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1.
Genet Med ; 26(6): 101081, 2024 06.
Artículo en Inglés | MEDLINE | ID: mdl-38293907

RESUMEN

PURPOSE: Progressive inherited retinal degenerations (IRDs) affecting rods and cones are clinically and genetically heterogeneous and can lead to blindness with limited therapeutic options. The major gene defects have been identified in subjects of European and Asian descent with only few reports of North African descent. METHODS: Genome, targeted next-generation, and Sanger sequencing was applied to cohort of ∼4000 IRDs cases. Expression analyses were performed including Chip-seq database analyses, on human-derived retinal organoids (ROs), retinal pigment epithelium cells, and zebrafish. Variants' pathogenicity was accessed using 3D-modeling and/or ROs. RESULTS: Here, we identified a novel gene defect with three distinct pathogenic variants in UBAP1L in 4 independent autosomal recessive IRD cases from Tunisia. UBAP1L is expressed in the retinal pigment epithelium and retina, specifically in rods and cones, in line with the phenotype. It encodes Ubiquitin-associated protein 1-like, containing a solenoid of overlapping ubiquitin-associated domain, predicted to interact with ubiquitin. In silico and in vitro studies, including 3D-modeling and ROs revealed that the solenoid of overlapping ubiquitin-associated domain is truncated and thus ubiquitin binding most likely abolished secondary to all variants identified herein. CONCLUSION: Biallelic UBAP1L variants are a novel cause of IRDs, most likely enriched in the North African population.


Asunto(s)
Distrofias de Conos y Bastones , Linaje , Pez Cebra , Humanos , Distrofias de Conos y Bastones/genética , Distrofias de Conos y Bastones/patología , Masculino , Femenino , Pez Cebra/genética , Animales , Genes Recesivos , Epitelio Pigmentado de la Retina/metabolismo , Epitelio Pigmentado de la Retina/patología , Mutación/genética , Células Fotorreceptoras Retinianas Conos/patología , Células Fotorreceptoras Retinianas Conos/metabolismo , Retina/patología , Retina/metabolismo , Adulto , Túnez , Retinitis Pigmentosa/genética , Retinitis Pigmentosa/patología , Fenotipo , Células Fotorreceptoras Retinianas Bastones/metabolismo , Células Fotorreceptoras Retinianas Bastones/patología
2.
Ophthalmology ; 2024 Apr 06.
Artículo en Inglés | MEDLINE | ID: mdl-38583493

RESUMEN

PURPOSE: To describe the clinical outcome and late-stage findings of extensive macular atrophy with pseudodrusen-like appearance (EMAP). DESIGN: Retrospective cohort study. PARTICIPANTS: Seventy-eight patients (156 eyes) affected by EMAP. METHODS: We collected data on best-corrected visual acuity, kinetic perimetry, OCT, short-wavelength autofluorescence, and near-infrared autofluorescence findings. Genetic testing for the TIMP3 and C1QTNF5 genes was performed via Sanger sequencing for 58 patients, with no pathogenic variants identified. MAIN OUTCOME MEASURES: The primary outcomes were best-corrected visual acuity at the last examination, visual field at the last examination, and incidence rates and time-to-event curves for blindness with the United States Social Security Administration and World Health Organization (WHO) criteria, foveal involvement, and atrophy enlargement beyond the 30° and 55° field of view. Imaging findings at the last examination were secondary outcomes. RESULTS: At the most recent visit, mean age was 70.9 ± 5.2 years. Using United States criteria, 58.1% of the patients were blind, and 25.8% were blind according to WHO criteria. All eyes showed large central scotomas, which were associated with visual field constriction in 22.2% of eyes. We detected focal openings or large dehiscences of Bruch's membrane (BM) in 25.4% of eyes. Near-infrared autofluorescence showed increased visibility of the choroidal vessels beyond the atrophy in 87.2% of eyes. The incidence rates for blindness were 3.95 per 100 patient-years with United States criteria and 1.54 per 100 patient-years according to WHO criteria. The incidence rates were 22.8 per 100 eye-years for foveal involvement, 12.0 per 100 eye-years for atrophy enlargement beyond 30°, and 6.6 per 100 eye-years for atrophy enlargement beyond 55°. The estimates were not influenced by the age at onset. CONCLUSIONS: We identified characteristic imaging findings, including BM ruptures, in elder patients with EMAP and calculated incidence rates for different functional and anatomic outcomes. FINANCIAL DISCLOSURE(S): Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

3.
Biomacromolecules ; 21(5): 1952-1961, 2020 05 11.
Artículo en Inglés | MEDLINE | ID: mdl-32223221

RESUMEN

This paper investigates a strategy to convert hydrophilic cellulose nanofibrils (CNF) into a hydrophobic highly cross-linked network made of cellulose nanofibrils and inorganic nanoparticles. First, the cellulose nanofibrils were chemically modified through an esterification reaction to produce a nanocellulose-based macroinitiator. Barium titanate (BaTiO3, BTO) nanoparticles were surface-modified by introducing a specific monomer on their outer-shell surface. Finally, we studied the ability of the nanocellulose-based macroinitiator to initiate a single electron transfer living radical polymerization of stearyl acrylate (SA) in the presence of the surface-modified nanoparticles. The BTO nanoparticles will transfer new properties to the nanocellulose network and act as a cross-linking agent between the nanocellulose fibrils, while the monomer (SA) directly influences the hydrophilic-lipophilic balance. The pristine CNF and the nanoparticle cross-linked CNF are characterized by FTIR, SEM, and solid-state 13C NMR. Rheological and dynamic mechanical analyses revealed a high dregee of cross-linking.


Asunto(s)
Nanofibras , Nanopartículas , Celulosa , Interacciones Hidrofóbicas e Hidrofílicas , Polimerizacion
4.
Biomacromolecules ; 18(6): 1947-1955, 2017 Jun 12.
Artículo en Inglés | MEDLINE | ID: mdl-28482654

RESUMEN

A strategy is devised for the conversion of hydrophilic cellulose nanofibrils (CNFs) into hydrophobic CNF that form a stable nanocomposite dispersion for functional reinforcement of a polypropylene matrix. For that purpose, CNF was converted to a CNF-based microinitiator through an esterification reaction on the nanofibril surfaces, which efficiently initiated the controlled radical grafting polymerization of stearyl acrylate. The grafting-from modification was performed with and without a sacrificial initiator and verified with solid-state 13C nuclear magnetic resonance and Fourier transform infrared spectroscopy. CNF-based nanocomposites were prepared using the combination of a twin-screw mini extruder and melt pressing. Scanning electron microscopy reveals a homogeneous dispersion of the hydrophobic CNF in composite matrix with no signs of aggregation. Hydrophobic CNF showed a strong compatibility with the polypropylene matrix.


Asunto(s)
Celulosa/química , Nanocompuestos/química , Nanofibras/química , Polipropilenos/química , Acrilatos/química , Radicales Libres , Interacciones Hidrofóbicas e Hidrofílicas , Nanocompuestos/ultraestructura , Nanofibras/ultraestructura , Polimerizacion , Estearatos/química , Propiedades de Superficie
5.
Biomacromolecules ; 17(3): 1101-9, 2016 Mar 14.
Artículo en Inglés | MEDLINE | ID: mdl-26789648

RESUMEN

A strategy is devised for the conversion of cellulose nanofibrils (CNF) into fluorescently labeled probes involving the synthesis of CNF-based macroinitiators that initiate radical polymerization of methyl acrylate and acrylic acid N-hydroxysuccinimide ester producing a graft block copolymer modified CNF. Finally, a luminescent probe (Lucifer yellow derivative) was labeled onto the modified CNF through an amidation reaction. The surface modification steps were verified with solid-state (13)C nuclear magnetic resonance (NMR) and Fourier transform infrared spectroscopy. Fluorescence correlation spectroscopy (FCS) confirmed the successful labeling of the CNF; the CNF have a hydrodynamic radius of about 700 nm with an average number of dye molecules per fibril of at least 6600. The modified CNF was also imaged with confocal laser scanning microscopy. Luminescent CNF proved to be viable biomarkers and allow for fluorescence-based optical detection of CNF uptake and distribution in organisms such as crustaceans. The luminescent CNF were exposed to live juvenile daphnids and microscopy analysis revealed the presence of the luminescent CNF all over D. magna's alimentary canal tissues without any toxicity effect leading to the death of the specimen.


Asunto(s)
Celulosa/análogos & derivados , Colorantes Fluorescentes/química , Isoquinolinas/química , Nanofibras/química , Coloración y Etiquetado/métodos , Acrilatos/química , Animales , Daphnia/citología , Colorantes Fluorescentes/farmacocinética , Isoquinolinas/farmacocinética , Microscopía Fluorescente/métodos
6.
Biomacromolecules ; 16(4): 1293-300, 2015 Apr 13.
Artículo en Inglés | MEDLINE | ID: mdl-25774999

RESUMEN

We have chemically modified cellulose nanofibrils (CNF) with furan and maleimide groups, and selectively labeled the modified CNF with fluorescent probes; 7-mercapto-4-methylcoumarin and fluorescein diacetate 5-maleimide, through two specific click chemistry reactions: Diels-Alder cycloaddition and the thiol-Michael reaction. Characterization by solid-state (13)C NMR and infrared spectroscopy was used to follow the surface modification and estimate the substitution degrees. We demonstrate that the two luminescent dyes could be selectively labeled onto CNF, yielding a multicolor CNF that was characterized by UV/visible and fluorescence spectroscopies. It was demonstrated that the multicolor CNF could be imaged using a confocal laser scanning microscope.


Asunto(s)
Celulosa/química , Química Clic/métodos , Colorantes Fluorescentes/química , Nanopartículas/química , Furanos/química , Maleimidas/química , Madera/química
7.
Langmuir ; 30(34): 10487-92, 2014 Sep 02.
Artículo en Inglés | MEDLINE | ID: mdl-25105229

RESUMEN

WO3 nanorods and wires were obtained via hydrothermal synthesis using sodium tungstate as a precursor and either oxalic acid, citric acid, or poly(methacrylic acid) as a stabilizing agent. Transmission electron microscopy images showed that the organic acids with different numbers of carboxylic groups per molecule influence the final sizes and stacking nanostructures of WO3 wires. Three-dimensional electron diffraction tomography of a single nanocrystal revealed a hexagonal WO3 structure with preferential growth along the c-axis, which was confirmed by high-resolution transmission electron microscopy. WO3 nanowires were also spin-coated onto an indium tin oxide/glass conducting substrate, resulting in the formation of a film that was characterized by scanning electron microscopy. Finally, cyclic voltammetry measurements performed on the WO3 thin film showed voltammograms typical for the WO3 redox process.

8.
Inorg Chem ; 53(10): 5067-72, 2014 May 19.
Artículo en Inglés | MEDLINE | ID: mdl-24766566

RESUMEN

Hydrothermal synthesis of GdPO4 in the presence of poly(methacrylic acid) yields nanorods with a diameter of 15 nm and an aspect ratio of 20. Powder X-ray diffraction patterns showed that the GdPO4 nanorods display peaks characteristics for both monoclinic and hexagonal structures. Three-dimensional electron diffraction tomography (3D EDT) was used to determine the structures ab initio on the basis of reciprocal volume reconstruction of electron diffraction data sets collected from single nanorods. The crystal structure of the monoclinic form was shown to be P21/n, corroborating previous work. We were able to solve the 3D structure of the hexagonal P6222 form, which has not been reported previously. Our work shows that 3D EDT is a powerful method that can be used for solving structures of single nanocrystals.

9.
Am J Ophthalmol ; 2024 Jun 28.
Artículo en Inglés | MEDLINE | ID: mdl-38945349

RESUMEN

PURPOSE: To investigate the clinical, functional, and imaging characteristics in patients affected by inherited retinal diseases associated with RDH5 and RLBP1 gene variants, and to report novel genotype-phenotype correlations. DESIGN: Retrospective single-center cohort study. METHODS: Twenty-two patients with molecularly confirmed RLBP1-associated retinopathy and 5 with RDH5-associated retinopathy. Medical records were reviewed to obtain data on family history and ophthalmologic examinations, including retinal imaging and full-field electroretinography (ffERG). Genotype was determined by targeted next-generation sequencing followed by confirmation and familial segregation by Sanger sequencing. RESULTS: The median (IQR) age at baseline for the RDH5 and RLBP1 cohort was 44.6 (38.2-67.9) years and 36.9 (23.1-45.2) years, respectively. Macular atrophy was found in approximately 80% of eyes from both cohorts. The RLBP1 genotype was associated with a lower macular volume by 0.28 mm3 (95% CI, -0.46 to -0.11; P = .005) compared to the RDH5 genotype. In both genotypic cohorts, we found a significant annual rate of macular volume loss, estimated at -0.007 mm3/y (95% CI, -0.012 to -0.001; P = .02), without any significant difference the two genotypes. Three unrelated patients homozygous for the c.361C>T p.(Arg121Trp) RLBP1 variant showed minimal impairment of both the rod and cone systems function on ffERG and absence of macular atrophy. CONCLUSIONS: Progressive macular atrophy in addition to congenital night blindness can be identified in adult patients with RDH5-associated retinopathy. Vice versa, hypomorphic RLBP1 variants may cause milder retinal phenotypes rather than the typical severe rod-cone dystrophy with macular atrophy. These findings could prove beneficial to improve the prognostication of patients and help in designing future interventional trials.

10.
Res Sq ; 2024 Feb 09.
Artículo en Inglés | MEDLINE | ID: mdl-38405922

RESUMEN

Inherited retinal degenerations are blinding genetic disorders characterized by high genetic and phenotypic heterogeneity. The implementation of next-generation sequencing in routine diagnostics, together with advanced clinical phenotyping including multimodal retinal imaging, have contributed to the increase of reports describing novel genotype-phenotype associations and phenotypic expansions. In this study, we describe sixteen families with early-onset non-syndromic retinal degenerations in which affected probands carried rare bi-allelic variants in CFAP410, a ciliary gene previously associated with syndromic recessive Jeune syndrome. The most common retinal phenotypes were cone-rod and rod-cone dystrophies, but the clinical presentations were unified by their early onset as well as the severe impact on central visual function. Twelve variants were detected (three pathogenic, seven likely pathogenic, two of uncertain significance), eight of which were novel. One deep intronic change, c.373+91A>G, led to the creation of a cryptic splice acceptor site in intron four, followed by the inclusion of a 200- base pair pseudoexon and subsequent premature stop codon formation. To our knowledge this is the first likely pathogenic deep-intronic variant identified in this gene. Meta-analysis of all published and novel CFAP410 variants revealed no clear correlation between the severity of the CFAP410-associated phenotypes and the identified causal variants. This is supported by the fact that the frequently encountered missense variant p.(Arg73Pro), often found in syndromic cases, was also associated with non-syndromic retinal degeneration. This study expands the current knowledge of CFAP410-associated ciliopathy by enriching its mutational landscape and supports its association with non-syndromic retinal degeneration.

11.
Langmuir ; 29(34): 10915-21, 2013 Aug 27.
Artículo en Inglés | MEDLINE | ID: mdl-23886357

RESUMEN

Light-matter interactions are of great interest for potential biological applications (bioimaging, biosensing, phototherapy). For such applications, sharp nanostructures exhibit interesting features since their extinction bands (surface plasmon resonance) cover a large bandwidth in the whole visible wavelength region due to the existence of "hot spots" located at the end of the tips. In this context, gold nanostars appear to be interesting objects. However, their study remains difficult, mainly due to complicated synthetic methods and further functionalization. This paper reports the synthesis, functionalization, and photophysics of luminescent hybrid gold nanostars prepared using a layer-by-layer (LbL) deposition method for the tuning of chromophore-to-particle distances together with the impact of the spectral overlap between the plasmon and the emission/absorption of the dyes. Several luminescent dyes with different optical signatures were selectively adsorbed at the nanoparticle surface. The optimized systems, exhibiting the highest luminescence recovery, clearly showed that overlap must be as low as possible. Also, the fluorescence intensities were quenched in close vicinity of the metal surface and revealed a distance-dependence with almost full recovery of the dyes emission for 11 LbL layers, which corresponded to 15 nm distances evaluated on dried samples. The photophysics of the luminescent core-shell particles were carried out in suspension and correlated with the response of isolated single objects.


Asunto(s)
Colorantes/química , Oro/química , Nanopartículas del Metal/química
12.
Analyst ; 138(2): 583-92, 2013 Jan 21.
Artículo en Inglés | MEDLINE | ID: mdl-23172138

RESUMEN

Dark field resonant light scattering by gold and silver nanoparticles enables the detection and spectroscopy of such particles with high sensitivity, down to the single-particle level, and can be used to implement miniaturised optical detection schemes for chemical and biological analysis. Here, we present a straightforward optical spectroscopic methodology for the quantitative spectrometric study of resonant light scattering (RLS) by nanoparticles. RLS spectroscopy is complementary to UV-visible absorbance measurements, and we apply it to the characterisation and comparison of different types of gold, silver and gold-silver alloy nanoparticles. The potential of gold and silver particles as alternatives for fluorescent probes in certain applications is discussed. RLS spectroscopy is shown to be useful for studying analyte-induced gold nanoparticle assembly and nanoparticle chemistry, which can induce radical changes in the plasmonic resonances responsible for the strong light scattering. Furthermore, the feasibility of dark field RLS detection and quantitation of metal nanoparticles in microfluidic volumes is demonstrated, opening interesting possibilities for the further development of microfluidic detection schemes.

13.
ACS Appl Mater Interfaces ; 15(4): 5687-5700, 2023 Feb 01.
Artículo en Inglés | MEDLINE | ID: mdl-36669131

RESUMEN

A cellulose nanofibril-based hybrid gel material was developed by grafting the polymerized stearyl acrylate (PSA) and upconversion nanoparticles (UCNPs) onto cellulose nanofibrils (CNFs) via Cu0-mediated radical polymerization (SET-LRP) to create a highly cross-linked CNF system. A two-step strategy was exploited to surface-exchange the ligand of the UCNPs from a hydrophobic ligand (oleic acid) to a hydrophilic small-molecule ligand (2-acrylamido-2-methyl-1-propanesulfonic acid, AMPS) and therefore be suitable for SET-LRP. The characteristics and properties of the hybrid material (UCNP-PSA-CNF) were monitored by Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), rheology, X-ray diffraction (XRD), and microscopic analysis. Those characterization techniques prove the efficient modification of the CNF, with the presence of 1.8% UCNPs. The luminescence measurement was carried out using a homebuilt confocal microscope with a 980 nm laser source. The nanostructure of UCNPs and their incorporated CNF species were measured by small-angle X-ray scattering (SAXS). In addition, this CNF-based hybrid gel has decisive rheological properties, such as good viscoelasticity (loss tangent was below 0.35 for the UCNP-PSA-CNF gel, while the PSA-CNF gel reached the highest value of 0.42), shear-thinning behavior, and shape retention, and was successfully applied to three-dimensional (3D) gel printing throughout various 3D print models.

14.
Nanotechnology ; 23(14): 145707, 2012 Apr 13.
Artículo en Inglés | MEDLINE | ID: mdl-22433232

RESUMEN

A great number of works focus their interest on the study of gold nanoparticle plasmonic properties. Among those, sharp nanostructures appear to exhibit the more interesting features for further developments. In this paper, a complete study on bipyramidal-like gold nanostructures is presented. The nano-objects are prepared in high yield using an original method. This chemical process enables a precise control of the shape and the size of the particles. The specific photophysical properties of gold bipyramids in suspension are ripened by recording the plasmonic response of single and isolated objects. Resulting extinction spectra are precisely correlated to their geometrical structure by mean of electron tomography at the single-particle level. The interplay between the geometrical structure and the optical properties of twisted gold bipyramids is further discussed on the basis of numerical calculations. The influence of several parameters is explored such as the structural aspect ratio or the tip truncation. In the case of an incident excitation polarized along the particle long axis, this study shows how the plasmon resonance position can be sensitive to these parameters and how it can then be efficiently tuned on a large wavelength range.


Asunto(s)
Tomografía con Microscopio Electrónico , Oro/química , Nanoestructuras/química , Resonancia por Plasmón de Superficie/métodos , Nanotecnología/métodos , Tamaño de la Partícula
15.
Nanotechnology ; 23(46): 465602, 2012 Nov 23.
Artículo en Inglés | MEDLINE | ID: mdl-23095344

RESUMEN

A great number of works have focused their research on the synthesis, design and optical properties of gold nanoparticles for potential biological applications (bioimaging, biosensing). For this kind of application, sharp gold nanostructures appear to exhibit the more interesting features since their surface plasmon bands are very sensitive to the surrounding medium. In this paper, a complete study of PEGylated gold nanostars and PEGylated bipyramidal-like nanostructures is presented. The nanoparticles are prepared in high yield and their surfaces are covered with a biocompatible polymer. The photophysical properties of gold bipyramids and nanostars, in suspension, are correlated with the optical response of single and isolated objects. The resulting spectra of isolated gold nanoparticles are subsequently correlated to their geometrical structure by transmission electron microscopy. Finally, the PEGylated gold nanoparticles were incubated with melanoma B16-F10 cells. Dark-field microscopy showed that the biocompatible gold nanoparticles were easily internalized and most of them localized within the cells.


Asunto(s)
Oro/química , Nanopartículas del Metal/química , Nanoestructuras/química , Animales , Línea Celular Tumoral , Cetrimonio , Compuestos de Cetrimonio/química , Endocitosis , Oro/farmacocinética , Histocitoquímica , Ensayo de Materiales , Ratones , Nanoestructuras/ultraestructura , Tamaño de la Partícula , Polietilenglicoles/química , Compuestos de Amonio Cuaternario/química , Espectrofotometría Ultravioleta , Tensoactivos/química
16.
JAMA Ophthalmol ; 140(12): 1163-1173, 2022 12 01.
Artículo en Inglés | MEDLINE | ID: mdl-36264558

RESUMEN

Importance: Congenital stationary night blindness (CSNB) is an inherited stationary retinal disorder that is clinically and genetically heterogeneous. To date, the genetic association between some cases with CSNB and an unusual complex clinical picture is unclear. Objective: To describe an unreported CSNB phenotype and the associated gene defect in 3 patients from 2 unrelated families. Design, Setting, and Participants: This retrospective case series was conducted in 2021 and 2022 at a national referral center for rare ocular diseases. Data for 3 patients from a cohort of 140 genetically unsolved CSNB cases were analyzed clinically and genetically. Exposures: Complete ocular examination including full-field electroretinography and multimodal fundus imaging (spectral-domain optical coherence tomography, color, infrared reflectance, and short-wavelength autofluorescence photographs) were performed. The gene defect was identified by exome sequencing and confirmed by Sanger sequencing and co-segregation analysis in 1 family. Screening was performed for genetically unsolved CSNB cases for VSX2 variants by direct Sanger sequencing. Main Outcomes and Measures: Ocular and molecular biology findings. Results: The series included 3 patients whose clinical investigations occurred at ages in the early 30s, younger than 12 years, and in the mid 40s. They had nystagmus, low stable visual acuity, and myopia from birth and experienced night blindness. Two older patients had bilateral lens luxation and underwent lens extraction. Full-field electroretinography revealed an electronegative Schubert-Bornschein appearance, combining characteristics of incomplete and complete CSNB, affecting the function of rod and cone ON- and OFF-bipolar cells. Exome sequencing and co-segregation analysis in a consanguineous family with 2 affected members identified a homozygous variant in VSX2. Subsequently, screening of the CSNB cohort identified another unrelated patient harboring a distinct VSX2 variant. Conclusions and Relevance: This case series revealed a peculiar pan-bipolar cell retinopathy with lens luxation associated with variants in VSX2. Clinicians should be aware of this association and VSX2 added to CSNB diagnostic gene panels.


Asunto(s)
Enfermedades Hereditarias del Ojo , Enfermedades Genéticas Ligadas al Cromosoma X , Miopía , Ceguera Nocturna , Humanos , Ceguera Nocturna/diagnóstico , Ceguera Nocturna/genética , Estudios Retrospectivos , Mutación , Enfermedades Hereditarias del Ojo/diagnóstico , Enfermedades Hereditarias del Ojo/genética , Enfermedades Genéticas Ligadas al Cromosoma X/diagnóstico , Enfermedades Genéticas Ligadas al Cromosoma X/genética , Miopía/diagnóstico , Miopía/genética , Electrorretinografía , Linaje , Factores de Transcripción/genética , Proteínas de Homeodominio/genética
17.
Sci Rep ; 11(1): 6461, 2021 03 19.
Artículo en Inglés | MEDLINE | ID: mdl-33742068

RESUMEN

In this work, we present an approach to cross-link cellulose nanofibrils (CNFs) with various metallic cations (Fe3+, Al3+, Ca2+, and Mg2+) to produce inks suitable for three-dimensional (3D) printing application. The printability of each hydrogel ink was evaluated, and several parameters such as the optimal ratio of Mn+:TOCNF:H2O were discussed. CNF suspensions were produced by mechanical disintegration of cellulose pulp with a microfluidizer and then oxidized with 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO). Finally, metal cations were introduced to the deprotonated TEMPO-oxidized CNF (TOCNF) suspension to cross-link the nanofibrils and form the corresponding hydrogels. The performances of each gel-ink were evaluated by rheological measurements and 3D printing. Only the gels incorporated with divalent cations Ca2+ and Mg2+ were suitable for 3D printing. The 3D printed structures were freeze-dried and characterized with Fourier transform infrared spectroscopy (FT-IR) and Scanning Electron Microscopy (SEM). The better interaction of the TOCNFs with the divalent metallic cations in terms of printability, the viscoelastic properties of the inks, and the variation trends owing to various metal cations and ratios are discussed.

18.
Photochem Photobiol Sci ; 9(7): 1042-54, 2010 Jul 30.
Artículo en Inglés | MEDLINE | ID: mdl-20514373

RESUMEN

The binding of disulfides to gold nanoparticles was investigated using fluorescence spectroscopy and a perylene-monoimide dye coupled to a dissymmetric disulfide via a tetraethyleneglycolalkyl chain (PMImSS). Quantum chemical calculations using the polarizable continuum model (PCM) predict a strong quenching of perylene-monoimide fluorescence by gold nanoparticles as a result of efficient excitation energy transfer from the dye to the particle. Such quenching is indeed observed when unfunctionalised gold nanoparticles are added to a solution of PMImSS. The fluorimetric titration curves show behaviour indicative of the existence of an equilibrium between free and bound ligands (association constant 5 x 10(5) M(-1)), whereas the affinity of thiols and disulfide for gold surfaces is in general assumed to be much higher. Gold nanoparticles fully functionalised with PMImSS were synthesised and purified. Fluorescence correlation spectroscopy shows the appearance of free PMImSS ligands in dilute (approx. pM) suspensions of these PMImSS-functionalised nanoparticles over a period of several days.

19.
Nanotoxicology ; 12(6): 509-521, 2018 08.
Artículo en Inglés | MEDLINE | ID: mdl-29732936

RESUMEN

Cellulose nanofibril (CNF)-based materials are increasingly used in industrial and commercial applications. However, the impacts of CNF on aquatic life are poorly understood, and there are concerns regarding their potential toxicity. Using a combination of standard ecotoxicological tests and feeding experiments, we assessed the effects of CNF exposure (0.206-20.6 mg/L) on the feeding (food uptake and gut residence time) and life-history traits (growth and reproduction) in the cladoceran Daphnia magna. No mortality was observed in a 48 h acute exposure at 2060 mg/L. Moreover, a 21-day exposure at low food and moderate CNF levels induced a stimulatory effect on growth, likely driven by increased filtration efficiency, and, possibly, partial assimilation of the CNF by the animals. However, at low food levels and the highest CNF concentrations, growth and reproduction were negatively affected. These responses were linked to caloric restriction caused by dilution of the food source, but not an obstruction of the alimentary canal. Finally, no apparent translocation of CNF past the alimentary canal was detected. We conclude that CNF displays a low toxic potential to filter-feeding organisms and the expected environmental risks are low.


Asunto(s)
Celulosa/toxicidad , Daphnia/efectos de los fármacos , Nanofibras/toxicidad , Animales , Daphnia/fisiología
20.
PLoS One ; 13(1): e0186329, 2018.
Artículo en Inglés | MEDLINE | ID: mdl-29293495

RESUMEN

Because of their abundance and their amenability to high-throughput genotyping techniques, Single Nucleotide Polymorphisms (SNPs) are powerful tools for efficient genetics and genomics studies, including characterization of genetic resources, genome-wide association studies and genomic selection. In wheat, most of the previous SNP discovery initiatives targeted the coding fraction, leaving almost 98% of the wheat genome largely unexploited. Here we report on the use of whole-genome resequencing data from eight wheat lines to mine for SNPs in the genic, the repetitive and non-repetitive intergenic fractions of the wheat genome. Eventually, we identified 3.3 million SNPs, 49% being located on the B-genome, 41% on the A-genome and 10% on the D-genome. We also describe the development of the TaBW280K high-throughput genotyping array containing 280,226 SNPs. Performance of this chip was examined by genotyping a set of 96 wheat accessions representing the worldwide diversity. Sixty-nine percent of the SNPs can be efficiently scored, half of them showing a diploid-like clustering. The TaBW280K was proven to be a very efficient tool for diversity analyses, as well as for breeding as it can discriminate between closely related elite varieties. Finally, the TaBW280K array was used to genotype a population derived from a cross between Chinese Spring and Renan, leading to the construction a dense genetic map comprising 83,721 markers. The results described here will provide the wheat community with powerful tools for both basic and applied research.


Asunto(s)
Genotipo , Polimorfismo de Nucleótido Simple , Poliploidía , Triticum/genética , Genes de Plantas , Filogenia , Triticum/clasificación
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