Luigi Gentile

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Papers by Luigi Gentile

The colloidal structure of a regenerated cellulose fibre

Acta Crystallographica Section A Foundations and Advances, 2021

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Secretion of Iron(III)-Reducing Metabolites during Protein Acquisition by the Ectomycorrhizal Fungus Paxillus involutus

Microorganisms, 2020

The ectomycorrhizal fungus Paxillus involutus decomposes proteins using a two-step mechanism, inc... more The ectomycorrhizal fungus Paxillus involutus decomposes proteins using a two-step mechanism, including oxidation and proteolysis. Oxidation involves the action of extracellular hydroxyl radicals (•OH) generated by the Fenton reaction. This reaction requires the presence of iron(II). Here, we monitored the speciation of extracellular iron and the secretion of iron(III)-reducing metabolites during the decomposition of proteins by P. involutus. X-ray absorption spectroscopy showed that extracellular iron was mainly present as solid iron(III) phosphates and oxides. Within 1 to 2 days, these compounds were reductively dissolved, and iron(II) complexes were formed, which remained in the medium throughout the incubation. HPLC and mass spectrometry detected five extracellular iron(III)-reducing metabolites. Four of them were also secreted when the fungus grew on a medium containing ammonium as the sole nitrogen source. NMR identified the unique iron(III)-reductant as the diarylcyclopenteno...

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Self-assembly of the peptide A10K – Intermediate state in aggregate formation

We have studied the synthetic surfactant-like peptide A10K in solution. Upon mixing the freeze dr... more We have studied the synthetic surfactant-like peptide A10K in solution. Upon mixing the freeze dried, essentially amorphous peptide powder in heavy water, the peptides self-assemble into long ribbon-like aggregates with a fixed cross section of circa 3x8 nm. It is still unclear whether this self-assembly is equilibrium like a surfactant micelle formation or whether it corresponds to a precipitation of a solid phase. Through light scattering measurements on dilution series, the solubility of the ribbons has been determined to 4.7 μM. However, quantitative NMR spectroscopy shows a monomer concentration of 3 mM, corresponding to a roughly 60 times supersaturation, and independent of the total concentration. Samples prepared directly at, or below this specific concentration shows no, or only minor signs of aggregation. In combination with a broad peak in high resolution 1H NMR spectroscopy we conclude that the formation of the A10K aggregates occurs through an intermediate state in equi...

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Comparison of small-angle neutron and X-ray scattering for studying cortical bone nanostructure

Scientific Reports, 2020

In this study, we present a combined small-angle neutron and X-ray scattering (SANS and SAXS) stu... more In this study, we present a combined small-angle neutron and X-ray scattering (SANS and SAXS) study of the nanoscale structure of cortical bone specimens from three different species. The variation of the scattering cross section of elements across the periodic table is very different for neutrons and X-rays. For X-rays, it is proportional to the electron density while for neutrons it varies irregularly with the atomic number. Hence, combining the two techniques on the same specimens allows for a more detailed interpretation of the scattering patterns as compared to a single-contrast experiment. The current study was performed on bovine, porcine and ovine specimens, obtained in two perpendicular directions with respect to the main axis of the bone (longitudinal and radial) in order to maximise the understanding of the nanostructural organisation. The specimens were also imaged with high resolution micro-computed tomography (micro-CT), yielding tissue mineral density and microstructu...

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Shape and Phase Transitions in a PEGylated Phospholipid System

Langmuir, 2019

Poly(ethylene glycol) (PEG) polymers and PEGconjugated lipids are widely used in bioengineering a... more Poly(ethylene glycol) (PEG) polymers and PEGconjugated lipids are widely used in bioengineering and drug transport applications. A PEG layer in a drug carrier increases hydrophilic repulsion, inhibits membrane fusion and serum opsonin interactions, and prolongs the storage and circulation time. It can also change the carrier shape and have an influence on many properties related to the content release of the carrier. In this paper, we focus on the physicochemical effects of PEGylation in the lipid bilayer. We introduce laurdanC as a fluorophore for shape recognition and phase transition detection. Together with laurdanC, cryogenic transmission electron microscopy, differential scanning calorimetry, molecular dynamics simulations, and small-angle X-ray scattering/wide-angle X-ray scattering, we acquire information of the particle/bilayer morphology and phase behavior in systems containing 1,2-dipalmitoyl-sn-glycero-3-phosphocholine:1,2-distearoyl-sn-glycero-3-phosphoethanolamine-PEG(2000) with different fractions. We find that PEGylation leads to two important and potentially usable features of the system. (1) Spherical vesicles present a window of elevated chain-melting temperatures and (2) lipid packing shape-controlled liposome-tobicelle transition. The first finding is significant for targets requiring multiple release sequences and the second enables tuning the release by composition and the PEG polymer length. Besides drug delivery systems, the findings can be used in other smart soft materials with trigger-polymers as well.

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Ferrihydrite Nanoparticle Aggregation Induced by Dissolved Organic Matter

The journal of physical chemistry. A, Jan 12, 2018

Ferrihydrite (Fh) nanoparticles are omnipresent in nature and often highly mobile because of thei... more Ferrihydrite (Fh) nanoparticles are omnipresent in nature and often highly mobile because of their colloidal stability. Thus, Fh serves as a vector for iron as well as associated nutrients and contaminants. Here, we demonstrate, using small-angle X-ray scattering combined with cryo-transmission electron microscopy (cryo-TEM), that dissolved organic matter (DOM), extracted from a boreal forest soil, induce aggregation of Fh nanoparticles, of radius 3 nm, into fractal aggregates, having a fractal dimension D = 1.7. The DOM consists of both fractal-like colloids (>100 nm) and small molecular DOM, but the attractive Fh interparticle interaction was mediated by molecular DOM alone as shown by cryo-TEM. This highlights the importance of using soil extracts, including all size fractions, in studies of the colloidal behavior of DOM-mineral aggregates. The Fh nanoparticles also self-assemble during synthesis into aggregates with the same fractal dimension as the DOM-Fh aggregates. We prop...

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On the dissolution state of cellulose in cold alkali solutions

Cellulose, 2017

We have characterized the dissolved state of microcrystalline cellulose (MCC) in cold alkali [2.0... more We have characterized the dissolved state of microcrystalline cellulose (MCC) in cold alkali [2.0 M NaOH(aq)] solutions using a combination of small angle X-ray (SAXS) and static light scattering (SLS), 1 H NMR, NMR self-diffusion, and rheology experiments. NMR and SAXS data demonstrate that the cellulose is fully molecularly dissolved. SLS, however, shows the presence of large concentration fluctuations in the solution, consistent with significant attractive cellulose-cellulose interactions. The scattering data are consistent with fractal cellulose aggregates of micrometre size having a mass fractal dimension D $ 1:5. At 25 C the solution structure remains unchanged on the time scale of weeks. However, upon heating the solutions above 35 C additional aggregation occurs on the time scale of minutes. Decreasing or increasing the NaOH concentration away from the ''optimum'' 2 M also leads to additional aggregation. This is seen as an increase of the SAXS intensity at lower q values. Addition of urea (1.8 and 3.6 M, respectively) does not significantly influence the solution structure. With these examples, we will discuss how scattering methods can be used to assess the quality of solvents for cellulose. Keywords Microcrystalline cellulose (MCC) Á Cold alkali (NaOH) Á Small angle X-ray scattering (SAXS) Á Static light scattering (SLS) Á NMR Á Rheology Á Urea Á Co-solvent Á Temperature dependence Á Aggregation

$Table 1 Overview of the experiment parameters Germany). In all cases the temperature was controlled by an external recirculating water bath with an accuracy of +0.2°C. The two-dimensional (2D) scattering pattern was recorded using a 2D 300k Pilatus detector (Dectris Ltd., Baden, Switzerland) and radially averaged using SAXSGui software to obtain I(q). The measured scattering curves were corrected for solvent scattering. For SLS measurements, we used an ALV/DLS/SLS- 5022F, CGF-8F-based compact goniometer system from ALV-GmbH, Langen, Germany with a 22 mW He-Ne laser as light source. The laser operates at 632.8 nm, and the intensity is varied using a software- controlled attenuator. A perfect vertical polarisation is achieved using a Glan laser polarizer prism with a polarization ratio better than 10° in front of the temperature controlled cell housing. The scattering cells used were made of borosilicate glass (10 mm inner diameter) and were immersed in a thermostated vat filled with a refractive index matched liquid (cis- decahydronaphthalene), and the temperature was controlled using a F32 Julabo heating circulator which kept an accuracy of +0.1°C. The unpolarised scat- tered light is collected using a detection unit that includes a near-monomodal optical fibre and two high- quality avalanche photodiodes placed in a pseudo- cross geometry. The rotary table of the goniometer has a range of scattering angles (0) between 20° and 140°.$

$Fig. 5 SAXS and viscosity results from a 0.010 g/cm? cellu- lose solution in different concentrations of NaOQH(aq), varying from 1.0 to 3.0 M. a SAXS patterns. The solid lines represent fractal model values. b Fits of the fractal dimension, D, and the correlation length, €, obtained (from Eq. 6) at different concentrations of NaOH(aq). ¢ Viscosity as a function of the shear rate of the samples$

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A peptide from human semenogelin I self-assembles into a pH-responsive hydrogel

Soft Matter, 2015

The 11-residue peptide GSFSIQYTYHV from human semenogelin I forms a hydrogel with optimal stabili... more

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A selective cellulose/hemicellulose green solvents extraction from buckwheat chaff

Carbohydrate Polymer Technologies and Applications, 2021

A two-phase extraction process was adopted to obtain cellulose and hemicellulose from buckwheat c... more A two-phase extraction process was adopted to obtain cellulose and hemicellulose from buckwheat chaff by using green solvents. We are proposing a combination of propylene carbonate (PC) and ionic liquids (ILs) in a 1:5 ratio. We compared the first-generation ILs 1-butyl-2,3-dimethylimidazolium chloride (BdmimCl), and 1butyl-3-methyl imidazolium acetate (BmimAc) with respect to the tetrabutyl ammonium acetate (TBAAc). The cellulose and hemicellulose were, firstly, extracted into the PC/IL mixture and subsequently precipitated by water addition. All precipitate materials were analysed by FTIR-ATR and TGA, while the organic phase and the supernatant after water addition were analysed by using self-diffusion NMR. The PC green co-solvent was proven to be an exceptional candidate to replace dimethyl sulfoxide. The highest amount of precipitate material after water addition was obtained with PC-BmimAc, while PC-TBAAc was showing the highest cellulose/hemicellulose selectivity. Furthermore, a preferential interaction of the supernatant cellulose residue with PC or acetate was observed by self-diffusion NMR.

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$Research paper thumbnail of A novel X-ray diffraction approach to assess the crystallinity of regenerated cellulose fibers$

A novel X-ray diffraction approach to assess the crystallinity of regenerated cellulose fibers

IUCrJ

Here, a new accurate approach is presented to quantify the degree of crystallinity of regenerated... more Here, a new accurate approach is presented to quantify the degree of crystallinity of regenerated cellulose textile fibers using wide-angle X-ray scattering. The approach is based on the observation that the contributions to the scattering from crystalline and amorphous domains of the fibers can be separated due to their different degree of orientation with respect to the fiber direction. The method is tested on Ioncell-F fibers, dry jet wet spun with different draw ratios from an ionic liquid solution. The analysis output includes, apart from an accurate estimate of the fiber crystallinity, the degrees of orientation of the cellulose nanocrystals and the cellulose chains in the amorphous domains.

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$Research paper thumbnail of Gold nanoparticles obtained by ns-pulsed laser ablation in liquids (ns-PLAL) are arranged in the form of fractal clusters$

Gold nanoparticles obtained by ns-pulsed laser ablation in liquids (ns-PLAL) are arranged in the form of fractal clusters

Journal of Nanoparticle Research

Gold nanoparticles (AuNPs), synthesized by ns-pulsed laser ablation in liquid (ns-PLAL) in the ab... more Gold nanoparticles (AuNPs), synthesized by ns-pulsed laser ablation in liquid (ns-PLAL) in the absence of any capping agents, are potential model systems to study the interactions with biological structures unencumbered by interference from the presence of stabilizers and capping agents. However, several aspects of the physics behind these AuNPs solutions deserve a detailed investigation. The structure in solution of ns-PLAL-synthesized AuNPs was investigated in solution by means of small-angle X-ray scattering (SAXS) and dynamic light scattering (DLS). Furthermore, the (dried) NPs have been examined using TEM. The analysis of the SAXS curve shows the presence of a large number of small aggregates with a fractal structure stabilized by strong long-range repulsive interactions. Fitting of the SAXS curve to a suitable “fractal model” allows the estimation of the features of the fractal including the fractal dimension d = 1.9. The latter allows to estimate the fraction of light scatter...

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Biobased Approach for Synthesis of Polymers and Sustainable Formulation of Industrial Hardeners

Coatings, 2022

The adhesive manufacturing industry needs more eco-sustainable processes. In this regard, the mai... more The adhesive manufacturing industry needs more eco-sustainable processes. In this regard, the main road is to replace raw fossil materials with renewable resources or waste biomass, and simultaneously improve synthetic steps by using clean and greener reagents under mild conditions. In this paper, a synthetic pathway for producing biobased succinyl peroxide (SP) from waste biomass is reported, and then the application range of this polymerization agent to methacrylates and styrene-free resins is extended. At the same time, new formulations of pastes based on benzoyl or succinyl peroxide, displaying an almost complete biobased carbon content, are investigated and tested as cross-linking agents for mastic marble and unsaturated polyester resins. Physicochemical characterization of the final products and polymers is carried out with thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), Fourier transform infrared (FT-IR), Gel Permeation Chromatography (GPC), Nuclear...

format_quotePEMA synthesized with succinyl peroxide reached a weight average molecular weight of 20,818 g/mol, comparable to traditional agents.format_quote

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Peptide hydrogels from twisted ribbon aggregates

We have studied the rheology of an aqueous solution phase formed in the model peptide system A10K... more We have studied the rheology of an aqueous solution phase formed in the model peptide system A10K (A=alanine, K=lysine), where the short hydrophobic peptides self-assemble into twisted ribbon structures consisting of laminated beta-sheets. The ribbons are crystalline in 2 dimensions, therefore rigid, and they are weakly charged. The average ribbon lengths, ≈ 60 nm, corresponding to an aspect ratio, L/d≈10. With increasing concentration a transition from a viscous liquid into a gel-like solid occurs around a volume fraction f ≈ 0.02, that we identify as the overlap concentration f*. Coinciding with the overlap concentration is also a phase transition, from the low concentration isotropic liquid phase to a nematic phase. This concentration is significantly lower than what is predicted for hard rods by Onsager theory for this given aspect ratio. We attribute this to the ribbon charge and long range electrostatic interactions, stabilizing the nematic phase. In this nematic phase, the st...

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Protein–polysaccharide interactions and aggregates in food formulations

Current Opinion in Colloid & Interface Science, 2020

The protein-polysaccharide combinations that lead to electrostatic complex and coacervates format... more The protein-polysaccharide combinations that lead to electrostatic complex and coacervates formation are the object of extensive research using both layer-by-layer and mixed emulsion approaches. The protein-polysaccharide conjugates demonstrated interesting physico-chemical properties as stabilizers and emulsifiers as well as texture modifiers in food products. Furthermore, they are potential optimal nutrient delivery systems. Their complex behavior due to several factors such as pH, ionic strength, concentration, heat, and mechanical treatments is the main reason behind the continuous growth of the research field. The review is reporting same recent advances on the topic, along with an overview on the possible interactions between protein and polysaccharide, from Maillard reaction to enzymatic crosslinking passing through coacervates.

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Probing Downstream Olive Biophenol Secoiridoids

International Journal of Molecular Sciences, 2018

Numerous bioactive biophenol secoiridoids (BPsecos) are found in the fruit, leaves, and oil of ol... more Numerous bioactive biophenol secoiridoids (BPsecos) are found in the fruit, leaves, and oil of olives. These BPsecos play important roles in both the taste of food and human health. The main BPseco bioactive from green olive fruits, leaves, and table olives is oleuropein, while olive oil is rich in oleuropein downstream pathway molecules. The aim of this study was to probe olive BPseco downstream molecular pathways that are alike in biological and olive processing systems at different pHs and reaction times. The downstream molecular pathway were analyzed by high performance liquid chromatography coupled with electrospray ionization mass spectrometry (HPLC-ESI/MS) and typed neglected of different overlap (TNDO) computational methods. Our study showed oleuropein highest occupied molecular orbital (HOMO) and HOMO-1 triggered the free radical processes, while HOMO-2 and lowest unoccupied molecular orbital (LUMO) were polar reactions of glucoside and ester groups. Olive BPsecos were foun...

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Arrested dynamics in a model peptide hydrogel system

Soft Matter, 2020

We report here on a peptide hydrogel system, which in contrast to most other such systems, is mad... more

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Characterization of Iron and Organic Carbon Colloids in Boreal Rivers and Their Fate at High Salinity

Journal of Geophysical Research: Biogeosciences, 2020

Riverine colloids are important carriers of macronutrients, trace metals, and pollutants into mar... more Riverine colloids are important carriers of macronutrients, trace metals, and pollutants into marine waters. The aim of the current study was to extend the understanding of iron (Fe) and organic carbon (OC) colloids in boreal rivers and their fate at higher salinities. X-ray absorbance spectroscopy (XAS) and dynamic light scattering (DLS) were combined to explore Fe speciation and colloidal characteristics such as size and surface charge and how these are affected at increasing salinity. XAS confirmed the presence of two Fe phases in the river waters-Fe-organic matter (OM) complexes and Fe(oxy)hydroxides. From DLS measurements on filtered and unfiltered samples, three particle size distributions were identified. The smallest particles (10-40 nm) were positively charged and suggested to consist of essentially bare Fe(oxy)hydroxide nanoparticles. The largest particles (300-900 nm) were dominated by Fe(oxy)hydroxides associated with chromophoric molecular matter. An intermediate size distribution (100-200 nm) with a negative surface charge was presumably dominated by OM and containing Fe-OM complexes. Increasing the salinity resulted in a removal of the smallest distribution. Unexpectedly, both the intermediate and largest size distributions were still detected at high salinity. The collective results suggest that Fe(oxy) hydroxides and Fe-OM complexes are both found across the wide size range studied and that colloidal size does not necessarily reflect either Fe speciation or stability toward salinity-induced aggregation. The findings further demonstrate that also particles beyond the typically studied <0.45-μm size range should be considered to fully understand the riverine transport and fate of macronutrients, trace metals, and pollutants. When rivers discharge into estuaries, Fe displays a distinctly nonconservative behavior, with a major loss of Fe from the surface water following salinity-induced aggregation and sedimentation (

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Regulation of fungal decomposition at single-cell level

The ISME Journal, 2020

Filamentous fungi play a key role as decomposers in Earth’s nutrient cycles. In soils, substrates... more Filamentous fungi play a key role as decomposers in Earth’s nutrient cycles. In soils, substrates are heterogeneously distributed in microenvironments. Hence, individual hyphae of a mycelium may experience very different environmental conditions simultaneously. In the current work, we investigated how fungi cope with local environmental variations at single-cell level. We developed a method based on infrared spectroscopy that allows the direct, in-situ chemical imaging of the decomposition activity of individual hyphal tips. Colonies of the ectomycorrhizal Basidiomycete Paxillus involutus were grown on liquid media, while parts of colonies were allowed to colonize lignin patches. Oxidative decomposition of lignin by individual hyphae growing under different conditions was followed for a period of seven days. We identified two sub-populations of hyphal tips: one with low decomposition activity and one with much higher activity. Active cells secreted more extracellular polymeric subst...

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Multilamellar Vesicle Formation Probed by Rheo-NMR and Rheo-SALS under Large Amplitude Oscillatory Shear

Langmuir : the ACS journal of surfaces and colloids, Jan 17, 2018

The formation of multilamellar vesicles (MLVs) in the lyotropic lamellar phase of the system trie... more The formation of multilamellar vesicles (MLVs) in the lyotropic lamellar phase of the system triethylene glycol mono n-decyl ether (CE)/water is investigated under large amplitude oscillatory shear (LAOS) using spatially resolved rheo-NMR spectroscopy and a combination of rheo-small angle light scattering (rheo-SALS) and conventional rheology. Recent advances in rheo-NMR hardware development facilitated the application of LAOS deformations in high-field NMR magnets. For the range of investigated strain amplitudes (10-50) and frequencies (1 and 2 rad s), MLV formation is observed in all NMR and most SALS experiments. It is found that the MLV size depends on the applied frequency in contrast to previous steady shear experiments where the shear rate is the controlling parameter. The onset of MLV formation, however, is found to vary with the shear amplitude. The LAOS measurements bear no indication of the intermediate structures resembling aligned multilamellar cylinders observed in ste...

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Non-lamellar lipid assembly at interfaces: controlling layer structure by responsive nanogel particles

Interface focus, Jan 6, 2017

Biological membranes do not only occur as planar bilayer structures, but depending on the lipid c... more Biological membranes do not only occur as planar bilayer structures, but depending on the lipid composition, can also curve into intriguing three-dimensional structures. In order to fully understand the biological implications as well as to reveal the full potential for applications, e.g. for drug delivery and other biomedical devices, of such structures, well-defined model systems are required. Here, we discuss the formation of lipid non-lamellar liquid crystalline (LC) surface layers spin-coated from the constituting lipids followed by hydration of the lipid layer. We demonstrate that hybrid lipid polymer films can be formed with different properties compared with the neat lipid LC layers. The nanostructure and morphologies of the lipid films formed reflect those in the bulk. Most notably, mixed lipid layers, which are composed of glycerol monooleate and diglycerol monooleate with poly(N-isopropylacrylamide) nanogels, can form films of reverse cubic phases that are capable of resp...

format_quoteMonoolein-based cubic LC phases can be swollen significantly through membrane modifications, enhancing functional properties.format_quote

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Luigi Gentile

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