BACKGROUND: Noble metal nanocrystals with high index facets have received much attention because of their enhanced catalytic performance. This paper describes the trisoctahedral gold nanocrystals (TOH Au NCs) with {441} high-index facets for the modification of a screen printed carbon electrode. RESULTS: TOH Au NCs enclosed high index facets provided high sensitivity as well as detecting H2O2 and NADH with a lower detection limit of 0.05 mmol L-1 at a signal-to-noise ratio of 3. The values of sensitivity for the disposable electrochemical sensors to H2O2 andNADHwere calculated to be 11.1 and 0.74 mu A mmol L-1 cm(2) at the working potentials of -0.2 and 0.2 V, respectively. In particular, the extremely small loading amount of TOH Au NCs (5.12x10(-5) gcm(-2)) shows unusually high sensing performance for the electrochemical reactions of H2O2 and NADH. CONCLUSIONS: Our discovery of the reaction mechanism in TOH Au NCs provides a new understanding of the interaction in Au-modified disposable electrochemical sensors, and gives a new way to control the interaction between gold and the support as well as electrocatalytic activities. Thus, TOH Au NCs as electrocatalyst can offer quite promising signal transduction in the disposable electrochemical sensors for biological and environmental application. (C) 2017 Society of Chemical Industry