CO2 responsive nanoscopic and macroscopic materials directed by peptides

Stimuli such as pH, light, and electromagnetic fields have enabled precise control over nanoscale interactions, yet gases remain relatively unexplored as regulators of material behavior despite their central roles in biology, energy, and climate. Here, we introduce carbon dioxide (CO2) as a dynamic and reversible stimulus for controlling nanoscale and macroscale matter using sequence-specific peptide design. Peptide-functionalized nanoparticles exhibit pronounced and tunable responses to CO2 across orders of magnitude changes in gas flow rate, with sensitivity governed by site- and sequence-specific changes in peptide structure. The aggregation sequence-dependence is described by six design principles while quantitative modeling show that aggregation rate scales with flow rate rather than cumulative CO2 dose. This gas-controlled response translates from colloidal nanoparticles to cm-scale biocompatible hydrogels that reversibly and colorimetrically respond to CO2. Leveraging this responsiveness, we further demonstrate spatial patterning of a hydrogel through a gas-permeable mask using CO2 as a lithographic stimulus. Consequently, this work establishes gas-mediated control as a general and scalable strategy for programming responsive materials across length scales. Stimuli responsive assemblies can offer precise control over behaviour, but use of gases for this control is rare. Here, the authors report the use of carbon dioxide for tuneable nanoparticle response, directed by changes in peptide structure.