Glycosylated protein-functionalized gold nanoparticle-based detection of heat-labile enterotoxin from complex samples

• Published in: Sensors and actuators. B, Chemical Vol. 322; p. 128640
• Main Authors: Selvaprakash, Karuppuchamy, Chen, Yu-Chie
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier B.V 01.11.2020; Elsevier Science Ltd
• Subjects: Binding; Chicken egg whites; Colorimetric; Colorimetry; E coli; Enterotoxigenic Escherichia coli; Galactosides; Glycoproteins; Gold; Heat-labile enterotoxin; Ions; Lactose; Maillard reaction; Mass spectrometry; Nanoparticles; Ovalbumin; Proteins; Glycoproteins; Heat-labile enterotoxin; Chicken egg whites; Enterotoxigenic Escherichia coli; Colorimetric
• ISSN: 0925-4005; 1873-3077
• DOI: 10.1016/j.snb.2020.128640

[Display omitted] •A new colorimetric-based sensing method against heat labile enterotoxins (LT) produced by enterotoxigenic Escherichia coli is explored.•Chicken ovalbumin decorated with additional galactosides is used as a reducing agent for generating functional gold nanoprobes.•The generated gold nanoprobes can be used to specifically target LT B chain (LT-B) from complex samples.•The presence of trace LT-B with the concentration of ≥31 nM in samples is able to be distinguished visually.•The limit of detection against LT-B is ∼4 nM when mass spectrometry is used as a detection tool. Enterotoxigenic Escherichia coli O78:H11 is a food-borne pathogen that can cause “traveler’s diarrhea.” The pathogenicity of E. coli O78:H11 is attributed to the expression of enterotoxin, particularly heat-labile enterotoxin (LT). LT is a pentameric protein composed of one A and five B subunits. The B subunit of LT (LT-B) contains the binding moieties toward Galβ(1→4)Glc. Chicken ovalbumin (COA) is a glycoprotein composed of Galβ(1→4)Glc termini and abundant (∼54%) in chicken egg white (CEW) proteins. COA decorated with ∼17 additional galactosides, obtained by reacting CEW proteins with lactose (Galβ[1→4]Glc) through the Maillard reaction, was used as a probe molecule against LT-B. The generated CEW derivatives, mainly dominated by glycated COA, were immobilized on gold nanoparticles (Au@Lac-CEW NPs) by reacting with aqueous tetrachloroaurate through one-pot reactions. Au@Lac-CEW NPs had a good binding affinity toward LT-B with a dissociation constant of ∼1.86 × 10−7 M. A colorimetric method by using Au@Lac-CEW NPs as sensing probes against LT-B (≥31 nM) that can be visualized was demonstrated. The limit of detection against LT-B was reduced to ∼4 nM as revealed by matrix-assisted laser desorption/ionization mass spectrometry as a detection tool.