Gas marble-film reactors with programmable particle shells and capillary-granular stability.

Motivated by gas-accessible thin liquid films in lung alveoli, we develop gas marble-film reactors in which particle-stabilized bubbles confine an ultrathin freestanding liquid film within a jammed solid shell. Hexagonal PET (poly(ethylene terephthalate)) plates, in addition to conventional spherical particles, generate faceted gas marbles with planar film regions that improve optical access. We quantify the pressure limits of microsphere- and plate-stabilized shells during inflation and deflation, and describe their response using a capillary-granular framework. In this framework, inflation rupture is governed by capillary breakthrough at particle-defined throats, whereas deflation collapse reflects the combined resistance of capillarity and interparticle jamming. The mechanically defined films then serve as gas-accessible interfacial reactors in two proof-of-concept demonstrations. In a Tollens reaction, aerosolized glucose delivery through the external gas phase localizes silver reduction to liquid-wetted regions of the particle shell, producing spatially patterned silver-deposited microspheres. In biological assays, plate-stabilized shells provide flat observation windows for monitoring aerobic E. coli growth and its inhibition by levofloxacin. These results establish gas marbles as programmable colloidal film reactors whose structure, pressure stability, and interfacial function can be coupled through particle geometry and capillary jamming.