RESUMEN
Using the density functional theory, the interactions between pristine, Stone-Wales defected graphenes (SW-graphene) and two small gas molecules (NH3 and NO2) were investigated and the potential applications of SW-graphene as gas sensors were exploited. Both NH3 and NO2 show weak interactions with pristine graphene. Introducing SW defect into the graphene structure has little effect on the NH3 adsorption, but dramatically enhances the adsorption of NO2 and causes significant deformation of the graphene sheet around the defect site. The strong interaction between NO2 and the SW-graphene also induces dramatic changes to the graphene's electronic structure. This work reveals that the SW-graphene could be an excellent candidate as highly selective sensing material for NO2.
RESUMEN
A facile and multi-response strategy for studying the transformations of human telomere DNA from single strand (ss) to double strand (ds) and G-quadruplex has been established by using positively charged gold nanorod (AuNR) as an optical label. The conformation change information of the telomere DNA was transferred into multiple optical signals, including changes in fluorescence emission, near infrared (NIR) absorption, plasma resonance light scattering (PRLS) and dynamic light scattering (DLS) response. The formations of dsDNA and G-quadruplex DNA induced fluorescence quenching of dye on DNA, and were accompanied by the intensity decrease and blue shift of the longitudinal absorption peak of AuNRs. Meanwhile, PRLS and DLS results revealed slightly increased AuNR aggregation due to increased charge density of dsDNA and G-quadruplex DNA as compared to ssDNA. Control experiment suggests that the AuNR-based assay is highly sequence specific; and the high sensitivity allows the study of human telomere DNA at a concentration as low as 58 nM.