of LMW PEI-PHEAA-b-PMPDSAH/DNA complexes was lower than that of PEI (25k)/DNA and LMW PEI-PHEAA/DNA complexes. LMW PEI-PHEAA-b-PMPDSAH₅₀ was much superior to PEI (25k) in mediating gene transfection in the presence of 10% serum. At higher serum contents, the transfection of LMW PEI-PHEAA and PEI (25k) was deteriorated, whereas LMW PEI-PHEAA-b-PMPDSAH₅₀ still retained better transfection efficiency, 8-fold more effective than PEI (25k). The expression of red fluorescence protein (RFP) was evaluated by small animal in vivo fluorescence imaging system and the results showed that the expression of RFP was much higher in the mice injected with LMW PEI-PHEAA-b-PMPDSAH₅₀/pDNA-RFP than with LMW PEI-HEAA/pDNA-RFP. Both in vitro and in vivo results suggested that LMW PEI-PHEAA-b-PMPDSAH_X copolymer holds a great potential as a vector for systemic gene therapy.     

A novel nonviral gene delivery vector: Low‐molecular‐weight polyethylenimine‐graft‐ovalbumin

A novel vector for gene delivery was synthesized. Here the ovalbumin (OVA) acts as a core and low‐molecular‐weight PEI600 was grafted to its surface. The finally product was characterized (¹H‐NMR, UV, and TGA) and its biophysical properties such as DNA condensing, particle size, and zeta potential were determined. The agarose gel assay indicated that OVA‐PEI600 could efficiently condense plasmid DNA. Its particle size was about 150 nm and zeta potential was around +20 mV. The MTT assay showed that the cytotoxicity of OVA‐PEI600 was less than PEI25 kDa. Its transfection efficiency in SKOV‐3 and HepG2 cell lines was higher than that of PEI600 and comparable to PEI25 kDa. In vivo, luciferase activity could be tested in liver, spleen, kidney, lung, and blood serum, respectively, in mice. The core‐shell structure of OVA‐PEI600 provided a novel strategy for nonviral gene delivery. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Analysis of the action mechanism of polymer dispersant on dense ethanol alumina suspension using colloidal probe AFM

The action mechanism of a polymer dispersant on dense Al₂O₃ ethanol suspension was investigated using a colloidal probe AFM and branched and linear polyethyleneimines (PEIs). To obtain the minimum viscosity and Newtonian flow property of the dense ethanol suspension, the optimum molecular weights of the branched PEIs were determined over the range from 10,000 to 70,000. The linear PEI with Mw 1400 did not reduce the suspension viscosity compared to the branched PEI with the same molecular weight. The amount of adsorbed PEI did not significantly change regardless of the molecular structure and weight of the PEIs. However, the surface interaction between α-Al₂O₃ solids depended on the molecular structure and weight of the PEIs. The branched chain of the PEI adsorbed on the Al₂O₃ surface facilitated the short-range steric repulsion between particles. Based on the results, the increase in steric repulsive force and the disappearance of the adhesion force by the adsorption of the polymer prompted the dispersion of aggregates in suspension and reduced the viscosity of ethanol dense suspension.     

Hyperbranched PEI grafted by hydrophilic amino acid segment poly[N‐(2‐hydroxyethyl)‐L‐glutamine] as an efficient nonviral gene carrier

A polyethylenimine‐poly(hydroxyethyl glutamine) copolymer (PEI‐PHEG) was designed and synthesized as a gene delivery system. The molecular structure of PEI‐PHEG was characterized using nuclear magnetic resonance. Moreover, PEI‐PHEG/pDNA complexes were fabricated and characterized by gel retardation assay, particle size analysis, and zeta potential analysis. The transfection efficiency and cytotoxicity of PEI‐PHEG were evaluated using human cervical carcinoma (HeLa), human embryonic kidney (HEK293), and murine colorectal adenocarcinoma (CT26) cells in vitro. The results show that PEI‐PHEG could effectively form positively charged nano‐sized particles with pDNA; the particle size was in a range of 130.2 to 173.0 nm and the zeta potential was in a range of 27.6 to 41.0 mV. PEI‐PHEG exhibited much lower cytotoxicity and higher gene transfection efficiency than PEI‐25K with different cell lines in vitro. An animal test was also conducted on a Lewis Lung Carcinoma tumor model in C57/BL6 mice by using subcutaneous intratumoral administration. The results show that in vivo transfection efficiency of PEI‐PHEG was improved greatly compared with that of commercial PEI‐25K. These results demonstrate that PEI‐PHEG can be a potential nonviral vector for gene delivery systems both in vitro and in vivo. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Folic‐Acid‐Targeted Self‐Assembling Supramolecular Carrier for Gene Delivery

A targeting gene carrier for cancer‐specific delivery was successfully developed through a “multilayer bricks‐mortar” strategy. The gene carrier was composed of adamantane‐functionalized folic acid (FA‐AD), an adamantane‐functionalized poly(ethylene glycol) derivative (PEG‐AD), and β‐cyclodextrin‐grafted low‐molecular‐weight branched polyethylenimine (PEI‐CD). Carriers produced by two different self‐assembly schemes, involving either precomplexation of the PEI‐CD with the FA‐AD and PEG‐AD before pDNA condensation (Method A) or pDNA condensation with the PEI‐CD prior to addition of the FA‐AD and PEG‐AD to engage host–guest complexation (Method B) were investigated for their ability to compact pDNA into nanoparticles. Cell viability studies show that the material produced by the Method A assembly scheme has lower cytotoxicity than branched PEI 25 kDa (PEI‐25KD) and that the transfection efficiency is maintained. These findings suggest that the gene carrier, based on multivalent host–guest interactions, could be an effective, targeted, and low‐toxicity carrier for delivering nucleic acid to target cells.     

Redox‐responsive polyethyleneimine‐coated magnetic iron oxide nanoparticles for controllable gene delivery and magnetic resonance imaging

Recently, theranostic candidates that provide a combination of gene delivery and image diagnosis have attracted much interest in medical research. However, there are still many challenges for their clinical applications, such as uncontrollable gene delivery, high cytotoxicity, low transfection efficiency and reduced image contrast. Herein, redox‐responsive polyethyleneimine‐coated magnetic iron oxide nanoparticles (IONs@rPEI) were prepared for both efficient gene delivery and magnetic resonance (MR) imaging. Firstly, crosslinked rPEI was synthesized by Michael addition reaction with N,N‐bis(acryloyl)cystamine, dopamine and low‐molecular‐weight branched PEI. The rPEI was then coated onto IONs by ligand exchange reaction forming IONs@rPEI. The physicochemical properties of the IONs@rPEI, such as chemical structure, size, zeta potential and DNA condensation ability, were investigated. In addition, a rapid degradation of the as‐prepared nanoparticles was observed, which was triggered by reducing glutathione via destruction of disulfide linkages suggesting a potential controllable DNA release in tumor cells. In MR imaging detection, the IONs@rPEI had a high T₂ relaxivity of 81 L mmol^?1 s^?1 indicating a potential usage as MR imaging contrast reagent. In cell assay, the IONs@rPEI exhibited low cytotoxicity and good transfection efficiency. In conclusion, the as‐prepared crosslinked IONs@rPEI can be used as a promising technology platform for gene therapy and MR imaging in theranostics. © 2019 Society of Chemical Industry     

Carbon Nanotube-Mediated Plasmid DNA Delivery in Rice Leaves and Seeds

CRISPR-Cas gene editing technologies offer the potential to modify crops precisely; however, in vitro plant transformation and regeneration techniques present a bottleneck due to the lengthy and genotype-specific tissue culture process. Ideally, in planta transformation can bypass tissue culture and directly lead to transformed plants, but efficient in planta delivery and transformation remains a challenge. This study investigates transformation methods that have the potential to directly alter germline cells, eliminating the challenge of in vitro plant regeneration. Recent studies have demonstrated that carbon nanotubes (CNTs) loaded with plasmid DNA can diffuse through plant cell walls, facilitating transient expression of foreign genetic elements in plant tissues. To test if this approach is a viable technique for in planta transformation, CNT-mediated plasmid DNA delivery into rice tissues was performed using leaf and excised-embryo infiltration with reporter genes. Quantitative and qualitative data indicate that CNTs facilitate plasmid DNA delivery in rice leaf and embryo tissues, resulting in transient GFP, YFP, and GUS expression. Experiments were also initiated with CRISPR-Cas vectors targeting the phytoene desaturase (PDS) gene for CNT delivery into mature embryos to create heritable genetic edits. Overall, the results suggest that CNT-based delivery of plasmid DNA appears promising for in planta transformation, and further optimization can enable high-throughput gene editing to accelerate functional genomics and crop improvement activities.     

Introducing primary and tertiary amino groups into a neutral polymer: A simple way to fabricating highly efficient nonviral vectors for gene delivery

In this work, a brushed polycationic polymer with primary and tertiary amino groups was designed and synthesized for gene delivery. The backbone polymer was poly(N‐hydroxyethylacrylamide) (PHEAA) by the atom transfer radical polymerization (ATRP), and then 3,3′‐diaminodipropylamine (DPA) was grafted onto the PHEAA by the reaction between hydroxyl and the secondary amine. A brushed PHEAA‐DPA cationic polymer was achieved with primary and tertiary amino groups and the ratio was 2 : 1. The PHEAA₁₀₀‐DPA and PHEAA₂₀₀‐DPA could effectively condense plasmid DNA (pDNA) at the weight ratio of vector/DNA of 0.6 and 0.4, respectively. The cytotoxicity of PHEAA‐DPA/pDNA to COS‐7 cells and HepG‐2 cells within the weight ratio of vector/DNA of 16 : 1 was lower than that of PEI25k, and cell viability decreased with the increment of the weight ratio. Although the cytotoxicity of PHEAA₁₀₀‐DPA/pDNA was lower than PHEAA₂₀₀‐DPA/pDNA, the latter possessed higher transfection efficiency at the same weight ratio both in COS‐7 cells and HepG‐2 cells, compared with PEI25k, the transfection efficiency of PHEAA₂₀₀‐DPA/pDNA was better in COS‐7 cells and HepG‐2 cells with the weight ratio of 12 : 1 and 10 : 1, respectively. These results showed that the PHEAA‐DPA with less cytotoxicity and higher gene transfection efficiency has a broad perspective in gene therapy. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40468.     

Bioreducible Guanidinylated Polyethylenimine for Efficient Gene Delivery

Cationic polymers are known to afford efficient gene transfection. However, cytotoxicity remains a problem at the molecular weight for optimal DNA delivery. As such, optimized polymeric gene delivery systems are still a sought‐after research goal. A guanidinylated bioreducible branched polyethylenimine (GBPEI‐SS) was synthesized by using a disulfide bond to crosslink the guanidinylated BPEI (GBPEI). GBPEI‐SS showed sufficient plasmid DNA (pDNA) condensation ability. The physicochemical properties of GBPEI‐SS demonstrate that it has the appropriate size (～200 nm) and surface potential (～30 mV) at a nitrogen‐to‐phosphorus ratio of 10. No significant toxicity was observed, possibly due to bioreducibility and to the guanidine group delocalizing the positive charge of the primary amine in BPEI. Compared with the nonguanidinylated analogue, BPEI‐SS, GBPEI‐SS showed enhanced transfection efficiency owing to increased cellular uptake and efficient pDNA release by cleavage of disulfide bonds. This system is very efficient for delivering pDNA into cells, thereby achieving high transfection efficiency and low cytotoxicity.     

Cytotoxicity mechanism of non-viral carriers polyethylenimine and poly-l-lysine using real time high-content cellular assay

Cationic polymers polyethylenimine (PEI) and poly-l-lysine (PLL) used as non-viral gene/drug delivery vehicles, showed high cytotoxicity but their molecular mechanisms of toxicity have been inadequately understood. Therefore, we tried to investigate the toxicity pathway triggered by these polymers through a high-content cellular imaging technique. The results revealed that PEI induced apoptosis via an intrinsic pathway, whereas PLL showed cytotoxicity through both intrinsic and extrinsic caspase cascade. Both PEI and PLL provide different apoptotic activities on HepG2 cells depending on their molecular weight. The degree of apoptosis of PEI also depends on its structure. The branched PEI showed higher cytotoxicity than linear PEI. This observation was verified through Annexin V-FITC/PI assay and real-time high-content monitoring of cytosolic calcium, mitochondrial membrane disruption, and caspase-3 activation methods. The study therefore provides important implications on the molecular mechanisms of PEI and PLL induced cytotoxicity.     

A new synthesis method and degradation of hyper-branched polyethylenimine grafted polycaprolactone block mono-methoxyl poly (ethylene glycol) copolymers (hy-PEI-g-PCL-b-mPEG) as potential DNA delivery vectors

Hyper-branched polyethylenimine grafted polycaprolactone block mono-methoxyl poly (ethylene glycol) copolymer (hy-PEI-g-PCL-b-mPEG) was obtained through the conjugation of mPEG-PCL with hyper-branched PEI (hy-PEI) based on the Michael addition. mPEG-PCL was synthesized by ring-opening polymerization of caprolactone using mPEG as the initiator. Compared earlier syntheses, this method offered a reduced number of reaction steps, milder reaction conditions, and a more efficient purification process. FTIR, ¹H NMR and ¹³C NMR spectra proved the structure of the copolymers and controllability of this new synthesis method. Using ¹H NMR spectroscopy the degradation of these copolymers was evaluated. Cytotoxicity of copolymers and gene transfection efficiency of polyplexes displayed prominent composition dependence. Increasing the graft density of mPEG-PCL on hy-PEI and longer lengths of both PCL and mPEG within the copolymers investigated here reduced transfection and cytotoxicity on A549 cells. The hy-PEI-g-PCL-b-mPEG copolymers with very short PCL segments (342 Da and 570 Da) demonstrated 6-fold higher transfection efficiency than hy-PEI25k on A549 cells. The polyplexes of the most promising candidate, hy-PEI25k-g-(PCL570-b-mPEG2k)₁, exhibited lower hemolysis compared to those of hy-PEI25k.     

Generation of carrier peptides for the delivery of nucleic acid drugs in primary cells

Now that the human genome has been decoded, the demand for novel therapeutic concepts, such as gene and stem cell therapy, is higher than ever before. Although new and better pharmaceutical agents are available, their efficient delivery to the intracellular site of action is still a serious challenge. A possible solution to this problem is the use of cell-penetrating peptides as delivery vectors, including derivatives of human calcitonin (hCT). The aim of this study was to synthesise novel branched hCT-derived peptides for the noncovalent delivery of nucleic acids. The uptake of the resulting oligocationic peptides into various cell lines as well as primary cells was monitored by fluorescence microscopy. To determine the appropriate peptide-plasmid charge ratios for efficient cell transfection, electromobility shift assays were carried out. Finally, flow cytometric and fluorescence microscopic studies of gene expression highlighted two novel hCT-derived peptides as highly effective in the delivery of noncovalently complexed plasmid DNA. Thus, the absence of cytotoxicity paired with highly efficient cell internalisation and transfection rates, in primary cells as well, make both peptides powerful candidates as drug delivery vectors, especially for plasmid DNA, for both in vivo and ex vivo therapeutic applications.     

Polyethylene glycol‐polyethylenimine‐tetrachloroplatinum (IV): A novel conjugate with good abilities of antitumor and gene delivery

It is much importance to develop novel multifunctional delivery systems for the combination therapy of drug and gene. In this work, a novel conjugate, polyethylene glycol‐polyethylenimine‐tetrachloroplatinum (IV) (PEG‐PEI‐Pt), with good abilities of antitumor and gene delivery was proposed by combining PEG (Mw 3400 Da), low molecular weight PEI (Mw 800 Da), and tetrachloroplatinum (IV). The antitumoral and gene transfection activities of PEG‐PEI‐Pt were analyzed in many tumor (A549, A375, HepG‐2, HuH‐7, and B16 cells) and normal (COS‐7 cells) cell lines. Similar to cisplatin (one platinum anticancer drug), PEG‐PEI‐Pt showed much higher sensitivity in tumor cells than in normal cells. More importantly, PEG‐PEI‐Pt had a potential to treat drug‐resistant tumors. Almost no transfection efficiency was observed for PEI (Mw 800 Da) and PEG‐PEI. Very interestingly, PEG‐PEI‐Pt could condense plasmid DNA efficiently, and exhibited good transfection efficiency in B16, HepG‐2, A375 and COS‐7 cells, comparable to even higher than PEI 25 kDa. In addition, PEG‐PEI‐Pt could also effectively deliver siRNA into the cytoplasm of tumor cells. With the good antitumoral and gene delivery abilities, PEG‐PEI‐Pt may have a great potential for combination therapy of drug and gene. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Preparation of reduction-triggered degradable microcapsules for intracellular delivery of anti-cancer drug and gene

The reduction-triggered degradable poly(methacrylic acid-co-N,N-bis(acryloyl)cystamine)/polyethyleneimine (P(MAA-co-BAC)/PEI) microcapsules were prepared by distillation–precipitation polymerization for delivery of anti-cancer drug and gene. N,N-bis(acryloyl)cystamine (BAC) as a crosslinker containing a disulfide bond can be triggered by reductive agents, such as glutathione (GSH) and dithiothreitol (DTT), to endow the functional microcapsules with reduction-triggered drug release. The P(MAA-co-BAC)/PEI microcapsules were characterized by transmission electron microscopy (TEM), Fourier-transform infrared spectra (FT-IR), laser particle size analyzer and elemental analysis. The degradable behavior of microcapsules was investigated by analysis of UV-vis spectroscopy. The controlled drug release behavior for P(MAA-co-BAC)/PEI microcapsules was strongly dependent on the absence/presence of GSH and the pH values with doxorubicin hydrochloride (DOX) as a model drug molecule. The in vitro gene transfection ability was evaluated by Hela cells with the transfection of plasmid DNA (pDNA) encoded with green fluorescent protein (GFP) and the transfection efficiency was determined by confocal fluorescence microscopy. Furthermore, the cytotoxicities of (P(MAA-co-BAC)/PEI) microcapsules before and after loading of DOX were assessed via WST-1 assay. The P(MAA-co-BAC)/PEI microcapsules provide the potential novel vectors for delivery of drugs and genes, promising for future applications in anticancer drug and gene combined therapy.