Printable Flavin-Nanoparticle–Polymer Composite for Oxygen Detection

Optical oxygen detection and sensing are essential for fields such as pharmaceutical and food packaging, anaerobic bioprocessing, or battery assembly. To date, sensors are often based on costly, toxic, and/or photolabile precious-metal complexes. Herein, we present a low-cost, biocompatible, and photostable alternative. A 2D/3D-printable composite ink composed of zirconyl flavin mononucleotide ([ZrO]2+[FMN]2–) inorganic–organic hybrid nanoparticles (IOH-NPs), an acrylate cross-linker, and a photoinitiator. The saline IOH-NPs consist of flavin mononucleotide anions ([FMN]2–) and zirconyl cations ([ZrO]2+). Oxygen detection relies on the redox state of FMN. In its oxidized form, FMN is yellow and shows intense fluorescence, whereas it becomes colorless and non-fluorescent after reduction. This redox-mediated transition of FMN introduces a concept for reliable and reversible oxygen sensing. The oxygen sensitivity can be tuned via the IOH-NP concentration and the composite material's thickness. Critically, we explore the time dependence of the oxygen detection. Low-cost biocompatible materials, optical readability, and light-based printing make the composite material and material concept ideal for simple, equipment-free oxygen detection and sensing (e.g., in food and pharmaceutical packaging, battery assembly, and semiconductor manufacturing).