This study investigates the removal of Congo Red dye from aqueous solution using functionalized generation 3.0 and 5.0 polyamidoamine dendrimer-silica gel composite (G-3PS, G-5PS). Fourier Transform-Infra Red spectros...This study investigates the removal of Congo Red dye from aqueous solution using functionalized generation 3.0 and 5.0 polyamidoamine dendrimer-silica gel composite (G-3PS, G-5PS). Fourier Transform-Infra Red spectroscopy, Brunauer Emmett and Teller, Thermo Gravimetric Analysis, pH at point of zero charge, and scanning electron microscopy measurements have been applied to characterize the synthetic nanohybrid composite, these techniques revealed the successful functionalization of both dendrimer molecules and subsequent immobilization onto silica gel. The implications of varying adsorption parameters such as contact time, initial concentration of adsorbate, temperature and pH on both composites were studied. Experimental data obtained from batch adsorption processes were fitted into two equilibrium isotherms (Langmuir and Freundlich) and 3 kinetic models (Pseudo-First-Order, Pseudo-Second-Order, Intra Particle Diffusion). Adsorption mechanism was mainly governed by film diffusion due to electrostatic interactions between the functionalized dendrimer surface and Congo Red molecules. Thermodynamic parameters illustrate that the adsorption is endothermic and spontaneous. Findings suggest the Nanocomposites (G-3PS and G-5PS) are good adsorbents for the removal of Congo Red dye from aqueous solutions.展开更多
Oxidation of cyclohexene under 1 atmospheric pressure of molecular oxygen at 70C in the absence of solvent catalyzed by PAMAM-SA-M (Where PAMAM = polyamidoamine; SA = salicyaldehyde; M = metal ions Fe3+, Co2+, Ni2+, M...Oxidation of cyclohexene under 1 atmospheric pressure of molecular oxygen at 70C in the absence of solvent catalyzed by PAMAM-SA-M (Where PAMAM = polyamidoamine; SA = salicyaldehyde; M = metal ions Fe3+, Co2+, Ni2+, Mn2+, Cu2+, Zn2+, respectively) dendrimers, afforded 2-cyclohexen-1-ol 1, 2-cyclohexen-1-one 2, 7-oxabicyclo [4,1,0] heptane 3 and 7-oxabicyl [4,1,0] heptan-2-one 4 as the major products. The factors that affect this reaction are also discussed.展开更多
The direct electron transfer of hemoglobin at the PAMAM-MWNTs-AuNPs composite film modified glassy carbon electrode was studied. In a phosphate buffer solution（PBS, pH=7.0）, the formal potential（E^0） of Hb was -0....The direct electron transfer of hemoglobin at the PAMAM-MWNTs-AuNPs composite film modified glassy carbon electrode was studied. In a phosphate buffer solution（PBS, pH=7.0）, the formal potential（E^0） of Hb was -0.105 V versus SCE, the electron transfer rate constant was 4.66 s-1. E^0＇ of Hb at the modified electrode was linearly varied in a pH range of 5.0-8.0 with a slope of-49.2 mV/pH. The Hb/PAMAM-MWNTs-AuNPs/GCE gave an excellent electrocatalytic response to the reduction of hydrogen peroxide. The catalytic current increased linearly with H2O2 concentration in a range of 1.0× 10^-6 to 2.2× 10^-3 mol/L. The detection limit was 2.0× 10^-7 mol/L at a signal to noise ratio of 3. The Michaelis-Menten constant（Km^app） was 2.95 mmol/L.展开更多
The interaction of biotinylated G4 poly(amidoamine) (PAMAM) dendrimer conjugates and G4 PAMAM dendrimers with in vitro models of the blood brain barrier (BBB) was evaluated using Langmuir Blodgett monolayer techniques...The interaction of biotinylated G4 poly(amidoamine) (PAMAM) dendrimer conjugates and G4 PAMAM dendrimers with in vitro models of the blood brain barrier (BBB) was evaluated using Langmuir Blodgett monolayer techniques, atomic force microscopy (AFM) and lactate dehydrogenase measures of cell membrane toxicity. Results indicate that both G4 and G4 biotinylated PAMAM dendrimers disrupt the composition of the liquid condensed (LC) and liquid expanded (LE) phases of the 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) lipid monolayer. The disruption is concentration dependent and more marked for G4 biotinylated PAMAMs. Lactate dehydrogenase (LDH) assays using endothelial cell culture models of the BBB indicate that biotinylation results in higher levels of toxicity than non-biotinylation. This approach provides valuable information to assess nanoparticle toxicity for drug delivery to the brain.展开更多
New functional dendrimers bearing 4, 8 and 16 axial chiral units on their surface were synthesized from achiral PAMAM dendrimers and axial chiral (R)-BINOL derivative.
Due to the special viscoelastic property, traditional rubber with high performance has been widely used in human life and production. However, it is challenging to improve the damping property without sacrificing the ...Due to the special viscoelastic property, traditional rubber with high performance has been widely used in human life and production. However, it is challenging to improve the damping property without sacrificing the extensibility. In this work, a novel type of second-generation polyurethane dendrimer terminated with pyridine(G2-Py) was synthesized by using thiolactone chemistry and subsequently complexed with Zn ions. The structure and morphology of G2-Py were characterized. G2-Py-Zn2+was then mixed with chlorinated butyl rubber(CIIR) by a two-roll mill. A series of CIIR/G2-Py-Zn2+elastomers were obtained through vulcanization. CIIR/G2-Py-Zn2+elastomers could achieve high stretchability(a strain of ~1035%), high mechanical strength(a tensile stress of 7.64 MPa). This was benefitted from the friction between G2-Py and CIIR as well as variety of non-covalent bonds provided by G2-Py-Zn2+,which can dissipate energy to further improve the strength and extensibility. The coordination of Zn2+-pyridine was confirmed by Fourier transform infrared spectroscopy, stress relaxation and cycle tensile test. To further investigate the morphology and damping properties of the elastomers, scanning electron microscopy and dynamic mechanical analysis were performed. CIIR-5 showed the best damping performance with higher tan δ_(max) and wider effective damping temperatures. Therefore, this dendrimer modification technology provides wider applications for CIIR elastomers in daily life.展开更多
Topological indices(TIs)have been practiced for distinct wide-ranging physicochemical applications,especially used to characterize and model the chemical structures of various molecular compounds such as dendrimers,na...Topological indices(TIs)have been practiced for distinct wide-ranging physicochemical applications,especially used to characterize and model the chemical structures of various molecular compounds such as dendrimers,nanotubes and neural networks with respect to their certain properties such as solubility,chemical stability and low cytotoxicity.Dendrimers are prolonged artificially synthesized or amalgamated natural macromolecules with a sequential layer of branches enclosing a central core.A present-day trend in mathematical and computational chemistry is the characterization of molecular structure by applying topological approaches,including numerical graph invariants.Among topological descriptors,Zagreb connection indices(ZCIs)have much importance.This manuscript involves the establishment of general results to calculate ZCIs,namely first ZCI(FZCI),second ZCI(SZCI),third ZCI(TZCI),modified FZCI,modified SZCI and modified TZCI of two special types of dendrimers nanostars,namely,poly propylene imine octamin(PPIO)dendrimer and poly(propyl)ether imine(PPEtIm)dendrimer.Furthermore,we provide the numerical and graphical comparative analysis of our calculated results for both types of dendrimers with each other.展开更多
OBJECTIVE The greatest challenge in chemotherapy of ischemic stroke is the construction a suitable delivery system to overcome the poor physicochemical properties of drug and its low permeability across the blood brai...OBJECTIVE The greatest challenge in chemotherapy of ischemic stroke is the construction a suitable delivery system to overcome the poor physicochemical properties of drug and its low permeability across the blood brain barrier(BBB).METHODS In the present study,dendrimer,polyamidoamine(PAMAM),was synthesized as the nano-drug carriers.Angiopep-2,which has been proved excellent ability to cross the BBB,was exploited as the targeting ligand to conjugate PAMAM via bifunctional polyethylene glycol(PEG).Then scutellarin(STA)was encapsulated into the functionalized nanoparticles(NPs)to formulate Angiopep-2 modified STA-loaded PEG-PAMAM NPs.Ischemic stroke model was established to evaluate the treatment efficacy and protective mechanism of Angiopep-2-STA-PEG-PAMAM NPs.RESULTS The pharmacokinetics and biodistribu-tion demonstrated that Angiopep-2-STA-PEG-PAMAM NPs exhibited significantly higher plasma concentration from 1 h to 10 h after intravenous administration and improve accumulation in brain(4.7-fold)compared with STA solution.Moreover,prolonged elimination half-life(4.8-fold)and lower clearance(3.4-fold)were observed.The brain uptake study of 6-coumarin confirmed that Angiopep-2-PEG-PAMAM NPs possessed better brain targeting efficacy(3.2-fold)than PEG-PAMAM NPs.Angiopep-2-STA-PEG-PAMAM NPs obviously ameliorated infarct volume,neurological deficit,histopathological severity and neuronal apoptosis.In addition,Angiopep-2-STA-PEG-PAMAM NPs markedly inhibited the calcium content and the levels of IL-12p40,IL-13,IL-17 and IL-23.Furthermore,Angiopep-2-STA-PEG-PAMAM NPs significantly decreased the m RNA and protein expressions of HMGB1,TLR2,TLR4,TLR5,My D88,TRIF,TRAM,IRAK-4,TRAF6,IкBα,IKKβand NF-кBp65.CONCLUSION The results suggested that Angiopep-2modified scutellarin-loaded PEG-PAMAM nanocarriers possessed remarkable neuroprotective effects on ischemic stroke through modulation of inflammatory cascades and HMGB1/TLRs/MyD 88-induced NF-κB activation pathways.展开更多
An azyl group of ethylene diamine was protected by N-tert-butoxycarbonyl.The remaining azyl group then successively reacted with methyl acrylate, ethylene diamine and methyl acrylate again to afford the compound Boc-N...An azyl group of ethylene diamine was protected by N-tert-butoxycarbonyl.The remaining azyl group then successively reacted with methyl acrylate, ethylene diamine and methyl acrylate again to afford the compound Boc-NH 2-(B-COOCH 3) 4 3 (AB-4).The ester groups and the Boc-end group of 3 were transferred to carboxylate 4 and azyl group 5 via hydrolyzation and deprotection respectively.The fan-shape dendron molecules with 16 exterior groups 6 were obtained by condensation of 4 and 5 in the presence of DCC.The dumbbell-like dendrimer molecules 7 could expediently prepared by coupling the dendrons with two functional groups of hexanedioyl chloride.The paper describes the synthesis procedures,reports the characterization results of FTIR、 1H-NMR、 13C-NMR and MALDI-TOF.Comparing with the PAMAM dendrimers from the divergent method, the synthesized compounds possess accurate structures and few defections.展开更多
文摘This study investigates the removal of Congo Red dye from aqueous solution using functionalized generation 3.0 and 5.0 polyamidoamine dendrimer-silica gel composite (G-3PS, G-5PS). Fourier Transform-Infra Red spectroscopy, Brunauer Emmett and Teller, Thermo Gravimetric Analysis, pH at point of zero charge, and scanning electron microscopy measurements have been applied to characterize the synthetic nanohybrid composite, these techniques revealed the successful functionalization of both dendrimer molecules and subsequent immobilization onto silica gel. The implications of varying adsorption parameters such as contact time, initial concentration of adsorbate, temperature and pH on both composites were studied. Experimental data obtained from batch adsorption processes were fitted into two equilibrium isotherms (Langmuir and Freundlich) and 3 kinetic models (Pseudo-First-Order, Pseudo-Second-Order, Intra Particle Diffusion). Adsorption mechanism was mainly governed by film diffusion due to electrostatic interactions between the functionalized dendrimer surface and Congo Red molecules. Thermodynamic parameters illustrate that the adsorption is endothermic and spontaneous. Findings suggest the Nanocomposites (G-3PS and G-5PS) are good adsorbents for the removal of Congo Red dye from aqueous solutions.
文摘Oxidation of cyclohexene under 1 atmospheric pressure of molecular oxygen at 70C in the absence of solvent catalyzed by PAMAM-SA-M (Where PAMAM = polyamidoamine; SA = salicyaldehyde; M = metal ions Fe3+, Co2+, Ni2+, Mn2+, Cu2+, Zn2+, respectively) dendrimers, afforded 2-cyclohexen-1-ol 1, 2-cyclohexen-1-one 2, 7-oxabicyclo [4,1,0] heptane 3 and 7-oxabicyl [4,1,0] heptan-2-one 4 as the major products. The factors that affect this reaction are also discussed.
基金Supported by the National Natural Science Foundation of China(No.20605009)
文摘The direct electron transfer of hemoglobin at the PAMAM-MWNTs-AuNPs composite film modified glassy carbon electrode was studied. In a phosphate buffer solution（PBS, pH=7.0）, the formal potential（E^0） of Hb was -0.105 V versus SCE, the electron transfer rate constant was 4.66 s-1. E^0＇ of Hb at the modified electrode was linearly varied in a pH range of 5.0-8.0 with a slope of-49.2 mV/pH. The Hb/PAMAM-MWNTs-AuNPs/GCE gave an excellent electrocatalytic response to the reduction of hydrogen peroxide. The catalytic current increased linearly with H2O2 concentration in a range of 1.0× 10^-6 to 2.2× 10^-3 mol/L. The detection limit was 2.0× 10^-7 mol/L at a signal to noise ratio of 3. The Michaelis-Menten constant（Km^app） was 2.95 mmol/L.
文摘The interaction of biotinylated G4 poly(amidoamine) (PAMAM) dendrimer conjugates and G4 PAMAM dendrimers with in vitro models of the blood brain barrier (BBB) was evaluated using Langmuir Blodgett monolayer techniques, atomic force microscopy (AFM) and lactate dehydrogenase measures of cell membrane toxicity. Results indicate that both G4 and G4 biotinylated PAMAM dendrimers disrupt the composition of the liquid condensed (LC) and liquid expanded (LE) phases of the 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) lipid monolayer. The disruption is concentration dependent and more marked for G4 biotinylated PAMAMs. Lactate dehydrogenase (LDH) assays using endothelial cell culture models of the BBB indicate that biotinylation results in higher levels of toxicity than non-biotinylation. This approach provides valuable information to assess nanoparticle toxicity for drug delivery to the brain.
文摘New functional dendrimers bearing 4, 8 and 16 axial chiral units on their surface were synthesized from achiral PAMAM dendrimers and axial chiral (R)-BINOL derivative.
基金supported by the National Natural Science Fundation of China((51873103)Capacity Building Project of Some Local Colleges and Universities in Shanghai(17030501200)+1 种基金Talent Program of Shanghai University of Engineering Science(2017RC422017)Postgraduate Research and Innovation Project of Shanghai University of Engineering Science(0234-E3-0903-19-01367).
文摘Due to the special viscoelastic property, traditional rubber with high performance has been widely used in human life and production. However, it is challenging to improve the damping property without sacrificing the extensibility. In this work, a novel type of second-generation polyurethane dendrimer terminated with pyridine(G2-Py) was synthesized by using thiolactone chemistry and subsequently complexed with Zn ions. The structure and morphology of G2-Py were characterized. G2-Py-Zn2+was then mixed with chlorinated butyl rubber(CIIR) by a two-roll mill. A series of CIIR/G2-Py-Zn2+elastomers were obtained through vulcanization. CIIR/G2-Py-Zn2+elastomers could achieve high stretchability(a strain of ~1035%), high mechanical strength(a tensile stress of 7.64 MPa). This was benefitted from the friction between G2-Py and CIIR as well as variety of non-covalent bonds provided by G2-Py-Zn2+,which can dissipate energy to further improve the strength and extensibility. The coordination of Zn2+-pyridine was confirmed by Fourier transform infrared spectroscopy, stress relaxation and cycle tensile test. To further investigate the morphology and damping properties of the elastomers, scanning electron microscopy and dynamic mechanical analysis were performed. CIIR-5 showed the best damping performance with higher tan δ_(max) and wider effective damping temperatures. Therefore, this dendrimer modification technology provides wider applications for CIIR elastomers in daily life.
文摘Topological indices(TIs)have been practiced for distinct wide-ranging physicochemical applications,especially used to characterize and model the chemical structures of various molecular compounds such as dendrimers,nanotubes and neural networks with respect to their certain properties such as solubility,chemical stability and low cytotoxicity.Dendrimers are prolonged artificially synthesized or amalgamated natural macromolecules with a sequential layer of branches enclosing a central core.A present-day trend in mathematical and computational chemistry is the characterization of molecular structure by applying topological approaches,including numerical graph invariants.Among topological descriptors,Zagreb connection indices(ZCIs)have much importance.This manuscript involves the establishment of general results to calculate ZCIs,namely first ZCI(FZCI),second ZCI(SZCI),third ZCI(TZCI),modified FZCI,modified SZCI and modified TZCI of two special types of dendrimers nanostars,namely,poly propylene imine octamin(PPIO)dendrimer and poly(propyl)ether imine(PPEtIm)dendrimer.Furthermore,we provide the numerical and graphical comparative analysis of our calculated results for both types of dendrimers with each other.
基金The project supported by National Natural Science Foundation of China(NSFC 21476054)the Natural Science Foundation of Heilongjiang Province(B201407)
文摘OBJECTIVE The greatest challenge in chemotherapy of ischemic stroke is the construction a suitable delivery system to overcome the poor physicochemical properties of drug and its low permeability across the blood brain barrier(BBB).METHODS In the present study,dendrimer,polyamidoamine(PAMAM),was synthesized as the nano-drug carriers.Angiopep-2,which has been proved excellent ability to cross the BBB,was exploited as the targeting ligand to conjugate PAMAM via bifunctional polyethylene glycol(PEG).Then scutellarin(STA)was encapsulated into the functionalized nanoparticles(NPs)to formulate Angiopep-2 modified STA-loaded PEG-PAMAM NPs.Ischemic stroke model was established to evaluate the treatment efficacy and protective mechanism of Angiopep-2-STA-PEG-PAMAM NPs.RESULTS The pharmacokinetics and biodistribu-tion demonstrated that Angiopep-2-STA-PEG-PAMAM NPs exhibited significantly higher plasma concentration from 1 h to 10 h after intravenous administration and improve accumulation in brain(4.7-fold)compared with STA solution.Moreover,prolonged elimination half-life(4.8-fold)and lower clearance(3.4-fold)were observed.The brain uptake study of 6-coumarin confirmed that Angiopep-2-PEG-PAMAM NPs possessed better brain targeting efficacy(3.2-fold)than PEG-PAMAM NPs.Angiopep-2-STA-PEG-PAMAM NPs obviously ameliorated infarct volume,neurological deficit,histopathological severity and neuronal apoptosis.In addition,Angiopep-2-STA-PEG-PAMAM NPs markedly inhibited the calcium content and the levels of IL-12p40,IL-13,IL-17 and IL-23.Furthermore,Angiopep-2-STA-PEG-PAMAM NPs significantly decreased the m RNA and protein expressions of HMGB1,TLR2,TLR4,TLR5,My D88,TRIF,TRAM,IRAK-4,TRAF6,IкBα,IKKβand NF-кBp65.CONCLUSION The results suggested that Angiopep-2modified scutellarin-loaded PEG-PAMAM nanocarriers possessed remarkable neuroprotective effects on ischemic stroke through modulation of inflammatory cascades and HMGB1/TLRs/MyD 88-induced NF-κB activation pathways.
文摘An azyl group of ethylene diamine was protected by N-tert-butoxycarbonyl.The remaining azyl group then successively reacted with methyl acrylate, ethylene diamine and methyl acrylate again to afford the compound Boc-NH 2-(B-COOCH 3) 4 3 (AB-4).The ester groups and the Boc-end group of 3 were transferred to carboxylate 4 and azyl group 5 via hydrolyzation and deprotection respectively.The fan-shape dendron molecules with 16 exterior groups 6 were obtained by condensation of 4 and 5 in the presence of DCC.The dumbbell-like dendrimer molecules 7 could expediently prepared by coupling the dendrons with two functional groups of hexanedioyl chloride.The paper describes the synthesis procedures,reports the characterization results of FTIR、 1H-NMR、 13C-NMR and MALDI-TOF.Comparing with the PAMAM dendrimers from the divergent method, the synthesized compounds possess accurate structures and few defections.
