Holographic Molecularly Imprinted Polymers for Label‐Free Chemical Sensing (Adv. Mater. 4/2013)

Abstract

A new material combining a molecularly imprinted polymer for specific analyte recognition, and a holographic structure for optochemical sensing is described by Karsten Haupt, Olivier Soppera, and co‐workers . The material is obtained in one step through photo‐polymerization with interfering laser beams, resulting in a holographic molecularly imprinted polymer film that is hierarchically structured at four length scales. Specific binding of the target analyte testosterone is measured by diffraction analysis.

Molecularly Imprinted Silver‐Halide Reflection Holograms for Label‐Free Opto‐Chemical Sensing

“…This may be the consequence of only small structural changes in the polymer matrix upon analyte binding by non‐covalent bonds. Nevertheless, the stability of the optical setup employed for the label‐free binding assays, and the spectroscopic resolution (0.50 nm for the particular configuration used, which could be increased with more sophisticated signal analysis) still allow for reliable measurements.The holographic sensor response time upon molecular binding was relatively long, which means that 50% cross‐linking is still high for this application and limits the polymer film swelling and delays the strain relaxation in the 3D network, which had also been found for MIP‐based transmission holographic sensors . Nevertheless, after 8 h of incubation, a good difference between MI‐SHRH and NI‐SHRH was obtained, resulting in imprinting factors of 18.6 (10 μ m testosterone) and of 19.4 (1 μ m testosterone).…”

“…The key‐point of the work presented here was to develop MIP matrices combining molecular specificity, fabrication of SHRH, and structural/optical changes upon analyte binding, thus providing a rapid generic method to build metal colloid‐based holograms in MIP materials. Unlike the development of MIP‐based transmission holograms recently reported by our group, the route described here is independent of the MIP formulation's properties (monomer viscosity, initiating systems, presence of porogenic solvent) since the MIP film synthesis and the hologram construction are separated. Holograms also show distinct advantages over molecularly imprinted photonic crystals obtained by colloidal templating, since they allow the rapid fabrication of macroscale films with homogeneous optical properties over a large surface area and also offer flexibility to produce virtual optical elements and other types of indicators (bar graphs, images etc.)…”

“…Schematic view of the strategy used to fabricate molecularly imprinted silver‐halide reflection holograms. The left part of the figure was reproduced with permission from …”