Non-Covalent Adsorption

However, once inordinate activity has been lost, the protein can be easily removed by a simple shift in pH and then the resin regenerated in situ. 

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Capillary coating can also stabilize the migration times and resolutions. This is in particular necessary in the case of peptide and protein analysis, because proteins tend to stick to capillary walls. Often low-concentration polyethylene oxide solutions are recommended as well as dynamic bilayer coating formed by a non-covalent adsorption of polybrene and polyvinylsulfonate (PVS). Due to the stability of the EOF, the variation of intra- and intercapillary migration time was less than 1% relative standard deviation (RSD) with basic analytes and peptides. 

Chambers E, Mitrigotri S. Prolonged circulation of large polymeric nanoparticles by non-covalent adsorption on erythrocytes. J Control Release 2004 100 111-119. 

The interaction of nanoparticles with the proteins is governed from the same type of interactions described for carbon nanotubes. Since NPs carry charges, they can electrostatically adsorb biomolecules with different charges, which depend on the pH that the immobilization takes place and the pi of the protein [3,191]. Moreover, hydrophobic interactions, hydrogen bonds and non-specific absorption can play a role for enzyme non-covalent adsorption onto the surface of nanoparticles. 

A series of close-to-spherical styrene/DVB resins of varying particle size and pore diameter were employed as supports for non-covalent adsorptive attachment of CALB by hydrophobic interaction. The effect of matrix particle and pore size on CALB i) adsorption isotherms, ii) fraction of active sites, iii) distribution within supports, and iv) catalytic activity for s-CL ring-opening polymerizations and adipic acid/l,8-octanediol polycondensations is reported. Important differences in the above for CALB immobilized on methyl methacrylate and styrene/DVB resins were found. The lessons learned herein provide a basis to others that seek to design optimal immobilized enzyme catalysts for low molar mass and polymerization reactions. 

This paper reviews the present status of affinity separation of cells based on the biospecific interaction of cellular receptors with proteinaceous ligands immobilized on a solid-phase matrix. Special emphasis was placed on the development of new matrix materials for immuno-affinity chromatography of lymphocyte subpopulations. Our newly developed matrix of poly(2-hydroxyethyl methacrylate)/polyamine graft copolymer offered novel advantages in (1) elimination of non-specific adsorption of lymphocytes and (2) simple immobilization procedure of ligand protein through non-covalent adsorption. This matrix allowed a rapid separation of preparative quantities of pure and vital lymphocyte subpopulations (IgG-positive and -negative cells) in excellent yield. 

Another paper " reported the development of two main strategies (i) the covalent grafting of hydrolyzable Si(OEt)3 groups on oxidised CNTs and (ii) the non-covalent adsorption of a polycation on pristine CNTs (Figure 4.9). These approaches enabled the performance of further sol-gel processing of functionalised CNTs and their incorporation into poly(methyl methacrylate)... 

Cellulose has been converted into more reactive forms by chelation with titanium(m), iron(ni), tin(iv), vanadium(m), and zirconium(iv) salts. The unsubstituted ligands of the bound metals could be replaced by electron-donating groups of antibiotics e,g. ampicillin, gentamicin, kanamycin, neomycin, paro-mycin, etc.) to yield materials possessing antimicrobial activity the original chelated celluloses were inactive. The chelation procedure offers an easy way of rendering cellulose more resistant to microbial attack than that afforded by non-covalent adsorption of the antibiotic. 

There are three modes by which clays and other materials can exert non-covalent adsorptive power on various molecules, from the liquid or gaseous state. These are 1) physical, non-ionic adsorption onto the surfaces of finely divided materials, such as clay particles with large surface areas that are comprised in a small volume, 2) ion exchange, by electrostatic interaction and exchange, and 3) zeolitic action, by inclusion of small molecules in cavities or pores, and partial or complete exclusion of larger molecules by such small cavities. 

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