Dear Sir. Concerning your issue about the best solvent and monomer to dissolve Triiodothyronine (T3) to prepare MIP. Molecular imprinting technology (MIT) is an emerging, powerful tool for sample extraction and chromatography. First used for solid-phase extraction, molecularly imprinted polymers (MIPs) are also effective chromatographic phases for the separation of isomers and structurally related molecules. In recent years, a number of analytical methods utilising MIT have been applied for the analysis of residues in food, and existing methodologies have been improved. The 3,3¢,5-Triiodo-L-thyronine  (T3) product is soluble in 4 M NH4OH in methanol (5 mg/ml). It is also soluble in NaOH. For use in cell culture, a 20 mg/ml stock solution can be prepared in the following manner: add 1.0 ml of 1.0 N NaOH to 1 mg, gently swirl to dissolve the powder and add 49 ml of sterile medium. The general working range is 0.02–50 ng/ml. I think the following below links and the attached files may help you in your analysis:

https://www.sigmaaldrich.com/content/dam/sigma-aldrich/docs/Sigma/Product_Information_Sheet/1/t2877pis.pdf

https://www.degruyter.com/downloadpdf/j/chem.2012.10.issue-3/s11532-012-0016-3/s11532-012-0016-3.pdf

Thanks