Evaluation of Linkers’ Influence on Peptide-Based Piezoelectric Biosensors’ Sensitivity to Aldehydes in the Gas Phase

Abstract

Recent findings qualified aldehydes as potential biomarkers for disease diagnosis. One of the possibilities is to use electrochemical biosensors in point-of-care (PoC), but these need further development to overcome some limitations. Currently, the primary goal is to enhance their metrological parameters in terms of sensitivity and selectivity. Previous findings indicate that peptide OBPP4 (KLLFDSLTDLKKKMSEC-NH2) is a promising candidate for further development of aldehyde-sensitive biosensors. To increase the affinity of a receptor layer to long-chain aldehydes, a structure stabilization of the peptide active site via the incorporation of different linkers was studied. Indeed, the incorporation of linkers improved sensitivity to and binding of aldehydes in comparison to that of the original peptide-based biosensor. The tendency to adopt disordered structures was diminished owing to the implementation of suitable linkers. Therefore, to improve the metrological characteristics of peptide-based piezoelectric biosensors, linkers were added at the C-terminus of OBPP4 peptide (KLLFDSLTDLKKKMSE-linker-C-NH2). Those linkers consist of proteinogenic amino acids: group one: glycine, L-proline, L-serine, and non-proteinogenic amino acids; and group two: β-alanine, 4-aminobutyric acid, and 6-aminohexanoic acid. Linkers were evaluated with in silico studies, followed by experimental verification. All studied linkers enhanced the detection of aldehydes in the gas phase. The highest difference in frequency (60 Hz, non-anal) was observed between original peptide-based biosensors and ones based on peptides modified with the GSGSGS linker. It allowed evaluation of the limit of detection for non-anal at the level of 2 ppm, which is nine times lower than that of the original peptide. The highest sensitivity values were also obtained for the GSGSGS linker: 0.3312, 0.4281, and 0.4676 Hz/ppm for pentanal, octanal, and non-anal, respectively. An order of magnitude increase in sensitivity was observed for the six linkers used. Generally, the linker’s rigidity and the number of amino acid residues are much more essential for biosensors’ metrological characteristics than the amino acid sequence itself. It was found that the longer the linkers, the better the effect on docking efficiency.

Assessment of Cellulose Nanofiber-Based Elastase Biosensors to Inflammatory Disease as a Function of Spacer Length and Fluorescence Response

“…Serine proteases such as those described above have a central role in a wide array of inflammatory diseases that overlap in their pathology with chronic wounds . Whereas previous studies for protease detection have shown varying degrees of affinity with dependence on linker length, − to date, no studies have addressed the role of spacer length and design in the context of biosensor to nanocellulose surface relationship. Prior studies utilized long-chain (up to 10 000 MW) polyethylene glycol (PEG) repeat units or short peptide units to prepare self-assembled monolayers for analyte detection on gold surfaces, typically by surface plasmon resonance or quartz crystal microbalance for piezoelectric response. , In a separate example, an electrochemical assay used a gold substrate and an eight-carbon aliphatic linker, or a PEG moiety containing 2–12 repeat units, to detect bovine serum albumin (BSA) and trypsin.…”

“…Prior studies utilized long-chain (up to 10 000 MW) polyethylene glycol (PEG) repeat units or short peptide units to prepare self-assembled monolayers for analyte detection on gold surfaces, typically by surface plasmon resonance or quartz crystal microbalance for piezoelectric response. 27 , 28 In a separate example, an electrochemical assay used a gold substrate and an eight-carbon aliphatic linker, or a PEG moiety containing 2–12 repeat units, to detect bovine serum albumin (BSA) and trypsin. In that context, this study employs cotton cellulose as a nanocellulose-based substrate for both neutrophil and pancreatic elastases.…”