To gain insight into the attachment of =Si^＋ （SC） ion （regarded as guest） to the lowest generation, NH2-terminated poly（amidoamine） （PAMAM） dendrimers （regarded as host） in the liquid phase, density functio...To gain insight into the attachment of =Si^＋ （SC） ion （regarded as guest） to the lowest generation, NH2-terminated poly（amidoamine） （PAMAM） dendrimers （regarded as host） in the liquid phase, density functional theory is used to investigate the structures and energetics of the host-guest complex. The effect of solvent on the structures and energetics is also investigated. Various initial configurations of the ion bound to PAMAM are tested, and two stable conformers are found, i.e, types A （=Si^＋ is bound to the amine site） and C （=Si^＋ is bound to the amide site）. Types A and C are the most stable due to the chemical bond formations of Si-N° （amine nitrogen atoms） and Si-O, respectively. The IR spectra for the lowest energy conformers are thoroughly analyzed and compared with the available experimental data.展开更多
A novel quaternary ammonium chitosan hydrogel modified by poly（amidoamine）（PAMAM） dendrimer was prepared by using glutaraldehyde as a cross-linker. The hydrogel was characterized by Fourier transform infrared spec...A novel quaternary ammonium chitosan hydrogel modified by poly（amidoamine）（PAMAM） dendrimer was prepared by using glutaraldehyde as a cross-linker. The hydrogel was characterized by Fourier transform infrared spectroscopy（FTIR） and scanning electron microscopy（SEM）. The results confirmed its highly porous three-dimensional network structure. The swelling test of hydrogel proved that it had excellent swelling and p H-sensitive properties. The increasing PAMAM content or quaternization degree led to the increase in swelling properties. And the hydrogel with lower cross-linking agent concentration or quaternary ammonium chitosan concentration exhibited better swelling properties. The antibacterial results indicated that with the increase in the PAMAM content, quaternary ammonium chitosan concentration or cross-linking agent concentration, the hydrogels showed better antibacterial activities against both Staphylococcus aureus（S. aureus） and Escherichia coli（E. coli）. Thus, the hydrogel could serve as a promising antibacterial material in the future.展开更多
A series of dendrimer-encapsulated poly(phenyleneethynylene)s 4～6 were Synthesize d. The light-harvesting antenna functions of dendrimer frameworks together with the blue-light emitting activities of 4～6 were highli...A series of dendrimer-encapsulated poly(phenyleneethynylene)s 4～6 were Synthesize d. The light-harvesting antenna functions of dendrimer frameworks together with the blue-light emitting activities of 4～6 were highlighted.展开更多
In order to control the size and shape of Ag nanoparticles obtained by using poly（amidoamine） （PA- MAM） dendrimer as template, the complexation between Ag^＋ ions and dendrimer studied extensively by UV-Vis spectr...In order to control the size and shape of Ag nanoparticles obtained by using poly（amidoamine） （PA- MAM） dendrimer as template, the complexation between Ag^＋ ions and dendrimer studied extensively by UV-Vis spectroscopy and FTIR. After the Ag＋/PAMAM demdrimer being reduced by direct chemical reduction, Ag （0） nanopartides was formed, whose structure and characterization were studied by UV-Vis spectroscopy, transmission electron microscopy （TEM） and electron diffraction （ED） respectively. The results reveal that Ag nanopartides is a kind of face center cubic crystal and its average size is 4.5 nm. The solubility and stability of the solution containing Ag nanopartides also indicate that dendrimer is a good kind of template, as well as a protective agent.展开更多
Luteinizing hormone-releasing hormone (LHRH) is the key regulator of the hypothalamic-pituitary-gonadal (HPG) axis, which is responsible for the development and functioning of the reproductive system. Delivery of a co...Luteinizing hormone-releasing hormone (LHRH) is the key regulator of the hypothalamic-pituitary-gonadal (HPG) axis, which is responsible for the development and functioning of the reproductive system. Delivery of a continuous supply of LHRH agonists causes down-regulation of the LHRH receptors, resulting in a marked decrease in androgens in males and estrogens in females. LHRH analogues are widely used in the treatment of various diseases, including prostate and breast cancer, and reproductive disorders, such as infertility and precocious puberty. However, they require parenteral administration, and no oral formulations are currently available. We synthesized two types of LHRH mini-dendrimers using thioether ligation, aiming to enhance the stability and bioavailability of the peptide drug while maintaining its biologically active conformation. These two compounds include a poly-lysine core conjugated to either the C-terminus of LHRH or a D-amino acid in position 6 of the LHRH sequence. The synthesized dendrimers were analysed using dynamic light scattering, and showed particle sizes of 155 and 115 nm, respectively. The nanometer size, well-defined structure and water solubility of these dendritic analogues make them excellent candidates for further exploration in oral peptide drug delivery.展开更多
Using amino-poly(ethylene glycol) and amino-propyl silica gel as initiator cores, two dendrimers were prepared by a two-step procedure. The progress of dendrimers during each step was monitored by infrared spectroscop...Using amino-poly(ethylene glycol) and amino-propyl silica gel as initiator cores, two dendrimers were prepared by a two-step procedure. The progress of dendrimers during each step was monitored by infrared spectroscopy and elemental analysis. Papain was crosslinked to the solid dendrimer with silica gel core by glutaraldehyde, and the enzymatic activity of the immobilized papain kept almost unchanged after repeated usage for fifteen times.展开更多
Tumor associated macrophages(TAMs)tend to exhibit tumor-promoting M2 phenotype and contribute to the development of immunosuppressive microenvironment of solid tumors.Reprograming TAMs from M2 into tumoricidal M1 phen...Tumor associated macrophages(TAMs)tend to exhibit tumor-promoting M2 phenotype and contribute to the development of immunosuppressive microenvironment of solid tumors.Reprograming TAMs from M2 into tumoricidal M1 phenotype is robust for stimulating tumor immunosuppressive microenvironment(TIME).In this study,we developed a poly(amidoamine)(PAMAM)derivative dendrimer(denoted as fourth generation-N,N-diethylaminoethyl(G4-DEEA))for efficient loading of Toll-like receptor 7 and 8(TLR7/8)agonist(R848)to remodel the TIME for potent cancer immunotherapy,G4-DEEA exhibited a high loading capacity of R848 up to 35.9 wt%by taking advantage of its dendritic structure.The resulting formulation(designated as G4-DEEA@R848)effectively polarized M2 macrophages into M1 phenotype in vitro,and improved the maturation and activation of antigen-presenting cells.In the 4T1 orthotopic breast cancer model,G4-DEEA@R848 showed a stronger tumor inhibitory effect than free drug.The mechanistic studies suggested that G4-DEEA@R848 could significantly stimulate the TIME by repolarizing TAMs into M1 phenotype,reducing the presence of immunosuppressive myeloid cells and increasing the infiltration of tumor cytotoxic T cells.This study provides a simple but effective dendrimer-based strategy to improve the formulation of R848 for improved cancer immunotherapy.展开更多
The interaction between amino-terminated, and ethylenediamine core poly(amidoamine) (PAMAM) den-drimers and herring sperm DNA was investigated by various spectroscopic methods including UV spectroscopy, fluores-cence ...The interaction between amino-terminated, and ethylenediamine core poly(amidoamine) (PAMAM) den-drimers and herring sperm DNA was investigated by various spectroscopic methods including UV spectroscopy, fluores-cence spectroscopy, microscopic FTIR- and circular dichro-ism (CD-) spectroscopy. Ethidium bromide (EB) is used as a nucleic acid probe for this study. Experimental results show that PAMAM dendrimers can form stable complexes with DNA and the dendrimers bind to DNA sufficiently strong which cannot be displaced by EB, and we also found that the formation of the complexes can cause the conformation change of the DNA secondary structure. According to the Scatchard analysis, the association constant of PAMAM to DNA is calculated to be 2.53 × 104 mol/L?1.展开更多
An inorganic-organic composite was prepared by poly（amidoamine） （PAMAM） dendrimer reacting with cobalt（Ⅱ）-monosubstituted polyoxometalates Na5Co^Ⅱ（H2O）PW11O39 （PW11CO） in an aqueous solution. The hybrid co...An inorganic-organic composite was prepared by poly（amidoamine） （PAMAM） dendrimer reacting with cobalt（Ⅱ）-monosubstituted polyoxometalates Na5Co^Ⅱ（H2O）PW11O39 （PW11CO） in an aqueous solution. The hybrid composite PW11Co/PAMAM was characterized by FT-IR, UV-Vis diffuse reflectance spectra （DR-UV-Vis）, XPS, XRD and TG/DTA, indicating that the PWI iCo was chemically anchored to PAMAM. The morphologies of the title composite were characterized by scanning electron microscopy （SEM） and transmission electron microscopy （TEM）. The catalytic activity was evaluated by oxidation of isobutyraldehyde （IBA） to isobutyric acid （IBAc） in MeCN under mild conditions （20 ℃, ambient pressure）, showing that the title compound is a more effective and recoverable catalyst than corresponding PW11Co.展开更多
Poly（ethylene glycol） （PEG）-supported dendrimers have been synthesized using 2.4,6-trichloro-1,3,5-triazine （TCT） as dendrons and tris（hydroxymethyl）aminomethane as tinkers with high loading capacity, excellen...Poly（ethylene glycol） （PEG）-supported dendrimers have been synthesized using 2.4,6-trichloro-1,3,5-triazine （TCT） as dendrons and tris（hydroxymethyl）aminomethane as tinkers with high loading capacity, excellent solubility and thermal stability by divergent method. The new synthesized PEG-supported G2.0 dendrimer has 10 times as large functional group loading capacity as commercial PEG3400 with overall yield 44.0%.展开更多
Two novel amphiphilic poly(ester amine) dendrimers were synthesized and characterized by 1H NMR, 13 C NMR and IR spectra. Their properties of Langmuir film were investigated at the air/water interface....Two novel amphiphilic poly(ester amine) dendrimers were synthesized and characterized by 1H NMR, 13 C NMR and IR spectra. Their properties of Langmuir film were investigated at the air/water interface. The relationship between the surface pressure and area isotherms of the dendrimers was found to be dependent on the nature of subphases. Interaction between HgCl 2 and the dendrimers was observed, indicating that the amphiphilic dendrimers could act as a sensor for Hg 2+ .展开更多
Many pH-and temperature-responsive polymers have been designed for preparing hydrogel.In the present study,in order to decrease the pH sensitivity of reported poly(amidoamine)-poly(ethyleneglycol)-poly(amidoamine)(PAA...Many pH-and temperature-responsive polymers have been designed for preparing hydrogel.In the present study,in order to decrease the pH sensitivity of reported poly(amidoamine)-poly(ethyleneglycol)-poly(amidoamine)(PAA1580-PEG4600-PAA1580),we designed and synthesized poly(amidoamine)-poly(ethyleneglycol)-poly(amidoamine)(PAA-PEG-PAA)with shorter length of PAA chain by decreasing reaction temperature for preparing PAA-PEG-PAA hydrogel solution containing doxorubicin(DOX).The PAA-PEG-PAA was synthesized via the Michael-addition polymerization.The characteristic of PAA-PEG-PAA was evaluated.The PAA-PEG-PAA hydrogel solution was prepared and investigated.DOX-loaded PAA-PEG-PAA hydrogel solution was prepared,and its in vitro DOX release and in vitro anti-tumor activity were evaluated.Our results indicated that the viscosity of PAA-PEG-PAA hydrogel solution was concentration-and temperature-dependent.The sol-gel transition temperature of PAA-PEG-PAA hydrogel solution(12%,w/w)ranged from 35 to 29℃,and its pH ranged from 6.0 to 7.4.The released DOX from DOX-loaded PAA-PEG-PAA hydrogel showed sustained release characteristics.The in vitro anti-tumor activity of DOX-loaded PAA-PEG-PAA hydrogel was confirmed in B16 F10 cell line.Considering the acidic tumor microenvironment,this DOX-loaded PAA-PEG-PAA hydrogel solution would be easy in situ administration for intra-tumor injection or para-tumor injection forming hydrogel at body temperature.We suggested that this DOX-loaded PAA-PEG-PAAhydrogel solution,if containing photothermal conversion agents,would have a potential further use for photothermal therapy.展开更多
文摘To gain insight into the attachment of =Si^＋ （SC） ion （regarded as guest） to the lowest generation, NH2-terminated poly（amidoamine） （PAMAM） dendrimers （regarded as host） in the liquid phase, density functional theory is used to investigate the structures and energetics of the host-guest complex. The effect of solvent on the structures and energetics is also investigated. Various initial configurations of the ion bound to PAMAM are tested, and two stable conformers are found, i.e, types A （=Si^＋ is bound to the amine site） and C （=Si^＋ is bound to the amide site）. Types A and C are the most stable due to the chemical bond formations of Si-N° （amine nitrogen atoms） and Si-O, respectively. The IR spectra for the lowest energy conformers are thoroughly analyzed and compared with the available experimental data.
基金Funded by the National Natural Science Foundation of China(Nos.51303145,51273156,51373130)
文摘A novel quaternary ammonium chitosan hydrogel modified by poly（amidoamine）（PAMAM） dendrimer was prepared by using glutaraldehyde as a cross-linker. The hydrogel was characterized by Fourier transform infrared spectroscopy（FTIR） and scanning electron microscopy（SEM）. The results confirmed its highly porous three-dimensional network structure. The swelling test of hydrogel proved that it had excellent swelling and p H-sensitive properties. The increasing PAMAM content or quaternization degree led to the increase in swelling properties. And the hydrogel with lower cross-linking agent concentration or quaternary ammonium chitosan concentration exhibited better swelling properties. The antibacterial results indicated that with the increase in the PAMAM content, quaternary ammonium chitosan concentration or cross-linking agent concentration, the hydrogels showed better antibacterial activities against both Staphylococcus aureus（S. aureus） and Escherichia coli（E. coli）. Thus, the hydrogel could serve as a promising antibacterial material in the future.
文摘A series of dendrimer-encapsulated poly(phenyleneethynylene)s 4～6 were Synthesize d. The light-harvesting antenna functions of dendrimer frameworks together with the blue-light emitting activities of 4～6 were highlighted.
文摘In order to control the size and shape of Ag nanoparticles obtained by using poly（amidoamine） （PA- MAM） dendrimer as template, the complexation between Ag^＋ ions and dendrimer studied extensively by UV-Vis spectroscopy and FTIR. After the Ag＋/PAMAM demdrimer being reduced by direct chemical reduction, Ag （0） nanopartides was formed, whose structure and characterization were studied by UV-Vis spectroscopy, transmission electron microscopy （TEM） and electron diffraction （ED） respectively. The results reveal that Ag nanopartides is a kind of face center cubic crystal and its average size is 4.5 nm. The solubility and stability of the solution containing Ag nanopartides also indicate that dendrimer is a good kind of template, as well as a protective agent.
文摘Luteinizing hormone-releasing hormone (LHRH) is the key regulator of the hypothalamic-pituitary-gonadal (HPG) axis, which is responsible for the development and functioning of the reproductive system. Delivery of a continuous supply of LHRH agonists causes down-regulation of the LHRH receptors, resulting in a marked decrease in androgens in males and estrogens in females. LHRH analogues are widely used in the treatment of various diseases, including prostate and breast cancer, and reproductive disorders, such as infertility and precocious puberty. However, they require parenteral administration, and no oral formulations are currently available. We synthesized two types of LHRH mini-dendrimers using thioether ligation, aiming to enhance the stability and bioavailability of the peptide drug while maintaining its biologically active conformation. These two compounds include a poly-lysine core conjugated to either the C-terminus of LHRH or a D-amino acid in position 6 of the LHRH sequence. The synthesized dendrimers were analysed using dynamic light scattering, and showed particle sizes of 155 and 115 nm, respectively. The nanometer size, well-defined structure and water solubility of these dendritic analogues make them excellent candidates for further exploration in oral peptide drug delivery.
文摘Using amino-poly(ethylene glycol) and amino-propyl silica gel as initiator cores, two dendrimers were prepared by a two-step procedure. The progress of dendrimers during each step was monitored by infrared spectroscopy and elemental analysis. Papain was crosslinked to the solid dendrimer with silica gel core by glutaraldehyde, and the enzymatic activity of the immobilized papain kept almost unchanged after repeated usage for fifteen times.
基金supported by National Key R&D Program of China(No.2017YFA0205600)Guangdong Natural Science Funds for Distinguished Young Scholar(No.2017A030306018)+2 种基金National Natural Science Foundation of China(Nos.51922043 and 31771091)Guangdong Provincial Programs(Nos.2017ZT07S054 and 2017GC010304)the Science and Technology Program of Guangzhou(No.201902020018),and Fundamental Research Funds for Central Universities.
文摘Tumor associated macrophages(TAMs)tend to exhibit tumor-promoting M2 phenotype and contribute to the development of immunosuppressive microenvironment of solid tumors.Reprograming TAMs from M2 into tumoricidal M1 phenotype is robust for stimulating tumor immunosuppressive microenvironment(TIME).In this study,we developed a poly(amidoamine)(PAMAM)derivative dendrimer(denoted as fourth generation-N,N-diethylaminoethyl(G4-DEEA))for efficient loading of Toll-like receptor 7 and 8(TLR7/8)agonist(R848)to remodel the TIME for potent cancer immunotherapy,G4-DEEA exhibited a high loading capacity of R848 up to 35.9 wt%by taking advantage of its dendritic structure.The resulting formulation(designated as G4-DEEA@R848)effectively polarized M2 macrophages into M1 phenotype in vitro,and improved the maturation and activation of antigen-presenting cells.In the 4T1 orthotopic breast cancer model,G4-DEEA@R848 showed a stronger tumor inhibitory effect than free drug.The mechanistic studies suggested that G4-DEEA@R848 could significantly stimulate the TIME by repolarizing TAMs into M1 phenotype,reducing the presence of immunosuppressive myeloid cells and increasing the infiltration of tumor cytotoxic T cells.This study provides a simple but effective dendrimer-based strategy to improve the formulation of R848 for improved cancer immunotherapy.
文摘The interaction between amino-terminated, and ethylenediamine core poly(amidoamine) (PAMAM) den-drimers and herring sperm DNA was investigated by various spectroscopic methods including UV spectroscopy, fluores-cence spectroscopy, microscopic FTIR- and circular dichro-ism (CD-) spectroscopy. Ethidium bromide (EB) is used as a nucleic acid probe for this study. Experimental results show that PAMAM dendrimers can form stable complexes with DNA and the dendrimers bind to DNA sufficiently strong which cannot be displaced by EB, and we also found that the formation of the complexes can cause the conformation change of the DNA secondary structure. According to the Scatchard analysis, the association constant of PAMAM to DNA is calculated to be 2.53 × 104 mol/L?1.
基金Project supported by the Natural Science Foundation of Fujian Province （No. E0510012） and a key item of Education Department of Fujian Province （No. JA04167）.Acknowledgements The authors thank professor Luo Yunjun and Li Guoping, School of Chemical Engineering and Materials Science, Beijing Institute of Technology for the support of PAMAM dendrimer compound.
文摘An inorganic-organic composite was prepared by poly（amidoamine） （PAMAM） dendrimer reacting with cobalt（Ⅱ）-monosubstituted polyoxometalates Na5Co^Ⅱ（H2O）PW11O39 （PW11CO） in an aqueous solution. The hybrid composite PW11Co/PAMAM was characterized by FT-IR, UV-Vis diffuse reflectance spectra （DR-UV-Vis）, XPS, XRD and TG/DTA, indicating that the PWI iCo was chemically anchored to PAMAM. The morphologies of the title composite were characterized by scanning electron microscopy （SEM） and transmission electron microscopy （TEM）. The catalytic activity was evaluated by oxidation of isobutyraldehyde （IBA） to isobutyric acid （IBAc） in MeCN under mild conditions （20 ℃, ambient pressure）, showing that the title compound is a more effective and recoverable catalyst than corresponding PW11Co.
基金Project supported by the National Natural science Foundation of China （No. 20372019）.
文摘Poly（ethylene glycol） （PEG）-supported dendrimers have been synthesized using 2.4,6-trichloro-1,3,5-triazine （TCT） as dendrons and tris（hydroxymethyl）aminomethane as tinkers with high loading capacity, excellent solubility and thermal stability by divergent method. The new synthesized PEG-supported G2.0 dendrimer has 10 times as large functional group loading capacity as commercial PEG3400 with overall yield 44.0%.
基金theNationalNaturalScienceFoundationofChina (No .5 0 2 3 3 0 3 0 )theBasicResearchFoundationofTsinghuaUniversity (No .2 0 0 2 0 3 0 )
文摘Two novel amphiphilic poly(ester amine) dendrimers were synthesized and characterized by 1H NMR, 13 C NMR and IR spectra. Their properties of Langmuir film were investigated at the air/water interface. The relationship between the surface pressure and area isotherms of the dendrimers was found to be dependent on the nature of subphases. Interaction between HgCl 2 and the dendrimers was observed, indicating that the amphiphilic dendrimers could act as a sensor for Hg 2+ .
基金The National Key Research and Development Program of China(Grant No.2017YFA0205600)the National Natural Science Foundation of China(Grant No.81773646)the Innovation Team of the Ministry of Education(Grant No.BMU2017TD003)
文摘Many pH-and temperature-responsive polymers have been designed for preparing hydrogel.In the present study,in order to decrease the pH sensitivity of reported poly(amidoamine)-poly(ethyleneglycol)-poly(amidoamine)(PAA1580-PEG4600-PAA1580),we designed and synthesized poly(amidoamine)-poly(ethyleneglycol)-poly(amidoamine)(PAA-PEG-PAA)with shorter length of PAA chain by decreasing reaction temperature for preparing PAA-PEG-PAA hydrogel solution containing doxorubicin(DOX).The PAA-PEG-PAA was synthesized via the Michael-addition polymerization.The characteristic of PAA-PEG-PAA was evaluated.The PAA-PEG-PAA hydrogel solution was prepared and investigated.DOX-loaded PAA-PEG-PAA hydrogel solution was prepared,and its in vitro DOX release and in vitro anti-tumor activity were evaluated.Our results indicated that the viscosity of PAA-PEG-PAA hydrogel solution was concentration-and temperature-dependent.The sol-gel transition temperature of PAA-PEG-PAA hydrogel solution(12%,w/w)ranged from 35 to 29℃,and its pH ranged from 6.0 to 7.4.The released DOX from DOX-loaded PAA-PEG-PAA hydrogel showed sustained release characteristics.The in vitro anti-tumor activity of DOX-loaded PAA-PEG-PAA hydrogel was confirmed in B16 F10 cell line.Considering the acidic tumor microenvironment,this DOX-loaded PAA-PEG-PAA hydrogel solution would be easy in situ administration for intra-tumor injection or para-tumor injection forming hydrogel at body temperature.We suggested that this DOX-loaded PAA-PEG-PAAhydrogel solution,if containing photothermal conversion agents,would have a potential further use for photothermal therapy.
