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
Direct ligand exchange kinetics between hydrophilic molecules and quantum dots（QDs） was investigated. Meanwhile, pyrene was exploited as probe to detect the efficiency of the ligand exchange reaction between octade-...Direct ligand exchange kinetics between hydrophilic molecules and quantum dots（QDs） was investigated. Meanwhile, pyrene was exploited as probe to detect the efficiency of the ligand exchange reaction between octade- cylamine-coated QDs（ODA-QDs） and different ligands[ligand 1： NH2G3-OH, ligand 2： G4.5-PEG5-FA5, ligand 3： （COOH）2G3-OH or ligand 4： G4.5-PEG1-FAl]. It was indicated that water-soluble QDs exhibit the same fluores- cence and absorption spectra as ODA-QDs when they were dissolved in chloroform. Furthermore, the cellular expe- riments demonstrated that the folic acid（FA） targeting poly（amidoamine）（PAMAM） modified QD conjugates could be used as molecular targeting sensing systems for nanoparticle probes.展开更多
Using B3LYP and M06-2X functionals,eight noncovalent configurations for the adsorption of D-penicillamine drug(DPA)drug on poly(amidoamine)G0 generation dendrimer(PAMAMG0)carrier have been investigated.The quantum mol...Using B3LYP and M06-2X functionals,eight noncovalent configurations for the adsorption of D-penicillamine drug(DPA)drug on poly(amidoamine)G0 generation dendrimer(PAMAMG0)carrier have been investigated.The quantum molecular descriptors and the binding and solvation energies were examined in aqueous solution and gas phase.The binding energies demonstrated the energetic stability of non-bonded species(PAMAMG0/DPA1-8).The solvation energies showed that solubility of DPA rises in the vicinity of PAMAMG0 carrier which is a fundamental factor for applicability of a carrier.Considering quantum molecular descriptors such as electrophilicity power and global hardness,the toxicity of DPA drug in the vicinity of PAMAMG0 carrier decreases and drug release is facilitated.The AIM analysis for all PAMAMG0/DPA1-8 structures indicated that the hydrogen and pseudo-hydrogen bonds play important roles in the functionalization of PAMAMG0 with DPA drug.The configuration in which DPA drug interacts simultaneously with two-NH2 functional groups of PAMAMG0 is the most stable configuration.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
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
The interactions of amino-terminated, and ethylenediamine core poly(amidoamine) (PAMAM) den-drimers and their derivatives with bovine serum albumin (BSA) were investigated by fluorescence spectroscopy. Ex-perimental r...The interactions of amino-terminated, and ethylenediamine core poly(amidoamine) (PAMAM) den-drimers and their derivatives with bovine serum albumin (BSA) were investigated by fluorescence spectroscopy. Ex-perimental results showed that the fluorescence intensity of BSA decreased after the addition of different modified den-drimers, and the extent of the fluorescence quenching caused by various modified dendrimers strongly depends upon the different functional groups on their surfaces. We also inves-tigated the influence of pH and ionic strength on the interac-tion between various modified dendrimers and BSA. Circu-lar dichroism (CD) spectroscopic measurements showed that the content of α-helix structure of BSA decreased after the addition of different modified dendrimers, which indicated that dendrimers induced changes in the secondary structure of BSA.展开更多
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Supported by the National Natural Science Foundation of China （No.21304084）, the Youth Foundation of Jilin Province, China（No.20080119） and the Graduate Innovation Program of Jilin University, China（No.20091010）.
文摘Direct ligand exchange kinetics between hydrophilic molecules and quantum dots（QDs） was investigated. Meanwhile, pyrene was exploited as probe to detect the efficiency of the ligand exchange reaction between octade- cylamine-coated QDs（ODA-QDs） and different ligands[ligand 1： NH2G3-OH, ligand 2： G4.5-PEG5-FA5, ligand 3： （COOH）2G3-OH or ligand 4： G4.5-PEG1-FAl]. It was indicated that water-soluble QDs exhibit the same fluores- cence and absorption spectra as ODA-QDs when they were dissolved in chloroform. Furthermore, the cellular expe- riments demonstrated that the folic acid（FA） targeting poly（amidoamine）（PAMAM） modified QD conjugates could be used as molecular targeting sensing systems for nanoparticle probes.
文摘Using B3LYP and M06-2X functionals,eight noncovalent configurations for the adsorption of D-penicillamine drug(DPA)drug on poly(amidoamine)G0 generation dendrimer(PAMAMG0)carrier have been investigated.The quantum molecular descriptors and the binding and solvation energies were examined in aqueous solution and gas phase.The binding energies demonstrated the energetic stability of non-bonded species(PAMAMG0/DPA1-8).The solvation energies showed that solubility of DPA rises in the vicinity of PAMAMG0 carrier which is a fundamental factor for applicability of a carrier.Considering quantum molecular descriptors such as electrophilicity power and global hardness,the toxicity of DPA drug in the vicinity of PAMAMG0 carrier decreases and drug release is facilitated.The AIM analysis for all PAMAMG0/DPA1-8 structures indicated that the hydrogen and pseudo-hydrogen bonds play important roles in the functionalization of PAMAMG0 with DPA drug.The configuration in which DPA drug interacts simultaneously with two-NH2 functional groups of PAMAMG0 is the most stable configuration.
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supported by the National Natural Science Foundation of China(Grant No.30370405).
文摘The interactions of amino-terminated, and ethylenediamine core poly(amidoamine) (PAMAM) den-drimers and their derivatives with bovine serum albumin (BSA) were investigated by fluorescence spectroscopy. Ex-perimental results showed that the fluorescence intensity of BSA decreased after the addition of different modified den-drimers, and the extent of the fluorescence quenching caused by various modified dendrimers strongly depends upon the different functional groups on their surfaces. We also inves-tigated the influence of pH and ionic strength on the interac-tion between various modified dendrimers and BSA. Circu-lar dichroism (CD) spectroscopic measurements showed that the content of α-helix structure of BSA decreased after the addition of different modified dendrimers, which indicated that dendrimers induced changes in the secondary structure of BSA.
