Research Of Android Smartphone-based Immunoassays For Microcystin-LR Detection

Microcystin-LR（MC-LR）is a strong hepatotoxin produced by cynobacteria,posing serious threats to human through the drinking water or aquatic products that accumulated with MC-LR.What’s worse,its extensive natural distribution and seasonal outbreak make it really hard for traditional detection methods to cover the requirement of MC-LR in situ screening,which exhibites the demand of continuous analysis to monitor the MC-LR level and high portability to ease the situation of different distribution.All of these demonstrate the urgency to develop portable on-site monitor techniques for MC-LR.In recent years,with the rapid development of cellphone technology,smartphones can be conditioned as an integrated platform to receive,analyze,and display data,thanks to its strong central processing unit,humanized touch-screen display and large-scale data storage.Combined with sensitive biosensors,the smartphone-based MC-LR biosensing platform exhibit huge competitive edge over the conventional methods performed in centralized laboratories.In this research,a smartphone-controlled electrochemical analyzer（SCEA）and a smartphone-based multifunctional fluorimetry analyzer（SMFA）was proposed and implemented for MC-LR in situ detection.The main research contents were as follows:1)Smartphone-based electrochemical MC-LR immunoassay.In this research,the screen printing carbon electrodes（SPCEs）were modified with prussian blue-chitosan（PB-CS）nanocomposite to conjugate MC-LR antigen as the sensitive sensors.The detector consisted of a smartphone app and a portable electrochemical analyzer,the former was responsible for signal processing and huaman-computor interacting（parameters setting,displaying and storaging,etc）,while the latter can record and then send the data out.Under the optimal condition of six influencing factors,the calibration curve was built.In the linear range of 0.001 to 100μg/L,this sensor had the confidence to detect MC-LR in water sample as low as 0.00011μg/L.As a further demonstration,we plotted geospatial distribution of MC-LR contamination at six reservoirs in Pearl River Delta with good accuracy.This SCEA has merits of high sensitivity,strong specificity,low cost and portability,which not only realized the in situ detection of MC-LR,but also offer guidance for the onsite screening of other contaminations in waterbody.2)A smartphone-based multifunctional fluorimetric analyzer for microcystin-LR detectionIn this research,a multifunctional 3D-printing POCT（point-of-care testing）analyzer was fabricated for MC-LR fluorimetry detection,which integrated the incubation module,fluorescence excitation module,image capture module and self-powered module into a single device.Microfluidic chip,also called lab-on-a-chip,showed really high potential for the field detection due to its small size structure,high integration and low cost of reagents.As sensitive sensing module,the immune-magnetic beads that conjugated with MC-LR antigen were passed through the reaction pools of the 15-channel microfluidic chip by the magnetic force,indicating the high throughput of MC-LR monitor.Under the catalysis of HRP-Labeled antibody and the following exicitation of LED array,the fluorogenic substrate（Amplex red）finally generated signals that can be recorded by the smartphone-based analyzer.After optimizing the five influencing factors,a calibration curve was built whose LOD was 0.0006μg/L in the linear range of 10^-3to 1000μg/L.Using this proposed method,a LOD of 0.0054μg/L in the linear range of 10^-2to 1000μg/L with acceptable recovery rates of 90.9%-100.8%was yeilded in prawn samples.What’s more,a comtamination map in the above 6 reservoirs was also obtained in Spring and a preliminary analysis of two different results was given.This system owns advantages of sensitive,effective,rapid and simple,which can not only offer reference to the MC-LR monitor in water head sites,but also support the technical measures that prevent the damages to prawn culture as well as human health by giving effective early warnings according to the detection results.In conclusion,both of the two smartphone-based MC-LR immunoassays were sensitive,stable and practical,presenting important references for the development of MC-LR in situ detection.