Appeal No. 1996-3973
Application No. 08/048,657
elements (i.e., test strips), including coating an initial layer on a support and thereafter coating
successive layers directly on those coated previously and adjusting coating formulations to keep
adjacent layers discrete and to minimize or eliminate interlayer component migration (col. 9,
lines 13-41). Phillips describes applying an MBTH-DMAB dye solution to a porous nylon
matrix support, drying and then applying a low viscosity enzyme solution comprising glucose
oxidase and peroxidase thereto followed by drying (col. 11, line 34 - col. 12, line 13). Thus, it
would have been obvious to one of ordinary skill in the art to modify the generic test slide
described by Tietz or Eggert to assay for a clinically significant analyte, i.e., glucose, using a
conventional glucose oxidase-peroxidase-MBTH-DMAB reagent dye couple system as described
by Ngo and Phillips to improve the sensitivity, versatility, safety and specificity of the assay,
wherein the enzyme and chromogen reactions are separated into an enzyme and a dye-couple
layers, respectively, as suggested by Eggert, and because Przybylowicz suggests that separation
of reaction steps into separate, discrete layers can enhance the overall assay reaction. It would
have been further both conventional and within ordinary skill in the art to coat an initial dye layer
comprising MBTH-DMAB on a support, such as nylon, and thereafter coat successive layers,
including an overlying enzyme layer comprising glucose oxidase and peroxidase using a higher
viscosity enzyme solution to maintain a separate, discrete enzyme layer, thereby minimizing or
eliminating interlayer component migration, as suggested by Eggert, Tietz, Przybylowicz and
Phillips.
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