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1.
J Colloid Interface Sci ; 576: 376-384, 2020 Sep 15.
Artículo en Inglés | MEDLINE | ID: mdl-32450370

RESUMEN

We describe the use of citrate to control the electroless plating of silver metal on silica nanoparticles. We find that the incorporation of relatively small amounts of citrate during the reduction of the Tollens' reagent in the presence of sensitized silica nanoparticles induces a continuous transition from conformal to raspberry particle coatings. This transition is dependent on both the citrate concentration and the silver precursor concentration. We characterize this transition using electron microscopy and spectroscopy and use these results to confirm citrate's ability to cap and restrict silver growth. We compliment these structural measurements with in-situ quartz crystal microbalance experiments to quantify citrate's role as a complexing agent to slow silver reduction kinetics. These results confirm citrate's dual role in controlling the morphology of silver deposits produced in this work.

2.
Chemistry ; 23(54): 13284-13288, 2017 Sep 27.
Artículo en Inglés | MEDLINE | ID: mdl-28667783

RESUMEN

Iron pyrite has long been an attractive material for environmental and energy applications, but is hampered by a lack of control over morphology and purity. Hollow porous iron pyrite nanoparticles were synthesized by a direct sulfurization of iron oxide derived from Prussian blue. The high efficiencies of these hollow porous iron pyrite nanoparticles as effective dye-sensitized solar cell counter electrodes were demonstrated, with an efficiency of 7.31 %.

3.
ACS Appl Mater Interfaces ; 8(49): 33394-33398, 2016 Dec 14.
Artículo en Inglés | MEDLINE | ID: mdl-27960425

RESUMEN

In this work, the impacts of varying surface modification, matrix parameters, and fabrication conditions on the performance of optically printed (0-3) piezoelectric polymer nanocomposites are examined. For example, we find that a 75% reduction in nanoparticle edge-length boosted the piezoelectric coefficient (d33) by over 100%. By optimizing the composition and fabrication conditions, 10% by mass loading barium titanate nanocomposites are able to yield d33 values of ∼80 pC/N compared to <5 pC/N when parameters are not optimized. With a more complete understanding of how to enhance the performance of (0-3) piezoelectric polymer nanocomposites, these materials should find use in a wide range of applications.

4.
Phys Chem Chem Phys ; 17(41): 27653-7, 2015 Nov 07.
Artículo en Inglés | MEDLINE | ID: mdl-26428279

RESUMEN

This study illustrates the directed self-assembly of mesoporous TiO2 with magnetic properties due to its colloidal crystal structure with Fe3O4. The Fe3O4 nanoparticles were synthesized using co-precipitation techniques to a size of 28.2 nm and a magnetic saturation of 66.9 emu g(-1). Meanwhile, mesoporous titania nanoparticles (MTNs) with a particle diameter of 373 nm, a specific surface area of 236.3 m(2) g(-1), and a pore size of 2.8 nm were prepared by controlling the rate of hydrolysis. Magnetic colloidal crystals (a diameter of 10.2 µm) were formed by the aggregation of Fe3O4 and MTNs caused by the interface phenomena during solvent evaporation in emulsion. Even the anatase octahedrite produced from the colloidal crystal after a hydrothermal reaction retained a magnetic saturation of 2.8 emu g(-1). This study also investigates the photodegradation activity of our synthesized material as a photocatalyst, while utilizing its capability for magnetic separation to prove its usefulness in catalyst recycling.

5.
Tissue Eng ; 11(5-6): 923-39, 2005.
Artículo en Inglés | MEDLINE | ID: mdl-15998232

RESUMEN

This study investigates the osseointegration of poly(propylene fumarate) (PPF) with beta-tricalcium phosphate (beta-TCP) scaffolds in a critical-size (diameter, 1.6 cm), cranial defect in 4-month-old rabbits (n = 51), killed at 6 or 12 weeks. Two molecular weights of PPF were used to produce bilayer scaffolds with 0.5-mm solid external and 2.0-mm porous internal layers. The porous layer was infused with bone marrow aspirate, with half the animals receiving 0.8 microg of transforming growth factor beta2 (TGF-beta2). No foreign body or inflammatory response was observed externally or on histological examination of explants. Statistical analysis of histological areal and linear measures of new bone formation found significantly more bone at the later sacrifice time, followed by implants receiving TGF-beta2, followed by low molecular weight PPF implants. Approximately 40% of the explants were tested for incorporation strength with a one-point "push-in" test. Because no permanent fixation was used, implant strength (28.37-129.03 N; range, 6.4 to 29.0 lb of resistance) was due entirely to new bone formation. The strongest bone was seen in implants receiving TGF-beta2-infused marrow in animals killed at 12 weeks. These results support the use of PPF as an osteogenic substrate and future research into preoperative fabrication of critical size and supercritical-size cranial prosthetic implants.


Asunto(s)
Células de la Médula Ósea , Sustitutos de Huesos , Fumaratos , Polipropilenos , Cráneo/anomalías , Ingeniería de Tejidos , Factor de Crecimiento Transformador beta/farmacología , Animales , Anomalías Craneofaciales/cirugía , Fumaratos/síntesis química , Microscopía Electrónica de Rastreo , Polipropilenos/síntesis química , Conejos , Factores de Tiempo , Factor de Crecimiento Transformador beta2
6.
Tissue Eng ; 9(3): 495-504, 2003 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-12857417

RESUMEN

This pilot study investigates the osseointegration of four types of critical-size (1.5-cm diameter) rabbit cranial defect (n = 35) bone graft scaffolds. The first is a solid poly(propylene fumarate)/beta-tricalcium phosphate(PPF/beta-TCP) disk; the three remaining constructs contain a PPF/beta-TCP core coated with a 1-mm resorptive porous foam layer of PPF or PLGA [poly(DL-lactic-co-glycolic acid)], and bone marrow. Animals were killed at 6, 12, and 20 weeks. There was no evidence of a foreign body inflammatory response at any time during the study. Histomorphometric analyses of new bone formation sorted lineal and areal measures of new bone into three cranial layers (i.e., external, middle, and internal). Statistical analyses revealed significantly more bone in the PLGA foam-coated constructs than in the PPF foam-coated constructs (p < 0.03). No implant fixation was used; there is no strength at time 0. Twenty percent of all explants were tested for incorporation strength with a one-point "push-in" test, and failure ranged from 8.3 to 34.7 lb. The results of this study support the use of PPF as a biocompatible material that provides both a structural and osteogenic substrate for the repair of cranial defects.


Asunto(s)
Materiales Biocompatibles , Glicolatos , Polipropilenos , Cráneo , Ingeniería de Tejidos/métodos , Animales , Ácido Láctico , Microscopía Electrónica de Rastreo , Ácido Poliglicólico , Copolímero de Ácido Poliláctico-Ácido Poliglicólico , Conejos
7.
J Biomed Mater Res ; 61(1): 159-64, 2002 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-12001259

RESUMEN

This study investigated the in vitro degradation of poly(propylene fumarate)/beta-tricalcium phosphate (PPF/beta-TCP) scaffolds in pH 7.4 phosphate-buffered saline at 37 degrees C. Scaffold design consisted of three layers: two solid layers about a central layer of porous PPF foam. Solid PPF with molecular weights of 810 and 1450 Da was crosslinked under UV light. PPF foam was prepared by a photocrosslinking, porogen-leaching method with an initial porogen content of 80 wt % and two sizes, 150-300 and 300-500 microm. Comparison of initial and residual weights demonstrated a 14.3 +/- 2.0% loss of mass at 3 weeks and a 16.6 +/- 1.8% loss of mass at 6 weeks. Observed pH values for all constructs remained stable (7.15-7.40) throughout the 3 to 6 weeks. Scanning electron micrographs of these scaffolds revealed some loss of foam material between 3 and 6 weeks; however, foam microarchitecture was intact. Solid PPF fracture toughness was tested for high and low molecular weight PPF, 0.376 +/- 0.004 and 0.134 +/- 0.015 MPa(m)1/2, respectively. These values are roughly one magnitude less than human cortical bone.


Asunto(s)
Fosfatos de Calcio/química , Fumaratos/química , Polipropilenos/química , Ingeniería de Tejidos/métodos , Fenómenos Biomecánicos , Cementos para Huesos/química , Concentración de Iones de Hidrógeno , Microscopía Electrónica de Rastreo , Porosidad
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