Label-free detection of biomolecular interaction — DNA — Antimicrobial peptide binding

Interest to biosensors employing surface or localized plamons is rapidly growing both in research and clinical application. Plasmon-based sensors offer extremely high sensitivity, only second to the optical detection techniques involving fluorescent labeling, but without the necessity to label the molecule. In particular, surface plasmon resonance (SPR) sensors have been already demonstrated suitable for food-safety control, label-free screening for various disease markers in bodily fluids, as well as for real-time continuous monitoring of drug levels in intensive care environment. We envisage such sensors to be integrated into wireless communication infrastructure for e-health and environmental monitoring applications. One of the important threats in hospital environment is multi-resistant organisms that are not affected by common antibiotics. The growth of multi-resistant infections spurred an interest in Antimicrobial peptides that are active against broad range of infections including bacteria, fungi and viruses and were shown to be capable of treating multi-resistant infection either alone or in combination with the conventional antibiotics. In this paper, we demonstrate an application of plasmon based biosensors to the study of the interaction of Antimicrobial peptide IL4 and DNA. Our results indicate high affinity binding between IL4 and DNA thereby preventing DNA replication and eventually killing the affected cell. We speculate that this is common for a large class of Antimicrobial peptides and can be a key point explaining their broad range of activity against various pathogens.