Synthesis, Characterization and Antibacterial Properties of Rare Earth Complexes with L-Phenylalanine and o-Phenanthroline

New solid ternary complexes of rare earth with L-Phenylalanine （ L-Phe ） and o-Phenanthroline （Phen） were synthesized in ethyl alcohol solution. Their composition were characterized by elemental analysis, molar conductance, IR, Raman, UV-VIS, TG-DTA. The compositions of the complexes were confirmed to be RE （ Phe ）3Phen Cl3 · 3H2O （ RE = La^3＋, Ce^3＋, Pr^3＋, Nd^3＋, Sm^3＋, Eu^3＋, Er^3＋, Y^3＋）. The antibacterial activities testing indicates that all these solid ternary complexes have antibacterial ability against Escherich coli, Staphy lococcus aureus, Candida albican （MIC are about 65 × 10^-4%, 15 × 10^-3%, 4 × 10^-2%, respectively）.

EFFECTS OF L-PHENYLALANINE ON THE RADIATION SYNTHESIS OF POLY(N,N'-METHYLENEBISACRYLAMIDE-co-4-VINYLPYRIDINE)(MICRO)GELS

The effects of L-phenylalanine （L-Phe） on the synthesis ofpoly（N,N＇-methylenebisacrylamide-co-4-vinylpyridine） （poly（Bis-co-4-VP）） （micro）gels by γ-ray irradiation were studied. The addition of L-Phe could not only decrease the gelation dose （Dg） of the synthesis obviously, but also transform the morphology of copolymer from microgel to gel. In addition, the swelling ability of the （micro）gels was also affected in the presence of L-Phe. The decrease of Dg was ascribed to the effect of pH, while the transformation of the morphology was ascribed to the effect of L-Phe on the stability of the poly（Bis-co-4-VP） microgel. Such an effect was confirmed further as compared with the effects of L-alanine, L-glutamic acid, L-arginine, sulfuric acid and aqueous ammonia.

Colorimetric Recognition of 3,4-Dihydroxy-D,L-phenylalanine with Tetrapeptide-modified Copper Nanoparticles as Chiral Nanozymes

The construct of artificial nanocatalyts by simulating natural enzymes and thereby bringing new properties for practical applications is still a challenging task to date.In this study,chiral tetrapeptide(L-phenylalanine-L-phenylalanine-L-cysteine-L-histidine)-engineered copper nanoparticles(FFCH@CuNPs)were fabricated as an artificial peroxidase(POD).More interestingly,the nano-catalysts exhibited chiral identification function.In comparison with other nanocatalysts like L-cysteine-,L-histidine-,chiral dipeptide(L-cysteine-L-histidine)-,or chiral tripeptide(L-phenylalanine-L-cysteine-L-histidine)-modified CuNPs,FFCH@CuNPs demonstrated higher POD-mimetic catalytic activity in the 3,3',5,5'-tetramethylbenzidine(TMB)-H_(2)O_(2) system and stronger enantioselectivity in the recognition of 3,4-dihydroxy-D,L-phenylalanine(D,L-DOPA)enantiomers.Considering the strength difference between the intermolecular hydrogen bonding and theπ-πinteractions,the principle behind the chiral discrimination of D,L-DOPA was explored.Furthermore,higher contents of surface Cu2+ions and hydroxyl radicals were found in the FFCH@CuNPs-D-DOPA-TMB-H_(2)O_(2) system than in the FFCH@CuNPs-L-DOPA-TMB-H_(2)O_(2) system.Based on these results,a protocol for distinguishing between D,L-DOPA enantiomers through colorimetric recognition was established.This study provides a new insight into the design and fabrication of oligopeptides@CuNPs-based chiral nanozymes with improved catalytic performance and features additional to those of natural enzymes.

Synthesis of novel copolymer:Poly(p-dioxanone-co-L-phenylalanine)

In order to expand the application of poly（p-dioxanone） or PPDO in biomedical area,a series of novel copolymers were synthesized successfully by one-step,melted copolymerization of p-dioxanone（PDO） and L-phenylalanine N-carboxyanhydride（L-Phe-NCA） monomers.With the in-feed molar ratio of L-PheNCA /PDO equal to 1/20,the conversions of the two kinds of monomers were calculated from 1H NMR. The average molecular weight and polydispersity of the copolymer increase with the increasing reaction time and catalyst concentration.However,the conversions of the two kinds of monomers did not change with the reaction conditions.A three-step mechanism is presented and proved by high resolution 1H NMR and IR spectrums.

Computational Design and Fabrication of Enantioselective Recognition Sorbents for L-phenylalanine Benzyl Ester on Multiwalled Carbon Nanotubes Using Molecular Imprinting Technology

Computational strategies have been employed to investigate the influence of the nature of monomers and cross-linker in order to design three dimensional imprinted polymers with selective recognition sites for L-phenylalanine benzyl ester(L-PABE)molecule.Here,computational chemistry methods were applied to screen the molar quantity of functional monomers that interact with one mole of the template molecule.Effects of the nature of functional monomer,cross-linker,and molar ratio were determined computationally using density functional calculations with B3LYP functional and generic 6-31G basis set.Methacrylic acid(MAA)and ethylene glycol dimethacrylate(EGDMA)were used as the functional monomer and crosslinking agent,respectively.L-PABE imprinted polymer layered on multiwalled carbon nanotube(MWCNT)and conventional bulk MIP were synthesised and characterized as well.To investigate the influence of pre-organization of binding sites on the selectivity of L-PABE,respective non-imprinted polymers were also synthesised.MWCNT-MIPs and MIPs exhibited the highest adsorption capacity towards L-PABE.The synthesized polymers revealed characteristic adsorption features and selectivity towards L-PABE in comparison with those of its enantiomer analogues.

Preparation and Chiral Recognition of Thermosensitive Poly（N-isopropylacrylamide） Microgels Containing Modified L-Phenylalanine Groups

Thermosensitive poly[N-isopropylacrylamide（NIPAM）-co-N-acryloyl-L-phenylalanine ethyl ester （NALPE）] microgels were prepared by the free radical polymerization of NIPAM and chiral monomer, NALPE. Such microgels exhibited spherical shape and favorable monodispersity. Increasing the content of NALPE units would en- hance the average diameter, but decrease the thermosensitivity and volume-phase transition temperatures of the mi- crogels. Compared with PNIPAM microgels, the microgels containing NALPE units performed chiral recognozable capacities for D-phenylalanine and D-tartaric acid, and the enantioselectivity and adsorption capacity of the microgels improved with increasing the temperature and/or the content of NALPE units.

Syntheses, Structures and Interactions with DNA of Two in situ Generated Palladium(Ⅱ) Complexes

Two new complexes [Pd（L-phe）2·2H2O] （1） and [Pd（4,4＇-dcbpy）（en）·H2O] （2） （L-phe = L-phenylalanine, 4,4＇-dcbpy = 2,2＇-bipyridyl-4,4＇-dicarboxylate, en = ethylenediamine） were synthesized and characterized. L-phenylalanine was in situ formed via the hydrolysis of N-（tert-butoxycarbonyl）-L-phenylalanine, and ethylenediamine came from the in situ reaction of piperazine （pip） under hydrothermal conditions. The single-crystal X-ray structure analyses reveal that the Pd（Ⅱ） ion constructs a square planer coordination geometry in complexes 1 and 2, respectively. Complex 1 extends into a 2D layered structure via H-bond interactions and complex 2 connects into a 3D network through hydrogen bonds and 7r-tr stacking interactions. The interactions of 1 and 2 with fish sperm DNA （FS-DNA） were examined via UV-Vis absorption spectra and fluorescence spectroscopy. The cleavage reaction for plasmid DNA has been assayed by agarose gel electrophoresis. The results indicate that two complexes interact with DNA and the insertion is the main binding mode.

Effect of Chloride Ions and Dissolved Oxygen on the Deactivation of Phenylalanine Ammonia-lyase

With the method of synthesizing the L-phenylalanine by trans-cinnamic acid and ammonia in the presence of phenylalanine ammonialyase (PAL) under high pH and high concentration of cinnamic acid, it is not favorable for the conversion because of the deactivation of the PAL.For this reason, it is important to find out the suita-