Colorimetric detection of α-glucosidase activity using Ni-CeO_(2)nanorods and its application to potential natural inhibitor screening

In this work,we established an exceptionally facile method for the preparation of Ni-CeO_(2)nanorods in a kind of deep eutectic solvents(DESs)composed of l-proline and Ce(NO_(3))_(3)·6H_(2)O.First,Ni-CeO_(2)nanorods were successfully prepared by adding Ni(NO_(3))_(3)·6H_(2)O to DESs.Then,we found that Ni-CeO_(2)nanorods prepared in DESs have more prominent oxidase-like activity than pure CeO_(2).The outstanding catalytic activity of Ni-CeO_(2)could be ascribed to its high Ce^(3+)/Ce^(4+)ratio.As a proof-of-concept application,the Ni-CeO_(2)nanorods were successfully acted as a colorimetric platform for the sensitive determination of ascorbic acid andα-glucosidase activity,which displays excellent analytical performance.Moreover,this sensing platform was applied for screening naturalα-glucosidase inhibitors,such as terpenoids from natural products.The results indicated that ursolic acid and oleanolic acid had good inhibitory rates.This strategy not only provides a new way to construct more kinds of nanomaterials from DESs,but also offers a facile and effective tool to screen theα-glucosidase natural inhibitors as potential anti-diabetic drugs.

Colorimetric Detection of Acid Phosphatase and Malathion Using NiCo_(2)O_(4)Nanosheets as Peroxidase-Mimicking Activity

The establishment of a low-cost and facile approach for the assay of acid phosphatase(ACP)and its inhibitor is a research focus.In this paper,we successfully synthesized NiCo_(2)O_(4)nanosheets with peroxidase-mimicking activity in alkaline deep eutectic solvents(DESs)composed of NaOH and PEG-200,which can catalyze 3,3',5,5'-tetramethylbenzidine(TMB)to the oxidation state TMB(ox-TMB)in the presence of H2O2.Due to L-ascorbic acid-2-phosphate can be hydrolyzed into ascorbic acid by ACP,the peroxidase-like activity of NiCo_(2)O_(4)nanosheets is inhibited.However,the addition of malathion,an inhibitor of ACP,can inhibit the activity of ACP and thus limit the production of ascorbic acid(AA).Therefore,a colorimetric approach can be established for highly sensitive and selective detection of ACP and malathion with detection limits of 0.032 U/L and 0.65 nmol/L,respectively.More importantly,this method can be successfully applied to malathion detection in environmental samples tap water and food cucumber juice,indicating that it has potential application prospects in environmental and agricultural fields.