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2022
Peer-reviewed Publications |
Le Sech, C. (2022). Changes induced in a covalent bond confined in a structured cavity. Chemical Physics Letters, 791, 139396.
Résumé: A simple correlated wave function is proposed to study the confined hydrogen molecule. Three confinement structural forms are considered: a hard sphere, a cone, and a composite sphere-cone to simulate the effects of a structured cavity. The changes in the molecular energy, in particular the vibration, are calculated through a variational non Born-Oppenheimer approach.
In all three cases, a steep rise in the molecule energy is observed. The composite sphere-cone structure is the most efficient. A compression/relaxation cycle in such a cavity, produced by the conformational molecular dynamics, augments the energy. This finding could be of interest in chemical catalysis in supramolecular cavities.
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Thébault, P., Ammoun, M., Boudjemaa, R., Ouvrard, A., Steenkeste, K., Bourguignon, B., & Fontaine-Aupart, M. - P. (2022). Surface functionalization strategy to enhance the antibacterial effect of nisin Z peptide. Surf. Interfaces, 30, 101822.
Résumé: One of the main challenges when building antibacterial surfaces with antimicrobial peptides (AMPs) is to preserve their antimicrobial activity after stable immobilization of the peptides. Among all parameters, order/conformation of self-assembled monolayers, used as spacer, is one the most important. Herein we report the covalent immobilization of the nisin Z peptide on a gold surface functionalized with a self-assembled monolayer of 11-mercaptoundecanoic acid (MUA) alone or mixed with 6-mercaptohexanol, used as a spacer. The MUA acid is activated by treatment with carbodiimide/N-hydroxysuccinimidine and then reacts with nisin Z to form amide bonds via the N terminal part of the peptide. We have characterized each step of the surface modification using X-ray photoelectron spectroscopy, FTIR-ATR spectroscopy and contact angle measurements. The combined results show the success of each functionalization step. Additionally, SFG brings information on the orientation and conformational ordering of the self-assembled monolayers. Indeed, a better order of MUA25 layers compared to MUA was observed due to the spacing of carboxylic acid groups. The antibacterial activity of the immobilized AMPs against Staphylococcus aureus is evaluated using confocal microscopy and bacterial counting: it increases with a better order of the SAMs rather than a greater peptide concentration. This study provides fundamental insights on how to engineer AMPs and substrate to produce efficient biocidal surfaces.
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