Shahgaldian, Patrick
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Development and validation of a liquid chromatography-triple quadrupole mass spectrometry method for the determination of isopeptide ε-(γ-glutamyl) lysine in human urine as biomarker for transglutaminase 2 cross-linked proteins
Enzymes for consumer products to achieve climate neutrality
Today, the chemosphere’s and biosphere’s compositions of the planet are changing faster than experienced during the past thousand years. CO2 emissions from fossil fuel combustion are rising dramatically, including those from processing, manufacturing and consuming everyday products; this rate of greenhouse gas emission (36.2 gigatons accumulated in 2022) is raising global temperatures and destabilizing the climate, which is one of the most influential forces on our planet. As our world warms up, our climate will enter a period of constant turbulence, affecting more than 85% of our ecosystems, including the delicate web of life on these systems, and impacting socioeconomic networks. How do we deal with the green transition to minimize climate change and its impacts while we are facing these new realities? One of the solutions is to use renewable natural resources. Indeed, nature itself, through the working parts of its living systems, the enzymes, can significantly contribute to achieve climate neutrality and good ecological/biodiversity status. Annually they can help decreasing CO2 emissions by 1–2.5 billion-tons, carbon demand by about 200 million-tons, and chemical demand by about 90 million-tons. With current climate change goals, we review the consequences of climate change at multiple scales and how enzymes can counteract or mitigate them. We then focus on how they mobilize sustainable and greener innovations in consumer products that have a high contribution to global carbon emissions. Finally, key innovations and challenges to be solved at the enzyme and product levels are discussed.
Coordination-driven monolayer-to-bilayer transition in two-dimensional metal–organic networks
We report on monolayer-to-bilayer transitions in 2D metal–organic networks (MONs) from amphiphiles supported at the water–air interface. Functionalized calix[4]arenes are assembled through the coordination of selected transition metal ions to yield monomolecular 2D crystalline layers. In the presence of Ni(II) ions, interfacial self-assembly and coordination yields stable monolayers. Cu(II) promotes 2D coordination of a monolayer which is then diffusively reorganizing, nucleates, and grows a progressive amount of second layer islands. Atomic force microscopic data of these layers after transfer onto solid substrates reveal crystalline packing geometries with submolecular resolution as they are varying in function of the building blocks and the kinetics of the assembly. We assign this monolayer-to-bilayer transition to a diffusive reorganization of the initial monolayers owing to chemical vacancies of the predominant coordination motif formed by Cu2+ ions. Our results introduce a new dimension into the controlled monolayer-to-multilayer architecturing of 2D metal–organic networks.
Decoding the ocean's microbiological secrets for marine enzyme biodiscovery
A global census of marine microbial life has been underway over the past several decades. During this period, there have been scientific breakthroughs in estimating microbial diversity and understanding microbial functioning and ecology. It is estimated that the ocean, covering 71% of the earth's surface with its estimated volume of about 2 × 1018 m3 and an average depth of 3800 m, hosts the largest population of microbes on Earth. More than 2 million eukaryotic and prokaryotic species are thought to thrive both in the ocean and on its surface. Prokaryotic cell abundances can reach densities of up to 1012 cells per millilitre, exceeding eukaryotic densities of around 106 cells per millilitre of seawater. Besides their large numbers and abundance, marine microbial assemblages and their organic catalysts (enzymes) have a largely underestimated value for their use in the development of industrial products and processes. In this perspective article, we identified critical gaps in knowledge and technology to fast-track this development. We provided a general overview of the presumptive microbial assemblages in oceans, and an estimation of what is known and the enzymes that have been currently retrieved. We also discussed recent advances made in this area by the collaborative European Horizon 2020 project 'INMARE'.
Nanobiocatalysts with inbuilt cofactor recycling for oxidoreductase catalysis in organic solvents
The major stumbling block in the implementation of oxidoreductase enzymes in continuous processes is their stark dependence on costly cofactors that are insoluble in organic solvents. We describe a chemical strategy that allows producing nanobiocatalysts, based on an oxidoreductase enzyme, that performs biocatalytic reactions in hydrophobic organic solvents without external cofactors. The chemical design relies on the use of a silica-based carrier nanoparticle, of which the porosity can be exploited to create an aqueous reservoir containing the cofactor. The nanoparticle core, possessing radial-centred pore channels, serves as a cofactor reservoir. It is further covered with a layer of reduced porosity. This layer serves as a support for the immobilisation of the selected enzyme yet allowing the diffusion of the cofactor from the nanoparticle core. The immobilised enzyme is, in turn, shielded by an organosilica layer of controlled thickness fully covering the enzyme. Such produced nanobiocatalysts are shown to catalyse the reduction of a series of relevant ketones into the corresponding secondary alcohols, also in a continuous flow fashion. © 2023 RSC.
Design of a biocatalytic flow reactor based on hierarchically structured monolithic silica for producing galactooligosaccharides (GOSs)
Climate change mitigation requires the development of greener chemical processes. In this context, biocatalysis is a pivotal key enabling technology. The advantages of biocatalysis include lower energy consumption levels, reduced hazardous waste production and safer processes. The possibility to carry out biocatalytic reactions under flow conditions provides the additional advantage to retain the biocatalyst and to reduce costly downstream processes. Herein, we report a method to produce galactooligosaccharides (GOSs) from a largely available feedstock (i.e. lactose from dairy production) using a flow reactor based on hierarchically structured monolithic silica. This reactor allows for fast and efficient biotransformation reaction in flow conditions.
Spectrophotometric study of the interaction of active pharmaceutical ingredients with colloidal silver nanoparticles capped by sulfonato-calix[6]arene derivatives
Three sulfonato-calix[6]arene derivatives, namely para-sulfonato-calix[6]arene, calix[6]arene-O-propyl-3-sulphonate and para-sulfonato-calix[6]arene-O-propyl-3-sulphonate have been used as capping agents for silver nanoparticles. The sulfonato-calix[6]arene derivatives were demonstrated to stabilise the nanoparticles, and to act as ligands for molecular recognition at the surface of the nanoparticles. The nanoparticles were characterised by UV-visible spectroscopy, dynamic light scattering, zeta potential and scanning electron microscopy. The localised surface plasmon resonance of the nanoparticles was shown to be highly sensitive to the local environment, and was used to evaluate molecular interactions with four active pharmaceutical ingredients: streptomycin, gentamycin, D-penicillamine and chloramphenicol. Changes in spectral intensity and wavelength have shown that the interactions are dependent on both the nature of the active pharmaceutical ingredient and that of the calix[6]arene receptor.
Plasmonic photothermal activation of an organosilica shielded cold-adapted lipase co-immobilised with gold nanoparticles on silica particles
Gold nanoparticles (AuNPs), owing to their intrinsic plasmonic properties, are widely used in applications ranging from nanotechnology and nanomedicine to catalysis and bioimaging. Capitalising on the ability of AuNPs to generate nanoscale heat upon optical excitation, we designed a nanobiocatalyst with enhanced cryophilic properties. It consists of gold nanoparticles and enzyme molecules, co-immobilised onto a silica scaffold, and shielded within a nanometre-thin organosilica layer. To produce such a hybrid system, we developed and optimized a synthetic method allowing efficient AuNP covalent immobilisation on the surface of silica particles (SPs). Our procedure allows to reach a dense and homogeneous AuNP surface coverage. After enzyme co-immobilisation, a nanometre-thin organosilica layer was grown on the surface of the SPs. This layer was designed to fulfil the dual function of protecting the enzyme from the surrounding environment and allowing the confinement, at the nanometre scale, of the heat diffusing from the AuNPs after surface plasmon resonance photothermal activation. To establish this proof of concept, we used an industrially relevant lipase enzyme, namely Lipase B from Candida Antarctica (CalB). Herein, we demonstrate the possibility to photothermally activate the so-engineered enzymes at temperatures as low as −10 °C.
Hydrophobicity-responsive engineered mesoporous silica nanoparticles: application in the delivery of essential nutrients to bacteria combating oil spills
Facile chemical modification of mesoporous silica particles allows the production of gated reservoir systems capable of hydrophobicity-triggered release. Applied to the delivery of nutrients specifically to an oil phase, the systems developed have been shown to reliably assist the bacterial degradation of hydrocarbons. The gated system developed, made of C18 hydrocarbon chains, is demonstrated to be in a closed collapsed state in an aqueous environment, yet opens up through solvation by lipophilic alkanes and releases its content on contact with the oil phase.