A Research-Inspired Chemical Biology Laboratory Module: Synthesis and Evaluation of an H 2 S-Responsive Diselenide Theranostic

Chemical biology integrates organic synthesis, mechanistic insight, and functional evaluation of small molecules in biological contexts, yet undergraduate laboratory instruction rarely reflects this interdisciplinary workflow. Here, we describe a six-week, research-inspired laboratory module, compatible with a standard 4 h undergraduate laboratory course, in which students synthesize and evaluate a hydrogen sulfide (H 2 S)-responsive diselenide theranostic derived from the clinically relevant anticancer agent SN-38. Through a concise two-step synthetic sequence, students gain hands-on experience with redox chemistry, multistep synthesis, and modern purification and characterization techniques. The module further incorporates fluorescence spectroscopy to investigate stimulus-responsive activation, enabling students to quantify concentration-dependent release behavior and assess selectivity toward H 2 S over competing biologically relevant species. By integrating disease-relevant biological concepts, molecular design, organic synthesis, and functional evaluation, this experiment exposes students to a complete chemical biology workflow that extends well beyond traditional undergraduate organic laboratory exercises. To our knowledge, undergraduate laboratory modules that guide students through the biological rationale, design, synthesis, and functional evaluation of a stimulus-responsive small molecule remain rare. This accessible and reproducible experiment provides a practical framework for incorporating contemporary chemical biology concepts and research-inspired learning experiences into an upper-division undergraduate curriculum.