We report a synthetic strategy to produce nano-immobilised and organosilica-shielded enzymes of which the biocatalytic activity is, by design, chemically enhanced under reductive conditions. The enzymes were immobilised onto silica nanoparticles through a reduction-responsive crosslinker and further shielded in an organosilica layer of controlled thickness. Under reducing conditions, disulphide bonds linking the protein to the carrier material were reduced, triggering enzyme activation.
View Article and Find Full Text PDFEnzyme stability and activity are pivotal factors for their implementation in different industrial applications. Enzyme supramolecular engineering relies on the fabrication of a tailor-made enzyme nano-environment to ensure enzyme stability without impairing activity. Cyclodextrins (CDs), cyclic oligomers of glucose, act as protein chaperones and stabilize, upon interaction with hydrophobic amino acid residues exposed at the protein surface, its three-dimensional structure.
View Article and Find Full Text PDFPolyethylene significantly contributes to marine plastic pollution. This study focuses on isolating bacteria from sea water and microplastic samples collected from the Tyrrhenian Sea and evaluating their ability to degrade virgin plasticizers-free linear low-density polyethylene (LLDPE) films. The isolates grew on the plastic film under aerobic conditions in shaken flasks leading to LLDPE mass losses of up to 2.
View Article and Find Full Text PDFThe effectiveness of nanocrystals in many applications depends on their surface chemistry. Here, we leverage the atomically precise nature of zirconium and hafnium oxo clusters to gain fundamental insight into the thermodynamics of ligand binding. Through a combination of theoretical calculations and experimental spectroscopic techniques, we determine the interaction between the MO (M = Zr, Hf) cluster surface and various ligands: carboxylates, phosphonates, dialkylphosphinates, and monosubstituted phosphinates.
View Article and Find Full Text PDFWe report a method of enzyme stabilisation exploiting the artificial protein chaperone properties of β-cyclodextrin (β-CD) covalently embedded in an ultrathin organosilica layer. Putative interaction points of this artificial chaperone system with the surface of the selected enzyme were studied using a protein energy landscape exploration simulation algorithm. We show that this enzyme shielding method allows for drastic enhancement of enzyme stability under thermal and chemical stress conditions, along with broadening the optimal temperature range of the biocatalyst.
View Article and Find Full Text PDFClimate 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.
View Article and Find Full Text PDFThe 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.
View Article and Find Full Text PDFMetal complexes introduced into protein scaffolds can generate versatile biomimetic catalysts endowed with a variety of catalytic properties. Here, we synthesized and covalently bound a bipyridinyl derivative to the active centre of an esterase to generate a biomimetic catalyst that shows catecholase activity and enantioselective catalytic oxidation of (+)-catechin.
View Article and Find Full Text PDFDetermination of the levels of protein cross-linking catalysed by the activity of transglutaminase 2 in various disease states has remained a significant challenge. The ability to quantify the isopeptide ε-(γ-glutamyl) lysine, which can form as a heterogeneous bond within or between proteins has significant analytical and clinical potential as a biomarker in biofluids such as human urine. Increased transglutaminase 2 activity is associated with a number of diseases, such as fibrosis.
View Article and Find Full Text PDFGold 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.
View Article and Find Full Text PDFWe report a method of glycosylated enzymes' surface immobilisation and stabilisation. The enzyme is immobilised at the surface of silica nanoparticles through the reversible covalent binding of vicinal diols of the enzyme glycans with a surface-attached boronate derivative. A soft organosilica layer of controlled thickness is grown at the silica surface, entrapping the enzyme and thus avoiding enzyme leaching.
View Article and Find Full Text PDFWe 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.
View Article and Find Full Text PDFWe report a method to equip proteolytic nanobiocatalysts with intrinsic disulphide bond reducing properties. After immobilisation onto silica particles, selected protease enzymes are partially shielded in a nanometre-thick mercaptosilica layer acting not only as a protective system but also as a substrate reducing agent. The biocatalysts produced efficiently perform simultaneous disulphide bond reduction and protein digestion.
View Article and Find Full Text PDFOwing to their outstanding catalytic properties, enzymes represent powerful tools for carrying out a wide range of (bio)chemical transformations with high proficiency. In this context, enzymes with high biocatalytic promiscuity are somewhat neglected. Here, we demonstrate that a meticulous modification of a synthetic shell that surrounds an immobilized enzyme possessing broad substrate specificity allows the resulting nanobiocatalyst to be endowed with enantioselective properties while maintaining a high level of substrate promiscuity.
View Article and Find Full Text PDFWe report the first method of enzyme protection enabling the production of partially shielded enzymes capable of processing substrates as large as proteins. We show that partially shielded sortase retains its transpeptidase activity and can perform bioconjugation reactions on antibodies. Moreover, a partially shielded trypsin is shown to outperform its soluble counterpart in terms of proteolytic kinetics.
View Article and Find Full Text PDFFacile 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 C 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.
View Article and Find Full Text PDFStable, single-nanometer thin, and free-standing two-dimensional layers with controlled molecular architectures are desired for several applications ranging from (opto-)electronic devices to nanoparticle and single-biomolecule characterization. It is, however, challenging to construct these stable single molecular layers via self-assembly, as the cohesion of those systems is ensured only by in-plane bonds. We herein demonstrate that relatively weak noncovalent bonds of limited directionality such as dipole-dipole (-CN⋅⋅⋅NC-) interactions act in a synergistic fashion to stabilize crystalline monomolecular layers of tetrafunctional calixarenes.
View Article and Find Full Text PDFAngew Chem Int Ed Engl
August 2018
A trifunctional, partially fluorinated anthracene-substituted triptycene monomer was spread at an air/water interface into a monolayer, which was transformed into a long-range-ordered 2D polymer by irradiation with a standard UV lamp. The polymer was analyzed by Brewster angle microscopy, scanning tunneling microscopy measurements, and non-contact atomic force microscopy, which confirmed the generation of a network structure with lattice parameters that are virtually identical to a structural model network based on X-ray diffractometry of a closely related 2D polymer. The nc-AFM images highlight the long-range order over areas of at least 300×300 nm .
View Article and Find Full Text PDFTransaminases are enzymes capable of stereoselective reductive amination; they are of great interest in the production of chiral building blocks. However, the use of this class of enzymes in industrial processes is often hindered by their limited stability under operational conditions. Herein, we demonstrate that a transaminase enzyme from Aspergillus terreus can be immobilized at the surface of silica nanoparticles and protected in an organosilica shell of controlled thickness.
View Article and Find Full Text PDFWe report a cluster of genes encoding two monooxygenases (SadA and SadB) and one FMN reductase (SadC) that enable Microbacterium sp. strain BR1 and other Actinomycetes to inactivate sulfonamide antibiotics. Our results show that SadA and SadC are responsible for the initial attack of sulfonamide molecules resulting in the release of 4-aminophenol.
View Article and Find Full Text PDFA flexible and versatile method to fabricate two-dimensional metal-organic coordination networks (MOCNs) by bottom-up self-assembly is described. 2D crystalline layers were formed at the air-water interface, coordinated by ions from the liquid phase, and transferred onto a solid substrate with their crystallinity preserved. By using an inherently three-dimensional amphiphile, namely 25,26,27,28-tetrapropoxycalix[4]arene-5,11,17,23-tetracarboxylic acid, and a copper metal node, large and monocrystalline dendritic MOCN domains were formed.
View Article and Find Full Text PDFA series of synthetic nanomaterials capable of molecular recognition and/or biocatalysis have been produced by exploiting the self-sorting, self-assembly and polycondensation of organosilane building blocks around protein templates. The established methodology allows for the production of thin organosilica layers of controlled thickness, down to nanometer precision. Fully synthetic virus recognition materials have been shown to specifically bind their target virus down to picomolar concentrations.
View Article and Find Full Text PDFThe availability of highly stable and reusable enzymes is one of the main challenges in bio-based industrial processes. Enzyme immobilization and encapsulation represent promising strategies to reach this goal. In this chapter, the synthetic strategy to produce hybrid organic/inorganic nanobiocatalysts (NBC) is reported.
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