CAREER: Probing Quantum Coherence in Biomolecular Microenvironments via Electron Spin Molecular Quantum Sensors

California Institute Of Technology, Pasadena CA

Investigators

Abstract

The National Science Foundation’s Quantum Leap initiative seeks to promote understanding and application of quantum mechanics towards areas such as computation, modeling, communication, and sensing. Innovation in these areas will meet societal needs for technologies that include sensors with exquisite sensitivity and resolution. Towards these challenges, molecular Quantum Information Science (QIS) makes use of the fine tunability of synthetic chemistry to understand, design, and utilize new molecules and materials with measurable and controllable quantum properties. This research project aims to develop new molecular systems, models, and protocols for quantum sensing in biology towards the goal of enabling atomically-precise magnetic imaging. The molecular and biological sensors constructed through this project will be used to study chemical micro-environments in biological systems with high sensitivity and to understand quantum effects in biological systems and processes. In turn, this research utilizes a reciprocal relationship that will not only develop quantum sensors for biological applications but will also improve understanding of quantum processes needed for future applications of molecular QIS in technological devices. Through an educational component to this project, open educational resources will be developed to amplify the impact of this work by expanding and simplifying access to chemical education and research. These resources will alleviate cost barriers that limit understanding of the quantum paradigm and success in STEM. Additionally, a new research training program will be developed to provide chemistry techniques to students in a neighboring community college, enabling students with little to no research experience to continue in STEM careers. Current research in molecular Quantum Information Science (QIS) seeks to develop quantum-enabled technologies for computation, communication, and sensing through chemical synthesis and spectroscopic characterization. This project combines QIS and biophysics to fundamentally understand intramolecular and intermolecular effects on decoherence dynamics and to quantify changes in decoherence times for probing biochemical micro-environments. The goal of this research is the development of molecular quantum sensors for biology towards atomically-precise magnetic resonance imaging using electron spin decoherence. This project contains four objectives: 1) the development of theoretical/experimental descriptions of decoherence-based quantum sensing mechanisms, 2) the investigation of decoherence properties of molecular quantum sensor (qusor)-labeled membranes, 3) the elucidation of secondary sphere contributions to decoherence in paramagnetic metalloprotein active sites, and 4) the selective targeting of protein-specific qusor binding. First, theoretical models for spin-lattice and spin-spin relaxation times will be developed for organic molecules and low-symmetry transition metal complexes, then expanded to computations for macromolecular systems. Second, paramagnetic organic molecules will be introduced into lipid assemblies for studying micellar morphologies and interfaces with ultrafast spectroscopy at room temperature. Third, the decoherence dynamics of paramagnetic metalloproteins and their mutants will be probed to quantify the maximum distance for secondary sphere effects and to improve the accuracy of computational methods. Fourth, molecular qusor-protein complexes will be synthesized and assembled to demonstrate decoherence effects for sensing site-specific binding events. Techniques to be employed for this project include chemical synthesis, protein expression and purification, X-ray crystallography, optical and magnetic spectroscopies, and theoretical and computational methods. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.