Visible-Light-Assisted Photoelectrochemical Biosensing of Uric Acid Using Metal-Free Graphene Oxide Nanoribbons.

In this study, we demonstrate the visible-light-assisted photoelectrochemical (PEC) biosensing of uric acid (UA) by using graphene oxide nanoribbons (GONRs) as PEC electrode materials. Specifically, GONRs with controlled properties were synthesized by the microwave-assisted exfoliation of multi-walled carbon nanotubes. For the detection of UA, GONRs were adopted to modify either a screen-printed carbon electrode (SPCE) or a glassy carbon electrode (GCE). Cyclic voltammetry analyses indicated that all Faradaic currents of UA oxidation on GONRs with different unzipping/exfoliating levels on SPCE increased by more than 20.0% under AM 1.5 irradiation. Among these, the GONRs synthesized under a microwave power of 200 W, namely GONR(200 W), exhibited the highest increase in Faradaic current. Notably, the GONR(200 W)/GCE electrodes revealed a remarkable elevation (~40.0%) of the Faradaic current when irradiated by light-emitting diode (LED) light sources under an intensity of illumination of 80 mW/cm2. Therefore, it is believed that our GONRs hold great potential for developing a novel platform for PEC biosensing.

Antioxidant Graphene Oxide Nanoribbon as a Novel Whitening Agent Inhibits Microphthalmia-Associated Transcription Factor-Related Melanogenesis Mechanism.

In the melanin synthesis process, oxidative reactions play an essential role, and it is a good strategy to inhibit melanin production by reducing oxidative stress. Fullerene and its derivatives, or the complexes, were considered as strong free-radical scavengers, and we further applied multilayered sp2 nanocarbons to discover melanin synthesis inhibitory mechanisms. In the present study, we used novel nanomaterials, such as multiwalled carbon nanotubes (MWCNTs), short-type MWCNTs, graphene oxide nanoribbons (GONRs), and short-type GONRs, as anti-oxidative agents to regulate melanin production. The results showed that GONRs had better anti-oxidative capabilities in intracellular and extracellular oxidative stress analysis platforms than others. We proposed that GONRs have oxygen-containing functional groups. In the 2',7'-dichlorodihydrofluorescein diacetate assay, we found out GONR could chelate metal ions to scavenge reactive oxygen species. In the molecular insight view, we observed that these nanomaterials downregulated the melanin synthesis by decreasing microphthalmia-associated transcription factor-related gene expressions, and there were similar consequences in protein expressions. To sum up, GONRs is a potential agent as a novel antioxidant and skin-whitening cosmetology material.