May 14, 2021
Research Highlight

A New Class of Highly Bright and Photostable Two-Dimensional Materials

These membrane-mimetic materials offer new opportunities in the development of photoactive technologies

Peptoid-based fluorescent crystalline 2D membranes

Peptoid-based fluorescent crystalline 2D membranes containing green dansyl dye at specific sites exhibit long-lasting fluorescence in vivo.

(Composite by Nathan Johnson | Pacific Northwest National Laboratory)

The Science                                 

Two-dimensional (2D) nanomaterials contain intrinsic physical and chemical properties that can be used for a wide range of applications including molecular separation, electronics, catalysis, optics, and biomedicine. In this study, a team of researchers designed and synthesized a new class of highly bright and photostable 2D membranes. These novel 2D membranes were constructed through the self-assembly of peptoids with covalently attached dansyl dyes. The controllable density and ordered alignment of dansyl molecules within the nanomembrane allowed the material to exhibit high quantum yield and enhanced photostability.

The Impact

These new 2D membranes are highly bright, displaying an increased fluorescence quantum yield over dansyl dyes alone, and photostable, demonstrating long-lasting fluorescence over other organic dyes. They are also biocompatible and contain tunable surface charges for lysosomal escape if used for intercellular trafficking. Because of their exceptional properties, these 2D membranes should offer additional opportunities in the development of photoactive materials for photocatalysis and photovoltaics, and biological applications including live cell imaging, cell labeling, and macromolecular drug delivery.


Building on its previous research—in which peptoid nanomembranes were first synthesized—the team covalently linked dansyl molecules to the hydrophilic end of peptoid to create a fluorescent molecule. Self-assembly of this peptoid into a crystalline structure revealed increased fluorescence quantum yield compared to dansyl or the dansyl-peptoid hybrid alone due to the ordered alignment and restricted intramolecular rotation of dye molecules within the crystal.  

In addition to being highly bright, these new 2D membranes are photostable and biocompatible. When used for live cell imaging in human lung cancer cells, they displayed low cytotoxicity and long-lasting fluorescence detectable for more than 400 s. Further, the surface charge of these 2D membranes can be altered to allow for lysosomal escape, granting these highly programmable and biocompatible materials potential as intracellular drug-delivery vehicles. Because of these properties, this new class of 2D membranes may be useful in the development of both photoactive materials and various theranostic applications.


Chun-Long Chen
Physical and Computational Sciences Directorate, Pacific Northwest National Laboratory


  • U.S. Department of Energy, Office of Science, Basic Energy Sciences program
  • Materials Synthesis and Simulation Across Scales (MS3) Initiative, a Laboratory Directed Research and Development program at Pacific Northwest National Laboratory
  • U.S. Department of Energy, Office of Science, User Facilities

Published: May 14, 2021

Song, Y; et al., “Highly bright and photostable two-dimensional nanomaterials assembled from sequence-defined peptoids.” ACS Materials Letters, (2021).

DOI: 10.1021/acsmaterialslett.1c00110