Peptoid-Based Programmable 2D Nanomaterial Sensor for Selective and Sensitive Detection of H2S in Live Cells

During the past few decades, a variety of two-dimensional (2D) nanomaterials have been developed through molecular self-assembly. Among them, those assembled from sequence-defined polymers have received particular attention because they enable a programmable display of functional groups, including fluorescent dyes, on their surfaces for applications. On the other hand, due to fluorescence self-quenching, synthesis of 2D nanomaterials exhibiting high fluorescence quantum yields is a significant challenge. Herein, we design and synthesize peptoid-based crystalline 2D nanomembranes (2DNMs) as a biocompatible and programmable sensor for selectively and sensitively detecting H2S in live cells. This 2DNM sensor is assembled from peptoids covalently attached with H2S-responsive molecular probes. Compared with its amorphous controls, this crystalline 2DNM sensor exhibits a significantly stronger fluorescence intensity and a higher sensitivity as a result of long-range structural ordering and alignment of H2S-responsive molecular probes. By sonication-cutting these 2DNM sensors into a colloidal form in an aqueous solution, we further demonstrated the use of colloidal 2DNMs for detecting exogenous and endogenous H2S inside cells and targeted cell organelles. Because peptoids are biocompatible and peptoid-based 2DNMs are programmable, we expect that this class of 2DNM sensors offer great potential for detecting H2S in live cells and for investigating H2S-related diseases.