Metal-organic framework/enzyme coated optical fibers as waveguide-based biosensors

Metal organic frameworks (MOFs) have applied as promising vectors for encapsulating enzymes due to their porous structures. Glucose oxidase (GOx) encapsulated zeolitic imidazole-based metal organic frameworks (ZIF-8) were integrated, with long period grating (LPG) to develop highly stable, label-free optical fiber biosensors. Various morphologies of ZIF-8/GOx composites were synthetized with different concentrations of GOx, Zn2+ and 2-methylimidazole (2-MIM) in precursor solutions. The composites can achieve high protein encapsulation efficiency and show high activity and stability under harsh conditions. In the optical biosensing system, the ZIF-8( Zn-based MOF) acts not only as a protective shell for GOx but also as an analyte collector on fibers. The wavelength shifts are linearly corelated with glucose concentrations in range of 1-8 mM with a response coefficient of (similar to)0.5 nm/mM. The ZIF-8/GOx shows high stability under harsh conditions that would decompose free GOx.