Optimal Construction Of Paper-based Analytical Devices And Its Application On Dairy Safety Detection

Since the first microfluidic paper-based analytical devices(?PADs)was introduced by Whitesides and co-workers in 2007,the fabrication of microfluidic analytical devices using paper as substrate has emerged a hotspot of research.The paper-based microfluidic device technology is a new mode of monitoring food safety,and it is also a developing interdisciplinary technology,which has a positive significance to improve the current situation of food safety.The properties and structure of paper have important influence on the reaction process and results,but it has not been systematically studied at present.Therefore,through the study of paper performance,this paper selects the appropriate detection substrate,so as to improve the detection performance of paper-based devices,and provides a new idea for the detection and monitoring of paper-based devices in the food field.The main works are as follows:(1)The patterned paper-based devices were fabricated rapidly by ultraviolet-curing screen-printing method,which were optimized and characterized to obtain the paper-based devices with good hydrophilic/hydrophobic effect and to realize the preparation of a variety of regular and irregular patterns.In addition,a variety of techniques were used to analyze and characterize the fiber appearance and precipitate microstructure of different paper substrates,and the optimal paper-based devices were customized by colorimetric methods.The results show that No.102 qualitative filter paper has the best detection performance.(2)Based on a low-cost,portable paper analysis device,the high throughput detection and dynamic degradation monitoring of tetracycline residues in dairy products were realized by visual colorimetric reaction.Tetracycline was measured by colorimetric method,and the concentration of tetracycline-color intensity was quantified by image technology.Besides,21 kinds of samples(milk and water samples)were tested for tetracycline.The results shows that the method has good repeatability and recovery,and it is in good agreement with the results determined by UV spectrophotometry.In addition,a convenient pre-concentration and detection technology for tetracycline in dairy products was proposed,which realized the colorimetric detection of low concentration tetracycline(0.1ppm)in national standard dairy products.(3)Griess method was used to determine the nitrite,the practicability analysis of paper-based device in dairy products was further explored,and the device was assembled.At the same time,combined with the optimized experimental results,it provides the best color intensity and clarity for the detection of nitrite.The results showed that nitrite not only had good linear correlation in water and various dairy products,but also had good recovery and reproducibility in corresponding experiments,and also had good agreement with the results determined by UV spectrophotometry.In addition,the service life of the labeled paper-based device was also explored.The results show that the method has good visibility and repeatability.