I want to develop a sensor. I am confused because some sources say I have to add a capture antibody and then a detection antibody. While searching the products I can only find anti-marker Ab and marker Ag. Are these the same? Where can I find capture antibodies?
Hello Patricia,
I am not completely sure what you are aiming to do here, so I am making some guesses!
There is a lot of interest in developing a wide range of biosensors for a variety of applications, especially for medical diagnosis and biomedical research. Your question relates to the particular type of biosensor that uses immunological principles, in which there is a highly specific process involving an 'antibody' recognising a particular 'antigen'.
One important application currently is in the detection of a so-called "bio-marker" which is a molecule that indicates the presence of a particular disease or condition. In this case, the molecule could be referred to as the "marker antigen", and it could be detected by using a specific antibody to capture that marker antigen.
A simple example could be that we want to detect molecule X which indicates, is a Biomarker for, cancer. We would call this "marker antigen X", or AgX. Now we need an antibody that can specifically recognise and capture AgX, and this antibody will be called AbX. Then we need to think of what kind of sensor will be constructed, the main options being, electrochemical, optical, or piezoelectric.
One kind of immunosensor to detect the biomarker X could be an optical device. The antibody, AbX, would be attached to the surface of a thin gold film deposited on the surface of a glass prism. When marker X arrives at this gold surface it will be captured by AbX. This process will be highly selective for AgX. A a result of the binding between the antibody and the antigen (the marker) there could be a change I refractive index at the glass/gold surface which can be measured.
Once you know molecule X you can either buy or make a suitable antibody, AbX.
I have made many assumptions here so there is a chance I have misunderstood what you are trying to do. Nevertheless, the basic principles of immunosensors I think will apply to the kind of sensor that I think you are trying to make.
Finally, I should say that the above is only the very simplest kind of immunosensor and there are many problems to be overcome with this approach, and this requires a much more complex solution.
Good luck.
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