Photoacoustic reporter genes for noninvasive molecular imaging and theranostics

Noninvasive molecular imaging makes the observation and comprehensive understanding of complex biological processes possible. Photoacoustic imaging (PAI) is a fast evolving hybrid imaging technology enabling in vivo imaging with high sensitivity and spatial resolution in deep tissue. Among the various probes developed for PAI, genetically encoded reporters attracted increasing attention of researchers, which provide improved performance by acquiring images of a PAI reporter gene's expression driven by disease-specific enhancers/promoters. Here, we present a brief overview of recent studies about the existing photoacoustic reporter genes (RGs) for noninvasive molecular imaging, such as the pigment enzyme reporters, fluorescent proteins and chromoproteins, photoswitchable proteins, including their properties and potential applications in theranostics. Furthermore, the challenges that PAI RGs face when applied to the clinical studies are also examined.