Real-time and Label-free Monitoring of Biomolecular Interactions within Complex Biological Media Using a Silica Colloidal Crystal Film.

A method capable of real-time and label-free monitoring of biomolecular interactions within whole blood, with-out any sample separation and label process is described. This was accomplished using silica colloidal crystal (SCC) films, three-dimensionally ordered silica particle arrays whose interference effect is a function of their optical thickness, as interfer-ence sensitive substrates. Interaction between immunoglobulins G (IgG) and protein A from staphylococcus aureus (SPA) con-jugates with changes in optical thickness of SCC films was monitored spectroscopically. Successful detection of IgG was achieved in buffer and whole blood. This system constitutes a simple label-free analysis showing great potential in monitoring interactions between biomolecules in complex biological media.