Researches On The Determination Of Several Evaluation Indicators Of Chinese Medicines With Paper-based Analytical Devices

Though the quality detection technology of traditional Chinese medicines(TCMs)has developed rapidly in the past two decades,it is necessary to develop rapid and low-cost quality detection methods.Paper-based analytical technology was used to detect TCM quality in this thesis.Three quality indicators including α-glucosidase inhibitory activity,antioxidant activity,and total phenol content were chosen as the examples in the thesis.The main contents of this thesis are listed as follows.1.A paper-based analytical device was used to detect the inhibitory activity of mulberry leaf extracts on α-glucosidase.The modified filter paper was obtained by 3D printing and melting treatment.The paper-based analytical device was prepared by adding α-glucosidase solution to the modified filter paper.A positive drug acarbose was added to the paper-based analytical device and a smart phone was used to read color results.According to the relationship between the color components and the contents of the added acarbose solutions,the color component Y was selected as the best detection index.The definitive screening design was used to optimize the activity detection conditions.The detection results of mulberry leaf extracts obtained by the paper-based analytical method and the conventional microplate reader were compared.There is no significant difference between the results obtained with these two methods after statistical testing.Bovine serum albumin was used as an enzyme stabilizer and the detection capacity of paper-based analytical devices can be maintained for more than a week.The method verification and application of the paper-based analytical method were carried out.2.A paper-based analytical device was used to detect the antioxidant activity of Danhong injection.A modified mold was printed on quantitative filter paper by 3D printing.The filter paper and the mold were soaked in a paraffin n-heptane solution.Then it was dried and heated to prepare modified filter paper for chemical reactions in ethanol solution.The DPPH reagent was added to the modified filter paper to make a paper-based analytical device.Ascorbic acid was added to the paper-based analytical device and a smart phone was used to read color results.According to the relationship between the color components and the ascorbic acid contents,the color component G and grey scale were selected as the best detection indexes.The optimized indexes were used to detect the antioxidant activity of Danhong injection.The method verification and application were also carried out.3.Carbon quantum dots were prepared by continuous flow synthesis reaction for phenol content detection.A continuous flow reaction device was set up and tetraethylene glycol aqueous solution was used as the solvent system.Nitrogen-doped carbon quantum dots were synthesized using citric acid and ethylenediamine as raw materials.The optical properties of the carbon quantum dot were characterized.A definitive screening design was used to establish a quantitative relationship between experimental conditions and quantum yield.High fluorescence yield was taken as the optimization goal.The design space was established by the simulating experiment error method and verified.It was found that the carbon quantum dots can be quenched by phenols such as chlorogenic acid,salvianolic acid B,and rutin.There is a linear relationship between the fluorescence quenching degree of carbon quantum dots and the amount of chlorogenic acid added,indicating that the carbon quantum dot obtained by continuous flow synthesis have the potential application for quantitative detection of phenolic substances.Compared with traditional synthesis methods,continuous flow synthesis technology provides a basis for high-efficiency preparation of carbon quantum dots.4.The carbon quantum dot paper-based analytical method was used to detect the total phenol content of the honeysuckle extracts.The chromatography paper was cut with a lettering machine to obtain a square piece of paper.The carbon quantum dot solution was added to the paper to obtain a carbon quantum dot paper-based analytical device.After chlorogenic acid solutions of different concentrations were added to the paperbased analytical device,it exhibited fluorescence of different intensities under ultraviolet light.A smartphone was used to obtain the color data and the color component G was selected as the detection index.The paper-based analytical device was used to detect the total phenol contents in the honeysuckle extracts.The results were compared with the total phenol detection method in the Chinese Pharmacopoeia.The statistical testing result showed that there is no significant difference between the two methods.After completing the method verification,the method was applied to determine the total phenol content of different batches of the honeysuckle extracts.Compared with the Chinese Pharmacopoeia method,the carbon quantum dot paperbased analytical method did not require use of an ultraviolet spectrometer and did not require preparation of unstable Folin-Ciocalteau reagents.