DIAMOND-LIKE CARBON-COATED FILMS FOR ENZYME ELECTRODES - CHARACTERIZATION OF BIOCOMPATIBILITY AND SUBSTRATE DIFFUSION LIMITING PROPERTIES

The biocompatibility and substrate diffusion limiting properties for a range of diamond like carbon (DLC) coated microporous polycarbonate a nd DLC coated dialysis (haemodialysis) membranes have been studied. Th is characterisation builds upon previous findings where DLC coated mem branes imparted enhanced enzyme electrode performance. in this study e lectrode linear ranges have been extended from 10 mM glucose for a 0.0 1 mu m pore size membrane to 160 mM. These findings correlated with th e duration of DLC deposition and associated reductions in permeability for glucose. Permeability coefficient ratios for both microporous and dialysis membranes were also found to be important with low glucose/O -2 permeability ratios imparting extensions in glucose linear response range. DLC coated membranes employed within enzyme electrodes have al so been shown to exhibit enhanced haemocompatibility as determined by both sensitivity change and surface deposition of blood components exa mined by scanning electron microscopy. Correlations are made between t he reduced losses in sensor response to biofouling/working electrode p assivation processes, and extended linear ranges that DLC coated membr anes may impart to enzyme electrode performance. Particular reference is made to the determination of glucose levels within whole blood.