title: Enhancing sensitivity and selectivity in a label-free colorimetric sensor for detection of iron(II) ions with luminescent molybdenum disulfide nanosheet-based peroxidase mimetics.
abstract: In the present study, we demonstrated that the luminescent molybdenum disulfide (MoS2) nanosheets, which were prepared hydrothermally by using sodium molybdate and thiourea as precursors, possessed peroxidase-like activity, and could catalyze the oxidation of peroxidase substrate o-phenylenediamine (OPD) in the presence of hydrogen peroxide (H2O2) to produce a yellow color reaction. Further addition of Fe(2+) into the nanosheets led to peroxidase mimetics with greatly enhanced catalytic activity. The observation was exploited to develop a label-free colorimetric nanozyme sensor for detection of Fe(2+). The fabricated MoS2/OPD/H2O2 sensor showed a wide linear range of 0.01-0.8 µM with a detection limit of 7 nM. Moreover, it was found that the MoS2/OPD/H2O2 sensor displayed enhanced sensitivity and selectivity toward Fe(2+) compared with the OPD/H2O2 sensor, suggesting that the MoS2 nanosheets could improve the performance of the Fe(2+) sensor. An advanced chemometrics algorithm, multivariate curve resolution by alternating least squares (MCR-ALS), was further applied to interpret the origin of enhancing sensitivity and selectivity in the Fe(2+) sensor with the MoS2 nanosheets. The time-dependent UV-vis spectral data of the studied systems were collected, and submitted to the MCR-ALS. The results showed that the increased sensitivity and selectivity of the MoS2/OPD/H2O2 sensor for Fe(2+) detection likely arose from its large reaction rate constant. Finally, the proposed MoS2/OPD/H2O2 sensor was successfully applied for detection of Fe(2+) in water samples.
authors.affiliation: College of Chemistry, Nanchang University, Nanchang 330031, China. Electronic address: wangyong@ncu.edu.cn.
authors.forename: Yong
authors.initials: Y
authors.lastname: Wang
authors.affiliation: College of Chemistry, Nanchang University, Nanchang 330031, China.
authors.forename: Jie
authors.initials: J
authors.lastname: Hu
authors.affiliation: College of Chemistry, Nanchang University, Nanchang 330031, China.
authors.forename: Qianfen
authors.initials: Q
authors.lastname: Zhuang
authors.affiliation: College of Chemistry, Nanchang University, Nanchang 330031, China; State Key Laboratory of Food Science and Technology, Nanchang University, Nanchang 330047, China. Electronic address: ynni@ncu.edu.cn.
authors.forename: Yongnian
authors.initials: Y
authors.lastname: Ni
mesh_terms: D015374:Biosensing Techniques; D003124:Colorimetry / Q000379:methods; D004220:Disulfides / Q000737:chemistry; D006861:Hydrogen Peroxide / Q000737:chemistry; D007501:Iron / Q000302:isolation & purification*; D049449:Luminescence; D008982:Molybdenum / Q000737:chemistry; D049329:Nanostructures / Q000737:chemistry; D010544:Peroxidases / Q000737:chemistry*
chemical_list: D004220:Disulfides; D008982:Molybdenum; D006861:Hydrogen Peroxide; D007501:Iron; D010544:Peroxidases; C082964:molybdenum disulfide
keywords: Chemometric model; Colorimetric sensor; Enhanced sensitivity; Iron(II); Luminescent molybdenum disulfide; Peroxidase