Lateral-flow chromatographic and flow-through tests offer fast detection of critical components for use in point-of-care testing
The key to lateral-flow chromatographic and flow-through tests is the ability to covalently attach antibodies to intensely colored, nanometer particles. Gold sols that bind ligands through a sulfur bond have proved highly successful for this application. For optimal binding of the antibody or protein while retaining a high degree of specific activity, the pH of the gold sol must be adjusted to slightly above the iso-electric point of the coating antibody or protein. This is done through a series of pH titrations with the provided buffers. Varying amounts of buffers are added to the gold to create a pH 5-11 range (pH charts are includes in the kit). Next, antibody or protein is added and after 30 minutes the reaction is stopped. BioAssay Works® developed a convenient Gold-in-a-Box™ kit to give researchers a reliable method for quickly determining the optimal coating range for an antibody or soluble protein (in less than 50 minutes).
Gold-in-a-Box™ is a gold conjugation kit that works without boiling gold or centrifuging conjugate. The kit contains BioAssay Works' proprietary gold sols, Naked Gold®, and all the buffers, blocking solution and protocol for optimal coating. In addition, the company supplies drying buffer and an optional treated polyester conjugate pad ribbon. Instructions for using the kit can be viewed at http://bioassayworks.com/goldbox.html.
[See titrated gold sol image below, along with caption for the image.]
Pictured above is titrated gold sol and an evaluation antibody demonstrating the BioAssay Works buffer determining optimal-coating conditions for antibody or protein. As seen in the photo, the combination of gold sol, buffers and the addition of an antibody of interest will produce a reaction indicating the isoelectric point of the antibody or protein of interest.
[See below for another image, along with a caption]
The example pictured above demonstrates microwell-ELISA-like sensitivity on a rapid, lateral-flow platform. Pictured is an Ecoli 0157:H7 assay that achieves an impressive 10^3 level of sensitivity. Traditional rapid assays have a detection limit of 1-5 ng/ml. BioAssay Works' Gold-in-a-Box product has demonstrated that a patented C-FLAT® assay platform will permit detection levels of 50 to 250 pg/ml.
[See below for a picture of the product.]
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