Study of prototropic reactions of indole chalcone derivatives in ground and excited states using absorption and fluorescence spectroscopy

A novel fluorescent probe of alkyne compounds for putrescine detection based on click reaction

Putrescine is a toxic biogenic amine produced in the process of food spoilage, and a high concentration of biogenic amines in foods will cause health problems such as abnormal blood pressure, headaches and tachycardia asthma/worsening asthma. The detection of putrescine is necessary. However, traditional putrescine detection requires specialized instruments and complex operations. To detect putrescine quickly, sensitively and accurately, we designed and successfully prepared a fluorescent probe (DPY) with active alkynyl groups. DPY takes p-dimethoxybenzene as the raw material, adding a highly active alkyne group. It is stable in experimental pH (∼7) because the UV-vis absorption and fluorescence emission spectra in pH = 3-12 have little change. The fluorescence intensity of DPY decreased only about 1% under the irradiation of 420 nm within 2 h, showing its better photostability. DPY has a high selectivity to putrescine because of the amino-alkyne click reaction without any catalyst in presence of different biogenic amines. The obvious response to putrescine was found in 30 seconds at room temperature. The mechanism between DPY and putrescine was investigated before and after adding putrescine by 1H NMR spectra and the Job plot. The results indicated a typical 1 : 1 stoichiometry between the DPY and DAB. Furthermore, the higher sensitivity of DPY to putrescine was obtained with the detection of limit (LOD) of 3.19 × 10-7 mol L-1, which was better than that of the national standard (2.27 × 10-5 mol L-1). The novel fluorescent probe was successfully applied to beer samples to detect putrescine. The proposed strategy is expected to provide some guidance for the development of some new ways to detect food security.