Layer-by-layer assembly of light-responsive polymeric multilayer systems

Layer-by-Layer (LbL) assembly is a simple and highly versatile method tomodify surfaces and fabricate robust and highly-ordered nanostructured coatingsover almost any type of substrate. Such versatility enables the incorporationof a plethora of building blocks, including materials exhibiting switchableproperties, in a single device through a multitude of complementary intermolecularinteractions. Switchable materials may undergo reversible physicochemicalchanges in response to a variety of external triggers. Althoughmost of the works in the literature have been focusing on stimuli-responsivematerials that are sensitive to common triggers such as pH, ionic strength, ortemperature, much less has been discussed on LbL systems which are sensitiveto non-invasive and easily controlled light stimulus, despite its uniquepotential. This review provides a deep overview of the recent progressesachieved in the design and fabrication of light-responsive LbL polymericmultilayer systems, their potential future challenges and opportunities, andpossible applications. Many examples are given on light-responsive polymericmultilayer assemblies built from metal nanoparticles, functional dyes, and metal oxides. Such stimuli-responsive functional materials, and combinationsamong them, may lead to novel and highly promising nanostructured smartfunctional systems well-suited for a wide range of research fields, includingbiomedicine and biotechnology.The research leading to this work has received funding from the European Union's Seventh Framework Programme (FP7/2007-2013) under grant agreement no REGPOT-CT2012-316331-POLARIS, and from QREN (ON.2 - NORTE-01-0124-FEDER-000016). The research was also funded by FEDER through the Competitive Factors Operational Program (COMPETE) and by National funds through the Portuguese Foundation for Science and Technology (FCT) in the scope of the projects PTDC/FIS/115048/2009 and PTDC/CTM-BIO/1814/2012. J. Borges and L. C. Rodrigues contributed equally to this work