Study And Application Of The Detection Method Of Nano Gold Strip Based On The Aptamer Of The Saxitoxin

Saxitoxin(STX)is a kind of marine paralytic shellfish toxins,mainly from toxic algae.Consumption of toxic algae,the shellfishes accumulate highly toxic STX in the body,whose lethal dose to human is only around 1 mg.Poisoning symptoms of STX is significant,including diarrhea or even the death of shock.In recent years,the poisoning incidents due to the ingestion of toxic shellfish are increasing,which urgently demands a rapid,sensitive in-situ detection method for the effective monitoring of STX.Compared with other commonly used detection methods,test strip has the following characteristics:deal with the pretreatment of complex sample easily;the results are intuitive and visible;short detection time by a small portable instrument.This paper is mainly to prepare a nano gold strip biosensor based on the aptamer,and adopt the recognition mechanism of competition law.The resulting biosensor will be able to have a rapid detection of high sensitivity of saxitoxin,which could be applied for detecting shellfish toxins.The main contents of this paper include:(1)This study prepared aptamer-gold nano particles composite materials,and built a nano gold strip of STX based on aptamer.The detection conditions of optimal STX were determined:buffer solution of Tris-Hcl 0.01mol/L + Nacl 0.6mol/L + 2%BSA GNPs-DNA probel combination mat(Conjugate)complexes for the amount of 2uL,the amount of nucleic acid aptamer Conjugate composite is 2 OD,spraying concentration test line position of STX DNAprobe2 on NC film is 1 ug/mL.Under these conditions,the signal of noise ratio is the best.(2)This study investigated the nano gold test strip based on aptamer for the reproducibility,the sensitivity,the specificity and the stability.The results showed that the test strip in the range of 10?1000 ng/mL had a good linear relationship,y=-269.79x + 1011.93,R2=0.99035,the minimum detection limit of the strip reached to 1.3 ng/mL,the test strip for other non target toxins(e.g.:okadaic acid,aflatoxin,etc.)had on obviously signal and demonstrated the specificity of this strip.The experiments for the various STX levels of 0 ng/mL,10 ng/mL,200 ng/mL and 800ng/mL were repeated for six times,and the relative standard deviation is 21%,3%,15%and 19%,respectively.The results indicated that the test strip has good repeatability,good stability within 8 weeks and at room temperature.The nano gold strip biosensor based on aptamer has a good analysis performance,which could provide a quick and simple detection method for the rapid detection of STX.(3)In the actual detection of shellfish samples,the strip in response to the target signal intensity and the concentration of toxin in complex matrix in the range of 0?1000 ng/mL had a good linear relationship,and the detection limit could reach to 2.54 ng/mL.The test results were consistent with the standard,which confirmed that the test strip in the complex environment of the target matrix could keep the selectivity to the target toxin,which could not be easily disturbed.At the last,the testing results of strip applied in the actual shellfish samples were consistent with the testing results from traditional mouse assay.