Preliminary analysis of pore distributions using NMR in natural coral and hydrothermally prepared hydroxyapatite

McCutcheon, Alan L; Kannangara, G. S. Kamali; Wilson, Michael; Ben‐Nissan, Besim

doi:10.1023/b:jmsc.0000040080.98372.04

Cited by 6 publications

(5 citation statements)

References 12 publications

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“…It was also indicated that most of the crushed and ground particles have pore The porosity of coral particles was determined to be 58% in the size range considered (3 nm 350 nm). The results are consistent with results reported previously, using Nuclear Magnetic Resonance (NMR) [14].…”

Section: Pla Thin Film Composites and Drug Loadingsupporting

confidence: 93%

Biocompatibility of a new biodegradable polymer-hydroxyapatite composite for biomedical applications

Macha

Ben‐Nissan

Santos

et al. 2017

Journal of Drug Delivery Science and Technology

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Section: Pla Thin Film Composites and Drug Loadingsupporting

confidence: 93%

Biocompatibility of a new biodegradable polymer-hydroxyapatite composite for biomedical applications

Macha

Ben‐Nissan

Santos

et al. 2017

Journal of Drug Delivery Science and Technology

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“…Clodronate loaded in HAp is located on the surface, and also in nano‐ and mesopores of the particles (McCutcheon et al ., ). There is also some clodronate dispersed in the matrix alone, which degrades as in PLABP.…”

Section: Resultsmentioning

confidence: 97%

“…Briefly, coral powder was mixed with the required amount of diammonium hydrogen phosphate [(NH 4 ) 2 HPO 4 ] to obtain HAp and then converted in a Parr reactor at 250°C and 8.0 MPa pressure. Coral has been characterized previously (Ben‐Nissan et al ., ; Cegla et al ., ; Chou et al ., ; McCutcheon et al ., ). Hydrothermally converted coralline hydroxyapatite was loaded with 25% w/w clodronate by dissolving the required amount of clodronate in purified 18 MilliQ water (Millipore), mixed with HAp, sonicated and then allowed to dry in a Rotavapor R‐210 coupled with a vacuum controller (V‐850, BUCHI, In Vitro Technologies, Australia) at 60°C.…”

Section: Methodsmentioning

confidence: 97%

Development and dissolution studies of bisphosphonate (clodronate)-containing hydroxyapatite-polylactic acid biocomposites for slow drug delivery

Macha

Cazalbou

Shimmon

et al. 2015

J Tissue Eng Regen Med

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An increase in clinical demand on the controlled release of bisphosphonates (BPs) due to complications associated with systemic administration, has been the current driving force on the development of BP drug-release systems. Bisphosphonates have the ability to bind to divalent metal ions, such as Ca , in bone mineral and prevent bone resorption by influencing the apoptosis of osteoclasts. Localized delivery using biodegradable materials, such as polylactic acid (PLA) and hydroxyapatite (HAp), which are ideal in this approach, have been used in this study to investigate the dissolution of clodronate (non-nitrogen-containing bisphosphonate) in a new release system. The effects of coral structure-derived HAp and the release kinetics of the composites were evaluated. The release kinetics of clodronate from PLA-BP and PLA-HAp-BP systems seemed to follow the power law model described by Korsmeyer-Peppas. Drug release was quantified by P-NMR with detection and quantification limits of 9.2 and 30.7 mM, respectively. The results suggest that these biocomposite systems could be tuned to release clodronate for both relatively short and prolonged period of time. In addition to drug delivery, the degradation of HAp supplies both Ca and phosphate ions that can help in bone mineralization. Copyright © 2015 John Wiley & Sons, Ltd.

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“…For example, clay coating of the pore space can induce internal field gradients leading to reduced T 2 relaxation rates. The reduction in T 2 time can, erroneously, be interpreted as a result of smaller pore sizes, ,− thus leading to an underestimation of NMR derived porosity. , …”

Section: Introductionmentioning

confidence: 99%

The Effect of Clay Content on the Spin–Spin NMR Relaxation Time Measured in Porous Media

et al. 2020

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Clays, hydrous aluminous phyllosilicates, have a significant impact on the interpretation of physical measurements and properties of porous media. In particular, the presence of paramagnetic and/or ferromagnetic ions like iron, nickel, and magnesium in clays can complicate the analysis of nuclear magnetic resonance (NMR) data for porous media characterization. This is due to the internal magnetic field gradient induced by the clay minerals. In this study, we aim to investigate the impact of clay content on spin–spin relaxation time (T 2), which is strongly influenced by the pore surface chemistry. Seven rock core plugs, characterized with variable clay content, were used for this purpose. The clay mineralogy and volume were determined by means of quantitative evaluation of minerals by scanning electron microscopy (QEMSCAN). The T 2 relaxation time was measured using a Carr–Purcell–Meiboom–Gill (CPMG) sequence with variable echo spacing (T E). The maximum percentage difference in dominant T 2 values (MRDT 2) between shortest and longest echo spacing was subsequently correlated with clay content obtained from QEMSCAN. Our results show that the reduction in T 2 distribution with increasing echo time T E is more significant in samples characterized by higher clay contents. The MRDT 2 was found to be strongly correlated with clay content. An analytical equation is presented expressing MRDT 2 as a function of clay content providing a quick and non-destructive approach for clay content estimation. Moreover, the MRDT 2–clay content relationship showed a nonlinear behavior: MRDT 2 increases drastically as the clay content increases up to 15%, beyond which the rate of MRDT 2 change with clay content diminishes. This behavior could be attributed to the clay distribution. At higher clay contents (above 15%), it is more likely for clay to form clusters (structural clays), which will not significantly increase the clay surface in contact with the pore fluid. Further, experimental data suggests that ignoring the impact of clay on internal magnetic gradients and T 2 signal may result in considerable underestimation of the actual pore size distribution.

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Preliminary analysis of pore distributions using NMR in natural coral and hydrothermally prepared hydroxyapatite

Cited by 6 publications

References 12 publications

Biocompatibility of a new biodegradable polymer-hydroxyapatite composite for biomedical applications

Biocompatibility of a new biodegradable polymer-hydroxyapatite composite for biomedical applications

Development and dissolution studies of bisphosphonate (clodronate)-containing hydroxyapatite-polylactic acid biocomposites for slow drug delivery

The Effect of Clay Content on the Spin–Spin NMR Relaxation Time Measured in Porous Media

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