Immobilisation of proteins by atomic clusters on surfaces

In this Opinion article, we describe a nanotechnology-based approach to immobilize and orient proteins onto surfaces using atomic clusters prepared by physical methods. This is relevant to future protein biochips where dilute arrays of protein binding sites, each designed to immobilize no more than one protein molecule, would be ideal. In the case of a surface consisting of size-selected atomic gold clusters, proteins containing free cysteine residues can chemisorb directly to the bare cluster surface, thus effecting oriented immobilisation. The selection of atomic gold clusters in the size range 1-100 atoms (< 3 nm in diameter) is intended to ensure that, typically, only one protein can bind directly to the cluster surface. These nanoclusters of a smaller size scale than that of the protein present minimal contact between the gold and the protein, and hence imply a reduced risk of protein denaturing compared with gold films or extended surfaces.