A robust sensor platform for label-free detection of anti-Salmonella antibodies using undiluted animal sera

Abstract

We present a portable and easy-to-use biosensor platform, allowing for label-free detection of diagnostic markers in undiluted animal serum. Exemplarily, this is shown for the detection of anti-Salmonella antibodies. 1-lambda-Reflectometry was used as detection method, making the new biosensor platform portable, cheap, and robust. As recognition elements, lipopolysaccharides (LPSs) from Salmonella typhimurium bacteria were immobilized as sensitive layer on the transducer to carry out serological tests via a direct assay format. For this purpose, a new surface preparation protocol has been worked out allowing for immobilization of the LPS via hydrophobic interactions. It has been shown that results obtained by 1-lambda-Reflectometry are equivalent to those obtained by the non-portable Reflectometric Interference Spectroscopy setup. The new sensor platform was calibrated in both matrices, buffer and undiluted serum. Good sensitivity, selectivity and intra chip reproducibility have been observed. Furthermore, inter chip reproducibility was examined and recovery rates were found to be between 99 and 117% in undiluted serum.

Analytical evaluation of sensor measurements

“…Direct assays are preferable, but can be realized only for a few biomarkers. Another application is the detection of antibodies against Salmonella [18]. Frequently, sandwich assays are used.…”

“…One can optimize the result by changing the area of the curve to be fitted and the range of the fit [19]. A further discussion of the biomolecular interaction analysis with limits of and comments regarding black box programs can found in [18,[20][21][22].…”

Anabel: An Online Tool for the Real-Time Kinetic Analysis of Binding Events

“…For label-free binding measurements, the most prominent techniques are surface plasmon resonance (SPR; from Biacore) 1 , biolayer interference (BLI; from FortéBio), 2 and single color reflectometry (SCORE; from Biametrics). [3][4][5][6][7] Yet, every company and their methods feature different exclusive analysis software which are typically hard-wired into their own devices (eg, Octet software and BIAevaluation). 8,9 Quite often, the device has to be registered to download and use the corresponding analysis software.…”

Diagnostic performance study of an antigen microarray for the detection of antiphospholipid antibodies in human serum

“…1-λ-reflectometry The 1-λ-reflectometry setup was described by Ewald et al [17]. In our system, the flow cell was connected to a tubing pump (ISMATEC, IDEX Health & Science, Wertheim, Germany) that allows for manual control of the injection speed.…”