The Fundamental Reseaches On Visually Detection Of Melamine Based On Polymerized Vesicles

Food safety is an important social problem, which directly influences national economy, people's livelihood and social stability. Recent years, the high incidence of food safety events attracts much attention. Food examination is always based on instruments testing, greatly constrained by high price of instruments, complex pretreatment, limited units of test sample, high level of skill and other factors, so they could not meet the food safety requirements.The article taken the hot issues of food safety—melamine as key point, explored new ideas of melamine detection based on molecular recognition which is the essence of food examination, and expressed the sign by visual material. Previously, we have designed a vitamin derived bolaamphiphile (12-diaminododecanediorotate, DDO) which bears molecular recognition function moieties. In this paper, melamine involved molecular recognition events was successfully transformed into visible color changes using polymerized vesicles as the matrix lipid which was incorporated with bolaamphiphiles DDO bearing molecular recognition sites as the receptor. The mechanism of color transition polydiacetylene vesicles and was investigated by Differential Scanning Calorimetry (DSC) and ultraviolet spectrum during the molecular recognition occurred on the vesicle interface. The overwhelming significance of this method is not only embodied in the melamine detection, also other substance. The way of detection has enriched the food examination approaches, widened the platform of examination. The main research workings are as follows:(1) Reseach of polymerized vesicles as the color indicators in the melamine detection.It is the indispensable premise of using the polymerized vesicles as the color indicators that realizing the properties. We have reseached the conformation and steady of polymerized vesicles in different dissolvent environment and the situation of amphiphilic molecule inserting by DSC and ultraviolet spectrum analysis, for the preparation of construction of melamine detection experiment(2) Optimization of the polymerized vesicles as the color indicators.Building six kinds of color indicators with characteristic of polymerized vesicles and the assist materials, we compared performance of these indicators in the melamine detection by the Ultraviolet data. The results showed that the DDO/TCDA vesicles were the best color indicator for melamine detection.(3) Detection mechanism reseachesUsing sucrose and urea as model compounds for comparison, the kosmotropic and chaotropic effect of non-ionic small molecules on the phase transition of polydiacetylene vesicles and thermodynamics during molecular recognition process was also evaluated. A chaotrope-assisted colorimetric visualization mechanism was found during the color transition of polydiacetylene vesicles in which both multipoint interactions between melamine and DDO and chaotropic effect of the excess melamine dissolved in the solution contribute to the blue-red color transition of DDO/TCDA vesicles.