Designing Protein‐Based Probes for Sensing Biological Analytes with Magnetic Resonance Imaging

Abstract

Genetically encoded sensors provide unique advantages for monitoring biological analytes with molecular and cellular-level specificity. While sensors derived from fluorescent proteins represent staple tools in biological imaging, these probes are limited to optically accessible preparations owing to physical curbs on light penetration. In contrast to optical methods, magnetic resonance imaging (MRI) may be used to noninvasively look inside intact organisms at any arbitrary depth and over large fields of view. These capabilities have spurred the development of innovative methods to connect MRI readouts with biological targets using protein-based probes that are in principle genetically encodable. Here, we highlight the stateof-the-art in MRI-based biomolecular sensors, focusing on their physical mechanisms, quantitative characteristics, and biological applications. We also describe how innovations in reporter gene technology are creating new opportunities to engineer MRI sensors that are sensitive to dilute biological targets.

Molecular imaging with aquaporin-based reporter genes: quantitative considerations from Monte Carlo diffusion simulations

“…Unlike optical methods, magnetic resonance imaging (MRI) can image deep tissues and generate volumetric scans with a high spatial resolution. We recently developed an MRI-based reporter that enables imaging of genetic activity in deep tissues [5][6][7] . This reporter utilizes aquaporin-1 (Aqp1), a channel that allows water molecules to diffuse freely across the plasma membrane 8,9 .…”