# Coelenterazine Analogs for Bioassays and Molecular Imaging

## TL;DR

This review discusses recent advances in coelenterazine analogs, highlighting their improved optical properties and diverse applications in bioassays and molecular imaging.

## Contribution

The paper introduces new CTZ analogs with unique functionalities like color tunability and specificity to various proteins and ions.

## Key findings

- CTZ analogs can emit light across the visible spectrum without luciferases.
- Modified CTZs show specificity to proteins such as albumin and virus proteins.
- Some CTZ analogs are activatable by ions, reactive oxygen species, and anticancer drugs.

## Abstract

Coelenterazine (CTZ) is a common substrate of marine luciferases upon emission of bioluminescence (BL) in living organisms. Because CTZ works as a “luminophore” in the process of BL emission, the chemical modification has been centered for improving the optical properties of BL. In this review, we showcase recent advances in CTZ designs with unique functionalities. We first elucidate the light-emitting mechanisms of CTZ, and then focus on how the rational modification of CTZ analogs developed in recent years are connected to the development of unique functionalities even without luciferases, which include color tunability covering the visible region, specificity to various proteins (e.g., luciferase, albumin, and virus protein), and activatability to ions or reactive oxygen species (ROS) and anticancer drugs. This review provides new insights into the broad utilities of CTZ analogs with designed functionalities in bioassays and molecular imaging.