Ex Parte KRANTZ et al - Page 14

                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                                  

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