2D ultrathin nanosheets of Co–Al layered double hydroxides prepared in l-asparagine solution: enhanced peroxidase-like activity and colorimetric detection of glucose

In this report, a novel approach for exfoliation of Co-Al layered double hydroxides (LDHs) in aqueous solution of l-asparagine was proposed. l-Asparagine is a water-soluble amino acid whose carbonyl groups would have a strong interaction with the LDH host layers and the amino groups might weaken the interlayer interactions. This simple method did not need reflux at high temperature, overcame the drawback of using organic solvents, and even resulted in a stably stored colloidal suspension of 2D nanosheets. Besides, the peroxidase-like activity of the exfoliated Co-Al LDH (Co-Al ELDH) was enhanced compared with unexfoliated LDH. Co-Al ELDH could rapidly catalyze oxidation of the peroxidase substrate 3,3',5,5'-tetramethylbenzidine (TMB) in the presence of H₂O₂, producing a blue color reaction. On this basis, simple, rapid and selective colorimetric methods for H₂O₂ and glucose detection were developed. The presented means was used for glucose detection in fruit juices and fine results were obtained.