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Mesoporous MCM-41-supported Schiff base and CuSO4·5H2O (MCM-41@Schiff base-CuSO4·5H2O) catalyzed one-pot three-component condensation of cyclic ketones, amines and thioglycolic acid in toluene. And a series of corresponding spiro thiazolidinone derivatives were obtained in high yields (up to 97%). The synthesized catalyst was characterized via FT-IR, XRD, SEM, TEM and EDS and can be easily recovered by centrifugation and reused at 10 times without any change in catalytic activity. Moreover, the scale-up experiment also demonstrated the practicability of the catalytic system on the condensation. The possible mechanisms pave the way to investigation on the reactions of other cyclic ketones with thioglycolic acid.

To examine the reinforcing effects of isocyanated graphene oxide (NCO-GO) on a waterborne polyurethane matrix, the surface of GO was respectively modified by isophorone diisocyanate (IPDI), hexamet...

A heterogeneous catalytic system (unfunctional mesoporous material MCM-41), which efficiently promoted one-pot synthesis of spiro[indoline-3,2′-pyrrolidin]-ones, has been developed. Under mild reaction conditions, a series of spiro[indoline-3,2′-pyrrolidin]-ones derivatives were synthesized in good yields (up to 95%) in water/ethanol = 2/1 as solvent. Notably, the unfunctional MCM-41 catalyst could be easily recovered by centrifugation and reused at least 10 times without loss in activity. And the scale up experiments also demonstrated the practicability of the catalystic system. Reusability, operational simplicity and eco-friendly are highlight of this study.

To study the dispersity of different amine-graphene oxide (amine-GO) in polymer matrix and the interfacial interactions between functionalized graphene oxide and matrix, two kinds of modifiers—organoamine- and aminosilane-coupling agents—were used to functionalize graphene nanosheets to obtain functionalized graphene oxide/waterborne polyurethane nanocomposites by in situ polymerization. The chemical structure, morphology, and interlayer space of amine-GO nanoplatelets were confirmed by FT-IR, Raman, TGA, XPS, TEM, AFM, and XRD. The dispersity behaviors between different amine-GOs and polymers were evaluated by FESEM. The thermal, mechanical, and hydrophobic properties of the nanocomposites were investigated by TGA, tensile testing machine, and water contact angle test, respectively. It was found that the tensile strength of nanocomposites was increased from 10.13 to 27.79 and 28.96 Mpa after the addition of amine-GO functionalized by APTMS and APTES, respectively. The better thermal stability and hydrophobicity of nanocomposites were also achieved by the addition of amine-GO, especially those modified by aminosilane-coupling agents. This study paves a new route for designing and developing chemically converted graphene oxide nanosheets/polymer nanocomposite materials by altering suitable amine-modifier to functionalize graphene oxide nanosheets and then optimizing the interphases between graphene oxide nanosheets and polymer matrices.

Polycationic gene carriers, mPEG-b-PLL-g-succinyl sulfathiazole (denoted as PPS), were synthesized and characterized as a shielding system for cationic gene delivery. DNA/PEI/PPS ternary complexes were prepared by shielding PPS to DNA/PEI polyplex solution. PPS can shield the surface charge of DNA/PEI polyplexes from positive (27.7 mV) to negative (−24.6 mV), and the acidic condition should trigger the disassembly of ternary complex. The gene transfection efficiency of DNA/PEI/PPS was lower than DNA/PEI at pH 7.4, but at pH 6.0, it recovered to the same level as DNA/PEI. CLSM results showed the same trend as transfection at different pH. The suitable pH-triggered shielding/deshielding ability estimated that PPS should be a potential shielding system to be used in in vivo gene delivery.

Cationic gene vectors increased attractive for gene therapy. However, unstable systemic circulation due to the interaction of gene delivery system with blood cells limited the further application. Therefore, pH sensitive shielding systems were exploited, by which, the positive surface charge density of polyplexes was reduced, circulation time was improved and pH-triggered targeting delivery was promised. This mini review mainly focuses on the development of solid tumors pH environment activated shielding systems for cationic gene vectors. This shielding strategy shows great potential for enhancing efficient gene transporting and achieving better therapeutic effects in acidic tumor treatment.

For the purpose of increasing the in vivo stability of polycation gene carriers, we prepared a kind of pH-sensitive poly(ethylene glycol)-poly (γ-benzyl-L-glutamate-co-glutamic acid) (PEG-PGA(65), 65 denotes the molar ratio of glutamic acid in poly(γ-benzyl-L-glutamate-co-glutamic acid)). PEG-PGA(65) showed low cytotoxicity and could shield the positive charge of DNA/PEI (1:1) polyplexes efficiently. The transfection was enhanced due to the partially charge shielding in HeLa cell line at pH of 7.4. There was almost no transfection efficiency when the surface charge of the ternary particles turned to negative at pH of 7.4. However, the transfection efficiency recovered a lot by culturing at pH of 6.0 at the beginning of transfection. Confocal microscopic observation and flow cytometry results showed DNA/PEI polyplexes should be efficiently released and endocytosized at pH 6.0, because of the pH triggered deshielding action of PEG-PGA(65). Due to the good biocompatibility and suitable pH triggered shielding/deshielding property, PEG-PGA(65) could be a potential shielding system for polycationic gene carriers used in vivo.

In this study, the fully degradable soybean oil-based waterborne polyurethanes (SWPU) were prepared, and the mechanical properties, thermal properties and hydrophilicity of SWPU films were adjusted by changing the R value. First, soybean oil-based polyol was fabricated via epoxy soybean oil and ricinoleic acid in the absence of solvent and catalyst. Then, the resulting polyol was mixed with isophorone diisocyanate (IPDI), dimethylolpropionic acid (DMPA), trimethylamine (TEA) and ethylenediamine (EDA) to synthesize polyurethane emulsion with different R value (the molar ration of –NCO/–OH). The result showed that as the R value increased, the tensile strength of SWPU film was increased from 10.02 to 27.32 MPa, the initial decomposition temperature of polyurethane films was improved from 201 ℃ to 246 ℃, the Tg,h was increased from 68 to 130 ℃ and the water contact angle of SWPU films were enhanced from 82.4° to 95.5°. It can be explained that the degree of crosslinking of the polyurethane elastomer was improved and the interaction of the molecular chains became stronger with larger R value. Also, all SWPU films were placed in the 3 wt% sodium hydroxide solution at 45 ℃ to test the degradability, and the weight loss of samples at different degradation time were calculated, respectively. Finally, the morphology, FT-IR and tensile strength of samples was observed before and after degradation, and a possible mechanism of degradation was studied. The technique reported here demonstrated that it was possible to develop the degradable materials.

In this study, a graft modified Octa(aminopropyl) polyhedral oligomeric silsesquioxane (OPOSS)/ TEMPO-oxidized cellulose microfibrils (TOCMF) nanocomposite material (named PC) was prepared by a simple peptide-forming reaction to overcome the disadvantages of nanocellulose materials which have limited their application in environmentally friendly waterborne polyurethanes. The modified vegetable oil-based waterborne polyurethane (WPU) was prepared by reacting the excess amino group on the POSS with the -NCO group on the polyurethane matrix in the in-situ polymerization, in which the POSS particles function as a button-like bond between the oxidized cellulose and the polyurethane matrix. And the similar filamentous structure of TOCMF to the linear polyurethane matrix structure could greatly weaken the negative impact of the rigid structure of POSS particles on processability (Elongation at break). The performance test results showed that the mechanical properties, thermal stability and water resistance of the modified WPU composite film are greatly improved by the synergistic effect of the two nano materials. The initial decomposition temperature and water contact angle of the WPU composite film with a PC content of 0.7 wt.% were increased by 41.9 °C and 10°, respectively. Especially, the tensile strength of WPU/PC-0.7 wt.% was twice that of pure WPU.

An environmentally friendly waterborne polyurethane based on castor oil was prepared and modified by 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO)-oxidized cellulose microfibers (TOCMF). The TOCMF with surface-attached active carboxyl groups was obtained by TEMPO/NaClO/NaBr system, and then the modified castor oil-based waterborne polyurethane was prepared by the synergistic action of covalent bond and hydrogen bond between TOCMF and prepolymer in the in-situ polymerization reaction. The introduction of carboxylate on the surface of TOCMF facilitated stabilization of the thickness of the double layer of the emulsion particles to form stable WPU/TOCMF dispersions. Benefiting from the filamentous structural effects of TOCMF and the covalent bond and hydrogen bond dual interactions in WPU matrix, WPU/TOCMF composite films showed improvement in tensile strength and thermal decomposition temperature. Tensile strength of composite films increased from 17.89 to 30.31 MPa with increasing TOCMF amount from 0 to 1.00 wt%. T5% of composite films increased from 202.6 to 239.3 °C with increasing TOCMF amount from 0 to 0.75 wt%. It was observed by SEM that the presence of agglomeration in the composite film with 1.25 and 1.50 wt% TOCMF, and the occurrence of agglomeration caused the performance of the composite film to deteriorate sharply.

Novel thermo- and pH-dual responsive amphiphilic copolymers were synthesized based on hyperbranched polyethylenimine (PEI) by grafting L-phenylalanine. The phenylalanine-modified PEI exhibited lower cytotoxicity than commercial PEI. These copolymers showed the phenomena of phase transitions in response to pH and temperature. The dilute copolymer solution at lower pH displayed the higher LCST. Furthermore, LCST increased with the increasing of phenylalanine grafting density. LCST of these copolymers were tunable from 7.2 to 59.6 °C by the degree of amidation and pH of solution. DLS and TEM experiments certified that the copolymer chains aggregated to form small size particles as increasing the temperature above LCST. For these reasons, the obtained smart copolymers were considered to be potential gene/drug carriers in biomedical field.

A novel graphene nanomaterial functionalized by octa(aminopropyl) polyhedral oligomeric silsesquioxane (OapPOSS) was synthesized and then confirmed by Fourier transform infrared spectroscopy, thermogravimetric analysis (TGA), Raman spectroscopy, X-ray photoelectron spectroscopy, transmission electron microscopy, scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM EDX), atomic force microscopy, and X-ray diffraction. The obtained functionalized graphene (OapPOSS-GO) was used to reinforce waterborne polyurethane (WPU) to obtain OapPOSS-GO/WPU nanocomposites by in situ polymerization. The thermal, mechanical, and hydrophobic properties of nanocomposites as well as the dispersion behavior of OapPOSS-GO in the polymer were investigated by TGA, a tensile testing machine, water contact angle tests, and field emission SEM, respectively. Compared with GO/WPU and OapPOSS/WPU composites, the strong interfacial interaction between OapPOSS-GO and the WPU matrix facilitates a much better dispersion and load transfer from the WPU matrix to the OapPOSS-GO. It was found that the tensile strength of the OapPOSS-GO/WPU composite film with 0.20 wt % OapPOSS-GO exhibited a 2.5-fold increase in tensile strength, compared with neat WPU. Better thermal stability and hydrophobicity of nanocomposites were also achieved by the addition of OapPOSS-GO. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 44440.

Low molecular weight polyethyleneimines were conjugated onto gold nanoparticles to form Au-PEI conjugates. Au-PEI is the first reported gene carrier which has both high transfection efficiency and strong fluorescence. Au-PEI showed higher transfection efficiency and it can be used for bioimaging because it can be detected by confocal laser scanning microscopy and in vivo bioimaging system.

RGD peptides were grafted to the carboxyl groups of poly(glutamic acid) to get a targeting shielding carrier (PGA-RGD) for polyethyleneimine (PEI) gene carrier. The experiment results showed that PGA-RGD can effectively shield PEI/DNA complex particles. Gel retardation assay showed that DNA can not be released by PGA-RGD from complexes under experimental conditions for gene transfection. For PGA/PEI/DNA system, its gene transfection efficiency obviously decreased because PGA shielding carrier coating on PEI/DNA complex decreased the surface charges of the complex particles. On the other hand, for PGA-RGD/PEI/DNA shielding system, although its surface charges were decreased by PGA-RGD shielding, its gene transfection efficiency were effectively improved because of the specific binding affinity between RGD and receptors on tumor endothelial cell membranes. MTT assay further presented that PGA-RGD/PEI/DNA has better biocompatibility than PEI/DNA. The improvement method developed in this paper for gene carriers can not only shield the positive charges on complex particles and decrease the non-specific uptake by non-targeting cells, but also introduce targeting functions to gene carrier system. The shielding system for gene complex particles is an effective strategy for promoting in vivo application of polycation gene carriers.

Novel polymers composed of net-like PEGylated poly(β-amino ester) (N-P-1, M(w) = 6900 or N-P-2, M(w) = 21,400) and oligoethylenimine (OEI) (OEI423 or OEI600) were synthesized and evaluated as gene carriers. The molecular weights of these polymers were well-controlled by the concentration of the cross-linking reaction. The synthesized polymers showed high biodegradability, less cytotoxicity, and efficient DNA retard ability. The N-P-1-OEI600/DNA complex showed much slower aggregation in the presence of 10 and 20% serum solutions. In vitro transfection assays, N-P-2-OEI423, N-P-1-OEI600, and N-P-2-OEI600 showed enhanced transfection efficiency compared with the PEI25K control in the presence or in the absence of serum in different cell lines. In particular, in Cos-7 cells, the transfection efficiency of N-P-1-OEI600 was 20.9 times higher than that of PEI25K in the presence of serum. The polymer/DNA complex stability, lower cytotoxicity, and higher transfection efficiency in the presence of serum revealed that N-P-1-OEI600 could be a potential nonviral gene carrier for In Vivo application.

Low molecular weight polyethylenimine-poly(gamma-benzyl L-glutamate) (PEI-PBLG) was crosslinked by N,N′-cystamine-bisacrylamide (CBA) to get the polymer named as CBA-PEI-PBLG (CPP). CPP not only inherits PEI-PBLG’s amphiphilic advantages, but also possesses reducible properties. CPP can complex with DNA to form nanoparticles. CPP/DNA complex particles were characterized by particle size and zeta potential analysis. The result showed that the complex particles have suitable size and surface charges for gene delivery. And gel retardation assay also prove CBA-PEI-PBLG has proper condensing ability for DNA. CPP has good reducible property, and also has good biocompatibility because of introducing PBLG segment. The cytotoxicity of CPP was evaluated using MTT assay, and the results showed CPP has lower cytotoxicity compared with PEI 25 K. The transfection properties were characterized in different cells by using plasmid DNA as a reporter. CPP showed higher transfection efficiencies and lower cytotoxicity in HeLa cells. This was attributed to bioreducible and biocompatibility properties of the CPP. These results suggested that CPP is a promising low-toxic, highly effective non-viral gene carrier.

A series of amphiphilic multi-armed PPn copolymers were prepared by ROP of Phe-NCA with PEI-25k as a macroinitiator. The particle size of the PPn/DNA complexes was about 100 nm and the zeta potentials were below 20 mV. An MTT assay demonstrated that all the PPn copolymers had lower cytotoxicity compared to PEI-25k. In vitro gene transfection studies were also conducted in HeLa, 293 and CT 26 cells. The optimal quantity of hydrophobic phenylalanine segments in PP80 led to higher transfection efficiency in various cell lines based on this study. The results indicate that PP80 was the best candidate for gene delivery among these PPn copolymers.

To increase the in vivo stability of polycation gene carriers, a pH-sensitive shielding system, γ-benzyl l-glutamate-co-glutamate acid polymer (PGA(60) (60 refers to the molar ratio of glutamate acid in the polymer)), was synthesized and characterized. PGA(60) showed pH sensitivity at about pH 6.0. PGA(60) shielded the positive charge of DNA/PEI (1:1) complexes. Gel retardation assay showed that no DNA-strand exchange with PGA(60) occurred after PGA(60) was added to DNA/PEI complexes at different proportions. MTT cytotoxicity tests demonstrated that neither PGA(60) nor DNA/PEI/PGA(60) ternary complexes had cytotoxicity at the test concentration. The transfection efficiency was improved when the positive charge was partly shielded by PGA(60). Because of the charge repulsion between the surface of cells and ternary complex particles, there was almost no transfection efficiency when the zeta potential of ternary complexes turned to negative. Because of the suitable pH sensitive range, PGA(60) may be a potential shielding system for polycation gene carriers to be used in vivo.

In search for effective non-viral gene vectors for the delivery of siRNA, a copolymer was designed and synthesized by grafting hydrophobic poly(gamma-benzyl L-glutamate) segment (PBLG) to hyperbranched polyethylenimine (PEI-PBLG). PEI-PBLG could efficiently deliver siRNA to cells to silence the targeted gene. Markedly, PEI-PBLG caused lower cytotoxicity in comparison to unmodified PEI. The siRNA complexed with PEI-PBLG showed a remarkable knockdown (75.23% relative to untreated cells, without changing the medium after 6 h of incubation) of the targeted luciferase gene in stable expressing luciferase CT26 cells while the Lipofectamine2000 and unmodified PEI could only achieve knockdown rates of 57.92% and 15.31%, respectively. The siRNA complexed with PEI-PBLG also demonstrated that it had greater gene silencing ability than unmodified PEI and Lipofectamin2000 in both 4T1 cells stably transfected with the luciferase gene and HeLa cells transiently transfected with the luciferase gene. The internalization efficiency of carrier/Alexa647-labeled siRNA was quantified using flow cytometry. PEI-PBLG/Alexa647-labeled siRNA showed internalization efficiency of 52.67% while PEI and Lipofectamine2000 demonstrated 27.23% and 37.91%, respectively. Confocal laser scanning microscopy (CLSM) assay also indicated that PEI-PBLG induced higher cell uptake efficiency than other commercial reagents. PEI-PBLG was shown to be a promising siRNA carrier with potential application in cancer therapy.

1,4-di(4′-N,N-diphenylaminostyryl)benzene (DPA-DSB) is a well known compound with a large two-photon absorption (TPA) section and strong fluorescence in solution. However, the ease with which it crystallizes results in the formation of discontinuous crystalline phases during vacuum deposition processes, thereby greatly limiting its applicability in solid-state devices. A cruciform dimer of DPA-DSB, 2,5,2′,5′-tetra(4′-N,N-diphenylaminostyryl)biphenyl (DPA-TSB) is reported, wherein two DPA-DSB molecules are linked through a central biphenyl bond. The DPA-TSB molecules take on a cruciform configuration because of the steric crowding around the central biphenyl core, which has the effect of efficiently suppressing crystalline and intermolecular interactions. The neat DPA-TSB solid shows strong green–blue fluorescence because of both steady-state absorption as well as TPA. The DPA-TSB solid exhibits a photoluminescence (PL) efficiency (ηsolid) of 29 % and a solid-state two-photon action cross section (δηsolid) of 954 GM (1 GM = 1 × 10–50 cm4 s photon–1 molecule–1), which is much greater than for the model compound DPA-DSB (ηsolid = 16 % and δηsolid = 150 GM, where δ is the TPA cross section and η is the fluorescence quantum yield). Based on its high PL efficiency, good film-forming ability, and strong TPA, DPA-TSB seems to be a good candidate for applications in solid-state optical devices.

A novel pH-responsive gene delivery system for tumor acidity-targeted p DNA delivery is prepared by introducing a rapid charge-conversional zwitterionic copolymer to the positive surface of PEI/ p DNA complexes through electrostatic interaction. The shielding system (OEAL) consists of oligoethylenimine (OEI), poly( l -aspartate) (PBLA), and poly( l -lysine) (PLL). The charge-conversional behavior of the OEAL/PEI/DNA ternary complex is evaluated by zeta potential assay. The surface charges of the complexes can change from negative to positive in the pH range of 7.4–6.8. Under a simulative in vivo environment, OEAL/PEI/DNA exhibits promotion of cellular uptake by tumor cells and enhanced gene transfection efficiency because of its good charge-conversional properties. Antitumor experiments further show that the pH-responsive charge-conversional system can mediate a therapeutic gene that can induce tumor apoptosis ( p KH3-rev-casp-3) to achieve effective tumor inhibition. Accordingly, OEAL can be regarded as a promising tumor microenvironment-sensitive gene delivery shielding system for antitumor therapy. Statement of Significance This manuscript focused on the novel pH-responsive gene delivery system for tumor acidity-targeted p DNA delivery. The novel system is prepared by introducing a rapid charge-conversional zwitterionic copolymer, consisting of oligoethylenimine, poly( l -aspartate) and poly( l -lysine), to the positive surface of PEI/ p DNA complexes. The surface charges of the complexes can change from negative to positive from pH 7.4 to 6.8. OEAL/PEI/DNA shows promoting cellular uptake by tumor cells and enhanced gene transfection efficiency. The antitumor experiments further show that the pH responsive charge conversional system can mediate p KH3-rev-casp-3 to achieve effective tumor inhibition. Accordingly, OEAL can be regarded as a promising tumor microenvironment sensitive gene delivery shielding system for antitumor therapy.

For improving the therapeutic efficiency of tumors and decreasing undesirable side effects, ternary complexes were developed by coating pH-sensitive PEG-b-PLL-g-succinylsulfathiazole (hereafter abbreviated as PPSD) with DNA/PEI polyplexes via electrostatic interaction. PPSD can efficiently shield the surface charge of DNA/PEI. The gene transfection efficiency of ternary complexes was lower than that of DNA/PEI at pH 7.4; however, it recovered to the same level as that of DNA/PEI at pH 6.0, attributed to the pH-triggered release of DNA/PEI from ternary complexes. Cell uptake results also exhibited the same trend as transfection at different pH values. The suitable ability for pH-triggered shielding/deshielding estimated that PPSD demonstrates potential as a shielding system for use in in vivo gene delivery.

Summary Novel net-polymers were prepared by grafting oligoethylenimine (OEI) on net-poly(amino ester) (N-P-g-OEI) and applied as gene carriers. N-P-g-OEI can effectively condense DNA to form small-sized complex particles (