Simultaneous detection of Escherichia coli O157:H7, Salmonella spp. and Listeria monocytogenes with an array-based immunosorbent assay using universal protein G-liposomal nanovesicles.

A novel universal reagent for immunoassays, protein G-liposomal nanovesicles has been developed and successfully used in an immunomagnetic bead sandwich assay for the detection of Escherichia coli O157:H7 [C.-S. Chen, A.

Investigation of NeutrAvidin-tagged liposomal nanovesicles as universal detection reagents for bioanalytical assays.

Ligand-tagged liposomes, obtained by covalent conjugation of ligands to the liposomal surface, have been widely used as detection reagents in bioanalytical assays. A non-covalent conjugation method where IgG was attached to protein G-tagged liposomes has been recently utilized. To enlarge the application of non-covalent methods to a greater variety of ligands, including peptides, proteins, and nucleic acids, we developed and optimized a new method for the preparation of NeutrAvidin-tagged liposomes with subsequent attachment of biotinylated ligands.

Protein G-liposomal nanovesicles as universal reagents for immunoassays.

To improve the antigen-binding activity of liposome-coupled antibodies and to develop universal liposomal nanovesicles for immunoassays, protein G was conjugated to dye-loaded liposomal nanovesicles for the preparation of immunoliposomes. Sulfosuccinimidyl-4-(N-maleimidomethyl) cyclohexane-1-carboxylate (sulfo-SMCC), a heterobifunctional cross-linker, was used to modify protein G for conjugation to the liposomal nanovesicles. Liposome immunosorbent assays were used to evaluate the binding ability of protein G after sulfo-SMCC modification, to optimize the protein G density on the liposome surface and to determine the amount of IgG binding to the protein G-liposomal nanovesicles.

Human pathogenic Cryptosporidium species bioanalytical detection method with single oocyst detection capability.

A bioanalytical detection method for specific detection of viable human pathogenic Cryptosporidium species, C. parvum, C. hominis, and C.

Detection of cholera toxin in seafood using a ganglioside-liposome immunoassay.

Microbiological contamination of foods continues to be a major concern in public health. Biological toxins are one class of important contaminants that can cause various human diseases. Outbreaks related to contamination by biological toxins or toxin-producing microorganisms have made it extremely important to develop rapid (approximately 20 min), sensitive and cost-effective analytical methods.

Peanut Allergy, Peanut Allergens, and Methods for the Detection of Peanut Contamination in Food Products.

  Attention to peanut allergy has been rising rapidly for the last 5 y, because it accounts for the majority of severe food-related anaphylaxis, it tends to appear early in life, and it usually is not resolved. Low milligram amounts of peanut allergens can induce severe allergic reactions in highly sensitized individuals, and no cure is available for peanut allergy. This review presents updated information on peanut allergy, peanut allergens (Ara h1 to h8), and available methods for detecting peanuts in foods.

Application of ganglioside-sensitized liposomes in a flow injection immunoanalytical system for the determination of cholera toxin.

Cholera, an acute infectious disease associated with water and seafood contamination, is caused by the bacterium Vibrio cholerae, which lives and colonizes in the small intestine and secretes cholera toxin (CT), a causative agent for diarrhea in humans. Based on earlier lateral flow assays, a flow injection liposome immunoanalysis (FILIA) system with excellent sensitivity was developed in this study for the determination of CT at zeptomole levels. Ganglioside (GM1), found to have specific affinity toward CT, was inserted into the phospholipid bilayer during the liposome synthesis.

Development of a competitive liposome-based lateral flow assay for the rapid detection of the allergenic peanut protein Ara h1.

A competitive lateral flow assay for detecting the major peanut allergen, Ara h1, has been developed. The detector reagents are Ara h1-tagged liposomes, and the capture reagents are anti-Ara h1 polyclonal antibodies. Two types of rabbit polyclonal antibodies were raised either against the entire Ara h1 molecules (anti-Ara h1 Ab) or against an immunodominant epitope on Ara h1 (anti-peptide Ab).

Development of an immunomagnetic bead-immunoliposome fluorescence assay for rapid detection of Escherichia coli O157:H7 in aqueous samples and comparison of the assay with a standard microbiological method.

The objective of this study was to develop and optimize a protocol for the rapid detection of Escherichia coli O157:H7 in aqueous samples by a combined immunomagnetic bead-immunoliposome (IMB/IL) fluorescence assay. The protocol consisted of the filtration or centrifugation of 30- to 100-ml samples followed by incubation of the filter membranes or pellet with anti-E. coli O157:H7 immunomagnetic beads in growth medium specific for E.

Modified immunoliposome sandwich assay for the detection of Escherichia coli O157:H7 in apple cider.

Detection of Escherichia coli O157:H7 in fruit juices such as apple cider is necessary for diagnosis of infection and epidemiological investigations. However, inhibitors in the apple cider, such as endogenous polyphenols and acids, often decrease the sensitivity of PCR assays and immunoassays, thus routinely requiring laborious cell separation steps to increase the sensitivity. In the current study, polyethylene glycol (PEG)-derivatized liposomes encapsulating sulforhodamine B were tagged with anti-E.

Ganglioside-liposome immunoassay for the detection of botulinum toxin.

A rapid and highly sensitive receptor immunoassay for botulinum toxin (BT) has been developed using ganglioside-incorporated liposomes. Botulism outbreaks are relatively rare, but their results can be very severe, usually leading to death from respiratory failure. To exert their toxicity, the biological toxins must first bind to receptors on the cell surface, and the trisialoganglioside GT1b has been identified as the cell receptor for BT.

Ganglioside-liposome immunoassay for the ultrasensitive detection of cholera toxin.

An extremely sensitive bioassay has been developed for cholera toxin (CT) detection, using ganglioside-incorporated liposomes. Cholera is a diarrheal disease, often associated with water or seafood contamination. Ganglioside GM1 was used to prepare the liposomes by spontaneous insertion into the phospholipid bilayer.

Detection of fumonisin B1: comparison of flow-injection liposome immunoanalysis with high-performance liquid chromatography.

Fumonisins are secondary metabolites of the fungus Fusarium moniliforme, a common mycotoxin in corn, which are known to cause cancer in a number of experimental animals and have been linked to human esophageal cancer in China and South Africa. A high-performance liquid chromatographic (HPLC) method is currently the most widely used method for the quantitative determination of fumonisins. This method utilizes precolumn derivatization with o-phthaldialdehyde, isocratic elution, and fluorescence detection.

On the Applications of Discontinuous Bessel Integrals to Chronoamperometry.

Discontinuous Bessel integrals are applied to a boundary value problem related to chronoamperometry, with zero concentration at the disk satisfied on the average and the zero flux at the shroud satisfied approximately only. Current functions are derived, series expansion at long time and asymptotic expansion at short times are given. Plots of numerical calculations of current functions are presented.

Near Infrared Spectrophotometric Method for the Determination of Hydration Numbers.

The 980 m absorption band of water is employed in a new method for the determination of hydration numbers. The decrease in the concentration of "free" water is calculated from the change in absorbance resulting on the addition of an electrolyte. Data are given for chromic chloride and nitrate salts in water-methanol solutions, and an extrapolation is made to give the hydration number in pure water.