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231224s2017 xx |||||o 00| ||eng c |
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|a 10.1002/mrc.4427
|2 doi
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|a pubmed24n0861.xml
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|a (DE-627)NLM258521929
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|a (NLM)26987451
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|a DE-627
|b ger
|c DE-627
|e rakwb
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| 041 |
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|a eng
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| 100 |
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|a Ferreira, Ana S D
|e verfasserin
|4 aut
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| 245 |
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|a Probing sol-gel matrices microenvironments by PGSE HR-MAS NMR
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|c 2017
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|a Text
|b txt
|2 rdacontent
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|a ƒaComputermedien
|b c
|2 rdamedia
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|a ƒa Online-Ressource
|b cr
|2 rdacarrier
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|a Date Completed 11.04.2018
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|a Date Revised 11.04.2018
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|a published: Print-Electronic
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|a Citation Status MEDLINE
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|a Copyright © 2016 John Wiley & Sons, Ltd.
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|a We applied Pulsed Gradient Spin Echo diffusion with high-resolution magic angle spinning NMR to study sol-gel matrices used to encapsulate enzymes for biocatalysis (TMOS/MTMS and TMOS/BTMS) to gain insight into the local chemical microenvironment. Transport properties of solvents with different polarities (1-pentanol, acetonitrile and n-hexane) were studied through their apparent self-diffusion coefficients. The spin echo attenuation of the solvents shows two distinct diffusion domains, one with fast diffusion (Dfast ) associated with interparticle diffusion and another with slow diffusion (Dslow ) corresponding to the displacement inside the pores within the sol-gel particles. The analysis of the root mean square displacements at different diffusion times showed that the Dfast domain has a free diffusion regime in both matrices (the root mean square displacement is linearly dependent of the diffusion time), while the Dslow domain shows a different regime that depends on the matrix. We investigated the exchange regime between the two diffusion sites. In both matrices, n-hexane was in intermediate exchange between diffusion domains, while the polar solvents were in slow exchange in TMOS/BTMS and in intermediate exchange in TMOS/MTMS. Data were fitted for TMOS/BTMS with the Kärger model, and the physical parameters were obtained. The results add to the evidence that the pores are a hydrophobic environment but that the presence of some free hydrophilic groups inside the pore, as observed in the TMOS/BTMS, has a key role in slowing down the exchange of polar solvents and that this is relevant to explain previously reported enzyme activity in these materials. Copyright © 2016 John Wiley & Sons, Ltd
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|a Journal Article
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|a high-resolution magic angle spinning
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|a nuclear magnetic resonance
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|a pulsed-field gradient
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|a sol-gel matrices
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|a Acetonitriles
|2 NLM
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|a Hexanes
|2 NLM
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|a Pentanols
|2 NLM
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|a Silanes
|2 NLM
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|a Solvents
|2 NLM
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|a n-hexane
|2 NLM
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|a 2DDG612ED8
|2 NLM
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|a tetramethoxysilane
|2 NLM
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|a 681-84-5
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|a Silicon Dioxide
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|a 7631-86-9
|2 NLM
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|a Polyvinyl Alcohol
|2 NLM
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|a 9002-89-5
|2 NLM
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|a n-pentanol
|2 NLM
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|a M9L931X26Y
|2 NLM
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|a trimethoxysilane
|2 NLM
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|a V1J39XPF91
|2 NLM
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|a acetonitrile
|2 NLM
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|a Z072SB282N
|2 NLM
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|a Barreiros, Susana
|e verfasserin
|4 aut
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1 |
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|a Cabrita, Eurico J
|e verfasserin
|4 aut
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| 773 |
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|i Enthalten in
|t Magnetic resonance in chemistry : MRC
|d 1985
|g 55(2017), 5 vom: 18. Mai, Seite 452-463
|w (DE-627)NLM098179667
|x 1097-458X
|7 nnns
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| 773 |
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|g volume:55
|g year:2017
|g number:5
|g day:18
|g month:05
|g pages:452-463
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|u http://dx.doi.org/10.1002/mrc.4427
|3 Volltext
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|d 55
|j 2017
|e 5
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|h 452-463
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