Defoaming and Toughening Effects of Highly Dispersed Graphene Oxide Modified by Amphoteric Polycarboxylate Superplasticizer on Oil Well Cement.

The aggregation of graphene oxide (GO) during the hydration process limits its wide application. Polymer superplasticizers have been used to improve the dispersion state of GO due to their adsorption and site-blocking effects, though the formation of a large amount of foam during the mixing process weakens the mechanical properties of cement. A highly dispersed amphoteric polycarboxylate superplasticizer-stabilized graphene oxide (APC/GO) toughening agent was prepared by electrostatic self-assembly. Results demonstrate that the APC/GO composite dispersed well in a cement pore solution due to the steric effect offered by the APC. Additionally, the well-dispersed GO acted as an antifoaming agent in the cement since GO nanosheets can be absorbed at the air-liquid interface of APC foam via electrostatic interactions and eliminate the air-entraining effect. The well-dispersed APC/GO sheets promoted cement hydration and further refined its pore structure owing to the nucleation effect. The flexural and compressive strength of the cement containing the APC/GO composite were enhanced by 21.51% and 18.58%, respectively, after a 7-day hydration process compared with a blank sample. The improved hydration degree, highly polymerized C-S-H gel, and refined pore structure provided enhanced mechanical properties.

Design of Janus Nanoparticles for Mobility Control in Heterogeneous Reservoirs.

Unfavorable mobility ratios in heterogeneous reservoirs have resulted in progressively poor waterflood sweep efficiency and diminishing production. In order to address this issue, our study has developed amphiphilic-structured nanoparticles aimed at enhancing the microscopic displacement capability and oil displacement efficiency. First, the transport process of Janus nanoparticles in porous media was investigated. During the water flooding, Janus nanoparticle injection, and subsequent water flooding stages, the injection pressure increased in a "stepped" pattern, reaching 0.023, 0.029, and 0.038 MPa, respectively. Second, emulsification effects and emulsion viscosity experiments demonstrated that the amphiphilic structure improved the interaction at the oil-water interface, reducing the seepage resistance of the oil phase through emulsification. In porous media, Janus nanoparticles transported with water exhibit 'self-seeking oil' behavior and interact with the oil phase, reducing the viscosity of the oil phase from 19 to 5 mPa·s at 80 °C. Finally, the core model displacement experiment verified the characteristics of Janus nanoparticles in improving the oil-water mobility ratio. Compared with the water flooding stage, the recovery percent increased by 20.8%, of which 13.7% was attributed to the subsequent water flooding stage. Utilizing the asymmetry of the Janus particle structure can provide an effective path to enhanced oil recovery in inhomogeneous reservoirs.

Preparation of a Polycarboxylate Superplasticizer with Different Monomer Regulations and Its Effect on Fluidity, Rheology, and Strength of Cement.

Polycarboxylate superplasticizers (PCEs) are indispensable functional ingredients in modern construction, and their usage is extensive. Herein, a polyether macromonomer (VPEG) with high reactivity was used to prepare VAPCEs with different interfacial adsorption properties (acid-ether ratio) at low temperatures and reacted in 30 min. The effects of various VAPCEs on the fluidity, rheology, and strength of cement were investigated with a w/c (water/cement) ratio of 0.35. Results showed that VAPCE-3 (acid-ether ratio is 3) exhibited the best dispersion, and the fluidity of cement slurry with VAPCE-3 (280 mm) is 278.38% higher than that of the control sample (74 mm). The reason is summarized as VAPCE-3 having good adsorption performance on the surface of cement particles and having a large steric hindrance between particles. The compressive strength of cement with VAPCE-3 was enhanced by 8.29% compared with pure cement in 3 days of curing age due to its densification on microstructure and lowest R orientation index of calcium hydroxide. With the amount of acrylic acid in VAPCE increasing, the flexural strength enhanced because a more cross-linking network was formed with Ca2+ in cement with the increase of COO- content in VAPCEs.

Occurrence Mechanism of the Abnormal Gelation Phenomenon of High Temperature Cementing Slurry Induced by a Polycarboxylic Retarder.

The class G oil well cement is a type of special cement that can be subjected to a high temperature formation environment. It was found that the class G cement tail slurry with a low polycarboxylic retarder dosage (usually ≤1% by weight of cement) was more prone to cause the abnormal gelation phenomenon (AGP) than the lead slurry with a high retarder dosage at a high temperature (usually when T ≥ 120 °C). This study aimed at the occurrence mechanism of this unfavorable phenomenon that seriously endangers the cementing security. Results showed that the abnormal gelatinous region underwent premature hydration; namely, the calcium hydroxide and calcium silicate hydrate (C-S-H) content were all higher than the nongelatinous region, while the copolymer content was the opposite. Correspondingly, the theory of "premature hydration and crystal nucleation" was proposed to explain the abnormal gelation mechanism of a cementing tail slurry with an insufficient retarder dosage. Furthermore, a novel functionalized copolymer retarder "PAIANS" was synthesized to alleviate the AGP.

Water-Adaptive Microcapsules with a Brittle-Ductile-Brittle Transition Based on an O/W/O Emulsion for the Self-Healing of Cementitious Materials.

Cementitious materials inevitably develop cracks, posing a serious threat to the long-term security of infrastructure, especially in the complex underground environment of cementing engineering. Microcapsules are facing the problem of encapsulated structure damage during the mixing and breaking difficultly during self-healing when applied in cementitious materials, resulting in the decline of self-healing efficiency. Herein, the calcium alginate water-adaptive microcapsules (CaAlg-NS/E-51) were prepared via an O/W/O emulsion, and the water adaptability of the shell was applied to achieve a rapid brittle-ductile transition by absorbing water. The water adaptability of the microcapsule is conducive to resisting shear stress during stirring due to the decreased elastic modulus and the increased ductility of the shell when it absorbs water. Meanwhile, the water-bearing shell loses water and becomes brittle during dry curing, making it prone to fracture when self-healing. In the self-healing measurement, the self-healing efficiency of cementitious specimens with microcapsules absorbing water for 10 min improved by 234.9 and 60.0% at 1 and 7 days, respectively, compared with those containing dry microcapsules, owing to the water adaptability of the shell.

Effects of Hybrid Graphene Oxide-Nanosilica on Calcium Silicate Hydrate in the Simulation Environment and Cement.

This research aims to investigate the synergistic reinforcing mechanisms of chemically combined graphene oxide and nanosilica (GO-NS) in the structure of calcium silicate hydrate (C-S-H) gels compared with physically combined GO/NS. The results confirmed that the NS chemically deposited on the GO surface formed a coating to keep GO from aggregation, while the connection between GO and NS in GO/NS was too weak to prevent GO from clumping, making GO-NS better dispersed than GO/NS in pore solution. When applied to cement composites, the incorporation of GO-NS enhanced the compressive strength by 27.3% after 1-day hydration compared to that of the plain sample. This is because that GO-NS generated multiple nucleation sites at early hydration, reduced the orientation index of calcium hydroxide (CH), and increased the polymerization degree of C-S-H gels. GO-NS acted as the platforms for the growing process of C-S-H, enhancing its interface bonding strength with C-S-H and increasing the connection degree of the silica chain. Furthermore, the well-dispersed GO-NS was prone to insert in C-S-H and induced deeper cross-linking, thereby refining the microstructure of C-S-H. All these effects on hydration products resulted in the mechanical improvement of cement.

Development of Terminator-Promoter Bifunctional Elements for Application in Saccharomyces cerevisiae Pathway Engineering.

The construction of a genetic circuit requires the substitution and redesign of different promoters and terminators. The assembly efficiency of exogenous pathways will also decrease significantly when the number of regulatory elements and genes is increased. We speculated that a novel bifunctional element with promoter and terminator functions could be created via the fusion of a termination signal with a promoter sequence. In this study, the elements from a Saccharomyces cerevisiae promoter and terminator were employed to design a synthetic bifunctional element. The promoter strength of the synthetic element is apparently regulated through a spacer sequence and an upstream activating sequence (UAS) with a ~5-fold increase, and the terminator strength could be finely regulated by the efficiency element, with a ~5-fold increase. Furthermore, the use of a TATA box-like sequence resulted in the adequate execution of both functions of the TATA box and the efficiency element. By regulating the TATA box-like sequence, UAS, and spacer sequence, the strengths of the promoter-like and terminator-like bifunctional elements were optimally fine-tuned with ~8-fold and ~7-fold increases, respectively. The application of bifunctional elements in the lycopene biosynthetic pathway showed an improved pathway assembly efficiency and higher lycopene yield. The designed bifunctional elements effectively simplified pathway construction and can serve as a useful toolbox for yeast synthetic biology.

Engineered Organic Nanorockets with Light-Driven Ultrafast Transportability for Antitumor Therapy.

Nanomedicines confront various complicated physiological barriers limiting the accumulation and deep penetration in the tumor microenvironment, which seriously restricts the efficacy of antitumor therapy. Self-propelled nanocarriers assembled with kinetic engines can translate external energy into orientated motion for tumor penetration. However, achieving a stable ultrafast permeability at the tumor site remains challenging. Here, sub-200 nm photoactivated completely organic nanorockets (NRs), with asymmetric geometry conveniently assembled from photothermal semiconducting polymer payload and thermo-driven macromolecular propulsion through a straightforward nanoprecipitation process, are presented. The artificial NRs can be remotely manipulated by 808 nm near-infrared light to trigger the photothermal conversion and Curtius rearrangement reaction within the particles for robustly pushing nitrogen out into the solution. Such a two-stage light-to-heat-to-chemical energy transition effectively powers the NRs for an ultrafast (≈300 µm s-1 ) and chemical medium-independent self-propulsion in the liquid media. That endows the NRs with high permeability against physiological barriers in the tumor microenvironment to directionally deliver therapeutic agents to target lesions for elevating tumor accumulation, deep penetration, and cellular uptake, resulting in a significant enhancement of antitumor efficacy. This work will inspire the design of advanced kinetic systems for powering intelligent nanomachines in biomedical applications.

Mechanical Properties of Calcium Aluminate Cement Reinforced with Plasma-Treated Basalt Fibers for In Situ Combustion.

Brittleness and poor tensile/flexural properties restrict the application of calcium aluminate cement (CAC) in oil and gas wells. Reinforcing CAC with fibers is an effective method for improving its strength and toughness and overcoming the shortcomings of its mechanical properties. In this article, as an auxiliary cementing material, slag does not affect the thickening time of CAC. After adding slag, the cement slurry meets the thickening time during cementing construction, and basalt fiber is selected as the toughening material. The enhancement effect of basalt fiber on the mechanical properties of CAC slag composites is studied, including the evaluation of the macroscopic mechanical properties and microstructure at a high temperature (500 °C). The optimum composition of basalt and fiber-reinforced CAC was determined. Basalt fibers were added to CAC at different contents of 0, 0.1, 0.2, 0.3, 0.4, and 0.5% based on the weight of the cement. All the results showed that the introduction of basalt fibers could significantly enhance the strength of the cement at high temperatures. Compared with the control samples, an additional increase in the compressive and tensile strengths of the samples of 35.1 and 85.2%, respectively, was achieved at high temperature with approximately 0.4% fiber content. Plasma treatment further improved the reinforcing effect of the basalt fibers, where the high-temperature compressive and tensile strengths of the samples increased from 28.88 and 1.52 to 35.23 and 1.87 MPa, respectively, an increase of 21.98 and 20.6%, respectively, compared with the untreated basalt fibers. When the cement paste is cured by simulated curing for 28 d, the high-temperature compressive strength and tensile strength with plasma modification increased from 28.26 and 1.5 to 29.1 and 2.15 MPa, respectively, an increase of 3.0 and 43.3%, respectively. The structure of the formed hydrates was studied using scanning electron microscopy. Furthermore, toughening of the basalt fiber-reinforced CAC-based composites resulted mainly from crack bridging and fiber pull-out.

Dispersion Mechanism of Styrene-Butadiene Rubber Powder Modified by Itaconic Acid and Its Toughening Effect on Oil Well Cement.

Styrene-butadiene rubber (SBR) has been extensively applied to enhance the toughness of hardened cement. The instability of existing liquid latex leads to difficulties in storage and transportation, and even performance regression. Thus, the well-dispersed carboxylated butylbenzene (SISBR) latex powders were fabricated through the seed emulsion polymerization of liquid polybutadiene (LPB), styrene (St), itaconic acid (IA), and sodium p-styrenesulfonate (SSS) to overcome the difficulties. The dispersion performance of latex powders with various IA amounts was quantitatively evaluated using particle size distribution, zeta potential, and ultraviolet-visible spectrophotometry. Results showed that the carboxylic ionic (COO-) from IA enhanced the dispersing abilities of SISBR latex powders, which ensured the uniform distribution in water. Based on this, the influence of latex powder on cement was assessed mainly by fluidity, isothermal heat flow calorimetry, X-ray diffraction (XRD), and triaxial mechanical testing. Results showed the fluidity and dispersion performance of cement were improved with more IA in latex, while the hydration of cement was retarded due to excessive adsorption of carboxyl (-COOH) groups in IA. Triaxial mechanical testing showed that cement with SISBR-3 (latex containing 3% IA) exhibited the minimal elastic modulus of 3.16 GPa, which was lower than that of plain cement (8.34 GPa).

Synthesis and characterization of a phosphotungstic acid composite carrier and its application in solid chlorine dioxide disinfectant.

Chlorine dioxide (ClO2) is an antimicrobial compound used in water. The short release time of existing solid chlorine dioxide disinfectants significantly inhibits their bactericidal efficiency. We propose a novel approach in which attapulgite was introduced into phosphotungstic acid and SBA-15 to achieve the slow-release of chlorine dioxide disinfectant tablets. The emphasis of the study lies in slow release of chlorine dioxide and reducing the escape of chlorine dioxide gas to increase the reaction time and improve disinfection efficiency. When dissolved in water the decrease rate of chlorine dioxide within 15 days after mixing SBA-15/HPW with sodium chlorite is 78.6%. Moreover, the sterilization efficiency of Escherichia coli reaches 100% within 5 minutes, and the killing rate of Staphylococcus aureus exceeds 99.999% within 10 minutes. The research solved the storage and transportation problems of ClO2 and resulted in a solution for the disinfection of water requiring long-term disinfection.

Carotenoid Biosynthesis: Genome-Wide Profiling, Pathway Identification in Rhodotorula glutinis X-20, and High-Level Production.

Rhodotorula glutinis, as a member of the family Sporidiobolaceae, is of great value in the field of biotechnology. However, the evolutionary relationship of R. glutinis X-20 with Rhodosporidiobolus, Sporobolomyces, and Rhodotorula are not well understood, and its metabolic pathways such as carotenoid biosynthesis are not well resolved. Here, genome sequencing and comparative genome techniques were employed to improve the understanding of R. glutinis X-20. Phytoene desaturase (crtI) and 15-cis-phytoene synthase/lycopene beta-cyclase (crtYB), key enzymes in carotenoid pathway from R. glutinis X-20 were more efficiently expressed in S. cerevisiae INVSc1 than in S. cerevisiae CEN.PK2-1C. High yielding engineered strains were obtained by using synthetic biology technology constructing carotenoid pathway in S. cerevisiae and optimizing the precursor supply after fed-batch fermentation with palmitic acid supplementation. Genome sequencing analysis and metabolite identification has enhanced the understanding of evolutionary relationships and metabolic pathways in R. glutinis X-20, while heterologous construction of carotenoid pathway has facilitated its industrial application.

Photoactivated Organic Nanomachines for Programmable Enhancement of Antitumor Efficacy.

Limited permeability in solid tumors significantly restricts the anticancer efficacy of nanomedicines. Light-driven nanomotors powered by photothermal converting engines are appealing carriers for directional drug delivery and simultaneous phototherapy. Nowadays, it is still a great challenge to construct metal-free photothermal nanomotors for a programmable anticancer treatment. Herein, one kind of photoactivated organic nanomachines is reported with asymmetric geometry assembled by light-to-heat converting semiconducting polymer engine and macromolecular anticancer payload through a straightforward nanoprecipitation process. The NIR-fueled polymer engine can be remotely controlled to power the nanomachines for light-driven thermophoresis in the liquid media and simultaneously thermal ablating the cancer cells. The great manipulability of the nanomachines allows for programming of their self-propulsion in the tumor microenvironment for effectively improving cellular uptake and tumor penetration of the anticancer payload. Taking the benefit from this behavior, a programmed treatment process is established at a low drug dose and a low photothermal temperature for significantly enhancing the antitumor efficacy.

Synthesis of a hydrophobic associating polymer and its application in plugging spacer fluid.

The high temperature of formation and multiple stages of leakage zone seriously affect the efficiency and safety of drilling and cementing operations. To improve leakage plugging quality before the cementing process, the hydrophobic associating polymer PHAAO was synthesized from acrylamide (AM), 2-acrylamide-2-methyl propane sulfonic acid (AMPS), and the long side-chain hydrophobic monomer octadecyl dimethyl allyl ammonium chloride (ODAAC) in this study. The structure and molecular weight of the polymer were characterized, and it was proved that the polymer has strong association properties and excellent heat resistance. Utilizing the bridge plugging principle, the polymer PHAAO was used with 36-mesh walnut shells and lignin fiber to form a compound plugging agent. This agent was added to spacer fluid to become a plugging spacer. API water loss tests and loading capacity tests under high temperatures show that the filter cake formed by the spacer fluid is dense. The sealing pressure of the spacer fluid on a 1 mm crack can reach 6.5 MPa at 160 °C, and it has good compatibility with cement slurry. A scanning electron microscopy (SEM) test was conducted to explore the membrane formation mechanism of the polymer. An ultra-low permeability membrane is formed on the surface of the filter cake from the spacer fluid due to the hydrophobic association and hydrogen bonding between the polymer and lignin fiber, thereby greatly reducing the loss of spacer fluid.

Superlow Dosage of Intrinsically Bioactive Zinc Metal-Organic Frameworks to Modulate Endothelial Cell Morphogenesis and Significantly Rescue Ischemic Disease.

Despite long-term efforts for ischemia therapy, proangiogenic drugs hardly satisfy therapy/safety/cost/mass production multiple evaluations and meanwhile with a desire to minimize dosages, thereby clinical applications have been severely hampered. Recently, metal ion-based therapy has emerged as an effective strategy. Herein, intrinsically bioactive Zn metal-organic frameworks (MOFs) were explored by bridging the dual superiorities of proangiogenic Zn2+ and facile/cost-effective/scalable MOFs. Zn-MOFs could enhance the morphogenesis of vascular endothelial cells (ECs) via the PI3K/Akt/eNOS pathway. However, high dosage is inevitable and Zn-MOFs suffer from insolubility and low stability, which lead to the bioaccumulation of Zn-MOFs and seriously potential toxicity risks. To alleviate this, it is required to decrease the dosage, but this can be entrapped into the dosage/therapy/safety contradiction and disappointing therapy effect. To address these challenges, the bioavailability of Zn-MOFs is urgent to improve for the minimization of dosage and significant therapy/safety. The mitochondrial respiratory chain is Zn2+ active, which inspired us to codecorate EC-targeted and mitochondria-localizing-sequence peptides onto Zn-MOF surfaces. Interestingly, after codecoration, a 100-fold reduced dosage acquired equally powerful vascularization, and the superlow dosage significantly rescued ischemia (4.4 µg kg-1, about one order of magnitude lower than the published minimal value). Additionally, no obvious muscle injury was found after treatment. Potential toxicity risks were alleviated, benefiting from the superlow dosage. This advanced drug simultaneously satisfied comprehensive evaluations and dosage minimization. This work utilizes engineering thought to rationally design "all-around" bioactive MOFs and is expected to be applied for ischemia treatment.

A two-pronged approach to regulate the behaviors of ECs and SMCs by the dual targeting-nanoparticles.

Inhibiting vascular restenosis remains a tricky challenge for the postoperative development of cardiovascular interventional therapy. The ideal approaches should activate endothelial cells (ECs) and restrain smooth muscle cells (SMCs), however, they are commonly contradictory. Herein, a strategy was developed for synchronizing ECs promotion and SMCs inhibition by codelivery DNA and siRNA for combination therapy. Thus, an easy and efficient strategy integrated dual-superiorities of precise targeting and dual therapeutic genes to precisely regulate the behaviors of ECs and SMCs. The ECs-targeting REDV peptide and SMCs-targeting VAPG peptide grafted anionic polymers were used to surface-functionalize the delivery nanoplatforms for vascular endothelial growth factor (VEGF) plasmids and ERK2 siRNA delivery, respectively. The dual targeting-nanoparticles were prepared by physical mixing method, and their outstanding advantages were confirmed by the co-culture experiments. In comparison with single targeting-nanoparticles and dual non-targeting-nanoparticles, the dual targeting-nanoparticles simultaneously enhanced ECs proliferation/migration and restrained SMCs proliferation/migration. Moreover, the dual targeting-nanoparticles group manifested the highest VEGF expression in ECs and the lowest ERK2 expression in SMCs. In summary, the two-pronged strategy with dual targeting-nanoparticles provides a valuable cornerstone for synchronizing ECs promotion and SMCs inhibition.

Redox stimulus disulfide conjugated polyethyleneimine as a shuttle for gene transfer.

Redox-responsive cationic polymers have gained considerable attention in gene delivery due to low cytotoxicity and spatio-temporal release of DNA into the cells. Here, we reported the synthesis of reducible disulfide conjugated polyethyleneimine (1.8 kDa) (denoted as SS-PEI) and its application to transfer pEGFP-ZNF580 plasmid (pZNF580) into EA.hy926 cell. This reducible SS-PEI polymer was prepared by one-step polycondensation reaction of low molecular weight PEI with bis-(p-nitrophenyl)-3,3'-dithiodipropionate. The SS-PEI successfully condensed pZNF580 into nano-sized complexes (170 ± 1.5 nm to 255 ± 1.6 nm) with zeta potentials of 3 ± 0.4 mV to 17 ± 0.9 mV. The complexes could be triggered to release pZNF580 when exposed to the reducing environment of 5 mM dithiothreitol. Besides, the SS-PEI exhibited low cytotoxicity. In vitro transfection results showed that SS-PEI exhibited good transfection efficiency comparable to PEI25kDa. Thus, the SS-PEI could act as an reducible gene carrier with good transfection efficiency and low cytotoxicity.

Cascaded bio-responsive delivery of eNOS gene and ZNF580 gene to collaboratively treat hindlimb ischemia via pro-angiogenesis and anti-inflammation.

Gene therapy is a promising strategy for treating ischemic disease by solving the dual dilemma of ischemia and inflammation. However, its development remains limited by inefficient gene transfection. Hence, we propose a "dual genes + all-adaptive carrier" idea. We have innovatively co-delivered eNOS gene and the ZNF580 gene encoding its transcription factor to enhance the efficiency of eNOS expression. The overexpressed ZNF580 protein significantly promotes angiogenesis via regulating the transcription of multiple genes. This implies a potential synergistic effect of eNOS and ZNF580 genes in anti-ischemic therapy. Additionally, we have designed an all-adaptive gene carrier with cascaded bio-responsive functions based on the characteristic bio-signals of the ischemic site (including extracellular excessive matrix metalloproteinase-2, the endo/lysosomal pH gradient and high cytoplasmic glutathione level). This carrier can sequentially overcome transfection bottlenecks and achieve high transfection. Excitingly, this cascaded bio-responsive delivery strategy remarkably enhanced blood perfusion, accelerated angiogenesis and alleviated inflammation in critical limb ischemia (CLI) mice, which was attributed to the combined effects of pro-angiogenic ZNF580 expression and synergistically produced eNOS expression. Thereby, we believe that the co-delivery of eNOS and ZNF580 genes assisted by a cascaded bio-responsive carrier is a powerful strategy to treat CLI.

Agmatine-grafted bioreducible poly(l-lysine) for gene delivery with low cytotoxicity and high efficiency.

Bioreducible cationic polymers have gained considerable attention in gene delivery due to their low cytotoxicity and high efficiency. In the present work, we reported a cationic polymer, poly(disulfide-l-lysine)-g-agmatine (denoted as SSL-AG), and evaluated its ability to transfer pEGFP-ZNF580 plasmid (pZNF580) into human umbilical vein endothelial cells (HUVECs). This SSL-AG polymeric carrier efficiently condensed pZNF580 into positively charged particles (<200 nm) through electrostatic interaction. This carrier also exhibited excellent buffering capacity in the physiological environment, good pDNA protection against enzymatic degradation and rapid pDNA release in a highly reducing environment mainly because of the responsive cleavage of disulfide bonds in the polymer backbone. The hemolysis assay and in vitro cytotoxicity assay suggested that the SSL-AG carrier and corresponding gene complexes possessed both good hemocompatibility and great cell viability in HUVECs. The cellular uptake of the SSL-AG/Cy5-oligonucleotide group was 3.6 times that of the poly(l-lysine)/Cy5-oligonucleotide group, and its mean fluorescence intensity value was even higher than that of the PEI 25 kDa/Cy5-oligonucleotide group. Further, the intracellular trafficking results demonstrated that the SSL-AG/Cy5-oligonucleotide complexes exhibited a high nucleus co-localization rate (CLR) value (36.0 ± 2.8%, 3.4 times that of the poly (l-lysine)/Cy5-oligonucleotide group, 1.6 times that of the poly(disulfide-l-lysine)-g-butylenediamine/Cy5-oligonucleotide group) at 24 h, while the endo/lysosomal CLR value was relatively low. This suggested that SSL-AG successfully delivered plasmid into HUVECs with high cellular uptake, rapid endosomal escape and efficient nuclear accumulation owing to the structural advantages of the bioreducible and agmatine groups. In vitro transfection assay also verified the enhanced transfection efficiency in the SSL-AG/pZNF580 group. Furthermore, the results of CCK-8, cell migration and in vitro/vivo angiogenesis assays revealed that pZNF580 delivered by SSL-AG could effectively enhance the proliferation, migration and vascularization of HUVECs. In a word, the SSL-AG polymer has great potential as a safe and efficient gene carrier for gene therapy.

From single to a dual-gene delivery nanosystem: coordinated expression matters for boosting the neovascularization in vivo.

In the past decade, the development of gene carriers has been key in enhancing gene therapy. Gene therapy is associated with not only the delivery process but also gene expression as a prominent role. Herein, for the purpose of achieving a novel breakthrough in gene therapy, we creatively proposed a "strengthened gene expression" idea beyond the range of improving the gene carrier. We constructed three types of gene delivery systems, namely, single-pZNF580 delivery system, single-pVEGF165 delivery system, and dual-gene delivery system. These systems possessed approximate same sizes (∼120 nm) and zeta potentials (∼+20 mV), which indicated negligible differences in their cellular uptake. Interestingly, we found that the gene expression of dual-gene groups significantly increased at the level of both mRNA and protein at least 2 times and 1.5 times as high as single-gene groups, respectively. This "1 + 1 > 2" expression effect benefited from the coordinated expression of the angiogenesis-related genes of ZNF580 and VEGF165. Furthermore, the coordinated effect was also confirmed in HUVEC activities such as an obviously enhanced proliferation and migration of the dual-gene group. Rationally, we further evaluated the effects of coordinated interactions on neovascularization. We observed that the statistic tube number of dual-gene groups was approximately 1.44 times as high as that of single-gene groups. More importantly, this enhanced angiogenesis induced by the coordinated expression was also demonstrated in an in vivo environment. Therefore, we believed that the enhanced gene therapy via the gene expression pathway could provide a creative viewpoint for the design of gene delivery system and therapy.