Aptamer-based Label-free Fluorescent Detection Of Methamphetamine

Methamphetamine(METH),also known as methyl-amphetamine,is a central nervous stimulant.When methamphetamine enters the body,Dopamine and 5-hydroxytryptamine increase substantially,resulting in euphoria and hallucinations.In 2017,relevant researches showed that synthetic drugs had a large scale of users which ranked first in China,accounting for nearly 60.5% of drug addicts.METH does great harm to health and leads to physiological dependence.It also poses severe threat to social stability and harmony.Therefore,it is significant to study METH on-site detection techniques to maintain the public safety.The development of METH detection techniques and label-free fluorescent technique based on aptamer were summarized in this dissertation.A perylene-based fluorescent probe PBIs was synthesized by simple chemical synthesis.By modification,the probe could have good water solubility and stable fluorescence performance.Meanwhile,a label-free fluorescent sensor was developed by using the aptamer with specific recognition function.The sensor was used for METH detecting,and the detection conditions were optimized.We also studied the mechanism of the sensor.Subsequently,the sensor was used to detect the urinary methamphetamine.The main contents are as follows:1.A water-soluble fluorescent probe PBIs was synthesized by three-step reaction and purification.The raw materials contained PTCDA,tri-(2-aminoethyl)-amine,formic acid,formaldehyde,sodium carbonate,methanol and iodomethane.And we analyzed the molecule and structural characteristics of PBIs.Then,we studied the fluorescent properties of PBIs,and determined the optimum excitation wavelength.The concentration of probe was optimized.2.A fluorescent sensor was developed by using probe PBIs and aptamer,we used three strategies: ssDNA competition,dsDNA(aptamer-complementary chain)break and ssDNA-Exo I.We also studied the feasibility of the sensor detecting methamphetamine.To determine the proper concentration of aptamer,the fluorescence titration experiment of PBIs with aptamer was carried out firstly.Secondly,the fluorescence intensity at 548 nm was measured by using these strategies.The results showed that the concentration of methamphetamine in the range of 0-10 ?mol/L had a good linear relationship with the fluorescent value of the fluorescent system,and we calculated the detection limit.3.We studied the visual detection,specificity and selectivity of the sensor.Under the UV lamp,we set 20 ?mol/L as the visual detection limit,and the change of fluorescence could be discriminated.In terms of specificity and selectivity,the ssDNA-Exo I strategy performed well.4.We compared three strategies,and the ssDNA-Exo I strategy showed some advantages in the fluorescent detection.We also analyzed mechanism of ssDNA-Exo I strategy.5.The recovery experiment was carried out.We studied the feasibility of detecting urinary methamphetamine using ssDNA-Exo I strategy.We simulated the urine of drug addicts by adding methamphetamine into the urine from volunteers.The results showed that the strategy was highly accurate and stable.Subsequently,the urine from drug addicts was detected,and the fluorescence intensity of the system changed a lot.At the same time,the results of GC-MS proved that the strategy could be used for qualitative detection of methamphetamine in urine.