Determination of long-chain aldehydes using a novel quartz crystal microbalance sensor based on a biomimetic peptide

There is an increasingly popular trend aimed at improvement of fundamental metrological parameters of sensors via implementation of materials mimicking biological olfactory systems. This study presents investigation on usefulness of the peptide mimicking HarmOBP7 region as a receptor element of the piezoelectric sensor for selective analysis of long-chain aldehydes. Identification of odorant binding proteins creates new possibilities for design of peptides mimicking binding properties of their volatile compounds. Exploration of OBPs and new peptide sequences capable to effectively bind volatile compounds is necessary to enhance artificial olfaction. For the development of biosensors where simple detection is crucial rather than identification of subsequent metabolic activity, the use of sub-protein components (e.g. ligand-binding regions or synthetic peptides) is still escalating. Bearing all this in mind, a segment of a peptide sequence associated with a specific function of HarmOBP7 (involved in binding the long-chain aldehydes) has been designed, synthesised and immobilised on a piezoelectric transducer. The results of in silico investigations were correlated with the experimental measurements of gas substances. The correlated results confirm a high selectivity of the KLLFDSLTDLKKKMSEC-based sensor with respect to long-chain aliphatic aldehydes including octanal, decanal, undecanal, nonanal and helional. Odorant molecules interact with recognition peptide with specific affinities. The lowest limit of detection, 14 ppm was calculated for nonanal. The results can throw a new light on the possibility of synthetic peptide application as a receptor layer in biosensors in odorants analysis.