A simple and flexible model for laser-driven antibody – gold surface interactions: functionalization and sensing

Interactions between bio-molecules and between substrates and bio-molecules is a crucial issue in physics and applications to topics such as biotechnology and organic electronics. The efficiency of bio- and mechanical sensors, of organic electronics systems and of a number of other devices critically depends on how molecules are deposited on a surface so that these acquire specific functions. Here we tackle this vast problem by developing a coarse grained model of bio-molecules having a recognition function, such as antibodies, capable to quantitatively describe in a simple manner essential phenomena: antigen-antibody and antibody substrate interactions. The model is experimentally tested to reproduce the results of a benchmark case, such as (1) gold surface functionalization with antibodies and (2) antibody-antigen immune-recognition function. The agreement between experiments and model prediction is excellent, thus unveiling the mechanism for antibody immobilization onto metals at the nano-scale in various functionalization schemes. These results shed light on the geometrical packing properties of the deposited molecules, and may open the way to a novel coarse-grained based approach to describe other processes where molecular packing is a key issue with applications in a huge number of fields from nano- to bio- sciences.