Screen-printed enzymatic glucose biosensor based on a composite made from multiwalled carbon nanotubes and palladium containing particles

A composite material consisting of multiwalled carbon nanotubes and palladium containing particles was synthesized and applied to the preparation of bulk-modified screen-printed carbon electrodes (Pd-MWCNT-SPCE) and surface-modified screen-printed carbon electrodes (Pd-MWCNT/SPCE). They were characterized by cyclic voltammetry and hydrodynamic chronoamperometry in solution of pH 7.5. Both electrodes were then modified with glucose oxidase (GOx) by drop-coating a solution of GOx and NafionA (R) on their surface. Glucose can be determined via enzymatically formed H2O2. In an alternative approach, gold nanoparticles (5 nm) were incorporated into the biolayer of the electrodes. The resulting electrodes of type GOx/Pd-MWCNT-SPCE and GOx-Au/Pd-MWCNT-SPCE showed acceptable analytical performance at working potentials between -0.20 V and -0.50 V in case of hydrodynamic chronoamperometry. Both electrodes can be operated best at a working potential of -0.40 V vs SCE, with acceptable linearity of the methods in sub mM concentration ranges and with LOQs of 0.14 mM and 0.07 mM for glucose for the GOx/Pd-MWCNT-SPCE and GOx-Au/Pd-MWCNT-SPCE, respectively. Incorporation of gold nanoparticles prolongs the operational lifetime of the electrodes by two weeks. The GOx/Pd-MWCNT-SPCE based method was applied to the determination of glucose in multifloral honey, and the GOx-Au/Pd-MWCNT-SPCE method to the determination of glucose in blood serum. In both cases there was a good agreement with the results obtained by commercially available equipment for determination of glucose.