Development Of Spectrometer Quantum Dot Based Fluorescence Analyzer And Its Application In Pathogens And Antibiotics Detection

Food safety is highly related to people's daily life,and now it has become one of the most serious global problems.For food safety detection,traditional methods and instruments are mainly designed for laboratory use,which are too large and time-consuming to be used in the field.As for rapid detection methods,the method based on quantum dot fluorescence not only has the advantage of low detection limit but also is able for simultaneous detection of the multi-target,which can largely improve the efficiency.In this paper,the micro-spectrometer is used as the core device to do instrumental research on the fluorescence labeling method based on quantum dots in order to realize the rapid detection and application of this method in the field,which includes the following contents.1.A portable fluorescence detector based on USB4000 Mini-spectrometer was developed,including optical measurement unit,mechanical measurement unit,and LabVIEW-based control software.The problem that laboratory instruments are not suited for quantum dot fluorescence method for on-site rapid detection due to their large volume and the high cost was preliminarily solved,and the detection accuracy is high(when three foodborne pathogens are detected simultaneously,the detection limits are 98-350 CFU/mL).It also has the advantage of good repeatability and this instrument has already realized simultaneous detection of multiple foodborne pathogens using this method in the field.2.A performance evaluation platform for micro spectrometers was studied for the evaluation and comparison of four typical micro-spectrometers(C12666,C12880,Spark and INSION) in the market.This platform includes an optical part,circuit,and software.In optical research,LED was used as the excitation light source,and an open optical path was designed to avoid the use of optical fibers to reduce the overall volume.In the optimization of optical devices and optical design,we optimized four kinds of LED according to the monochromaticity and stability of luminescence.According to the enhancement of target fluorescence signal and the suppression of noise signal,seven kinds of lenses,twenty kinds of lenses and the distance between test tube and spectrometer,and seven kinds of reflective surface arrangement were optimized.Three kinds of glass tubes were optimized according to the intensity of background noise.Finally,the optimal detection optical paths for four spectrometers were determined.3.In the performance evaluation of quantum dot fluorescence detection between C12666,C12880,Spark and INSION spectrometers,four kinds of quantum dots(emission wavelength are530 nm,577 nm,623 nm,and D657 nm respectively) were used as objects.Compared with C12666 and C12880 spectrometer,the linearity and repeatability of their results are similar,but the light sensitivity of C12666 spectrometer is weaker than that of C12880 spectrometer by nearly one order of magnitude,which results in that C12666 spectrometer must use longer integration time in the detection of the same target,making the detection signal-to-noise ratio much worse;In the comparison between C12880,Spark and INSION spectrometer,for the detection of single quantum dot,except the most fluctuates of C12880 spectrometer in QD657 detection,this spectrometer has obviously better detection limit,linearity,and repeatability in the other three quantum dots.In the detection of four quantum dot mixtures,three spectrometers all can distinguish the mixed fluorescence peaks of four quantum dots,and after multi-peak Gauss fitting,the peaks can be separated.The results are fairly good,and the determination coefficients are all above 0.99.Comparing the prices of the three,the C12880 spectrometer has better detection effect and lower cost.4.A portable fluorescence detector based on C12880 micro-spectrometer with the application based on Android smartphone were studied.In the detection of typical antibiotics enrofloxacin,the Pearson correlation coefficient between the results of this instrument and that of the microplate reader is higher than 0.99.The results of the two instruments can be fitted with the four-parameter Logstic model to obtain outstanding results(both R~2 are higher than 0.99).The fitting effect of these two instruments is similar.The linear fitting results of linear segment data show that two instruments have similar determinant coefficients,R~2 is about 0.93.The detection limits of enrofloxacin by two instruments are very similar,which are 2.52 and 2.84 ng/mL,respectively,which has met the detection requirements of the maximum residue limit of enrofloxacin in the muscle of broilers(100?g/kg) stipulated by the Ministry of Agriculture.In the repeatability test,the absolute value of the coefficient of variation of both intra-group and inter-group detection of the micro-fluorometer is between 0.5% and 2.5%,and the repeatability is good.The instrument is very portable,whose overall weight is only 350 g.It can be used together with the smartphone and has great potential to be promoted in the future.