Expeditious solutions: Immunochromatography's Impact in Forensic Science

Article by By Kushi

Immunochromatography is the method of strip test to depict body fluids such as blood, as well as saliva, semen and urine. Immunochromatographic assay, a simple device intended to detect the presence or absence of a target analyzer, that is antigen or antibodies, in the sample without the need of specialized and costly equipment.

 

Principle of Immunochromatographic test.

It works on the principle of antigen-antibody interaction. Specifically, it involves the binding of a target antigen in a sample to specific antibodies immobilized on a chromatographic strip. This interaction leads to the formation of a visible signal, usually a colored line, indicating the presence of the target molecule in the sample.

 

Components of Immunochromatographic test.

1. Sample pad: This acts as a sponge to absorb excess fluid and once soaked the fluid is moved to the next element.
2. Conjugate pad: This contains dried bio active particles.Its material should swiftly release labeled conjugate upon contact with the sample, ensuring stability throughout the strip's lifespan.
3. Nitrocellulose Membrane: Critical for sensitivity, this membrane supports test and control lines. An ideal membrane minimizes nonspecific adsorption, and its wicking rate influences assay sensitivity.
4. Absorbent Pad: Located at the strip's end, it acts as a sink, maintains liquid flow over the membrane, and prevents sample backflow. Its capacity affects assay results.

 

Test result interpretation are as follows:

A clean line in the control zone and the test area on the membrane indicates a positive result. A single line in the control zone indicates a negative outcome. A single line in the test region with no corresponding control line is indicated as invalid.

 

Advantages and disadvantages of this technique.

Advantages:

●      Provide fast turnaround times, enabling quick decision-making and patient management.

●      Low cost.

●      Stability over a wide range of environmental conditions.

●      Simple and user friendly.

●      Requirement of a small amount of samples.

Disadvantages:

●      They may miss detecting low levels of antigens or antibodies, leading to potential false-negative results.

●      Interpretation can be subjective, affecting result accuracy.

●      Typically, they can only detect one analyte at a time, limiting their comprehensive diagnostic capability.

●      Some tests have a short shelf life, requiring careful storage and inventory management.

●      Maintaining consistent quality across batches can be challenging, affecting reliability.

 

Conclusion

Immunochromatographic tests are invaluable tools in forensic science. Their spontaneous and accurate results on biological fluids collected in the crime scenes can help to resolve criminal cases. Their ease of use and reliability of this test have become indispensable components in forensic investigations. Enhancing the efficiency and effectiveness of law enforcement agencies worldwide.