No abstract

The sputtering deposition of Au nanoparticles onto ionic liquid-graphene oxide combined with cholesterol oxidase affords an efficient biosensor for cholesterol detection.

In this work, imidazole-or imidazolium-based benzothiadiazole ligands functionalized on graphene oxide combined with cholesterol oxidase constitute efficient, robust, and easy-to-handle materials with high biosensing activity for the detection of cholesterol by colorimetric methods. The presence of lanthanum(III) supported on graphene oxide as a possible coordinating site for the benzothiadiazole ligands was also evaluated, and its bioactivity was compared to that of the analogous material without the rare-earth metal. Our results demonstrated that graphene oxide functionalized with 4,7-bis-(imidazol-1-yl)-2,1,3-benzothiadiazole exhibited the best performance for the quantification of total cholesterol with a sensitivity of 0.0649 (with lanthanum) and 0.0618 au dL mg −1 (without lanthanum). In addition, these materials presented a better percentage of immobilization (>90%), recovered activity, resistance to storage, and detection range than materials containing 4,7-[1-carboxymethyl-(imidazol-3-ium)]-2,1,3-benzothiadiazole chloride. Therefore, the combination of GO-BTD (Im/Ac)/ChOx (with or without lanthanum) affords efficient biosensors for the colorimetric detection of cholesterol.

Tantalum oxide nanoparticles prepared from the hydrolysis of 1-alkyl-3-methylimidazolium hexachlorotantalate ionic liquids showed an unprecedented efficiency for the photocatalytic degradation of methylene blue and methyl orange dyes in aqueous solutions. Indeed, the photodegradation of these aqueous dyes (up to 94 %) promoted by the Ta 2 O 5 nanoparticles occurred in shorter reaction times when compared to commercially available Ta 2 O 5 under the same reaction conditions. Moreover, the presence of residual ionic liquid and the pH of the medium seem to play significant roles in the photodegradation process. In particular, a significant synergistic effect occurred when the remaining ionic liquid and HCl are present at the surface of the hybrid nanoparticles. This effect provided favorable hydrophilic regions and pH conditions for the photodegradation of the dyes.