Nucleic acids design strategies

In the context of controlled release, the layer-by-layer fabrication procedure offers potential advantages over conventional protein and nucleic acid encapsulation strategies, including the ability to control the order and location of multiple polymer layers with nanometer scale precision, and the ability to define the concentrations of incorporated materials simply by varying the number of polymer layers incorporated [190-192]. Although numerous reports describe the application of these materials to the sustained release of permeable small molecules [193-197], there are few examples of these assemblies designed to release macromolecular components. Several groups have performed... 

In vitro selection strategies can be sub-divided into two types direct and indirect selections. These two types of selection experiments directed at the isolation of synthetic catalytic nucleic acids differ mainly by their technical concept, their design and their outcome. 

The more successful strategy for the isolation of RNA- and DNA-based catalysts involves the direct screening of nucleic acids libraries for catalytic activity. This approach is called direct selection [6, 65, 77, 78, 86, 101-107]. In direct selections, nucleic acids that are capable of catalyzing a particular chemical transformation modify themselves with a tag or other characteristic that allows their preferential enrichment over those molecules which are catalytically inactive [108]. The design of ribozyme-selections involving reactions between two small substrates requires that one reactant be covalently attached to every individual member of the starting RNA pool. After the reaction with another substrate which usually carries the selection-tag has occurred, the self-modified RNA is immobilized on a solid support, separated from non-active molecules, and then cleaved off the support. 

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