Amperometric biosensors for NADH based on hyperbranched dendritic ferrocene polymers and Pt nanoparticles

The electrocatalytic performance of electrodes modified with Pt nanoparticles (PtNPs) and two dendritic hyperbranched carbosilane polymers, polydiallylmethylsilane (PDAMS) and polymethyldiundecenylsilane (PMDUS) with interacting ferrocenes, has been investigated for the NADH oxidation. The catalytic synergy of PtNPs with the interacting ferrocenes is discussed in relation with the polymer structure. This effect have allowed us to develop efficient biosensors capable of measuring NADH from +0.3 V (vs. SCE) providing a total protection vs. the poisoning of the electrodes. The polymer/PtNPs/Pt electrodes tolerate wide linear concentration ranges for NADH to 2.5 mM (R = 0.9979) and 2.1 mM (R = 0.99849), with detection limits of 4.78 μM and 6.18 μM and sensitivities of 68.24 and 40.21 μA mM−1 cm−2 for the PDAMS/PtNPs/Pt and PMDUS/PtNPs/Pt respectively. In the light of the good results obtained, novel amperometric alcohol biosensors were also successfully prepared with alcohol dehydrogenase (ADH). These devices showed more affinity for methanol than for ethanol, with a wide linear range to 30 mM and sensitivities of 0.957 and 0.756 μA mM−1 cm−2 for the ADH/PDAMS/PtNPs/Pt and ADH/PMDUS/PtNPs/Pt respectively. The oxidation potential of the NADH enzymatically produced was negatively shifted to +0.25 V.