Light-triggered C release from a graphene/cyclodextrin nanoplatform for the protection of cytotoxicity induced by nitric oxide.

An ultraviolet (UV) light-triggered nanocarbon hybrid is developed for controlled C release with excellent nitric oxide (NO) quenching ability. This nanocarrier, consisting of reduced graphene oxide (rGO) and β-cyclodextrin (β-CD), is capable of hosting azobenzene functionalized C (Azo-C) synthesized by diazo chemistry. The hybridization of rGO, β-CD and Azo-C enhances cellular uptake and limits the aggregation of C, and shows enhanced protective effects on NO-induced cytotoxicity. More interestingly, azo groups can reversibly switch between trans- and cis-isomers upon UV irradiation, so that the Azo-C molecules exhibit photo-controlled release from rGO/β-CD in living cells. In vitro studies show that rGO/β-CD/C treated with UV irradiation causes higher NO scavenging efficacy, which further significantly increases the cell viability from 32.6% to 88.4% at low loading levels (50 μg mL). This represents an excellent NO quenching efficiency, better than other reports of the graphene/C nanohybrids, and indicates that this material can be an effective nanoplatform to combat oxidative damage. As the host-guest chemistry and diazo chemistry are versatile and universally applicable, it is worth noting that the present strategy can also be applied in preparing other photo-responsive nanohybrids, which should be valuable for use in life science and materials science.