Diagnostic polymers and coatings

In this paper we will describe diagnostic polymers and coatings. Background on dry chemistry, and medical aspects will also be addressed for completeness. 

Polymers and Coatings Advances ia polymer chemistry have resulted ia many successful medical devices, including diagnostic assays (26). Polymers (qv), which can be manufactured ia a wide range of compositions, ate used to enhance speed, sensitivity, and versatiUty of both biosensors and dry chemistry systems to measure vital analytes. Their properties can be regulated by composition variations and modifications. Furthermore, polymers can be configured iato simple to complex shapes. 

During the past several years, we have researched new diagnostic polymers and novel dry chemistries therefrom. These include water-borne tough coating films, nonaqueous coatings and molded plastic systems. These chemistries are described below. 

The non-aqueous diagnostic polymer must impart particular desirable properties to the resulting coating—film. Most importantly, hydrophilidty and hydrogel character to the film must be imparted, thus allowing intimate contact with aqueous whole blood sample. Furthermore, non-aqueous polymer may also provide some enzyme stabilizing effects. 

The diagnostic polymers used in the non-aqueous coatings are "hydrogel" in nature and are fully wetted by blood almost instantaneously. Microscopic dye penetration experiments have shown that the liquid penetrates the polymer as well as the coatings in less than 2 s. The generated colors remain stable immediately after reaction and also for an extended time. 

Some valuable products with applications in paper coating, leather treatment, binders for nonwoven fabrics, additives for paper, textiles and construction materials, impact modifiers for plastic matrices, and diagnostic tests and drug delivery systems, can only be produced by emulsion polymerization. In addition, when needed (for example, for rubber for tires) latexes are easy to process into dry polymer. The main disadvantage of emulsion polymerization is that the product contains emulsifier and residues of initiator, which give it water sensitivity. 

Ion channels play an essential role in medical diagnostics and drug development. Such applications require the integration of ion channels together with a lipid bilayer into an artificial microstructured polymer membrane (Fig. 4). The polymer membrane is attached to a metal coated optical prism. The membrane contains micropores of approximately one micrometer in diameter. Lipid bilayers are stretched across the pores. The bilayers host the receptor molecules. After activation of an ion channel, thousands of ions stream into the cavity below the ion channel. The change of ion concentration can easily be detected by SPR measurements. 

---