Ultrathin graphitic carbon nitride nanosheet: a highly efficient fluorosensor for rapid, ultrasensitive detection of Cu(2+)

Fluorescence quenching of carbon nitride nanosheet through its interaction with DNA for versatile fluorescence sensing

This work investigates the interaction of carbon nitride nanosheet (CNNS), a recently developed two-dimensional nanomaterial, with DNA and its fluorescence quenching mechanism on fluorophore labeled single-stranded DNA probes. The static quenching through the photoinduced electron transfer (PET) from the excited fluorophore to the conductive band of CNNS is identified. Utilizing the affinity change of CNNS to DNA probes upon their recognition to targets and the PET-based fluorescence quenching effect, a universal sensing strategy is proposed for design of several homogeneous fluorescence detection methods with short assay time and high sensitivity. This strategy is versatile and can be combined with different amplification tools for quick fluorescence sensing of DNA and extensive DNA related analytes such as metal cations, small molecules, and proteins. As examples, two simple fluorescence detection methods for DNA and Hg(2+), one facile detection method coupled with Exo III-mediated target recycling for sensitive DNA analysis, and a ratiometric fluorescence protocol for DNA detection are proposed. This work provides an avenue for understanding the interaction between two-dimensional nanomaterials and biomolecules and designing novel sensing strategies for extending the applications of nanomaterials in bioanalysis.

Efficient visible-light photocatalytic hydrogen evolution and enhanced photostability of core/shell CdS/g-C3N4 nanowires

CdS/g-C3N4 core/shell nanowires with different g-C3N4 contents were fabricated by a combined solvothermal and chemisorption method and characterized by X-ray powder diffraction, scanning electronic microscopy, transmission electron microscopy, and UV-vis diffuse reflection spectroscopy. The photocatalytic hydrogen-production activities of these samples were evaluated using Na2S and Na2SO3 as sacrificial reagents in water under visible-light illumination (λ≥420 nm). The results show that after a spontaneous adsorption process g-C3N4 is successfully coated on CdS nanowires with intimate contact and can significantly improve the photocatalytic hydrogen-production rate of CdS nanowires, which reaches an optimal value of up to 4152 μmol h(-1) g(-1) at the g-C3N4 content of 2 wt %. More importantly, g-C3N4 coating can substantially reinforce the photostability of CdS nanowires even in a nonsacrificial system. The synergic effect between g-C3N4 and CdS, which can effectively accelerate the charge separation and transfer corrosive holes from CdS to robust C3N4, was proposed to be responsible for the enhancement of the photocatalytic activity and photostability. The possible conditions necessary for the synergic effect to work in a CdS/g-C3N4 core/shell configuration is also discussed.

Ultrathin graphitic carbon nitride nanosheets: a low-cost, green, and highly efficient electrocatalyst toward the reduction of hydrogen peroxide and its glucose biosensing application

In this communication, we demonstrate for the first time that ultrathin graphitic carbon nitride (g-C₃N₄) nanosheets can serve as a low-cost, green, and highly efficient electrocatalyst toward the reduction of hydrogen peroxide. We further demonstrate its application for electrochemical glucose biosensing in both buffer solution and human serum medium with a detection limit of 11 μM and 45 μM, respectively.

Au-nanoparticle-loaded graphitic carbon nitride nanosheets: green photocatalytic synthesis and application toward the degradation of organic pollutants

Au nanoparticles (AuNPs) were loaded on graphitic carbon nitride (g-C3N4) nanosheets prepared by ultrasonication-assisted liquid exfoliation of bulk g-C3N4 via green photoreduction of Au(III) under visible light irradiation using g-C3N4 as an effective photocatalyst. The nanohybrids show superior photocatalytic activities for the decomposition of methyl orange under visible-light irradiation to bulk g-C3N4, g-C3N4 nanosheets, and AuNP/bulk g-C3N4 hybrids.