Light responsive metal-organic frameworks as controllable CO-releasing cell culture substratesElectronic supplementary information (ESI) available: PXRD, XRF and EDX quantification, electron microscopy, N2 adsorption isotherms, FTIR and UV-Vis spectroscopic characterization and TGA data. See DOI: 10.1039/c6sc04824b

A new carbon monoxide (CO)-releasing material has been developed by embedding a manganese carbonyl complex, MnBr(bpydc)(CO) 3 (bpydc = 5,5′-dicarboxylate-2,2′-bipyridine) into a highly robust Zr( iv )-based metal-organic framework (MOF). Efficient and controllable CO-release was achieved under exposure to low intensity visible light. Size-controllable nanocrystals of the photoactive MOF were obtained and their CO-releasing properties were correlated with their crystal sizes. The photoactive crystals were processed into cellular substrates with a biocompatible polymer matrix, and the light-induced delivery of CO and its subsequent cellular uptake were monitored using a fluorescent CO-probe. The results discussed here demonstrate a new opportunity to use MOFs as macromolecular scaffolds towards CO-releasing materials and the advantage of MOFs for high CO payloads, which is essential in future therapeutic applications. Carbon monoxide-releasing metal-organic frameworks are developed for investigating gas biology at the single cell level.