An international team has developed a mid-infrared biosensor based on a novel multi-resonant metasurface. This, they say, is the first to be able to discriminate between multiple analytes in heterogeneous biological samples non-destructively, in real-time, and with high sensitivity. [Rodrigo, D. et al. Nature Commun. (2018); DOI: 10.1038/s41467-018-04594-x]

The analysis of lipids, proteins, and nucleic acids and the way these biomolecules interact in mixed biological samples underpins medical diagnostics as well as biomedical research into the molecular mechanisms of disease processes. Unfortunately, the label-free techniques available to medicine and research cannot necessarily cope with different proteins inserting into the cell membrane for instant, the associated release of chemicals, and disruption processes that occur. This means that research usually requires several experiments to isolate different processes. A multitasking biosensor with high sensitivity and selectivity would greatly improve and accelerate research.

Researchers at École Polytechnique Fédérale de Lausanne, Switzerland and their colleagues in the USA have now introduced just such a biosensor, which works by accessing the distinct chemical fingerprints associated with different proteins, lipids, peptides, and other biomolecules. This will allow researchers to monitor simultaneously and independently the various target biomolecules and so observe their interaction dynamics more clearly than before.

The researchers have now demonstrated that they can spectroscopically resolve the interaction of biomimetic lipid membranes with different peptides as well as the dynamics of cargo release from cellular vesicles. Such processes are not addressable with standard label-free analytical techniques, no matter how sensitive the technique.

Importantly, the team has shown that their multi-tasking biosensor can resolve interactions between lipid membranes and toxic peptides such as melittin, which can punch holes in such membranes. Moreover, it can do so in both supported membranes and in surface-tethered vesicles loaded with neurotransmitter molecules. This means that it is possible to monitor the melittin-induced membrane disruption and neurotransmitter cargo release. This is an important proof of concept experiments that could, the team suggests, pave the way to using such biosensors to investigate the molecular mechanisms that underlie human disease where pore formation and membrane disruption occur. Examples of such diseases where these processes are induced by protein aggregation include the increasingly familiar neurodegenerative diseases such as Alzheimer's and Parkinson's disease.

The team suggests that their approach could lead to interesting new applications in diverse fields ranging from fundamental biology to pharmaceutical research and development.

David Bradley blogs at Sciencebase Science Blog and tweets @sciencebase, he is author of the popular science book "Deceived Wisdom".