TMB Liquid Substrate System

In this study, a hybrid material UIO-66-NH2/PB were synthesized through the modification of Prussian Blue on the surface of Metal Organic Frameworks for synergetic tumor therapy with hypoxia modulation. It was found that UIO-66-NH2/PB has good photo-thermal performance and photo-thermal stability, suitable for photo-thermal treatment. Dissolved oxygen analysis showed that UIO-66-NH2/PB can catalyze H2O2 into O-2. It was proved that this process is accompanied by the generation of center dot OH. Furthermore, with the irradiation of 808 nm for 5min, the TMB solution becomes darker blue, proving that more free radicals are produced. The produced O-2 can be used to modulate the hypoxia of tumor to improve the anti-cancer efficiency, and the generated center dot OH can kill cancer cells to achieve chemodynamic therapy. Doxorubicin (DOX) was selected as a model drug and the DOX loading of UIO-66-NH2/PB was 67%. Drug release experiments showed that DOX was not nearly released in pH 7.4, while 78% DOX was released in pH5.8 after 40 h, demonstrating the excellent pH-responsive release. In addition, with the irradiation of 808 nm for 5min, 87% DOX was released in pH 5.8, indicating photothermal effect could help achieve better release effect. The different cytotoxicity to L-02 cells and HeLa cells of UIO-66-NH2/PB shows UIO-66-NH2/PB is only harmful to cancer cells, indicating that Fenton-like reaction only occurred in tumor to generate center dot OH. In vivo experiment showed synergetic therapy can achieve satisfactory treatment efficiency. Therefore, UIO-66-NH2/PB is expected to combine multiple treatments to improve anti-cancer effect. (C) 2020 Elsevier B.V. All rights reserved.

Being superior to natural enzymes, nanoenzymes are drawing a great deal of attention in the field of biosensing. Herein, we developed an ultrasensitive, stable and selective colorimetric assay having dual functionalities of Au-tipped Pt nanorods (NRs). The optical and catalytic properties of Au-tipped Pt NRs were monitored using a spectrophotometer and the chromogenic substrate 3, 3 ', 5, 5 '-tetramethylbenzidine (TMB) in the presence of H2O2, respectively. We found that Au-tipped Pt NRs exhibited excellent peroxidase-like activity, which decomposed hydrogen peroxide (H2O2) into oxygen (O-2). The produced O-2 oxidized the chromogenic substrate into a blue color product. The oxidation rate of the chromogenic substrate could be monitored using a spectrophotometer at 652 nm. Notably, the peroxidase-like activity of Au-tipped Pt NRs decreased in the presence of ascorbic acid (AA). The produced O-2 preferentially reacted with AA, generating ascorbyl radicals (AA center dot) instead of oxidizing TMB, and thereby decreased the oxidation rate of TMB. Based on this inhibitory property, a selective colorimetric assay was developed using Au-tipped Pt NRs for the detection of AA. This work offers a novel detection method for AA.