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.
As for the ultrasensitive diagnosis of biomolecules via surface-enhanced Raman scattering spectroscopy (SERS), the primary requirement is to effectively enhance the activity of nano-substrates. Herein, we report an interesting strategy for further boosting SERS activity by thermal annealing treatment of as-prepared hybrid substrates. Initially, highly dense and monodisperse plasmonic Au nanoparticles (NPs) were loaded on two-dimensional (2D) graphitic carbon nitride (g-C 3 N 4 ) nanosheets . By adopting uric acids (UAs) as probe biomolecules, the g-C 3 N 4 /Au NPs with appropriate ~2.1% Au compositions exhibit much higher Raman signals than that of the hybrids with other Au contents. Besides the enhancement by routinely controlling hybrid components, the further maximizing SERS activity with a ~2.6-fold improvement than the original one can be obtained by thermal annealing of g-C 3 N 4 /Au NPs at 350 ℃ condition. It enables the thermal modified g-C 3 N 4 /Au NPs to be applied for highly sensitive monitoring of UAs in artificial urine. The corresponding detection limit is achieved at the ultralow level of 10 −11 M, which is nearly two orders of magnitude better than that of the unannealed sample. It should be attributed to the stronger synergistic coupling effect by thermal annealing treatment that gives rise to the higher-efficiency photoinduced electron transfer (PIET) between g-C 3 N 4 supports and plasmonic Au NPs. The present work provides a new opportunity for further promoting the SERS activity of prefabricating nano-substrates, holding great potential for practical monitoring of ultra-trace biomolecules in the near future.
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