We investigate metallic nanostructures that allow for tight confinement of electromagnetic field through the resonant excitation of surface plasmons. This coupling is accompanied with the strong enhancement of optical field intensity and increased local density of optical states, which provides efficient means for the amplification of weak optical spectroscopy signals. We are interested in a sub-class of metallic nanostructures assembled to geometries that can be reconfigured on demand, thus exhibit tuneable optical properties. In particular, these materials are prepared with the use of responsive polymer networks forming hydrogels and we explore them for actuation driven by an external stimulus. Among others, thermo-responsive hydrogels in combination with plasmonic heating are researched to function in miniature micro and nano-machines that can perform locomotion in conjunction with sensing functionality.