Paper of the week: Optimising the enzyme response of a porous silicon photonic crystal

There is a need for devices that can detect various biological species for the development of biotechnology and medical diagnostics. For instance, it is important to measure the activity of enzymes like proteinases released from cells for the understanding of fundamental cell biology and biomedical applications. One class of the proteinases is the matrix metalloproteinases (MMPs) which are known to be released by cells as part of their normal tissue remodelling processes, such as embryonic development and cell migration. Currently, the most common proteinase activity measurements are performed by fluorogenic or calorimetric methods with commercially available proteinase assay kits. Enzymatic responsive polymers have also been developed as sensing elements in biological devices.

Graphical abstract: Optimising the enzyme response of a porous silicon photonic crystal via the modular design of enzyme sensitive polymers

In this work, Gooding and co-workers have demonstrated a generic approach to optimize the sensing capability of porous silicon through a modular polymer conjugation strategy where the surface of the  porous silicon (PSi) was first modified with an antifouling polymer, then an enzyme cleavable link was added which bridged the antifouling polymer and a second sacrificial polymer that was lost upon enzyme cleavage of the peptide. Cleavage of the peptide–polymer network by the appropriate proteinase decreases the average refractive index of the photonic crystal resulting in a change in the reflectivity peak to lower wavelengths (blue-shift). The PSi–polymer constructs were shown to have selectivity towards different MMP enzymes. The approach could easily be tailored for different chemical/biochemical moieties, thus increasing the potential of such smart surfaces for biosensor applications. These structures could be easily expanded for other proteinase enzymes by simply changing the specific peptide sequences.

Optimising the enzyme response of a porous silicon photonic crystal via the modular design of enzyme sensitive polymers by Alexander H. Soeriyadi, Bakul Gupta, Peter J. Reece and J. Justin Gooding Polym. Chem. 2014, 5, 2333-2341.

Julien Nicolas is a web-writer and advisory board member for Polymer Chemistry. He currently works at Univ. Paris-Sud (FR) as a CNRS researcher.

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