Surface modified microfiltration membranes with molecularly recognising properties

Polyvinilidene fluoride (PVDF-phob and PVDF-phil) and polyethersulfone (PES) microfiltration membranes were surface modified with a thin layer of molecular imprinted polymer (MIP). This material is selective to adenosine 3:5-cyclic monophosphate (cAMP) via photoinitiated copolymerisation of 2-(dimethylamino)ethyl methacrylate as a functional monomer and trimethylopropane trimethacrylate as a cross-linker in the presence of cAMP in ethanol/water solutions. The specific and non-specific template binding of MIP during filtration of aqueous solutions of cAMP was studied for membranes with different degrees of modification. It was concluded that the ability of MIP membranes to bind cAMP is a result of both the specific size and shape of recognising sites in addition to the correct position of the functional groups involved in the template binding through ionic and hydrogen binding interactions. Profile imaging atomic force microscopy and scanning electron microscopy were used to visualise surfaces and cross-sections of MIP membranes. The main advantages of this approach for MIP membrane preparation are very fast MIP layer synthesis and the possibility to obtain MIP composite membranes by controlled deposition on different kind of polymeric supports. Atomic force microscopy in conjunction with the coated colloid probe technique has been used to measure interactions between a silica sphere coated with imprinted polymer and porous supports.