The thesis describes a broad range of responsive nanoscale devices and their application to biological systems. This thesis is composed of five projects aiming to develop responsive devices applicable in biological settings. The first four projects involve the design and application of supramolecular networks able to translate biological inputs, such as the presence of membrane proteins, luciferases or miRNA sequences, into functional outputs. The construction of the networks relies on peptide nucleic acid (PNA) technology, with a focus on PNA templated reactions capitalizing on the ruthenium catalysed photoreduction of picolinium immolative linkers. The last project describes the discovery of a small-molecule caged fluorophore that interacts with the motor protein kinesin-1 and responds by eliciting a fluorescent output. The systems described herein enable the visualisation of important biological processes such as motor protein movement, as well as cancer cell detection and targeted drug release.