Affinity porous silica

High-surface porous silica can be coated with functionalized monolayers so as to trap metal ions from polluted water by means of groups with high affinity for them. The process is so effective that the resulting water is often drinkable in addition, the material can be reused. One can measure its effectiveness with the distribution coefficient, Kj ... 

Tayot J-L, Tardy M (1980) Isolation of cholera toxin by affinity chromatography on porous silica beads with covalently coupled ganglioside Gmi- In Adv. Exp. Med. Biol. 125 471 -478. 

Adsorption chromatography exploits differences in the relative affinity of solutes for a solid adsorbent used as the stationary phase. Common stationary phase materials for adsorption chromatography are porous silica gel, activated alumina, activated carbon, magnesium oxide, carbonates, and highly cross-linked polymers such as styrene-divinylbenzene and methac-rylates. The chemical natures of these adsorbent stationary phase materials make them well suited for separations of solute mixtures that differ in polarity and chemical functionality. For example, silica is an acidic adsorbent that retains basic compounds to a greater extent than nonbasic ones. In contrast, alumina... 

RPLC is similar in principle to GLC in that both techniques rely on the differing affinities of analyte molecules for the mobile and stationary phases to enact a separation. The distinct difference between RPLC and GC is complexity. In RPLC, the stationary phase typically consists of dimethyl octadecyl silane chains grafted to the surfaces of highly porous silica particles and the mobile phase is a binary solvent containing water and an organic modifier, most commonly methanol or acetonitrile. The complex interplay between the stationary phase, solvent, and analyte has made a molecular-level description of RPLC extremely difficult. 

Porous silica is one of the ideal rigid supports, which can be made with different pore size distribution to efficiently increase the macromolecular transfer inside. However, it is difficult to be used directly for affinity chromatography because of its complex nonspecific adsorption of molecular target by hydrophobic interaction. Also, its poor stability at basic conditions limits its application. 

Xi F, Wu J. Macroporous chitosan layer coated on non-porous silica gel as a support for metal chelate affinity chromatographic adsorbent. J Chromatogr A 2004 1057 41 7. 

Silica gel. Silica gel is a porous amorphous form of silica (Si02) and is manufactured by acid treatment of sodium silicate solution and then dried. The silica gel surface has an affinity for water and organic material. It is primarily used to dehydrate gases and liquids. 

Porous supports like agarose, pol3mrethacrylate, or silica beads are generally used in current applications of affinity chromatography. However, in the past several years other types of supports have also become available commercially. Many of these newer materials have properties that give them superior performance in certain applications. Materials that fall in this category include nonporous supports, membranes, flow-through beads, continuous beds and expanded-bed particles. 

Support materials for low-pressure affinity chromatography include agarose (cross-linked with epichlorohydrin), cellulose, dextran, silica, and polyacrylamide 62 in HPLC a rigid, highly porous, hydrophilic polymer is typically used. Large pore sizes are necessary, as either the analyte or the affinity ligand are macromolecules. To provide unhindered access of... 

Porous materials with chemically modified surfaces have been extensively studied as adsorbents for heavy metal ions from water (see the review by Jal et al.2 and references therein). There is a continuously growing demand for adsorbents which are non-swelling, thermally and hydrothermally stable, exhibit large adsorption capacity, fast kinetics and high affinity towards heavy metal ions. Discovery of self-assembled ordered mesoporous silicas (OMSs)3 opened enormous opportunities for the design and synthesis of highly selective and efficient adsorbents for heavy metal ions. 

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