Biomedical subjects

Christian Bonhomme

Publications and source records attributed to Christian Bonhomme.

6 recordsLinked to original sources

PubMed2005

Selective protein adsorption property and characterization of nano-crystalline zinc-containing hydroxyapatite.

Nano-crystalline Zn-containing hydroxyapatite (ZnHAp) was prepared by the wet-chemical method and the selective adsorption of essential proteins was examined, taking bovine serum albumin (BSA) and pathogenic protein such as beta(2)-microglobulin (beta(2)-MG) as model proteins. Transmission electron microscopy observation and X-ray diffraction analysis indicated that the increase of Zn content led to smaller crystallites and their specific surface area of ZnHAps increased with increasing Zn content, accordingly. Furthermore, the amounts of BSA adsorption on ZnHAp particles decreased with increasing Zn content in spite of the increase in the specific surface area. It is thus concluded that nano-crystalline ZnHAps had a highly selective adsorption property with regard to beta(2)-MG.

Adsorption↗

PubMed2005

Combined first-principles computational and experimental multinuclear solid-state NMR investigation of amino acids.

13C, 14N, 15N, 17O, and 35Cl NMR parameters, including chemical shift tensors and quadrupolar tensors for 14N, 17O, and 35Cl, are calculated for the crystalline forms of various amino acids under periodic boundary conditions and complemented by experiment where necessary. The 13C shift tensors and 14N electric field gradient (EFG) tensors are in excellent agreement with experiment. Similarly, static 17O NMR spectra could be precisely simulated using the calculation of the full chemical shift (CS) tensors and their relative orientation with the EFG tensors. This study allows correlations to be found between hydrogen bonding in the crystal structures and the 17O NMR shielding parameters and the 35Cl quadrupolar parameters, respectively. Calculations using the two experimental structures for L-alanine have shown that, while the calculated isotropic chemical shift values of 13C and 15N are relatively insensitive to small differences in the experimental structure, the 17O shift is markedly affected.

Amino Acids↗

PubMed2005

Studies of silicophosphate derivatives by 31P-->29Si CP MAS NMR.

We show that it is possible to efficiently transfer magnetization from 31P to 29Si, using variable amplitude CP MAS experiment. This experiment is demonstrated by using Si5O(PO4)6, the synthesis protocol of which is described. From the obtained results, we show that the experiment allows the spectral edition of 29Si spectra from 31P-->29Si CP, enabling the studies of derivatives involving Si-O-P linkages, such as phosphosilicate glasses, microporous silicoaluminophosphates (SAPO) and bioactive phosphosilicates.

Journal Article↗

PubMed2005

1H/31P distance determination by solid state NMR in multiple-spin systems.

The results of two techniques of dipolar recoupling, REDOR and CPMAS, are compared in the case of a coupled multiple-spin system. A fundamentally different behavior is observed for these two techniques. In REDOR, the terms associated with each interaction S-I(k) commute with each other and no truncation takes place so that each addition of spin I(k) causes a splitting with its dipolar frequency. In CPMAS, the flip-flop terms of the dipolar Hamiltonian do not commute with the dominant term from the strongly coupled spin pair so that the weak coupling terms from the neighboring spin I(k) are effectively truncated by the dominant pair interaction. Spin dynamics calculations are in agreement with the experimental data in a cubane shaped cluster.

Journal Article↗

PubMed2004

Combined ab initio computational and experimental multinuclear solid-state magnetic resonance study of phenylphosphonic acid.

1H, 13C, 17O and 31P NMR parameters, including chemical shift tensors and quadrupolar parameters for 17O, were calculated for phenylphosphonic acid, C6H5PO(OH)2, under periodic boundary conditions. The results are in very good agreement with experimental data and permit the unambiguous assignment of all the sites present in the structure. In particular, the 17O NMR parameters of the P=O and P-OH environments were precisely determined, which should help in the characterization of the bonding mode of phosphonate molecules in hybrid solids. Moreover, the effect of intermolecular interactions on the NMR parameters were investigated by comparing the results of the calculations in the crystal and in an isolated molecule of phenylphosphonic acid.

Algorithms↗

PubMed2002

Synthesis and characterization of a novel cyclic aluminophosphinate: structure and solid-state NMR study.

We present the structure and a multinuclear solid-state NMR study of a new cyclic aluminophosphinate. The crystallographic structure of [Al(2)(HC(6)H(5)PO(2))(2)(C(4)H(9)OH)(8)]Cl(4) (compound 1) was obtained at low temperature (a = 11.830(7) A, b = 14.216(6) A, c = 17.790(6) A, beta = 91.25(4) degrees, monoclinic, P21/c, Z = 2). (13)C IRCP (inversion recovery cross polarization) and NQS (non quaternary suppression) NMR experiments allowed the complete assignment of the quaternary carbon atom of the phenyl ring and the precise determination of the isotropic /(1)J(P-C)/ coupling constant. (31)P CP MAS dynamics was carefully studied by varying the contact time. Dipolar oscillations even at slow MAS were observed. Up to 11 kHz, these oscillations were more pronounced, and the P-H distance was easily extracted. (27)Al NMR quadrupolar parameters for 1 were obtained with very good accuracy, and unusual satellite transition splitting was observed. Furthermore, the isotropic lines of the inner and outer transitions were clearly observable, leading to the unambiguous determination of the quadrupolar parameters.

Journal Article↗