Uniform-sized molecularly imprinted polymers for 2-arylpropionic acid derivatives selectively modified with hydrophilic external layer and their applications to direct serum injection analysis

Uniform-sized molecularly imprinted polymers (MIPs) for (S)-naproxen and -i buprofen selectively modified with hydrophilic external layer, restricted a ccess media (RAM)-MIPs,have been prepared. First, the MIP for (S)naproxen o r -ibuprofen was prepared using 4-vinylpyridine and ethylene glycol dimetha crylate as a functional monomer and cross-linker, respectively, by a multis tep swelling and thermal polymerization method. Next, a 1:1 mixture of glyc erol monomethacrylate and glycerol dimethacrylate was used for hydrophilic surface modification, and it was added directly to the MIP for (S)-naproxen or -ibuprofen 4 h after the start of molecular imprinting. The obtained RA M-MIP material for (S)-naproxen or -ibuprofen was applied for direct serum injection assays of the drug by a column-switching system, consisting of a RAM-MIP material and conventional C18-silica column, However, leakage of th e imprint molecule prevented accurate and precise assays of the drug. This problem has been overcome by using the RAM-MIP for (S)-naproxen for the ass ays of ibuprofen in rat plasma. The optimized column-switching system was a pplied successfully to the assay of ibuprofen in rat plasma after oral admi nistration.