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Ultrasensitive Detection of Biomarkers by Using a Molecular Imprinting Based Capacitive Biosensor
Published on: February 16, 2018
[Highly sensitive detection technology for biological toxins applying sugar epitopes]
1Research Center of Advanced Bionics, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Higashi, Tsukuba 305-8565, Japan. h.uzawa@aist.go.jp
Abstract:
The Shiga toxin is a highly poisonous protein produced by enterohemorrhagic Escherichia coli O157. This bacterial toxin causes the hemolytic uremic syndrome. Another plant toxin from castor beans, ricin, is also highly toxic. The toxin was used for assassination in London. Recently, there were several cases of postal matter containing ricin. Both toxins are categorized as biological warfare agents by the Centers of Disease Control and Prevention. Conventional detection methods based on the antigen-antibody reaction, PCR and other cell-free assays have been proposed. However, those approaches have drawbacks in terms of sensitivity, analytical time, or stability of the detection reagents. Therefore, development of a facile and sensitive detection method is essential. Here we describe new detection methods applying carbohydrate epitopes as the toxin ligands, which is based on the fact that the toxins bind cell-surface oligosaccharides. Namely, the Shiga toxin has an affinity for globobiosyl (Gb(2)) disaccharide, and ricin binds the beta-D-galactose residue. For Shiga toxin detection, surface plasmon resonance (SPR) was applied. A polyanionic Gb(2)-glycopolymer was designed for this purpose, and it was used for the assembly of Gb(2)-chips using alternating layer-by-layer technology. The method allowed us to detect the toxin at a low concentration of LD(50). A synthetic carbohydrate ligand for ricin was designed and immobilized on the chips. SPR analysis with the chips allows us to detect ricin in a highly sensitive and facile manner (10 pg/ml, 5 min). Our present approaches provide a highly effective way to counter bioterrorism.
Insights
New carbohydrate-based detection methods offer sensitive and rapid identification of Shiga toxin and ricin, crucial biological warfare agents. These advanced techniques overcome limitations of conventional assays, enhancing bioterrorism defense capabilities.
Area of Science:
- Biochemistry
- Molecular Biology
- Analytical Chemistry
Context:
- Shiga toxin (produced by enterohemorrhagic Escherichia coli O157) and ricin (from castor beans) are highly toxic proteins categorized as biological warfare agents.
- Conventional detection methods for these toxins, such as antigen-antibody reactions and PCR, face challenges with sensitivity, speed, and reagent stability.
- The development of facile and sensitive detection methods is essential for effective bioterrorism countermeasures.
Purpose:
- To develop novel, sensitive, and rapid detection methods for Shiga toxin and ricin using carbohydrate epitopes as ligands.
- To overcome the limitations of existing toxin detection assays.
- To provide effective tools for countering bioterrorism.
Summary:
- New detection methods utilize carbohydrate epitopes, specifically globobiosyl (Gb(2)) disaccharide for Shiga toxin and beta-D-galactose for ricin, leveraging their natural binding affinities to cell-surface oligosaccharides.
- Surface plasmon resonance (SPR) was employed with custom-designed carbohydrate ligands immobilized on chips (Gb(2)-glycopolymer for Shiga toxin, synthetic ligand for ricin).
- These methods demonstrate high sensitivity (detecting Shiga toxin at low LD50 concentrations) and rapid detection of ricin (10 pg/ml in 5 minutes).
Impact:
- The developed carbohydrate-based SPR assays provide a highly sensitive and facile approach for detecting potent biological warfare agents.
- These methods offer a significant advancement in bioterrorism defense by enabling rapid and accurate identification of toxins.
- The findings pave the way for improved security measures against biological threats through enhanced toxin detection capabilities.
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