Improved therapeutic nitric oxide delivery by microporous Cu-bearing titanosilicate

Abstract Copper was incorporated into microporous titanosilicate ETS-4 framework via the in situ hydrothermal synthesis to achieve a more controlled and extended nitric oxide (NO) release profile. Exogeneous delivery of this gasotransmitter may be effective in the therapeutic setting and titanosilicates, in particular ETS-4, has already evidenced its potential as a NO carrier. Copper ions have high affinity for NO coordination and their substitution within the ETS-4 framework was confirmed by energy dispersive X-ray spectrometry (EDS). Samples were also characterized by PXRD, SEM microscopy, UV–Vis and Raman spectroscopy, TG and DSC. ETS-4Cu presents higher NO adsorption capacity (up to 4.5 mmol g−1 solid) comparing with the parent material, excellent stability in biological media and exhibit high compatibility in different cell lines, including primary keratinocytes (HEKn). Its NO release profile in biological conditions demonstrated a controlled release over at least 4 h, never achieved by any other porous materials so far. This may be reflected by its peculiar NO adsorption mechanism through the formation of stable nitro species on the framework.