Interfacing semiconductor nanocrystals and coordination compounds for the multimodal detection of biological targets

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Semiconductor nanocrystals are well-explored materials that have risen to prominence in applications ranging from optoelectronics, energy conversion, and catalysis. Concomitantly, inorganic coordination compounds have been extensively exploited as both therapeutic and diagnostic agents in biomedicine. In coordination chemistry, variation of the coordination sphere around a metal center with judiciously selected ligands can lead to the formation of adducts that are capable of binding and/or interacting with biologically relevant molecules. A marriage of molecular coordination compounds with semiconductor nanocrystals leads to the formation of hybrid materials where the intrinsic properties of the nanocrystals can be influenced by the presence of the coordination compounds, and further still through the binding and/or interaction of the latter with a biological target. Semiconductor metal halide perovskite nanocrystals (with the stoichiometry ABX3) have been the source of a tremendous number of investigations recently, owing in part to their high photoluminescence quantum yields and narrow-band emission coupled with low cost and relatively facile syntheses. Most recently, critical modifications of the surface capping ligands of these nanocrystals has led to rapid and significant advances regarding the properties of these materials. This team research aims to leverage the modularity of the surface groups on perovskite nanocrystals to form an interface with custom-built biologically active coordination compounds. The resulting hybrid materials will be used as multimodal sensors for challenging biological targets. The primary modality involves photoelectrochemical response where the input (visible light excitation) and output (electrochemical response) signals are decoupled giving rise to a significant limit of detection. Conventional photoluminescence will be explored as a complementary modality, where mechanisms such as energy transfer between the surface coordination compound (with or without target binding) will offer an alternative pathway of detection. The lessons learned through this work are expected to advance the fundamental understanding of energy migration processes at the interface of semiconductor nanocrystals informing the future design of these systems as biosensors, but also as platform materials for energy conversion and catalysis.