Controllable Preparation And Applicaton Of Quantum Dots Aerogel Microsensor For Glucose

Diabetes,as a chronic disease which seriously endangers human physical and mental health,has been concerned by researchers in various fields.Because of the high cost of testing instruments and human resources,governments and individuals spend hundreds of billions of yuan annually on the diagnosis and treatment of diabetes.At the same time,in order to effectively manage diabetes and reduce the incidence of related complications,diabetic patients must monitor and strictly control blood sugar level every day.Therefore,a low-cost,efficient,fast and accurate visual sensor for glucose is very helpful.A novel microfluidic sensor for glucose based on quantum dots(QDs)aerogels and glucose oxidase(GOx)is presented.This new type of sensor is a low-cost and fast fluorescence microfluidic sensor,which can provide users with visual and qualitative detection of glucose for diabetic blood and urine sugar diagnostic cut-off points,and also can use the instrument to achieve high sensitivity of quantitative detection of glucose.The main contents of this paper include the following three aspects:(1)A design idea and preparation method of a monochrome fluorescent microfluidic biosensor for glucose were proposed.Its optical detection platform was built and its detection characteristics for glucose were constructed.A straight channel microfluidic chip was fabricated by maskless lithography and reversing mode technology,and CdTe-GOx aerogels were constructed in the microfluidic chip channel by freeze-drying technology.The aerogel has three dimensional porous structure,which can provide the sensor with a large specific surface area to improve the detection sensitivity,as well as to ensure the activity of GOx and improve the stability of the sensor.A corresponding optical detection platform is built for the sensor.The platform can provide 254 and 365 nm ultraviolet light to excite the red fluorescence of the sensor.At the same time,the fluorescence image of the sensor can be taken by camera and the gray value of the fluorescence image can be analyzed by ImageJ software.In order to realize the visual and qualitative detection function of the sensor corresponding to the cut point of human blood sugar diagnosis,the optical characteristics of the sensor were optimized.Experiments show that within the range of 0-13 mM glucose concentration,the sensor can provide visual qualitative detection and instrument quantitative detection for blood glucose and urine glucose within 5.5 minutes.The detection limit is 0.135 mM,and the required sample size is only 0.8 μL.The sensor has good selectivity,low cost and good stability in one month.(2)Carbon quantum dots(CDs)emitting green fluorescence were introduced into the sensor to construct a micro-sensor capable of detecting glucose by ratio-type two-color colorimetry,which was applied to the visualization qualitative and quantitative detection of urine glucose.In order to improve the visual detection performance of the sensor,green fluorescent CDs are introduced as the internal parameters of the sensor in the process of making the sensor,which makes the method of detecting glucose change from judging the brightness of a single red light to identifying the ratio of red CdTe QDs fluorescence intensity to green CDs fluorescence intensity,so as to eliminate unnecessary interference in the environment.In order to take advantage of the non-invasive advantages of urine sugar detection,the sensor optimizes the optical characteristics of the cut-off points of urine glucose detection,enabling users to determine whether their own urine sugar exceeds the standard according to their fluorescence color.Experiments show that within the range of 0-13 mM urine sugar concentration,the R/G value of the fluorescent image of the sensor has a good linear relationship with the urine glucose concentration.The detection limit is 2.17 mM and the required sample size is 0.8 μL.The detection results of the sensor for real samples are also consistent with those of the hospital.The sensor has good selectivity and stability,and its cost is much lower than the commercial blood glucose meter.(3)A novel micro-cup sensor structure was proposed and applied to the visualized qualitative and quantitative detection of urine glucose.In order to reduce the user’s threshold,a micro-cup CdTe-GOx optical sensor is improved and developed.The fabrication of sensor microcup chips was accomplished by laser processing,which realized the low-cost and rapid preparation of the sensors,and the three-dimensional porous CdTe-GOx aerogels were constructed by freeze-drying in the microcup.The optical characteristics of the sensor were optimized according to the cut point of human urine glucose,and the optimal temperature of the sensor was studied.Experiments show that the sensor can provide users with visual and qualitative detection of glucose in the range of 0-26 mM urine glucose concentration,and the fluorescence intensity of the sensor has a good linear relationship with urine glucose concentration through quantitative detection.The detection limit is 0.116 mM and the sample consumption is 10 μL.The results obtained by using the sensor are consistent with the results of the hospital.The sensor has good selectivity and stability.Compared with the microfluidic sensor,it has larger area for visual detection,easier to realize automatic sampling,higher detection range,lower detection limit and lower manufacturing cost.