Publications by authors named "Thanh Dinh Nguyen"

25 Publications

  • Page 1 of 1

Iridescent Cellulose Nanocrystal Films Modified with Hydroxypropyl Cellulose.

Biomacromolecules 2020 03 26;21(3):1295-1302. Epub 2020 Feb 26.

Department of Chemistry, University of British Columbia, 2036 Main Mall, Vancouver, British Columbia V6T 1Z1, Canada.

The introduction of polymers into a chiral nematic cellulose nanocrystal (CNC) matrix allows for the tuning of optical and mechanical properties, enabling the development of responsive photonic materials. In this study, we explored the incorporation of hydroxypropyl cellulose (HPC) into a CNC film prepared by slow evaporation. In the composite CNC/HPC thin films, the CNCs adopt a chiral nematic structure, which can selectively reflect certain wavelengths of light to yield a colored film. The color could be tuned across the visible spectrum by changing the concentration or molecular weight of the HPC. Importantly, the composite films were more flexible than pure CNC films with up to a ten-fold increase in elasticity and a decrease in stiffness and tensile strength of up to six times and four times, respectively. Surface modification of the films with methacrylate groups increased the hydrophobicity of the films, and therefore, the water stability of these materials was also improved.
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http://dx.doi.org/10.1021/acs.biomac.0c00056DOI Listing
March 2020

Solid-state Na NMR spectroscopy studies of ordered and disordered cellulose nanocrystal films.

Solid State Nucl Magn Reson 2019 02 14;97:31-39. Epub 2018 Dec 14.

Department of Chemistry, University of British Columbia, 2036 Main Mall, Vancouver, BC V6T 1Z1, Canada.

Cellulose nanocrystal films with either disordered or chiral nematic structures of varying helical pitch were investigated using Na solid-state nuclear magnetic resonance (NMR) spectroscopy. Spin lattice relaxation of H correlated with Na analyzed by indirect observation using polarization transfer from H nuclei to Na nuclei showed that the Na cations are well hydrated in the cellulose nanocrystal films. Linewidth analysis in solid-state Na NMR showed that the Na cations move in confined spaces, and that the Na cations in the film having disordered structure are more dynamic than in the films having ordered structure. From lineshape analysis of the Na 2D nutation NMR spectra, we can distinguish the Na environments within the ordered and disordered films, and find trends in anisotropic interaction parameters between ordered samples with different pitches. These are the first detailed Na NMR spectroscopic studies of CNC-Na films, and they show that this technique may be a powerful probe for characterizing the extent of order in nanocellulose samples.
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http://dx.doi.org/10.1016/j.ssnmr.2018.12.001DOI Listing
February 2019

Six-month evaluation of novel bioabsorbable scaffolds composed of poly-L-lactic acid and amorphous calcium phosphate nanoparticles in porcine coronary arteries.

J Biomater Appl 2018 08;33(2):227-233

1 Department of Cardiology, Renmin Hospital of Wuhan University, Wuhan, China.

Objective Using coronary angiography and intravascular ultrasound methods to evaluate the performance of the novel fully bioabsorbable scaffold (NFBS) composed of poly-L-lactic acid/amorphous calcium phosphate (PLLA/ACP) at six-month follow-up by comparing with PLLA scaffolds Methods Twelve PLLA/ACP scaffolds and 12 PLLA scaffolds were implanted into the coronary arteries of 12 miniature pigs. Quantitative coronary angiography (QCA) was used to measure the reference vessel diameter (RVD), mean lumen diameter (MLD) and late lumen loss (LLL). According to IVUS images, we calculated the strut malapposition rate (SMR) at post implantation, strut overlap rate (SOR), reference vessel area (RVA), mean stent area (MSA), mean lumen area (MLA) and luminal patency rate (LPR) at six-month follow-up. The radial strength of the scaffold was evaluated using a catheter tensile testing machine. Results QCA results indicated that, at six month, MLD of PLLA/ACP scaffolds was greater than those of PLLA scaffolds (2.47 ± 0.22 mm vs. 2.08 ± 0.25 mm, P < 0.05); LLL of PLLA/ACP scaffolds was less than those of PLLA scaffolds (0.42 ± 0.20 mm vs. 0.75 ± 0.22 mm, P < 0.05). IVUS results showed the SMR and SOR were all significantly less with the PLLA/ACP scaffolds than the PLLA scaffolds (5.84% ± 3.56% vs. 17.72% ± 4.86%, P < 0.05) (6.17% ± 4.63% vs. 17.65% ± 4.29%, P < 0.05). MSA, MLA and LPR of the PLLA/ACP scaffolds were all greater than those of PLLA scaffolds (6.35 ± 0.45 mm vs. 5.35 ± 0.51 mm, P < 0.05) (4.76 ± 0.46 mm vs. 3.77 ± 0.46 mm, P < 0.05) (78.01% ± 12.29% vs. 61.69% ± 9.76%, P < 0.05). Radial strength of PLLA/ACP scaffold at six month was greater than that of PLLA scaffold (76.33 ± 3.14 N vs. 67.67 ± 3.63 N). Conclusion The NFBS had less stent recoil, better lumen patency rate and greater radial strength than PLLA scaffolds. The results suggest the NFBS scaffolds can maintain the structural strength and functional performance, which are effective for up to six months when implanted in porcine coronary arteries.
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http://dx.doi.org/10.1177/0885328218790332DOI Listing
August 2018

Biocompatible Chitosan-Functionalized Upconverting Nanocomposites.

ACS Omega 2018 Jan 4;3(1):86-95. Epub 2018 Jan 4.

Department of Chemistry, University of British Columbia, 2036 Main Mall, Vancouver, British Columbia V6T 1Z1, Canada.

Simultaneous integration of photon emission and biocompatibility into nanoparticles is an interesting strategy to develop applications of advanced optical materials. In this work, we present the synthesis of biocompatible optical nanocomposites from the combination of near-infrared luminescent lanthanide nanoparticles and water-soluble chitosan. NaYF:Yb,Er upconverting nanocrystal guests and water-soluble chitosan hosts are prepared and integrated together into biofunctional optical composites. The control of aqueous dissolution, gelation, assembly, and drying of NaYF:Yb,Er nanocolloids and chitosan liquids allowed us to design novel optical structures of spongelike aerogels and beadlike microspheres. Well-defined shape and near-infrared response lead upconverting nanocrystals to serve as photon converters to couple with plasmonic gold (Au) nanoparticles. Biocompatible chitosan-stabilized Au/NaYF:Yb,Er nanocomposites are prepared to show their potential use in biomedicine as we find them exhibiting a half-maximal effective concentration (EC) of 0.58 mg mL for chitosan-stabilized Au/NaYF:Yb,Er nanorods versus 0.24 mg mL for chitosan-stabilized NaYF:Yb,Er after 24 h. As a result of their low cytotoxicity and upconverting response, these novel materials hold promise to be interesting for biomedicine, analytical sensing, and other applications.
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http://dx.doi.org/10.1021/acsomega.7b01355DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6044559PMC
January 2018

Self-aggregation of water-dispersible nanocollagen helices.

Biomater Sci 2018 Feb;6(3):651-660

Department of Chemistry, Hue University of Agriculture and Forestry, Hue University, 102 Phung Hung, Hue 530000, Vietnam.

Inspired by nature, collagen is an outstanding polypeptide utilized to exploit its bioactivity and material design for healthcare technologies. In this study, we describe the self-aggregation of water-dispersible nanocollagen helices upon solidification to fabricate different forms of natural collagen materials. Chemically extracted native collagen fibrils are uniform anisotropic nanoparticles with an average diameter of about 50 nm and a high aspect ratio. The as-prepared collagen nanofibrils are soluble in sodium acetate-acetic acid buffer and are dispersible in water, thus generating collagen liquids that are used as distinct biopolymer precursors for materials development. Our interesting findings indicate that water-dispersible collagen-derived alcogels undergo critical point drying to self-arrange hierarchical nanofibrils into helix bundles in collagen sponge-like aerogels. Notably, using lyophilization to remove water in the biopolymer dispersion, a full regeneration of solidified fibers is achieved, producing collagen aerogels with lightweight characteristics similar to natural cottons. The self-aggregation of water-dispersible collagen occurs under freeze-drying conditions to turn individual nanofibrils into sheets with layered structures in the aerogel networks. The development of transparent, water resistant collagen bioplastic-like membranes was achieved by supramolecular self-assembly of water-dispersible collagen nanofibrils. Our efforts present a reliable concept in soft matter for creating promising collagen examples of liquids, hydrogels, aerogels, and membranes to increase utilization value of native collagen for biomedicine, pharmaceuticals, cosmetics, and nutrients.
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http://dx.doi.org/10.1039/c7bm01141eDOI Listing
February 2018

Aerogel materials with periodic structures imprinted with cellulose nanocrystals.

Nanoscale 2018 Feb;10(8):3805-3812

Department of Chemistry, University of British Columbia, 2036 Main Mall, Vancouver, British Columbia V6T 1Z1, Canada.

Novel aerogel materials with periodic structures derived from chiral nematic liquid crystalline cellulose nanocrystals (CNCs) are reported. The liquid crystalline structure of phase-separated CNCs is locked by a simple solvent exchange method or silica condensation. Both cellulose and silica/cellulose aerogel materials were obtained after critical point drying, and subsequent calcination of the silica/cellulose composite afforded a silica aerogel with periodic order. Gas adsorption and electron microscopy studies revealed that these materials have high surface areas and a unique chiral nematic structure imparted from the helicoidal CNC template. This is a new, scalable approach to aerogel materials with highly anisotropic structures. The high porosity and periodic, chiral features of these new materials may make them suitable for applications that require anisotropic properties or as hard templates for the construction of other ordered aerogels.
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http://dx.doi.org/10.1039/c7nr07719jDOI Listing
February 2018

Water-soluble chitosan-derived sustainable materials: towards filaments, aerogels, microspheres, and plastics.

Soft Matter 2017 Oct;13(40):7292-7299

Department of Chemistry, Hue University of Sciences, Hue University, 77 Nguyen Hue, Hue City, Vietnam.

Bioinspired materials have aroused great interest as their inherent biocompatible and structural characteristics have given rise to sustainable applications. In this work, we have reported the phase and morphology transformation of chitosan from crystalline nanofibrils into amorphous sheets for fabricating sustainable materials. Acetylation-induced aqueous dissolution of native chitosan nanofibrils affords water-soluble chitosan as a biopolymeric liquid. Water-soluble chitosan macromolecules self-aggregate into amorphous sheets on solidification, presenting an interesting way to inspire new structures of chitosan assemblies. Through control over gelation, lyophilization, and self-assembled confinement of water-soluble chitosan, we have fabricated novel chitosan materials including filaments, aerogels, microspheres, and plastics that are promising for sustainable use.
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http://dx.doi.org/10.1039/c7sm01292fDOI Listing
October 2017

Chitin Liquid-Crystal-Templated Oxide Semiconductor Aerogels.

ACS Appl Mater Interfaces 2017 Sep 28;9(36):30812-30820. Epub 2017 Aug 28.

Department of Chemistry, University of British Columbia , 2036 Main Mall, Vancouver, British Columbia V6T 1Z1, Canada.

Chitin nanocrystals have been used as a liquid crystalline template to fabricate layered oxide semiconductor aerogels. Anisotropic chitin liquid crystals are transformed to sponge-like aerogels by hydrothermally cross-linked gelation and lyophilization-induced solidification. The hydrothermal gelation of chitin aqueous suspensions then proceeds with peroxotitanate to form hydrogel composites that recover to form aerogels after freeze-drying. The homogeneous peroxotitanate/chitin composites are calcined to generate freestanding titania aerogels that exhibit the nanostructural integrity of layered chitin template. Our extended investigations show that coassembling chitin nanocrystals with other metal-based precursors also yielded semiconductor aerogels of perovskite BaTiO and CuO nanocrystals. The potential of these materials is great to investigate these chitin sponges for biomedicine and these semiconductor aerogels for photocatalysis, gas sensing, and other applications. Our results present a new aerogel templating method of highly porous, ultralight materials with chitin liquid crystals.
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http://dx.doi.org/10.1021/acsami.7b07680DOI Listing
September 2017

Chiral nematic porous germania and germanium/carbon films.

Nanoscale 2015 Aug 17;7(31):13215-23. Epub 2015 Jul 17.

Department of Material Science and Engineering, College of Aerospace Science and Engineering, National University of Defense Technology (NUDT), Changsha, Hunan 410073, P. R. China.

We report our extensive attempts and, ultimately, success to produce crack-free, chiral nematic GeO2/cellulose nanocrystal (CNC) composite films with tunable photonic properties from the controlled assembly of germanium(iv) alkoxides with the lyotropic liquid-crystalline CNCs in a mixed solvent of water/DMF. With different pyrolysis conditions, the photonic GeO2/CNC composites can be converted into freestanding chiral nematic films of amorphous GeO2, and semiconducting mesoporous GeO2/C and Ge/C replicas. These new materials are promising for chiral separation, enantioselective adsorption, catalysis, sensing, optoelectronics, and lithium ion batteries. Furthermore, the new, reproducible synthesis strategies developed may be applicable for constructing other composites and porous materials with chiral nematic ordering.
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http://dx.doi.org/10.1039/c5nr02520fDOI Listing
August 2015

Tailoring the assembly, interfaces, and porosity of nanostructures toward enhanced catalytic activity.

Chem Commun (Camb) 2015 Jan;51(4):624-35

Department of Chemistry, University of British Columbia, British Columbia V6T 1Z1, Canada.

The evolution of nanotechnology has inspired materials scientists to invent nanostructures with achievements in numerous practical applications, particularly in catalysis. The great advancements typically involve flexible control over the unique properties of the nanomaterial through tuning their structural geometries and components. In this Feature Article, we present the recent progress of our recent research and that of other groups in tailoring the assembly, interfaces, and porosity of diverse inorganic nanostructures. The enhanced catalytic properties of the engineered nanostructures are discussed in relation to photocatalysis, with special emphasis on solar energy conversion, including water splitting, CO2 reduction, and organic photodecomposition. Considering their attributes of superior catalytic performance and long-term durability, the development of economical, active nanocatalysts opens up practical opportunities for endeavours in sustainable energy conversion and other applied fields. This review is expected to introduce readers to the general principles of engineering the nanostructured features of the inorganic nanomaterials capable of improving solar photocatalytic efficiency.
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http://dx.doi.org/10.1039/c4cc05741dDOI Listing
January 2015

Tuning the iridescence of chiral nematic cellulose nanocrystals and mesoporous silica films by substrate variation.

Chem Commun (Camb) 2013 Dec 24;49(96):11296-8. Epub 2013 Oct 24.

Department of Chemistry, University of British Columbia, 2036 Main Mall, Vancouver, BC V6T 1Z1, Canada.

We have discovered that the self-assembly of cellulose nanocrystals (CNCs) into chiral nematic phases varies significantly with the substrate and evaporation rate. These variables allow the reflectance peak of iridescent chiral nematic films of CNCs and mesoporous silica templated from CNCs to be tuned over a wide range of wavelengths.
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http://dx.doi.org/10.1039/c3cc47337fDOI Listing
December 2013

Mesoporous silica and organosilica films templated by nanocrystalline chitin.

Chemistry 2013 Nov 25;19(45):15148-54. Epub 2013 Sep 25.

Department of Chemistry, University of British Columbia, 2036 Main Mall, Vancouver, British Columbia, V6T 1Z1 (Canada), Fax: (+1) 604-822-2847.

Liquid crystalline phases can be used to impart order into inorganic solids, creating materials that mimic natural architectures. Herein, mesoporous silica and organosilica films with layered structures and high surface areas have been templated by nanocrystalline chitin. Aqueous suspensions of spindle-shaped chitin nanocrystals were prepared by sequential deacetylation and hydrolysis of chitin fibrils isolated from king crab shells. The nanocrystalline chitin self-assembles into a nematic liquid-crystalline phase that has been used to template silica and organosilica composites. Removal of the chitin template by either calcination or sulfuric-acid-catalyzed hydrolysis gave mesoporous silica and ethylene-bridged organosilica films. The large, crack-free mesoporous films have layered structures with features that originate from the nematic organization of the nanocrystalline chitin.
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http://dx.doi.org/10.1002/chem.201301929DOI Listing
November 2013

From formation mechanisms to synthetic methods toward shape-controlled oxide nanoparticles.

Nanoscale 2013 Oct;5(20):9455-82

Department of Chemical Engineering, Laval University, Quebec G1V 0A6, Canada.

Metal oxide nanomaterials have been intensively pursued for modern science and nanotechnology. Control over the size and shape of the oxide nanoparticles enables tunability of their unique properties sought for many useful applications. This review presents a comprehensive overview of the recent advances in the shape-controlled synthesis of colloidal oxide nanoparticles. We introduce the size- and shape-dependent properties of the oxide nanoparticles along with their potential applications and subsequent descriptions of the kinetic regime concepts of the formation of the monodisperse nanocolloids. Variations of the experimental conditions including capping molecules, precursor monomer concentration, and reaction temperature/aging have been explored to control the shape of the oxide nanoparticles in wet-chemistry syntheses. The different capping molecule-assisted synthetic methods of the hydro-solvothermal route, the two-phase route, heating-up thermolysis, and reverse micelle are presented as a collection of clear examples of the regular oxide nanoparticles. We also discuss the advantages and obstacles of the synthetic methods that have proven to be controllable and reproducible. The author concludes this review with valuable portraits on working hypotheses for the shape-controlled oxide nanoparticle synthesis.
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http://dx.doi.org/10.1039/c3nr01810eDOI Listing
October 2013

Controlled synthesis of ceria nanoparticles for the design of nanohybrids.

J Colloid Interface Sci 2013 Mar 28;394:100-7. Epub 2012 Dec 28.

Department of Chemical Engineering, Laval University, Quebec, G1V 0A6, Canada.

Ceria nanoparticles were synthesized from reaction mixture of cerium nitrate/hexamethylenediamine/water-ethylene glycol. Lamellar, particle-aggregated array, platelet, rice, cube, quasi-sphere shapes of the ceria nanoparticles can be controlled by tuning reaction parameters (reagent concentration, reagent components, pH, and reaction conditions). Studies on shape-dependent catalysis of the bare ceria samples toward CO oxidation indicated that the cube-shaped ceria nanoparticles show better catalytic activity than the nanospheres and the commercial micropowders. As capped by hexamethylenediamine (HEA) molecules, amine-functionalized ceria nanoparticles act as platforms for depositing copper particles to produce efficient Cu/CeO(2) hybrid nanocatalysts for CO conversion. Coupling of the copper clusters with the HEA-capped ceria nanocubes was achieved with the Cu contents up to 15 wt.%. The Cu/CeO(2) nanohybrids show an enhanced catalytic efficiency of low temperature CO conversion. This could be due to high exposure of the reactive {100} facets in the ceria nanocubes and interfacial copper-ceria interactions.
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http://dx.doi.org/10.1016/j.jcis.2012.12.020DOI Listing
March 2013

Portraits of colloidal hybrid nanostructures: controlled synthesis and potential applications.

Colloids Surf B Biointerfaces 2013 Mar 12;103:326-44. Epub 2012 Nov 12.

Department of Chemical Engineering, Laval University, Quebec G1K 7P4, Canada.

Inorganic hybrid nanostructures containing two or more nanocomponents have been emerging in many areas of materials science in recent years. The particle-particle interactions in a hybrid particle system could significantly improve existing local electronic structure and induce tunable physiochemical responses. The current work reviews the diverse inorganic hybrid nanostructures formed by adhesion of the different single components via seed-mediated method. The hybrid nanomaterials have great potentials for real applications in many other fields. The nanohybrids have been used as efficient heterocatalysts for carbon monoxide conversion and photodegradation of organic contaminants. The enhanced catalytic activity of these hybrid nanocatalysts could be attributed the formation of oxygen vacancies and electron transfer across the structural junction in a hybrid system as a result of the interfacial particle-particle interactions. The synergistic combination of up-converting and semiconducting properties in an up-converting semiconducting hybrid particle results in appearance of sub-band-gap photoconductivity. This behavior has a great significance for the design of photovoltaic devices for effective solar energy conversion. The functionalization and subsequent bioconjugation of the hybrid nanostructures to afford the multifunctional nanomedical platforms for simultaneous diagnosis and therapy are reviewed. The conjugated multifunctional hybrid nanostructures exhibit high biocompatibility and highly selective binding with functional groups-fabricated alive organs through delivering them to the tumor sites. The clever combinations of multifunctional features and antibody conjugation within these vehicles make them to generally offer new opportunities for clinical diagnostics and therapeutics.
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http://dx.doi.org/10.1016/j.colsurfb.2012.10.049DOI Listing
March 2013

Controlled synthesis of titanate nanodisks as versatile building blocks for the design of hybrid nanostructures.

Angew Chem Int Ed Engl 2012 Jul 25;51(27):6608-12. Epub 2012 May 25.

Department of Chemical Engineering and Centre de recherche sur les propriétés des interfaces et la catalyse, Laval University, Quebec, G1V 0A6 Canada.

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http://dx.doi.org/10.1002/anie.201202046DOI Listing
July 2012

Controlled growth of uniform noble metal nanocrystals: aqueous-based synthesis and some applications in biomedicine.

Colloids Surf B Biointerfaces 2011 Nov 18;88(1):1-22. Epub 2011 Jul 18.

Department of Chemistry, Faculty of Sciences, Hue University, Hue, Viet Nam.

Aqueous-dispersed single and binary noble metal nanocrystals have attracted much attention as key materials in many fields, especially in biomedicine, catalysis, etc. Controlled growth of the metal nuclei allow for the manipulation of uniform morphology of final products. This behavior would tailor their unique physiochemical and electronic properties and follows by their practical applications. This review presents an overall picture of kinetic formation of a particle and then summarizes an overview of recent progress in many research groups concerning aqueous- and/or polyol-based syntheses of many types of aqueous-dispersed single metallic and bimetallic nanocrystals with controlled shape. The main advantages in these synthetic approaches for the shape-controlled metal nanocrystals are simple, versatile, environmentally friendly, low cost, pure and single-crystalline products, and high yield. The formed products can be easily dispersed in water medium and compatible for biotechnological field. Particularly the biomolecule (antibody including protein and/or DNA)-conjugated gold nanocrystals have been utilized as an active agent for a broad range of biomedical applications. We expect that this review will have a high potential towards novel materials fabrication and nanotechnological fields.
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http://dx.doi.org/10.1016/j.colsurfb.2011.07.017DOI Listing
November 2011

A new route to size and population control of silver clusters on colloidal TiO₂ nanocrystals.

ACS Appl Mater Interfaces 2011 Jul 6;3(7):2228-34. Epub 2011 Jul 6.

Department of Chemical Engineering, Centre de recherche sur les propriétés des interfaces et la catalyse (CERPIC), Laval University, Quebec G1 V 0A6, Canada.

Formation of hybrid Ag-TiO(2) nanocrystals (NCs) in which Ag clusters are uniformly deposited on individual TiO(2) NC surface has been achieved by using hydrophobic surfactant-capped TiO(2) NCs in combination with a photodeposition technique. The population of Ag clusters on the individual TiO(2) NC surface can be controlled by the degree of hydrophobicity (e.g., the number of vacant sites) on the TiO(2) NC surface while their size may be altered simply by varying irradiation time. A reversible change in color of the resulting hybrid Ag-TiO(2) NCs is induced by alternating UV light and visible-light illumination; however, the size and population of Ag clusters on TiO(2) NCs are almost unchanged. Furthermore, these materials also exhibit much higher photocatalytic performance as compared to that of Ag supported on commercial TiO(2)-P25.
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http://dx.doi.org/10.1021/am200480bDOI Listing
July 2011

Large-scale synthesis of uniform silver orthophosphate colloidal nanocrystals exhibiting high visible light photocatalytic activity.

Chem Commun (Camb) 2011 Jul 1;47(27):7797-9. Epub 2011 Jun 1.

Department of Chemical Engineering, Laval University, Quebec, G1V 0A6, Canada.

Silver orthophosphate nanocrystals with controlled particle size have been synthesized using a simple, reproducible and easily scaled up route based on the reaction between silver ions, oleylamine and phosphoric acid. The obtained nanocrystals are highly uniform in size and exhibit high visible light activity for the photodecomposition of organic compounds.
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http://dx.doi.org/10.1039/c1cc12014jDOI Listing
July 2011

A general procedure to synthesize highly crystalline metal oxide and mixed oxide nanocrystals in aqueous medium and photocatalytic activity of metal/oxide nanohybrids.

Nanoscale 2011 Apr 15;3(4):1861-73. Epub 2011 Mar 15.

Department of Chemical Engineering, Laval University, Quebec, G1K 7P4, Canada.

A conventional and general route has been exploited to the high yield synthesis of many kinds of highly crystalline metal oxide and mixed oxide nanocrystals with different morphologies including belt, rod, truncated-octahedron, cubic, sphere, sheet via the hydrothermal reaction of inorganic precursors in aqueous solution in the presence of bifunctional 6-aminohexanoic acid (AHA) molecules as a capping agent. This method is a simple, reproducible and general route for the preparation of a variety of high-crystalline inorganic nanocrystals in scale-up. The shape of inorganic nanocrystals such as CoWO(4), La(2)(MoO(4))(3) can be controlled by simply adjusting the synthesis conditions including pH solution and reaction temperature. Further, by tuning precursor monomer concentration, the mesocrystal hierarchical aggregated microspheres (e.g., MnWO(4), La(2)(MoO(4))(3)) can be achieved, due to the spontaneous assembly of individual AHA-capped nanoparticles. These obtained AHA-capped nanocrystals are excellent supports for the synthesis of a variety of hybrid metal/oxide nanocrystals in which noble metal particles are uniformly deposited on the surface of each individual nanosupport. The photocatalytic activity of Ag/TiO(2) nanobelts as a typical hybrid photocatalyst sample for Methylene Blue degradation was also studied.
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http://dx.doi.org/10.1039/c1nr10109aDOI Listing
April 2011

Two-phase synthesis of colloidal annular-shaped Ce(x)La(1-x)CO3OH nanoarchitectures assembled from small particles and their thermal conversion to derived mixed oxides.

Inorg Chem 2011 Feb 21;50(4):1309-20. Epub 2011 Jan 21.

Department of Chemical Engineering, Laval University, Quebec G1K 7P4, Canada.

Undoped and cerium doped LaCO(3)OH annular-shaped nanoarchitectures with high specific surface area have been fabricated via the thermolysis of Ce(x)La(1-x)(oleate)(3) (x = 0-20 mol %) complexes in a toluene-water system containing tert-butylamine/oleylamine. The products exhibit 400 nm-sized monodisperse annular-shaped nanoarchitectures, which are constituted of 3-5 nm-sized primary particles. A possible mechanism of the reaction of Ce(x)La(1-x)(oleate)(3) and tert-butylamine for the formation of annular-shaped Ce(x)La(1-x)CO(3)OH nanoarchitectures is proposed. The thermal conversion of Ce(x)La(1-x)CO(3)OH to Ce(x)La(1-x)(CO(3))O(2) at 600 °C, to Ce(x)La(1-x)(OH)(3) at 800 °C, final to (Ce(x)La(1-x))(2)O(3-δ) at 900 °C were employed, while the original morphology was essentially unchanged. The dopant concentration was varied from 5 to 20 of cerium ions per LaCO(3)OH nanoparticle. The X-ray diffraction (XRD) results reveal that the cerium dopant could enter easily into the LaCO(3)OH structural lattice, whereas copper could unlikely enter into their lattice because of their large ionic radius difference. The cerium oxidation state was controlled by changing doping concentration. The X-ray photoelectron spectroscopy (XPS) results reveal that only one Ce(3+) oxidation state is in the as-synthesized Ce(x)La(1-x)CO(3)OH samples with cerium concentration ranging from 5 to 20 mol %, whereas both 3+ and 4+ ones coexisted in 20 mol % Ce:LaCO(3)OH structure. Remarkable luminescence emission intensity enhancement of 1.5-9.0 times were observed for Ce(x)La(1-x)CO(3)OH samples with cerium concentration ranging from 5 to 20 mol %, after doping with an undoped LaCO(3)OH.
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http://dx.doi.org/10.1021/ic101871vDOI Listing
February 2011

Shape- and size-controlled synthesis of monoclinic ErOOH and cubic Er2O3 from micro- to nanostructures and their upconversion luminescence.

ACS Nano 2010 Apr;4(4):2263-73

Department of Chemical Engineering, Laval University, Quebec G1K7P4, Canada.

A general approach has been developed for the synthesis of monoclinic ErOOH and cubic Er2O3 structures with high yield and controlled size and shape via the solvo-hydrothermal reaction of erbium nitrate in water/ethanol/decanoic acid media. The monoclinic ErOOH phase was formed at relatively low temperature (120-140 degrees C); however, the cubic Er2O3 phase was obtained at higher temperature (160-180 degrees C). By simply tuning different experimental parameters, such as the reaction temperature, the concentration of decanoic acid and erbium precursor etc., different sizes from 3 nm to 3 microm, and a variety of shapes including cores/dots to spheres, wrinkle-surfaced spheres, flowers, dog bonds, wires, rods, bundles, straw sheaves, and brooms can be achieved. The particle size of products decreased from micro- to nanometer as the decanoic acid concentration increased from 0.038 to 0.190 M. Furthermore, by using anhydrous ethanol instead of water-ethanol solvents, the particle size significantly decreased from 18 nm spheres to 3 nm cores. At high precursor monomer concentrations (76.25-152.50 mM), the nanorods were also obtained due to the anisotropic growth. On the basis of this study, a correlation between the experimental parameters and the phase, shape, and size of the products was proposed. The upconversion luminescence properties depend not only on crystalline phase but also on particle size of the products. The luminescence intensity increases with the decrease of particle size from micro- to nanometers.
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http://dx.doi.org/10.1021/nn100292sDOI Listing
April 2010

Shape-controlled synthesis of highly crystalline titania nanocrystals.

ACS Nano 2009 Nov;3(11):3737-43

Department of Chemical Engineering, Laval University, Quebec, Canada.

A versatile synthetic method based on solvothermal technique has been developed for the fabrication of TiO(2) nanocrystals with different shapes such as rhombic, truncated rhombic, spherical, dog-bone, truncated and elongated rhombic, and bar. The central features of our approach are the use of water vapor as hydrolysis agent to accelerate the reaction and the use of both oleic acid and oleylamine as two distinct capping surfactants which have different binding strengths to control the growth of the TiO(2) nanoparticles. We also show that the presence of an appropriate amount of water vapor along with the desired oleic acid/oleylamine molar ratio plays a crucial role in controlling size and shape of TiO(2) nanocrystals.
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http://dx.doi.org/10.1021/nn900940pDOI Listing
November 2009

Monodisperse samarium and cerium orthovanadate nanocrystals and metal oxidation states on the nanocrystal surface.

Langmuir 2009 Sep;25(18):11142-8

Department of Chemical Engineering, Laval University, Quebec G1K 7P4, Canada.

A new solvothermal method has been developed for the synthesis of monodisperse SmVO4 and CeVO4 nanocrystals with controlled size and shape. The obtained materials were characterized by X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), transmission electron microscopy (TEM), and selected area electron diffraction (SAED) techniques. The results reveal that uniform nanocrystals and pure tetragonal phase of SmVO4 and CeVO4 can be achieved. To investigate the oxidation states of the metals on the mixed oxide nanocrystal surface, the XPS technique was employed. The results exhibit that only one oxidation state of samarium, cerium, and vanadium for each metal (e.g., Sm3+, Ce3+, V5+) was surprisingly well stable on the particle surface at the nanoscale, even after calcination, while the existence of two oxidation states of these metals is observed (e.g., Sm3+/Sm2+, Ce4+/Ce3+, V5+/V4+) in the corresponding single metal oxide nanocrystals.
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http://dx.doi.org/10.1021/la901387qDOI Listing
September 2009

Solvo-hydrothermal approach for the shape-selective synthesis of vanadium oxide nanocrystals and their characterization.

Langmuir 2009 May;25(9):5322-32

Department of Chemical Engineering, Laval University, Quebec G1K 7P4, Canada.

A new solvo-hydrothermal method has been developed for the synthesis of uniform vanadium oxide nanocrystals (NCs) with various sizes and shapes in aliphatic amine/toluene/water using V(V) diperoxo alkylammonium complexes. The vanadium complex precursors were prepared from an ion exchange reaction of V(V) diperoxo gels and tetraalkylammonium bromide in the water-toluene mixture using H(2)O(2) solution and commercial bulk V(2)O(5) powders as starting vanadium gel source. The obtained VO(2) NC products were characterized by means of transmission electron microscopy (TEM), selected area electron diffraction (SAED), scanning electron microscopy (SEM), powder X-ray diffraction (XRD), X-ray photoelectron spectra (XPS), Fourier transform infrared absorption spectroscopy (FTIR), thermogravimetric differential thermal analysis (TGA-DTA), and nitrogen adsorption/desorption (BET). The size and shape of NCs can be controlled by different synthesis parameters such as water content, steric ligands of complexes, alkyl chain lengths of capping aliphatic amines, as well as nature of solvent. Monodisperse vanadium oxide NCs with various sizes and shapes, nanospheres, nanocubes, nanorices, and nanorods, can be easily achieved. The possible mechanisms for the formation of vanadium complex precursors and vanadium oxide NCs as well as the shape evolution of NCs were also discussed. The as-made vanadium oxide products exhibited the monoclinic rutile VO(2) structure, which was however converted to the orthorhombic V(2)O(4.6) structure after calcination in air. The XPS results also revealed only one V(4+) state for the as-made sample; however, the coexistence of V(5+) and V(4+) states and two components of oxygen associated with OV and O-V for the calcined samples on the vanadium oxide NC surface were observed. The surface chemical composition of both as-made and calcined samples were found to be VO(2) and V(2)O(5-x) (x = 0.4), respectively. Our approach may provide a novel route for the extended synthesis to other inorganic NCs.
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http://dx.doi.org/10.1021/la804073aDOI Listing
May 2009