Retrospective chemical analysis of tree rings by means of the scanning electrochemical microscopy with shear force feedback
Abstract
The imaging capabilities of scanning electrochemical microscopy (SECM) were used to characterise an enzyme-modified wood surface. To avoid the convolution of effects from local electrochemical properties of the surface and variations in the distance between the tip electrode and the surface owing to the roughness of the sample, a shear force constant-distance mode was integrated into the SECM set-up. In this way, we succeeded in simultaneously measuring the topography of the wood sample and mapping the distribution of the enzymatic activity along the tree or annual rings. Glucose oxidase was used to label the amino-groups present in the wood sample. Its enzymatic activity was monitored by amperometric detection of H2O2 using the SECM in collector mode.