Importantly, these transitions are reversible and as the structure is cooled back to T = 23 °C, which is below the VPTT, the LSPR wavelengths shift to its original position. The magnitude of the LSPR shift for the || probing polarization is ΔλLSPR = 22 nm (which is close to that measured for a pNIPAAm film that covers the whole area of similar AuNP arrays ) and it corresponds to the polymerization, the reported approach based on polymer crosslinking provides a facile means for local attachment of the functional hydrogel materials at the areas where the electromagnetic field is strongly confined. This functionality is highly relevant in the fields of optical bioanalytical technologies and optical spectroscopy that take advantage of plasmonically enhanced output optical signal. The used polymers can be converted into hydrogels serving as high-capacity 3D binding matrices in bioanalytical tools when post-modified with biorecognition elements, facilitating the diffusion and capture of target analytes inside the polymeric network. In addition, when responsive properties are utilized, the reported material holds potential for the development of the concept of extended plasmonic hotspots when the molecules captured in the responsive hydrogel are compacted at plasmonic hotspot via a thermally induced collapse of the polymer network. 57