Study On A New Method For Immune Detection Of Marine Red Tide Toxin Based On Microfluidic Chip

With the development of industry and agriculture,the problem of marine pollution has become increasingly serious.The phenomenon of eutrophication has gradually led to the frequent occurrence of red tide disasters,seriously affecting the marine ecological environment and human health.Shellfish produce red tide toxin through their own transformation after swallowing toxic red tide algae.And the red tide toxin can accumulate with the food chain.Human eating seafood contaminated by red tide toxin will cause poisoning phenomenon,which seriously threatens human life and health.The most seriously polluted red tide toxin in China’s sea area is diarrhoeal shellfish toxin(DSP).As one of the main virulence factors of diarrhoeal shellfish toxin,okadaic acid(OA)can cause acute toxic effects,including diarrhea,dizziness,vomiting,abdominal pain and other symptoms.At the same time,it was reported that the longterm cumulative effect of OA is extremely harmful,and has a strong tumorigenic and carcinogenic effect.At present,there are many detection methods for OA,including biological analysis,instrumental analysis and biochemical analysis.However,most of these methods depend on the laboratory.In the face of more and more extensive analysis fields and more and more complex analysis environment,for a wide range of application fields and complex detection environment it is urgent to propose a new detection method with high automation and portability.The combination of smartphone and microfluidic chip in the process of analysis and test makes the miniaturization and real-time analysis of the experimental device a reality.Therefore,it is a promising method to develop a simple,sensitive and low-cost on-site detection sensor with smartphone.In this paper,an immunosensor which combines microfluidic chips and smartphones was proposed for rapid and highly sensitive detection in the field.In this study,we effectively established a smartphone-assisted microarray immunosensor for quantitative colorimetric detection of OA.In order to further improve the detection sensitivity and match the imaging of smart phones,a new graphene oxide(GO)composite probe was developed by combining the unique physical and chemical properties of graphene oxide with the biotin-avidin signal amplification system to achieve multi-level signal amplification.The linear range of OA detection using indirect competitive enzyme linked immunosorbent assay(iELISA)technology system was 0.02-33.6 ng/mL,and the detection limit was 0.02 ng/mL.The recovery of OA in spiked shellfish samples was in the range of 80%-103.5%,which indicates the good applicability of this biosensor.In view of the complex manufacturing process and high cost of the PDMS microfluidic chip,the paper-based microfluidic chip was introduced to further improve the immunosensor.In order to solve the problem of low sensitivity of paper-based microfluidic chips,the gold nanoparticle composite probe was successfully prepared and used to improve the conventional direct competitive enzyme linked immunosorbent assay(ELISA).On the paper chip,the target component can be effectively separated from the sample mixture based on polarity differences,and was concentrated at the front end of the paper chip through lateral flow when the capillary force was dragged along the paper surface,greatly solving the current cleaning problem of the paper chip.The experimental results show that the immunosensor based on paper-based microfluidic chip has a good response to OA,with a linear range of 0.2-50 ng/mL and a detection limit of 0.2 ng/mL,and showed good specificity and high recovery.This work shows that the whole detection system has advantages of simplicity,low cost,high sensitivity and portability,which is expected to be a powerful alternative tool for on-site detecting and early warning of the pollution of marine products.