Since decades, nano-sized materials have been regarded as promising carriers and imaging agents for various healthcare applications. The interest typically arises from several advantageous properties of such materials as: i) a prolonged systemic circulation; ii) an easy extravasation in tumour vasculature; iii) a large surface to volume ratio; iv) their ability to host a large variety of ligand and drug moieties via both surface functionalization and encapsulation as well as v) the adaptive and responsive properties of supramolecular assemblies.
Self-organised nano-architectures have been widely explored in a variety of biomedical applications mainly due to their well-defined size and shape as well as their tunable dynamic behaviour. π-conjugated small molecules have recently gained considerable attention here, as they show attractive photophysical properties and aggregation stability in aqueous solutions. The vast majority of self-assembled fluorescent π-conjugated nanostructures for biomedical applications are either based on fluorene or perylene moieties. Decoration of these π-conjugated moieties with different side chains typically provides them with an amphiphilic character and hence leads to the formation of stable and well-defined supramolecular architectures. Decoration with bioactive ligands expands their functionality, for example by providing them with the ability to induce cellular uptake and to specifically deliver cargo.
Albert Schenning and co-workers (Eindhoven University of Technology) provide an overview on the recent advances in the self-assembly of intrinsically fluorescent nanoparticles from π-conjugated small molecules e.g. fluorene or perylene based chromophores for biomedical applications as well as a detailed discussion on the major challenges that have to be overcome in future studies.
The authors foresee that supramolecular architectures based on π-conjugated small molecules will have a broad and lasting impact on applications in the fields of i) sensing and targeted imaging, for example, by introducing different targeting ligands that might induce synergistic binding effects; ii) therapeutics, e.g. drug-delivery and iii) theranostics when reporter systems and therapeutic cargoes are combined in a single dynamic architecture.