Univ Shanghai Sci & Technol, Sch Med Instrument & Food Engn, 516 Jungong Rd, Shanghai 200093, Peoples R China.
Shanghai Jiao Tong Univ, Sch Mat Sci & Engn, 800 Dongchuan Rd, Shanghai 200240, Peoples R China.
Natl Engn Res Ctr Nanotechnol, 28 East Jiangchuan Rd, Shanghai 200241, Peoples R China.
Shanghai Univ Med & Hlth Sci, 279 Zhouzhu Rd, Shanghai 201318, Peoples R China.
Ningbo Fundenergy Co Ltd, 699 Haicheng Rd, Ningbo 315200, Peoples R China.
The crystal structures would directly affect the physical and chemical properties of the surface of the material, and would thus influence the catalytic activity of the material. alpha-MnO2, beta-MnO2 and gamma-MnO2 nanorods with the same morphology yet different crystal structures were prepared and tested as oxidase mimics using 3,3',5,5'-tetramethylbenzidine (TMB) as the substrate. beta-MnO2 that exhibited the highest activity had a catalytic constant of 83.75 mu mol center dot m(-2)center dot s(-1), 2.7 and 19.0 times of those of alpha-MnO2 and gamma-MnO2 (30.91 and 4.41 mu mol center dot m(-2)center dot s(-1)), respectively. The characterization results showed that there were more surface hydroxyls as well as more Mn4+ on the surface of the beta-MnO2 nanorods. The surface hydroxyls were conducive to the oxidation reaction, while Mn4+ was conducive to the regeneration of surface hydroxyls. The synergistic effect of the two factors significantly improved the activity of beta-MnO2 oxidase mimic. Using beta-MnO2, a beta-MnO2-TMB-GSH system was established to detect the content of glutathione (GSH) rapidly and sensitively by colorimetry. This method had a wide detection range (0.11-45 mu M) and a low detection limit (0.1 mu M), and had been successfully applied to GSH quantification in human serum samples.收起