Laser-Grafted Molecularly Imprinted Polymers for the Detection of Histamine from Organocatalyzed Atom Transfer Radical Polymerization

Abstract

To be applicable to in vivo measuring, molecularly imprinted polymer (MIP) based sensors need to have high reproducibility, require miniaturization, and must be free of toxic materials (such as heavy metals). To address these requirements, a metal-free photo atom transfer radical polymerization (ATRP) grafting procedure is described using a pulsed UV laser as light source to create thin molecularly imprinted polymer (MIP) films (similar to 10 nm thickness) on a sensor surface. Analysis via X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS) revealed the composition of the polymer film and the necessity for an excess of functional monomer to ensure its incorporation are demonstrated. MIP films were templated toward the target molecule histamine, for which in vivo studies can reveal unknown pathological pathways of inflammatory bowel diseases. By use of impedance spectroscopy, the biosensor surface is characterized in comparison to nonimprinted film grafts, and a high selectivity and sensitivity toward the target molecule are identified, revealing a histamine concentration limit of detection of 3.4 nM.