Quantum Dots: An Insight and Perspective of Their Biological Interaction and How This Relates to Their Relevance for Clinical Use

Due to their novel physico-chemical characteristics, semi-conductor nanocrystal quantum dots (QDs) provide an advantageous perspective towards numerous different consumer and medical applications. The most notable potential application of QDs is their use as therapeutic and diagnostic tools in nanomedicine. Despite the many benefits posed by QDs, the proposed, intentional exposure to humans has raised concerns towards their potential impact upon human health. These concerns are predominantly based upon the heterogeneous composition of QDs, which most commonly comprises of a cadmium-based core and zinc sulphide shell. Whilst other nanoparticle (NP) types possess a similar structure to QDs (i.e. core-shell technology (e.g. Fe2O3, Au and superparamagnetic iron oxide NPs)), the importance of the concerns surrounding human exposure to QDs is amplified further since, due to the sophisticated chemical and light-emitting properties of QDs, the use of these NPs within any (nano)medical setting/application could be suggested as realistic, rather than simply an advantageous possibility. It is therefore imperative that a thorough understanding of how QDs interact with various biological systems, predominantly those relative to humans and what the consequences of such interactions are is gained with extreme alacrity. It is the aim of this review to highlight the current knowledge base of QD-biological system interactions, where the knowledge gaps (still) remain and how the understanding of this interaction relates to the most notable of applications for QDs; their clinical relevance.