Molecularly imprinted polymer thin films on quartz crystal microbalance using a surface bound photo-radical initiator

The present work aims to study preparation of thin MIP films on a gold-coated QCM resonator in a well-controlled and reproducible manner. A surface-bound photo-radical initiator was used to furnish an imprinting polymerization in a dilute solution of template, functional monomer and crosslinker. Prior to polymerization, the photo-initiator was covalently coupled to a self-assembled monolayer of carboxyl terminated alkanethiol on a gold surface. With this approach we were able to control the thickness of the MIP film to be below 50 nm, where the selective recognition of target analytes can be easily detected by the underlying quartz crystal resonator. When used in a flow injection analysis system, the assembled QCM sensor generated a large frequency change (>30 Hz) upon encountering a small amount of analyte (0.19 mM). The sensor had a very short response time (<1 min), and displayed certain chiral selectivity towards the original template, (S)-propranolol at a concentration higher than 0.38 mM in aqueous solution.