In this work a range of organic, metal complex and nanoparticle architectures have been investigated and optimized as probes and drug delivery agents. With the aid of a range of super-resolution techniques the role of these new molecular systems in detecting and imaging structures, organelles and biological processes within cells were delineated. These studies have identified new probes to image mitochondria and nuclear DNA at < 50 nm resolutions, investigated the potential of organic probes to image reactive oxygen and nitrogen species in live cells, assessed the potential of new nanocapsules as putative drug delivery agents, and identified a new paradigm for the construction of probes based on organelle targeted twophoton upconversion nanoparticles.