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Instrument Detection Chemistry/Mechanism
Currently there are lots of new types of detection chemistry/mechanisms out there, probably too numerous to list, however, here is a short list of the ones I have come across:
- Voltage differential between reference and test probes. Lots of POC devices uses this type of detection system.
- Metal Complex Redox Reaction. Roche uses a organo-Ruthenium complex and when a voltage is applied the complex goes through a series of redox reactions to produce light. It's a little more complicated than the Acridan/Acridinium chemistry, but since you separate the liquid from the reaction vessel, you can get higher sensitivities.
- Acridinium or Acridan esters. Both Siemens and Abbott Laboratories use this type of chemistry on their systems.
- Fluorophores. These can be quite sensitive, however they are subject to lots of artifacts and these types of molecules can be very sticky and give rise to background issues. They also take a longer time to quantitate since they "glow" instead of "flash".
- Alkaline Phosphatase. This is a biological enzyme that removes a phosphate group from an organic molecule. There are organic subrates with attached phosphates that turn color and ones that can actually produce photons (similar to the Acridinium/Acridan molecules). The downside is that it takes time for the enzyme to act on the substrates which delays test results a little.
Now, there are some other detection technologies that I won't go into detail here, but currently, they have not proven to be robust enough for "lab quality" results. Here's a few of them:
- Quantum Dots - ~30 nm particles that exhibit band spectrum behavior.
- Magnetic Resonance
- Vibrational Frequency Changes
- Carbon Microfibers
- Refractive index changes