Effect of nanostructured metal surface on SEIRA spectra of albumin and nucleic acids

Abstract

Advantages and disadvantages of the usage of different nanostructured gold surfaces, namely, rough gold and colloidal gold in SEIRA (surface enhanced infrared absorption) experiments are discussed. We have studied SEIRA spectra, of biological polymers -DNA and bovine serum albumin. A small enhancement of the IR signal has been registered for multilayers of biopolymers (up to 7 in DNA on rough gold and up to 3 for albumin on colloidal gold) in comparison with small molecules (e. g. up 13 for Gly on rough gold). Alongside of this, we have registered a monolayer of albumin on rough gold. In this case the enhancement was more than 100. The most counspicuons disadvantage registered by us was connected with the influence of the colloidal gold on the DNA conformation. Colloidal gold could change the conformation state of A-DNA inducing the B-A conformation with elements of Z-form. We have found that rough gold does not practically influence the conformation state of DNA in comparison with those on CaF2 substrate.