Charge Transfer Between Quantum Dots and Peptide-Coupled Redox Complexes

Introduction: Nanotechnology has great potential for creating a new generation of multifunctional hybrid bio-inorganic assemblies that are capable of enhancing Navy capabilities and DoD battle systems in general. The unique properties of luminescent quantum dots (QDs) have made them an integral building block in this burgeoning field.1 In addition to their well known size-dependent emission spectra, QDs are extremely sensitive to the presence of additional charges either on their surfaces or in the surrounding environment, which can alter both their photoluminescence (PL) and absorption properties.2 Since the advent of successful techniques to interface QDs with biological molecules, there has been a strong desire to understand the interactions of QDs with redox-active complexes to create new sensors capable of monitoring specific biological and abiotic processes.2 However, as there is only a minimal understanding of these systems, rational design of QD-redox assemblies with control over both architecture and redox levels is needed to provide insight into the underlying mechanisms. Here we label peptides with a variety of metal complexes expressing different oxidation potentials and ratiometrically self-assemble them on the QD surfaces. This unique configuration allows us to gain insights into the underlying quenching processes involved and exploit them for biosensing.