Can Chen,Shiyu Zhang,Chengwu Zhang,Lin Li,Jixin Zhu,Jinhua Liu
Detection of H 2 O 2 is significant for the applications in environmental protection, pharmaceutical industries , food production, and clinical control. Current colorimetric kit of H 2 O 2 based on enzyme or nanomaterials always needs TMB or other peroxidases substrate as coloration species. Herein, we report a simple hydrothermal method to synthesize of TMB dot as the nanosubstrate construction colorimetric kit for highly selective and sensitive detection of H 2 O 2 based on Fenton reaction . Compared with TMB as the substrate, the synthesized TMB dots (TMBDs) show higher reaction activity in the presence of the same low-level Fe 2+ and H 2 O 2 , resulting in highly sensitive sensing H 2 O 2 down to 0.8 nM. Additionally, the obtained TMBDs can well disperse in solution, while generally TMB as substrate needs to be dissolved in organic solvents such as DMF and DMSO. Furthermore, the developed colorimetric kit is applied in detection of Mao-A, due to the reaction between epinephrine and Mao-A producing H 2 O 2 . More importantly, the proposed method has been successfully applied to the analysis of Mao-A in spiked human serum Hence, the TMBDs as the nanosubstrate provide an efficient, fast and sensitive approach for colorimetric kit of H 2 O 2 and Mao-A, promoting more extensive application in early diagnosis of disease and drug discovery.
Xiaofei Qin,Can Chen,Shiyu Zhang,Jixin Zhu,Yongxiang Wang,Jinhua Liu
3,3′,5,5′-Tetramethylbenzidine (TMB) is one of the traditional enzyme substrates that has been widely used in the fields of artificial enzyme mimics and natural enzymes. However, the development of TMB-based probes for fluorescence and colorimetric dual models remains a great challenge. Herein, we developed a facile method to fabricate a colorimetric and fluorescent nanoswitch based on near-infrared fluorescent TMB dots (TMBDs) for the reversible recognition (CFRR) of Fe3+ and Cys. The proposed CFRR nanoswitch was based on an oxidation–reduction mechanism by which the TMBDs are oxidized by Fe3+ to form ensembles and Cys reduces the ensembles to TMBDs. The CFRR nanoswitch exhibited high sensitivity for the colorimetric and fluorescent recognition of Fe3+ with limits of detection (LODs) of 0.17 μM and 7.5 μM and of Cys with LODs of 0.1 μM and 1.5 μM, respectively. The response speed was very fast, within 5 min. Moreover, two output signals, namely near-infrared fluorescent and colorimetric, were exhibited in this CFRR sensor; the recognition was reversible and retained good stability after three cycles. It is noteworthy to mention that the CFRR nanoswitch performed successfully in urine, and molecular logic gate systems were readily established. Therefore, these investigations will shed light on the development of multi-mode output signals for nanoprobes.
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