Supported silver clusters as nanoplasmonic transducers for protein sensing

Transducers for optical sensing of proteins are prepared using cluster beam deposition on quartz substrates. Surface plasmon resonance phenomenon of the supported silver clusters is used for the detection. It is shown that surface immobilisation procedure providing adhesion of the silver clusters to quartz and functionalisation of cluster surfaces for antibody coupling are the key issues for cluster stability and protein detection. Focus was put on these tasks and the processes have been optimised. In particular, conditions for coupling of the antibodies to the clusters are developed providing an enhancement of the plasmon absorption band used for the detection. Atomic force microscopy study allows to suggest that immobilisation of antibodies on silver clusters has been achieved, thus giving a possibility to incubate and detect an antigen of interest. Hence, by applying the developed preparation stages and protein immobilisation scheme the sensing of protein of interest can be assured using a relatively simple optical spectroscopy method.