Imprinted Membranes for Sensor Technology:  Opposite Behavior of Covalently and Noncovalently Imprinted Membranes

New types of polymeric membranes with molecular recognition sites for l-phenylalanine (l-Phe), 6-amino-1-propyluracil (APU), atrazine, and sialic acid have been prepared using the molecular imprinting approach. The membrane synthesis includes radical polymerization of ethylene glycol dimethacrylate (EDMA) and functional monomers in the presence of a template. Several compounds(diethylamino)ethyl methacrylate (DEAEM), methacrylic acid (MAA), allylamine (AA), and (4-vinylphenyl)boronic acidwere as functional monomers, which are able to form covalent, ionic, or hydrogen bonds with the corresponding templates. Template specific conductometric sensors, based on these polymers, were constructed and studied. An opposite response of covalently versus noncovalently imprinted membranes was demonstrated and discussed in detail. Sensors based on these materials could detect the target molecules at concentrations of 1−50 μM in solution. The high specificity and stability of these imprinted membranes render them promising alternatives to enzymes, antibodies, and other natural receptors usually used in sensor technology.