scholarly journals Pore size is a critical parameter for obtaining sustained protein release from electrochemically synthesized mesoporous silicon microparticles

PeerJ ◽  
2015 ◽  
Vol 3 ◽  
pp. e1277 ◽  
Author(s):  
Ester L. Pastor ◽  
Elaine Reguera-Nuñez ◽  
Eugenia Matveeva ◽  
Marcos Garcia-Fuentes
Keyword(s):  
Particle Size ◽  
Pore Size ◽  
Internal Surface ◽  
Protein Release ◽  
Burst Release ◽  
Internal Surface Area ◽  
Release Process ◽  
Mesoporous Silicon ◽  
Model Protein ◽  
Sustained Protein Release

Mesoporous silicon has become a material of high interest for drug delivery due to its outstanding internal surface area and inherent biodegradability. We have previously reported the preparation of mesoporous silicon microparticles (MS-MPs) synthesized by an advantageous electrochemical method, and showed that due to their inner structure they can adsorb proteins in amounts exceeding the mass of the carrier itself. Protein release from these MS-MPs showed low burst effect and fast delivery kinetics with complete release in a few hours. In this work, we explored if tailoring the size of the inner pores of the particles would retard the protein release process. To address this hypothesis, three new MS-MPs prototypes were prepared by electrochemical synthesis, and the resulting carriers were characterized for morphology, particle size, and pore structure. All MS-MP prototypes had 90 µm mean particle size, but depending on the current density applied for synthesis, pore size changed between 5 and 13 nm. The model proteinα-chymotrypsinogen was loaded into MS-MPs by adsorption and solvent evaporation. In the subsequent release experiments, no burst release of the protein was detected for any prototype. However, prototypes with larger pores (>10 nm) reached 100% release in 24–48 h, whereas prototypes with small mesopores (<6 nm) still retained most of their cargo after 96 h. MS-MPs with ∼6 nm pores were loaded with the osteogenic factor BMP7, and sustained release of this protein for up to two weeks was achieved. In conclusion, our results confirm that tailoring pore size can modify protein release from MS-MPs, and that prototypes with potential therapeutic utility for regional delivery of osteogenic factors can be prepared by convenient techniques.

Templated assembly of BiFeO3 nanocrystals into 3D mesoporous networks for catalytic applications

Nanoscale ◽  
2015 ◽  
Vol 7 (13) ◽  
pp. 5737-5743 ◽  
Author(s):  
I. T. Papadas ◽  
K. S. Subrahmanyam ◽  
M. G. Kanatzidis ◽  
G. S. Armatas
Keyword(s):  
Catalytic Activity ◽  
Pore Size ◽  
Surface Area ◽  
Internal Surface ◽  
High Catalytic Activity ◽  
Assembly Process ◽  
Internal Surface Area ◽  
Catalytic Applications ◽  
Surfactant Assisted ◽  
Uniform Pore Size

A 3D mesoporous network of 6–7 nm BiFeO3 nanoparticles has been successfully prepared by a surfactant-assisted aggregating assembly process. These porous assemblies exhibit large internal surface area, uniform pore size, and impart high catalytic activity for the reduction of p-nitrophenol.

Internal surface area and porosity of kaolinitic glaebules

Soil Research ◽  
1975 ◽  
Vol 13 (2) ◽  
pp. 235
Author(s):  
ID Sills
Keyword(s):  
Particle Size ◽  
Specific Surface ◽  
Pore Size ◽  
Surface Area ◽  
Sandy Loam ◽  
Average Pore Size ◽  
Particle Size Analysis ◽  
Size Analysis ◽  
Internal Surface Area ◽  
Pore Size Distributions

Specific surface areas, cation exchange capacities and pore size distributions have been determined on sieved fractions of a sandy loam from Merredin, W.A., certain horizons of which contain significant proportions of kaolinitic glaebules. The sand-sized glaebules are resistant to breakdown by normal dispersion techniques, and so remain in the sand fraction during particle size analysis. However, certain of their physicochemical characteristics are consistent with those of soil colloids. For instance, the 250-500 �m fraction of the 155-190 cm horizon has a specific surface area of 16.3 m2/g, an average pore size of some 6 nm plate separation and a surface charge density of 3.8 x 104 esu/cm2. In soils containing significant proportions of such glaebules, the physicochemical properties will differ markedly from those inferred from particle size analysis.

Small-angle neutron scattering study of the role of feedstock particle size on the microstructural behavior of plasma-sprayed yttria-stabilized zirconia deposits

2003 ◽  
Vol 18 (3) ◽  
pp. 624-634 ◽  
Author(s):  
Hacène Boukari ◽  
Andrew J. Allen ◽  
Gabrielle G. Long ◽  
Jan Ilavsky ◽  
Jay S. Wallace ◽  
...  
Keyword(s):  
Particle Size ◽  
Neutron Scattering ◽  
Surface Area ◽  
Small Angle ◽  
Small Angle Neutron Scattering ◽  
Internal Surface ◽  
Feedstock Powder ◽  
Stabilized Zirconia ◽  
Internal Surface Area ◽  
Plasma Sprayed

The microstructures of thick plasma-sprayed yttria-stabilized zirconia (8% mass fraction yttria) deposits were studied in a series of Porod small-angle neutron scattering (SANS) and multiple small-angle neutron scattering (MSANS) experiments. Three main void components were identified in the deposits: intrasplat cracks, interlamellar planar pores, and globular pores. The SANS and MSANS measurements were analyzed using the traditional theory for Porod scattering and a recently developed three-component model for MSANS evaluation. The average size, volume fraction, internal surface area, and orientation distribution for each void component within the deposits were determined. This study focused on gaining a better understanding of the effects of initial feedstock particle size and annealing temperatures on the microstructure of deposits sprayed under equivalent particle-impact conditions. Quantitative results are presented for each of four deposit samples: one prepared using the as-received feedstock particle wide-size distribution and three prepared from feedstock powder of different and relatively narrow particle size ranges with average sizes of 32, 47, and 88 μm. Except for the coarse (88 μm) feedstock powder, only mild monotonic variations were found in the microstructural anisotropies, the porosities (13 ± 1%), and the internal surface areas in the as-sprayed deposits. The internal surface area was independent of the feedstock particle size, even with the coarse feedstock. When the deposits were annealed at high temperatures (1100 and 1400 °C), the microstructures were altered with a reduction of the total internal surface area and a mild coarsening of the voids. These changes in the microstructural evolution were well-captured and described by the three-component model. The results were compared and related with those obtained from scanning electron microscopy images and elastic moduli measurements.

What catalysis needs from the electron microscopist

1988 ◽  
Vol 46 ◽  
pp. 694-695
Author(s):  
Alexis T. Bell
Keyword(s):  
Active Sites ◽  
Heterogeneous Catalysts ◽  
Catalyst Deactivation ◽  
Surface Composition ◽  
Internal Surface ◽  
Active Phase ◽  
Atomic Scale ◽  
Metal Catalyst ◽  
Internal Surface Area ◽  
Porous Support

Heterogeneous catalysts, used in industry for the production of fuels and chemicals, are microporous solids characterized by a high internal surface area. The catalyticly active sites may occur at the surface of the bulk solid or of small crystallites deposited on a porous support. An example of the former case would be a zeolite, and of the latter, a supported metal catalyst. Since the activity and selectivity of a catalyst are known to be a function of surface composition and structure, it is highly desirable to characterize catalyst surfaces with atomic scale resolution. Where the active phase is dispersed on a support, it is also important to know the dispersion of the deposited phase, as well as its structural and compositional uniformity, the latter characteristics being particularly important in the case of multicomponent catalysts. Knowledge of the pore size and shape is also important, since these can influence the transport of reactants and products through a catalyst and the dynamics of catalyst deactivation.

scholarly journals Heat-Up Performance of Catalyst Carriers—A Parameter Study and Thermodynamic Analysis

Energies ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 964
Author(s):  
Thomas Steiner ◽  
Daniel Neurauter ◽  
Peer Moewius ◽  
Christoph Pfeifer ◽  
Verena Schallhart ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Surface Area ◽  
Internal Surface ◽  
Installation Space ◽  
Parameter Study ◽  
Thin Wall ◽  
Primary Role ◽  
Internal Surface Area

This study investigates geometric parameters of commercially available or recently published models of catalyst substrates for passenger vehicles and provides a numerical evaluation of their influence on heat-up behavior. Parameters considered to have a significant impact on the thermal economy of a monolith are: internal surface area, heat transfer coefficient, and mass of the converter, as well as its heat capacity. During simulation experiments, it could be determined that the primary role is played by the mass of the monolith and its internal surface area, while the heat transfer coefficient only has a secondary role. Furthermore, an optimization loop was implemented, whereby the internal surface area of a commonly used substrate was chosen as a reference. The lengths of the thin wall and high cell density monoliths investigated were adapted consecutively to obtain the reference internal surface area. The results obtained by this optimization process contribute to improving the heat-up performance while simultaneously reducing the valuable installation space required.

Box-Behnken Design Optimized TPGS Coated Bovine Serum Albumin Nanoparticles Loaded with Anastrozole

2021 ◽  
Vol 18 ◽  
Author(s):  
Ashish Kumar ◽  
Ajit Singh ◽  
S.J.S Flora ◽  
Rahul Shukla
Keyword(s):  
Particle Size ◽  
Bovine Serum Albumin ◽  
Serum Albumin ◽  
Bovine Serum ◽  
Glycol Succinate ◽  
Burst Release ◽  
Spectroscopic Techniques ◽  
Potential Candidate ◽  
Box Behnken Design ◽  
Thermal Gelation

Purpose: In this study, a novel D-α-tocopheryl polyethylene glycol succinate (TPGS) modified bovine serum albumin (BSA) nanoparticles were developed for delivery of Anastrozole (ANZ) which is optimized by Box-Behnken design (BBD). This TPGS-ANZ-BSA NPs are evaluated for their physicochemical and drug release characteristics. Methods: TPGS-ANZ-BSA NPs were prepared by desolvation thermal gelation method andthe effects of critical process parameter (CPP)which are BSA amount, TPGS concentration and stirring speed on the critical quality attributes (CQA) such as % drug loading (%DL) and particle size were studied using BBD. TPGS-ANZ-BSA NPs were characterized using different spectroscopic techniques including UV-Visible and FTIR is used to confirm the entrapment of ANZ in BSA. DSC and PXRD revealed the amorphization of ANZ in the TPGS-ANZ-BSA NPs after freeze drying. Scanning electron microscopy (SEM) analysis was performed for the surface morphologyanalysesNPs. In vitro release studies were performed at pH 5.5 and pH 7.4 for 48h to mimic tumour microenvironment. Results: The BBD optimized batch showed 107 nm particle size with % DL of 8.5± 0.5 of TPGS-ANZ-BSA NPs. The spectroscopic and thermal characterizations revealed the successful encapsulation of ANZ inside the nanoparticles.The TPGS-ANZ-BSA NPs were found to exhibit burst release at pH 5.5 and sustained release at pH 7.4. The short-term stability of drug-loaded nanoparticles displayed no significant changes in physicochemical properties at room temperature for period of one month. Conclusion: The BBD optimized TPGS-ANZ-BSA nanoparticles showed enhanced physiochemical properties for ANZ and potential candidate for anticancer agent drugs delivery.

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