Capillary Modification by Noncovalent Polycation Adsorption:  Effects of Polymer Molecular Weight and Adsorption Ionic Strength

Wang, Y.; Dubin, Paul L.

doi:10.1021/ac990146k

Cited by 84 publications

(72 citation statements)

References 37 publications

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“…Collectively, CNTs in a polymer-based monolithic column were found to alter the retention times and improve the separation of some compounds and peptides in micro-HPLC and CEC [49]. In another experiment, SWCNTs have been combined with poly diallyldimethylammonium chloride (PDDA), a positively charged polymer and were coated to the interior surface of a capillary column and showed achiral separation of some basic proteins when used for capillary electrophoresis [174]. PDDA was used to coat the inside surface of a fused capillary that made it suitable for the physical attachment of c-SWCNTs [50].…”

Section: Swcnts For Achiral Separation In Purificationmentioning

confidence: 99%

Application of Carbon Nanotubes in Chiral and Achiral Separations of Pharmaceuticals, Biologics and Chemicals

Hemasa

Naumovski

Maher

et al. 2017

Preprint

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Carbon nanotubes (CNTs) possess unique mechanical, physical, electrical and absorbability properties coupled with their nanometer dimensional scale that renders them extremely valuable for applications in many fields including nanotechnology and chromatographic separation. The aim of this review is to provide an updated overview about the applications of CNTs in chiral and achiral separations of pharmaceuticals, biologics and chemicals. Chiral SWCNTs and MWCNTs have been directly applied for the enantioseparation of pharmaceuticals and biologicals by using them as stationary or pseudostationary phases in chromatographic separation techniques such as high-performance liquid chromatography (HPLC), capillary electrophoresis (CE) and gas chromatography (GC). Achiral MWCNTs have been used for achiral separations as efficient sorbent objects in solid-phase extraction techniques of biochemicals and drugs. Achiral SWCNTs have been applied in achiral separation of biological samples. Achiral SWCNTs and MWCNTs have been also successfully used to separate achiral mixtures of pharmaceuticals and chemicals. Collectively, functionalized CNTs have been indirectly applied in separation science by enhancing the enantioseparation of different chiral selectors whereas, non-functionalized CNTs have shown efficient capabilities for chiral separations by using techniques such as encapsulation or immobilization in polymer monolithic columns.

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Section: Swcnts For Achiral Separation In Purificationmentioning

confidence: 99%

Application of Carbon Nanotubes in Chiral and Achiral Separations of Pharmaceuticals, Biologics and Chemicals

Hemasa

Naumovski

Maher

et al. 2017

Preprint

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“…Whatever the relative molecular mass of the PDDA used, the PDDA coating procedure (adapted from Wang et al procedure [52]) was as follows. The capillary was rinsed with water for 10 min under 138 kPa, 0.1 M NaOH for 20 min (138 kPa), water (20 min, 138 kPa), solution of PDDA at 0.2% (m/v) in water for 120 min (3.5 kPa), water (20 min, 138 kPa), PDDA at 0.2% for 120 min (3.5 kPa) and finally water for 40 min under 138 kPa.…”

Section: Pdda Coatingmentioning

confidence: 99%

“…A PDDA-coating procedure, adapted from a published procedure [52] and described in Section 2, was developed in order to prevent the adsorption of the basic peptide at neutral pHs. Considering the results described above, the VIP analysis was performed using 30 mM Tricine at pH 7.2.…”

Section: Analysis With a Pdda-coated Capillarymentioning

confidence: 99%

Determination of binding constants of vasoactive intestinal peptide to poly(amidoamine) dendrimers designed for drug delivery using ACE

et al. 2007

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The purpose of the present paper was to study at physiological pH the affinity between vasoactive intestinal peptide (VIP) and four poly(amidoamine) dendrimers (PAMAMs) designed for drug delivery. Therefore, a fast and reproducible CE method was first developed to analyze the strongly basic peptide. To allow an accurate determination of binding constant (K) values, the ability to suppress peptide adsorption onto the silica capillary of nonpermanent coatings (poly(ethylene oxide) (PEO), low and medium relative molecular masses poly(diallyldimethylammonium chloride) (PDDA)) or poly(acrylamide) permanent coating (PAA) was evaluated. Very good intraday repeatability of VIP migration times and peak areas (0.1-0.6 and 2.9-4.9% RSD, respectively) was obtained using two of the investigated coatings (PEO and PDDA with medium molecular mass). ACE combined with these dynamic coatings was then employed to evaluate K between VIP and two amine-terminated PAMAM dendrimers of generation 2 and 5 (G2.NH2, G5.NH2) and two carboxyl-terminated PAMAM derivatives of generation 2 and 5 (G2.COOH, G5.COOH). Binding constant of (6.7 +/- 1.1) x 10(4)/M could be determined for the couple VIP/G5.NH2, while no affinity was evidenced between VIP and all other dendrimers investigated. These results suggest that G5.NH2 might be an interesting carrier for the delivery of VIP.

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“…However, it has also been shown that PDADMAC-coated capillaries may provide for selective protein interactions leading to improved resolution. 28 In particular, coating procedures that use a combination of high ionic strength and high molecular weight PDADMAC have been found to provide enhanced surface coverage and charge inversion and may facilitate the formation of "loops and tails" structures on the capillary surface, with which protein analytes may interact. Studies performed using such coated capillaries have demonstrated an enhancement in selectivity for bovine serum albumin and β-lactoglobulin 28 as compared to unmodified capillaries.…”

Section: Ce Separation Of the Oligomeric Protein Mixturesmentioning

confidence: 99%

Capillary Electrophoretic Screening for the Inhibition of Homocysteine Thiolactone-Induced Protein Oligomerization

et al. 2007

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We report the first demonstration of rapid electrophoretic monitoring of homocysteine thiolactoneinduced protein oligomerization (HTPO), a unique type of post-translational protein modification that may have clinical significance as an indicator of cardiovascular and neurovascular diseases. HTPO of the model protein bovine cytochrome c was initiated in vitro. The relative monomer and aggregate levels of the resultant protein mixtures were determined following separation using capillaries coated with the cationic polymer, poly(diallyldimethylammonium chloride). UV detection provided adequate sensitivity for the monitoring of higher order species, which exist at relatively low concentrations in the protein reaction mixture as compared to the monomeric species. Separations performed under standard injection conditions were optimized on the basis of applied voltage and sample denaturation conditions. Separations performed using short-end injection allowed for more rapid analyses, typically in less than 70 s. Relative errors for run-to-run migration times were less than 0.5%. This novel oligomeric system provides a rapid and straightforward in vitro method to screen therapeutic agents for their ability to inhibit HTPO. Changes in peak area for monomer and aggregate species were used to assess HTPO inhibition as a function of pyridoxal 5-phosphate (PLP) concentration. PLP was shown to effectively inhibit HTPO in vitro. Rapid analysis times of ~1.5 min were achieved for inhibition screening.Hyperhomocysteinemia is a disorder characterized by elevated plasma levels of the naturally occurring amino acid homocysteine (Hcy), which has been identified as an independent risk factor for cardiovascular disease. 1,2 Although the exact function of Hcy in the pathogenesis of cardiovascular disease remains unknown, there is a growing body of evidence that suggests Hcy thiolactone (HTL), the thioester metabolite of Hcy, is a contributing agent. 3-6 HTL is produced in vivo via enzymatic aminoacyl-tRNA synthase pathways at a rate proportional to extracellular Hcy concentration. 7 Thus, it is likely that HTL production is enhanced to some degree in individuals with hyperhomocysteinemia.Post-translational protein modification by HTL involves the site-specific acylation of lysine residues at ε-amino moieties to yield free thiols in the form of protein homocystamide (Scheme 1). 8,9 If left untreated, protein homocystamide can undergo spontaneous in vitro intermolecular disulfide bonding to yield oligomeric species. 10 Protein oligomerization can give rise to a range of adverse physiological affects. For example, oligomeric proteins often exhibit decreased biological activity, decreased solubility, 8 and increased immunogenicity. 11 As one would expect, the extent of physiological dysfunction caused by oligomerization *To whom correspondence should be addressed. strongin@pdx.edu. Tel: (225) In Vitro Protein ModificationProtein reaction mixtures were prepared by dissolving HTL (2.5 mM), and cyt c (10 mg/mL) in pH 7.4, 100 mM so...

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Capillary Modification by Noncovalent Polycation Adsorption: Effects of Polymer Molecular Weight and Adsorption Ionic Strength

Cited by 84 publications

References 37 publications

Application of Carbon Nanotubes in Chiral and Achiral Separations of Pharmaceuticals, Biologics and Chemicals

Application of Carbon Nanotubes in Chiral and Achiral Separations of Pharmaceuticals, Biologics and Chemicals

Determination of binding constants of vasoactive intestinal peptide to poly(amidoamine) dendrimers designed for drug delivery using ACE

Capillary Electrophoretic Screening for the Inhibition of Homocysteine Thiolactone-Induced Protein Oligomerization

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