Preparation Of Bimetallic Nano-cluster Fluorescent Probe And Its Performance For Detection Of Heavy Metal Ions

With the continuous reform and opening up of China and the rapid development of industrialization and modernization,more and more environmental problems have been exposed.With the frequent occurrence of human production and life activities such as mining,waste discharge and metal smelting,many heavy metal ions have been discharged into the ecosystem,which has brought a lot of indelible pollution and damage to the environment.Make the problem of environmental pollution more serious.After entering into the ecosystem,heavy metal ions will accumulate in the food chain due to their difficulty in degradation,which will eventually endanger human health.Therefore,more and more experts and scholars are committed to the detection of heavy metal ions in various environments.At present,most of the commonly used detection technologies have some shortcomings,such as expensive equipment,tedious and complex detection process,timeconsuming and so on.Fluorescent probe technology has been widely concerned by many scholars because of its low cost,convenient detection and real-time detection.In this paper,we discussed the preparation and properties of bimetallic nanocluster-based fluorescent probes and their applications in the detection of heavy metal ions.The main work is as follows:In this paper,copper/silver bimetallic nanoclusters with bright yellow fluorescence were synthesized by a simple and environmentally friendly method using penicillamine as stabilizer and reducer.Higher fluorescence intensity of copper/silver bimetallic nanoclusters can be obtained by controlling the molar ratio of Cu(Ⅱ)to Ag(Ⅰ)at 1:3 and reacting for 25 min after adding Ag(Ⅰ).The optimal excitation wavelength is 300 nm and the optimal emission wavelength is 555 nm.Through the experiments,it was found that the copper/silver bimetallic nanocluster could achieve high sensitivity and selectivity for the detection of silver ions,and its fluorescence intensity could show a linear relationship with the concentration of Ag(Ⅰ)in a certain range,and the minimum detection limit could reach 0.3μM by further calculation.Based on this,the copper/silver bimetallic nanoclusters can also be used as fluorescent probes to detect silver ions in real samples,and very excellent accuracy and reproducibility were obtained.Therefore,the copper/silver bimetallic nanocluster can be applied to the detection of actual water samples to broaden its practical performance.In addition,in order to change the drawback that the simple bimetallic nanocluster solution is not convenient for storage and use,we prepared and obtained a novel gold/copper bimetallic nanocluster-doped chitosan fluorescent composite film.In this study,gold/copper bimetallic nanoclusters with strong red fluorescence were firstly synthesized by chemical reduction method,and then a novel gold/copper bimetallic nanocluster-doped chitosan fluorescent composite film was successfully prepared by solution casting method,whose relative fluorescence intensity values only decreased by 0.9% and 1.2% after 60 min of UV irradiation and 30 days at room temperature,respectively.This indicates that its optical properties are stable and can be stored for a long time.The composite film has strong and bright red fluorescence,and can be used as a fluorescent probe to achieve real-time detection of Cr(VI),and has a low detection limit(0.26 ppb)for Cr(VI),so it can be applied to the detection of Cr(VI)in actual water samples,and achieved good detection results.According to its portability,high selectivity and high sensitivity,it can also be extended to chemical detection and food detection.