Closer look at the operating definition of protein recovery in <scp>CE</scp>

Espinal, Jose H.; Gómez, Jorge E.; Sandoval, Junior E.

doi:10.1002/elps.201200514

Cited by 4 publications

(3 citation statements)

References 26 publications

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“…), suggesting not only that a slow adsorption‐desorption factor is involved but also that such kinetic effect surpassed that of solute overloading, if at all. This behavior, described profusely elsewhere, is characteristic of compact high p I proteins such as lysozyme . Notice also that the extent of this effect is very notorious in the case of PrOH‐modified capillaries.…”

Section: Resultsmentioning

confidence: 76%

Novel 3‐hydroxypropyl‐bonded phase by direct hydrosilylation of allyl alcohol on amorphous hydride silica

2014

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A novel 3-hydroxypropyl (propanol) bonded silica phase has been prepared by hydrosilylation of allyl alcohol on a hydride silica intermediate, in the presence of platinum (0)-divinyltetramethyldisiloxane (Karstedt's catalyst). The regio-selectivity of this synthetic approach had been correctly predicted by previous reports involving octakis(dimethylsiloxy)octasilsesquioxane (Q8M8H) and hydrogen silsesquioxane (T8H8), as molecular analogs of hydride amorphous silica. Thus, C-silylation predominated (~ 94%) over O-silylation, and high surface coverages of propanol groups (5±1 µmol/m2) were typically obtained in this work. The propanol-bonded phase was characterized by spectroscopic (IR and solid state NMR on silica microparticles), contact angle (on fused-silica wafers) and CE (on fused-silica tubes) techniques. CE studies of the migration behavior of pyridine, caffeine, tris(2,2’-bipyridine)Ru(II) chloride and lysozyme on propanol-modified capillaries were carried out. The adsorption properties of these select silanol-sensitive solutes were compared to those on the unmodified and hydride-modified tubes. It was found that hydrolysis of the SiH species underlying the immobilized propanol moieties leads mainly to strong ion-exchange based interactions with the basic solutes at pH 4, particularly with lysozyme. Interestingly, and in agreement with water contact angle and electroosmotic mobility figures, the silanol-probe interactions on the buffer-exposed (hydrolyzed) hydride surface are quite different from those of the original unmodified tube.

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Section: Resultsmentioning

confidence: 76%

Novel 3‐hydroxypropyl‐bonded phase by direct hydrosilylation of allyl alcohol on amorphous hydride silica

2014

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“…To further complement our observations, such residual adsorption can be quantitatively assessed by analyte recovery measurements. This is accomplished by linear fitting of logarithmic peak area vs. effective length data (42). For a given tube id the slope, k , is proportional to the surface density of adsorption sites and, hence, is a useful figure to comparatively assess protein adsorption on different capillary coatings.…”

Section: Resultsmentioning

confidence: 99%

Neutral hydrophilic coatings for capillary electrophoresis prepared by controlled radical polymerization

Navarro

Gómez

Espinal

et al. 2016

Analytica Chimica Acta

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In the present study, porous silica particles as well as impervious fused-silica wafers and capillary tubes were modified with hydrophilic polymers (hydroxylated polyacrylamides and polyacrylates), using a surface-confined grafting procedure based on atom transfer radical polymerization (ATRP) which was also surface-initiated from α-bromoisobutyryl groups. Initiator immobilization was achieved by hydrosilylation of allyl alcohol on hydride silica followed by esterification of the resulting propanol-bonded surface with α-bromoisobutyryl bromide. Elemental analysis, IR and NMR spectroscopies on silica micro-particles, atomic force microscopy, ellipsometry and profilometry on fused-silica wafers, as well as CE on fused-silica tubes were used to characterize the chemically modified silica substrate at different stages. We studied the effect of monomer concentration as well as cross-linker on the ability of the polymer film to reduce electroosmosis and to prevent protein adsorption (i. e., its non-fouling capabilities) and found that the former was rather insensitive to both parameters. Surface deactivation towards adsorption was somewhat more susceptible to monomer concentration and appeared also to be favored by a low concentration of the cross-linker. The results show that hydrophilic polyacrylamide and polyacrylate coatings of controlled thickness can be prepared by ATRP under very mild polymerization conditions (aqueous solvent, room temperature and short reaction times) and that the coated capillary tubes exhibit high efficiencies for protein separations (0.3–0.6 million theoretical plates per meter) as well as long-term hydrolytic stability under the inherently harsh conditions of capillary isoelectric focusing. Additionally, there was no adsorption of lysozyme on the coated surface as indicated by a complete recovery of the basic enzyme. Furthermore, since polymerization is confined to the inner capillary surface, simple precautions (e.g., solution filtration) during the surface modification process are sufficient to prevent capillary clogging.

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“…Possible adsorption of the peptides to the channel wall was estimated by recovery studies according to a method adapted from Preisler et al 49 and described in detail by Tran et al 50 This equation is in accordance with the more general one proposed by Espinal et al for any distance employed. 51 The recovery of Ab 1-38, 1-40 and 1-42 amyloid peptides was determined by analyzing them individually at a concentration of 20 mM and by comparing the peak areas obtained during the same analysis at two detection points (35 mm and 70 mm).…”

Section: Recovery Calibration Curve and Lodmentioning

confidence: 99%

Neutral polymers as coatings for high resolution electrophoretic separation of Aβ peptides on glass microchips

Mesbah

Verpillot

Chiari

et al. 2014

Analyst

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This study reports a comparison of the performances of two neutral polymers, poly ethylene-oxide (PEO) and poly(dimethylacrylamide-co-allyl glycidyl ether) (EpDMA), in glass microchips to achieve zone electrophoresis separation of several truncated forms of beta amyloid (Aβ) peptides, sharing very similar structures. The peptides were derivatized by FluoProbes 488 NHS to allow their fluorescence detection. Two protocols based either on PEO or EpDMA led to good pH stabilities in addition to a significant reduction of the electroosmotic flow. These two polymer coatings allowed repeatable analyses and high resolution for the simultaneous analysis of three Aβ peptides, Aβ 1-38, Aβ 1-40 and Aβ 1-42, considered as potential biomarkers of Alzheimer's disease. A recovery study showed that EpDMA was superior in reducing the adsorption of the Aβ peptides on the coated inner wall. Finally, the separation method relying on the EpDMA coated microchips was validated as linear using a calibration curve and the LOD was estimated to be close to 200 nM. Despite very short migration distances, different N-terminal or C-terminal truncated Aβ peptides, corresponding to promising biomarker combinations for the future diagnostic, were fully resolved. The method was successfully applied to detect these peptides in spiked cerebrospinal fluid and has provided a first achievement towards the development of a microsystem that would integrate preconcentration and separation steps.

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Closer look at the operating definition of protein recovery in CE

Cited by 4 publications

References 26 publications

Novel 3‐hydroxypropyl‐bonded phase by direct hydrosilylation of allyl alcohol on amorphous hydride silica

Novel 3‐hydroxypropyl‐bonded phase by direct hydrosilylation of allyl alcohol on amorphous hydride silica

Neutral hydrophilic coatings for capillary electrophoresis prepared by controlled radical polymerization

Neutral polymers as coatings for high resolution electrophoretic separation of Aβ peptides on glass microchips

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