Storage and delivery of nitric oxide by microporous titanosilicate ETS-10 and Al and Ga substituted analogues

•The potential of ETS-10 for therapeutic storage and release of NO is shown.•Isomorphic substituted analogs with aluminium and gallium were studied.•Effective NO storage with a slow release profile convenient for therapeutics.•The titanosilicates studied have an outstandingly low cytotoxicity.

Exogenous administration of nitric oxide may be a therapy for several pathologies because this molecule regulates many biological systems. Here, the storage and release of NO by microporous titanosilicate ETS-10 and samples where the silicon was substituted by aluminium (ETAS-10) or gallium (ETGS-10) are studied. The Al- and Ga-doped materials exhibit an increase in the storage capacity of 95% and 55%, respectively, the highest values observed, so far, for microporous titanosilicates. ETAS-10 releases more NO and ETGS-10 almost the same amount as ETS-10. In ETAS-10 and ETGS-10, the irreversibly adsorbed NO amount increases relatively to ETS-10. Tests of NO release in haemoglobin solutions indicate that biologically relevant amounts are release and that ETS-10 and ETGS-10 display a release slower than ETAS-10, more adequate for a sustained delivery. Cytotoxicity studies show that the samples have very low toxicity (cell viability above 87%, after 72 h) at high concentration (0.45 mg cm−3). Tests at variable ETS-10 concentration further confirm the low cytotoxicity of this material, even at high concentrations (up to 1.8 mg cm−3).

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