Conformational Control of Energy Transfer: A Mechanism for Biocompatible Nanocrystal-Based Sensors

摘要

Recent advances have given access to a myriad of engineered nanomaterials, ranging from functional nanotubes and fluorescent nanocrystals (NCs) to oligonucleotide self-assemblies and polymer nanoparticles. The integration of these nanomaterials with dynamic molecular components will likely be a key component in realizing their full potential. In this regard, combining NCs with molecular machines presents an unexplored strategy for modulating NC properties in response to a specific stimulus. Herein, we outline this new approach by designing a self-referencing, NCanomachine-based sensor. A conformational switch, activated by a chosen specific analyte (here, H~+ ions), is used to vary the efficiency of energy transfer between the NC and an appended species. The analyte concentration is reported by a ratiometric fluorescence signal that is quantifiable and robust across a variety of imaging conditions, allowing for the high-resolution measurement of pH within individual endosomes in HeLa cells. This study thus exemplifies the strategy of disconnecting sensing and reporting functions to create a universal fluorescent sensor design that addresses many of the challenges associated with harnessing the unique optical properties of NCs.