The positron-emitter fluorine-18 labeled amino acid O-(2-[18F]fluoroethyl)-L-tyrosine ([18F]FET) has shown very promising perspectives for brain tumor diagnosis with positron emission tomography (PET). There have been...The positron-emitter fluorine-18 labeled amino acid O-(2-[18F]fluoroethyl)-L-tyrosine ([18F]FET) has shown very promising perspectives for brain tumor diagnosis with positron emission tomography (PET). There have been two existing preparation routes of [18F]FET named direct nucleophilic radiofluorination of protected L-tyrosine and radiofluoroalkylation of unprotected L-tyrosine, respectively. A general module was designed specifically for the routine synthesis of [18F]FET, which could be suitable for the present two chemical methods with simple modifica- tions. The fluorinated intermediates and the final product were separated and purified using solid phase extraction (SPE) on the Sep-Pak silica plus cartridge instead of the time-consuming high performance liquid chromatography (HPLC) procedures. The total synthesis time was about 50—60 min with good radiochemical yield (about 20—40%, no-decay-corrected) and good radiochemical purity (more than 97%) for both the synthetic methods.展开更多
Using density function theory （DFT）, the Cu-doped Aln （n=1-15） clusters have been stud- ied. The electron affinity, ionization potential, Mulliken population analysis of Cu, mean polarizability, polarizability ani...Using density function theory （DFT）, the Cu-doped Aln （n=1-15） clusters have been stud- ied. The electron affinity, ionization potential, Mulliken population analysis of Cu, mean polarizability, polarizability anisotropy, dipole moments and HOMO-LUMO gaps have also been calculated on the basis of optimized geometries. The results indicate that there is magic numbers in copper-doped aluminum clusters and electronic characteristic depended on the size of clusters. As n=13, the electron affinity and ionization potential of cluster changed more than 0.3 and 0.6 eV respectively, compared with neighborhood clusters.展开更多
Aim To explore interaction mode between amphoteric molecules with the orderedphospholipid membrane. Methods Membrane interactions were determined by immobilized artificialmembrane (IAM) chromatography and solutes'...Aim To explore interaction mode between amphoteric molecules with the orderedphospholipid membrane. Methods Membrane interactions were determined by immobilized artificialmembrane (IAM) chromatography and solutes' hydrophobicity was measured by n-octanol/buffer system.Results The ampholytes, similar to bases, generally exhibited higher membrane affinity than expectedfrom their hydrophobicity, resulting from the attractive polar interaction with phospholipidmembrane. Furthermore, the strength of additional polar interaction with membrane (Δlg k_(IAM)) wasthen calculated. The Δlg k_(IAM) values were far greater for bases and ampholytes ranging from0.50 - 1.39, than those for acids and neutrals with the scope from - 0.55 - 0.44. ConclusionConsidering the microspecies distribution of amphoteric molecules, it was assumed that not onlyneutral and positive but also zwitterionic microspecies are capable of partitioning into orderedamphoteric lipid membrane with complementarily conformational and energetically favorableinteractions.展开更多
文摘The positron-emitter fluorine-18 labeled amino acid O-(2-[18F]fluoroethyl)-L-tyrosine ([18F]FET) has shown very promising perspectives for brain tumor diagnosis with positron emission tomography (PET). There have been two existing preparation routes of [18F]FET named direct nucleophilic radiofluorination of protected L-tyrosine and radiofluoroalkylation of unprotected L-tyrosine, respectively. A general module was designed specifically for the routine synthesis of [18F]FET, which could be suitable for the present two chemical methods with simple modifica- tions. The fluorinated intermediates and the final product were separated and purified using solid phase extraction (SPE) on the Sep-Pak silica plus cartridge instead of the time-consuming high performance liquid chromatography (HPLC) procedures. The total synthesis time was about 50—60 min with good radiochemical yield (about 20—40%, no-decay-corrected) and good radiochemical purity (more than 97%) for both the synthetic methods.
基金The work was supported by the National Natural Science Foundation of China （No.10374036 and No. 10374037） and the Chinese Academic of Engineering Physics （No.51480030105JW1301）.
文摘Using density function theory （DFT）, the Cu-doped Aln （n=1-15） clusters have been stud- ied. The electron affinity, ionization potential, Mulliken population analysis of Cu, mean polarizability, polarizability anisotropy, dipole moments and HOMO-LUMO gaps have also been calculated on the basis of optimized geometries. The results indicate that there is magic numbers in copper-doped aluminum clusters and electronic characteristic depended on the size of clusters. As n=13, the electron affinity and ionization potential of cluster changed more than 0.3 and 0.6 eV respectively, compared with neighborhood clusters.
文摘Aim To explore interaction mode between amphoteric molecules with the orderedphospholipid membrane. Methods Membrane interactions were determined by immobilized artificialmembrane (IAM) chromatography and solutes' hydrophobicity was measured by n-octanol/buffer system.Results The ampholytes, similar to bases, generally exhibited higher membrane affinity than expectedfrom their hydrophobicity, resulting from the attractive polar interaction with phospholipidmembrane. Furthermore, the strength of additional polar interaction with membrane (Δlg k_(IAM)) wasthen calculated. The Δlg k_(IAM) values were far greater for bases and ampholytes ranging from0.50 - 1.39, than those for acids and neutrals with the scope from - 0.55 - 0.44. ConclusionConsidering the microspecies distribution of amphoteric molecules, it was assumed that not onlyneutral and positive but also zwitterionic microspecies are capable of partitioning into orderedamphoteric lipid membrane with complementarily conformational and energetically favorableinteractions.
