Biomolecule-sensitive polymers

The ion-exchangers used in LC consist either of an organic polymer with ionic functional groups, or silica coated with an organic polymer with ionic functional groups. The types of functional groups used are the same as described in Chapter 18. Since IEC can be carried out with an aqueous mobile phase near physiological conditions, it is an important technique in the purification of sensitive biomolecules such as proteins. 

Additives such as polyethylene glycol, cationic antibiotics, polymers, small uncharged molecules, and negatively charged proteins have been used extensively in order to avoid the denaturing of enzymes or to improve the sensitivity and operational stability of biosensors. DNA has been proposed as an additive to improve the response and stability of biosensors based on CP. The biomolecules studied, such as tyrosinase [93], peroxidase [94], cytochrome C [95], have been shown to improve its performance by using adsorbed DNA within CP as an additive. 

Trichlorosilane derivatives of large dye molecules are difficult to purify and owing to moisture sensitivity are hard to handle. Their organic solutions tend to become turbid rather quickly owing to the formation of insoluble polymers. Thus, solutions must be replaced frequendy. An exception may be the combination of self-assembly and surface chemical reaction (186-189,202). On the other hand, co-substituted alkyltrichlorosilane derivatives are easy to synthesize the purify. These could be used for the engineering of surface free energy through the control of chemical functionalities in their SAMs, or as active layers for attachment of biomolecules in biosensors. 

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