Development Of Automatic Instrument Based On Immunomagnetic Separation And Fluorescence Detection And Its Application In Antibiotic Detection

Magnetic nanobeads have been extensively used in biosensors for the capture and separation of target perior to detection.However,repeated manual operation of separation and liquid transfer is not only cumbersome and complicated,but also introduce serious errors.Therefore,in this study,we developed an instrument that consisted of side wall separation,liquid transfer by pipette and the combination of USB2000+ spectrometer and fluorescence probe to realize automatic magnetic separation,quantitative liquid transfer and fluorescence detection.The main research contents and conclusions are as follows.1)The stability of the side wall magnetic separation method was evaluated.The effects of magnetic separation time and washing times on the fluorescence intensity of the supernatant were studied.The results showed that the combination of side wall magnetic separation and pipette could effectively absorb the supernatant and transfer the liquid.The coefficient of variation of traferring 10 μL,20 μL and 200 μL of liquid was less than 11%.The magnetic separation time of 70 s and washing times of 3 displayed the highest capture efficiency for 100 nm magnetic beads.An automatic sample pretreatment instrument based on the side wall magnetic separation and pipette was established and used for enrofloxacin detection.The detection model could be described as F= 0.437 log C-0.513(F is fluorescence drop ratio,C is the concentration of enrofloxacin),and the detection limit was 54 ng/m L.2)As fluorescence intensity is the final detection standard,we compared two common fluorescence probes and three different spectrometers(USB4000 with slit width of 25 μm and200 μm and USB2000+ with slit width of 200 μm).By conducting a single variable experiment,the USB2000+ spectrometer equipped with a fluorescence probe and a slit width of 200 μm was selected as the optimum.For 0-8 n M quantum dots with a maximum emission at 525 nm,the detection model is Y =-10+1738 x;for 0-16 n M quantum dots with a maximum emission at 575 nm,the detection model is Y =-98.2+623 x;for 0-8 n M quantum dots with a maximum emission at 625 nm,the detection model is Y =-534 +6880 x(x is the concentration of corresponding quantum dots,Y is the fluorescence intensity).3)An automatic instrument consisted of sidewall magnetic separation,automatic liquid transfer and fluorescence detection was built,which can process two samples in parallel.DSP28335 is used as the main control chip for automatic liquid transfer control,and a tablet computer is used as the upper computer for command sending and interface display,which has the functions of local storage and cloud transmission.