چكيده به لاتين
In the past decades, the detection of living organisms that exist on the surface of plants and animals, especially those that are harmful and pathogenic, is of great importance, for this reason, tools are needed to identify these substances. There are different methods, but the PCR method and biosensor are more suitable and accurate than other methods and are used to detect and identify DNA, bacteria, viruses, etc. Biosensors are more accurate and cheaper than PCR testing. Reference genes are used to generate reliable results from diagnostic tests, including PCR. These genes are stable and have a fixed number of copies. 18S rRNA gene is an example of these reference genes. Fiber optic sensors have made significant progress in the field of biosensors in the past decades, and one of the most popular types of sensors are tapered fiber optic sensors. Also, due to advantages such as high accuracy in measurement, the ability to use different environments without disturbing the system under investigation, cheapness, etc., they have received a lot of attention. This thesis deals with the introduction and construction of the tapered fiber optic biosensor for the detection of 18S rRNA gene. By injecting PBS buffer, different concentrations of the desired probe, random target DNA, and the desired target DNA using a spectrophotometer (OSA) and a broadband source, the output spectrum of the tapered fiber optic biosensor is taken after the injection of each of the said materials, and the effect of change and displacement The output spectrum is examined and compared in the presence of said materials. According to the results of the experiment, the fixation of the probe followed by the target DNA on the tapered fiber optic surface and the tapered fiber optic biosensor has been successfully made and the biosensor has been able to detect the 18S rRNA gene. Also, the manufactured biosensor, because the amount of its spectrum shift, after the injection of random target DNA was 0.24 nm, and this value is very small compared to the maximum amount of shift of its spectrum, which was 8.12 nm, which was created after the injection of target DNA, is a biosensor. It is exclusive. The sensitivity of the biosensor made after the injection of target DNA 8.1208 ×10^(-4)nm/μM has been calculated. The developed biosensor can be used as an accurate, sensitive and cheap system to identify living organisms or their dependent components.
