Linker Loading capacity

Another interesting modification of glass surfaces was introduced by Beier and Hoheisel.23 They synthesized a flexible, dendritic linker system that enables covalent immobilization of oligonucleotides and PNAs with high loading capacity in a controlled manner. This method facilitates the modulation of surface properties such as hydrophobicity and charge. The synthesis of the linker system involves two consecutive reactions an acylation of surface-bound amine groups with acid chloride (4-nitrophenyl-chloroformate or acryloylchloride) and subsequent reaction with an amine. A bis-amine results in a linker system, while a polyamine produces a dendritic structure (Fig. 14.3). Because polyamines possess primary and secondary amine... 

The reactors selected were 432 aminomethylated MicroTubes 7.63, which are polystyrene-grafted polypropylene tubes with a 50 xM loading capacity per reactor, that encapsulate a preencoded radiofrequency tag (Fig. 7.38). The tubes were reacted with the Fmoc-protected, acid-labile Knorr linker (step a), the residual amine functions... 

It is noteworthy that the load capacity and the resolving capability increased when the tri-functional cross-linker PETRA was used instead of EDM A [20]. The same features have been seen with polymers prepared from TRIM, another trifunc-tional cross-linker. Poly(methacrylic acid-co-TRIM) imprinted with a dipeptide was able to resolve 1 mg of the racemate with almost base-line separation (analytical column 4.6 x 250 mm) (Fig. 17.7). 

Fig. 25. Relationship between loading capacity (in terms of mg protein/ml gel volume) and %T T = grams of acrylamide and cross-linker per 100 ml gel volume) value of the gel matrix. Notice that, though in the range 3 to 6%7 the protein load decreases linearly, in softer gels (3%T) it increases exponentially. (From Righetti and Gelfi, 1984. Reproduced with permission of the publisher.)...

Spectroscopic techniques nicely compliment synthesis and capacity work. One paper reviewed recent work on neutron powder diffraction, where MOFs loaded with different deuterium pressure were studied to directly pin point the location of hydrogen in these porous systems. For the first time the absorbed hydrogen molecules were located in the organic linker, and this highlights then-importance. It would be interesting to test this approach on the other systems that store weakly bound hydrogen. 

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