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 and DLC coated dialysis (haemodialysis) membranes have been studied. This characterisation builds upon previous findings where DLC coated membranes imparted enhanced enzyme electrode performance. in this study electrode linear ranges have been extended from 10 mM glucose for a 0.01 mu m pore size membrane to 160 mM. These findings correlated with the 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 also been shown to exhibit enhanced haemocompatibility as determined by both sensitivity change and surface deposition of blood components examined by scanning electron microscopy. Correlations are made between the reduced losses in sensor response to biofouling/working electrode passivation processes, and extended linear ranges that DLC coated membranes may impart to enzyme electrode performance. Particular reference is made to the determination of glucose levels within whole blood.