Liquid chromatography – mass spectrometry (LC-MS) experiments were used to qualitatively and semi-quantitatively monitor the impact of bead milling and the influence of the nature of the extraction solvents, Bligh and Dyer (B&D) versusn-heptane, on the composition of the structural lipids extracted from the microalgae Microchloropsis gaditana.
Our data reveal that lipid extraction with n-heptane as the solvent becomes as efficient as the standard Bligh and Dyer method when a milling step is included before the extraction. In all the extracts, using liquid chromatography separation combined to accurate mass measurements and tandem mass spectrometry experiments, we identified a huge number of lipids belonging to different structural lipid families. We further demonstrated that the milling step induces strong modifications in the lipid composition due to extensive lipid degradation into free fatty acids – probably by enzymatic processes, even when the milled cells are conserved at -20°C.
From a method development perspective, this work represents to the best of our knowledge the most complete structural analysis investigation of lipids extracted from intact and milled microalgae, including the use of a sector diagram representation that could be relevant for all lipidomic investigations. One of the main outcomes of the study is the confirmation that liquid chromatography – tandem mass spectrometry (LC-MS/MS) experiments are essential when lipid extraction procedures from any microalgae biomass have to be optimized. The analytical protocol developed in the present study certainly deserves to be extended to other microalgae.
We recently reported a joint experimental and theoretical study of peptoid ions bearing (S)-N-1-phenylethyl side chains. In this study, we demonstrated that the gas phase conformation, probed by ion mobility mass spectrometry, was different from the solution phase conformation (loop vs. helix) because the charge, mandatory for mass spectrometry analysis, must be stabilized and causes the backbone to wrap around to maximize the ion-dipole interactions. In the present study, we introduce another side chain, (S)-N-(1-carboxy-2-phenylethyl), that can form hydrogen bonds. Molecular modeling and ion mobility mass spectrometry of these protonated peptoids strongly suggest that a helical conformation is obtained in gas phase, despite the need to stabilize the charge. This is due to the combination of a hydrogen bond network between the side chains and the backbone carbonyls, and the steric hindrance of the side chains.
In this paper, we benefit from the expertise of Prof. Luca Muccioli in the modeling of self-assembly monolayers to study the interaction between peptoids and chiral guests. Indeed, peptoids can act as chiral selectors depending on the choice of the side chain. It was demonstrated experimentally that peptoids bearing (S)-N-1-phenylethyl side chains are enantioselective toward binaphthyl derivatives (BINOL) when grafted on silica and used as chiral stationary phase in chromatography columns. In this study, we take advantage of the steered molecular dynamics simulations to get atomistic insights into the factors that rule the enantioselectivity. We identified that these peptoids mainly adopt a right-handed helical conformation, similar to the poly(proline) type I, that better interacts with the (S)-BINOL because of the formation of stronger hydrogen bonds.
Recent advances in catalysis enriched the toolbox to prepare well-defined polyester materials such as polylactide (PLA). Herein, we report the use of crown ethers to speed up the polymerization of L-lactide (L-LA) initiated by an exogenous alcohol and catalyzed by potassium acetate (KOAc). With KOAc, the crown ethers played a crucial role as a complexing agent, with 18-crown-6 enabling the fastest polymerization kinetics outpacing the one obtained with the pristine catalyst by not less than 73. Experimental results suggested that the 18-c-6 crown ether complexed the KOAc ion pair to in situ produce free ions, which was much more appropriate to activate the propagating alcohol for the ring-opening reaction of L-LA.
On Friday October 30, Sébastien DELPIERRE has defended his PhD thesis entitled “Self-Healable and Recyclable Polymer Networks Based on Dynamic Covalent Boroxine Chemistry”.
The PhD thesis jury was composed by Prof Davide Bonifazi (University of Vienna), Prof Guy Van Assche (Vrije Universiteit Brussel), Dr Sylvain Calloil (University of Montpellier), Prof Philippe Dubois (UMONS), Prof Roberto Lazzaroni (UMONS), Prof Jérôme Cornil (UMONS), Prof Jean-Marie Raquez (UMONS) and Prof Pascal Gerbaux.
In this work, we evaluate whether a relationship exists between the primary structures of synthetic homo and copolymers and their secondary structures as gaseous ions. IMS−MS experiments are further complemented by MD simulations. To highlight the effectiveness of IMS separation, we selected isomeric homo and copolymers made of lactide (LA) and propiolactone (PL) units. In this way, the mass analysis becomes useless since isomeric comonomer sequences can coexist for any given chain length. An UPLC method is implemented in the workflow to successfully separate all PL−LA comonomer sequences before infusion in the IMS−MS instrument. The analysis of doubly charged copolymers shows that the comonomer sequence has an impact on the IMS response. However, this only holds for copolymer ions with precise sizes and charge states, and this is therefore not a rule of thumb.
On Friday September 25, Quentin DUEZ has defended his PhD thesis entitled “Gas-Phase Structure of Polymer Ions : Ionization, Relaxation, and Implications for Structural Characterization”.
The PhD thesis jury was composed by Prof Claudio Zannoni (University of Bologna), Prof Carlos Afonso (Université de Rouen), Prof Philippe Dubois (UMONS), Dr Kevin Giles (Waters, UK), Prof Roberto Lazzaroni (UMONS), Prof Jérôme Cornil (UMONS), and Prof Pascal Gerbaux.
Quentin will now move for one year at the Radboud University in Nijmegen, as a post-doctoral researcher in the group of Prof Jana Roithova.
On Friday September 18, Emmanuel Colson – Manu – has defended his PhD thesis entitled “Green Waste Valorization : tuning the biological properties of horse chestnut and quinoa husk saponins by molecular engineering”.
The PhD thesis jury was composed by Prof Jean-Hugues Renault (Université de Reims, Champagne-Ardenne), Prof Maxence Wisztorski (Université de Lille), Prof Pierre Duez (UMONS), Prof Roberto Lazzaroni (UMONS), Prof Patrick Flammang (UMONS), and Prof Pascal Gerbaux.
Emmanuel will already start his new job in November, at the company “Quality Assistance” as a MS scientist.
On Friday September 11, Romain Liénard, PhD student at the Organic Synthesis Lab (S²MOs) and Polymer Lab (SMPC), has defended his PhD thesis entitled “Original Cyclo-based Macrostructures: Elaboration and Characterization” under the joint supervision of Olivier Coulembier and Julien De Winter.
The PhD thesis jury was composed of Prof Chrys Wesdemiotis (University of Akron, USA), Prof Scott Grayson (Tulane University, USA), Prof Pascal Gerbaux (UMONS), Prof Roberto Lazzaroni (UMONS), Dr Julien De Winter (S²MOs Lab, UMONS) and Prof Olivier Coulembier (SMPC Lab, UMONS).
Although the presentation conditions were unusual due to the sanitary restrictions, the jury points out, unanimously, that Mr. Romain Liénard exposed his research work in a very clear and didactic manner, which demonstrated his excellent communication skills.