Microwave studies of insulin as a bio molecule for application in medical diagnostics

Abstract

Consistent increase in type II diabetes cases globally has made quantification of hormones, especially, Insulin a critical requirement in health care sector. Though there are, assay methods available for the purpose due to complexity of these methods, long turnaround time and skilled labor requirement. It is arguable whether these methods will be able to meet the future demand. Thus, the research study presented in this thesis is with the objective to offer an easy alternative to detect and quantify pM concentration of Insulin (a hormone) in HEPES buffer solution using microwave technology. With an orientation to develop a simple and easy to use method from literature review WGM-DR technique was found most suitable for characterization of small sample volume. Therefore, firstly composite WGM-DR system was designed and developed, which was then optimized using MATLAB programming and simulations on CST Microwave Studio. Then accordingly, experimental studies were carried out using a single crystalline sapphire DR with two types of very low cost disposable polycarbonate SHD for different samples of Insulin solutions. Designed and tested composite resonators were found resonating in Ku band of microwave frequency for WGE800 mode. From experimental results it was observed that developed resonators responded approximately in 5 seconds for small perturbation and the measured change in inverse quality factor increased as concentration of Insulin sample loaded on ring of SHD changed from 35 pM to 378.78 pM in 25 mM HEPES buffer solution for a particular volume. Furthermore, corresponding to variation in concentration of Insulin solution, no shift in frequency was observed due to which real part of permittivity was found constant for particular volume with both SHD. But with 0.5 mm ring SHD for 0.8, 1.2 and 1.6 µL volumes, real permittivity seemed decrease with increase in Insulin concentration at higher values. Also, calculated time delay exhibited change in slope of curve as concentration of Insulin increased from 200 pM value for both the SHD’s.