Macromolecule–semiconductor interfaces: from enzyme immobilization to photoelectrocatalytical applications

The development of hybrid biological–inorganic semi-conductor structures towards biophotoelectrocatalytically active systems is described. The aspect of immobilization is analyzed using the heterodimer reverse transcriptase of the avian myeloblastosis virus (RT AMV), deposited onto step-bunched Si(1 1 1) and the defect-rich layered semiconductor MoTe2. Surface site specific adsorption is observed in high-resolution tapping mode atomic force microscopy (TM-AFM) measurements of AMV RTs on Si and of the RT of human immunodeficiency virus (HIV) 1 by scanning tunnelling microscopy (STM) on MoTe2. Immobilization is described based on DLVO∗ and non-DLVO interactions. Images of the RTs reveal the tertiary structure of the enzymes in good resolution. The origin of the current in constant current STM experiments is attributed to solvation assisted electronic movement in the hydration shell of the proteins. The oxygen reducing enzyme laccase has been deposited on step-bunched Si(1 1 1) and upon illumination of the semiconductor, a photocurrent due to the activation of the enzyme is observed. Routes to further advanced systems in photoelectrocatalysis are outlined.