Multi-point covalent attachment

Table 4.1 Stabilization of Enzymes by Multi-Point Covalent Attachment to Glyoxyl-Agarose...

Blanco RM, Calvete JJ, Guisan JM (1988) ImmobiDzation-stabDization of enzymes. Variables that control the intensity of the trypsin (amine)-agarose (aldehyde) multi-point covalent attachment. Enzyme Microb Technol 11 353-359... 

The unique practical properties of adsorption have promoted its extensive use in genetic analysis. The disadvantages of adsorption with respect to covalent immobihzation are mainly that (1) nucleic acids may be readily desorbed from the substrate, and (2) base moieties may be unavailable for hybridization if they are bonded to the substrate in multiple sites [34]. However, the electrochemical detection strategy based on the intrinsic oxidation of DNA requires the DNA to be adsorbed in close contact with the electrochemical substrate by multi-point attachment. This multi-site attachment of DNA can be thus detrimental for its hybridization but is crucial for the detection based on its oxidation signals. 

The most successful immobilization techniques for DNA or oligonucleotides appear to be those involving multi-site attachment—either electrochemical or physical adsorption—or single-point attachment— mainly covalent immobilization or strept(avidin)/biotin linkage [26]. As an example, single-point covalent immobilization can be performed on... 

Flowever, the focus of the major part of the chapters lies on the couphng chemistry used for DNA immobilization. Successful immobihzation techniques for DNA appear to either involve a multi-site attachment of DNA (preferentially by electrochemical and/or physical adsorption) or a single-point attachment of DNA (mainly by surface activation and covalent immobihzation or (strept)avidin-biotin linkage). Immobilization methods described here comprise physical or electrochemical adsorption, cross-linking or entrapment in polymeric films, (strept)avidin-biotin complexation, a surface activation via self-assembled monolayers using thiol linker chemistry or silanization procedures, and finally covalent coupling strategies. 

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