Studies And Applications On High Selective Cobalt(Ⅱ) Sensor Utilizing Chemiluminescence By Layered Double Hydroxide Materials

Cobalt (Co(Ⅱ)) is an essential metal at trace levels to man, animals and plants for metabolic processes. As an important element of vitamin B12, Co(Ⅱ) affects the metabolism of coenzyme, amino acid and protein. Co(Ⅱ) deficiency is associated with a variety of disorders. It is clear that the detection of trace amounts of cobalt in biological and environmental samples is important in the fields of environmental analysis and clinical diagnosis. Chemiluminescence (CL) technique for the determination of Co(Ⅱ) is becoming a promising technique with cheap instrument, high sensitivity and simple operation. Generally, the quantification of Co(Ⅱ) could be achieved by using the luminol CL system. However, these CL methods suffered from the low selectivity due to serious interference from other metal ions. In this paper, based on the catalysis of LDHs materials, the CL signals of Co(Ⅱ) participated Fenton-like reaction could be enhanced dramatically, a high sensitive and selective method for Co(Ⅱ) sensing was established. The main results are as follows:(1) It was found that small sized LDHs could effectively enhance the CL signals of Co(Ⅱ) participated Fenton-like reaction, which was high selectively for Co(Ⅱ) sensing. The enhanced CL emission was attributed to the large surface area of LDHs. The reaction could be focus on the surface or interlayer spaces of LDHs, which facilitates the generation of hydroxyl radical (OH). In addition, the amount of OH induced by Co(Ⅱ) was more than other metal ions. Based on the good biocompatibility of LDHs, we successfully detect the Co(Ⅱ) contents in Hela cells.(2) DBS-modified LDHs could significantly enhance an ultra-weak CL from Co(Ⅱ) participated Fenton-like reaction. In this study, we tried to detect Co(Ⅱ) liberated from acidified vitamin B12 using DBS-modified LDH-catalyzed Fenton-like CL system. The proposed method has been applied to determining vitamin B12 in egg yolks. The CL intensity was proportional to the log concentration of vitamin B12 in the range from 1.0 ng mL-1 to 5 μg mL-1, and the limit of detection was found to be 0.57 ng mL-1. Recoveries from spiked real samples were 96-103%.