Research On Aptamer Based Rapid Detection Method For Antibiotic Residue

Aptamers,as a new type of biometric molecule,provide a new idea for the development of efficient and rapid detection methods.Aptamer technology can be used for biosensors to convert or amplify signals directly,such as colorimetric,optical,electrochemical,etc.mode.Aptamer sensors can also be combined with other techniques,such as nanotechnology,to achieve signal amplification,improved detection sensitivity,and unmarked detection.These aptamer sensors have been successfully used in the fields of biosensing,molecular imaging,targeted therapy,and food safety.Aptamers are also rated by Nature Methods as one of the most noteworthy technologies in 2014.Especially it has provided a better platform to the development of analytical testing methods.In the future,these methods based on aptamer technology will continue to be the trend of rapid detection and analysis of food.In this study,a method for rapid detection of antibiotic residues in food was established based on the aptamer technique by optimizing the reaction conditions.Aptamer based photometric assay for the antibiotic sulfadimethoxine based on the inhibition and reactivation of the peroxidase-like activity of gold nanoparticles;Aptamer based ultrasensitive determination of the Tetracycline Hydrochloride using PicoGreen as a fluorescent DNA probe;Determination of a method for rapid detection of chloramphenicol based on aptamers.The main contents of this paper are divided into three parts:1.It is known that gold nanoparticles(AuNPs)possess peroxidase-like activity.They can catalyze the oxidation of 3,3,5,5-tetramethylbenzidine by H202 which leads to a color change from red to blue.It is shown here that the peroxidase-like activity of AuNPs can be inhibited by passivating its surface passivation with a ssDNA aptamer against sulfadimethoxine.If,however,the target molecule(sulfadimethoxine)is present,the aptamer is desorbed from the AuNPs surface,and this results in the reactivation of the catalytic property of the AuNPs.The color change of the solution(from purple to blue)is related to the analyte concentration,and this can be judged visually or by UV-visible absorptiometry at 650 nm.The assay,under optimized conditions,has a detection limit of 10 ng·mL-1 of sulfadimethoxine,and the calibration plot is linear over a rather wide concentration range(0.01-1000 ?g·mL-1).The assay can be performed within<15 min,is sensitive,and therefore is well suited for fast screening in food analysis.Conceivably,it can be extended to many other small analytes for which aptamers are available.2.The tetracycline(TET)was determined by using PicoGreen(PG)as a dsDNA-specific fluorescent probe based on aptamer technique.In the absence of TET,the aptamer forms a double-stranded structure with its complementary sequence,resulting in enhanced PG fluorescence.When the aptamer binds to the target TET,the number of formed DNA duplexes is reduced and a decrease in the fluorescence intensity of the PG is measured at the excitation/emission wavelength of 480/520 nm.Under the best optimized conditions,the dynamic calibration curve covers a concentration range of 5 nM to 1000 nM with a detection limit of 5 nM.This is in line with the European Commission's safety regulations for the retention of TET residues in food.The method shows higher specificity than other antibiotics.This method represents a simple,fast and sensitive tool for field testing of TET in food.3.It has developed a Lateral Flow Strip Assay(LFSA)based on the aptamer and its complementary strand competition.In this fluorescent LFSA assay,chloramphenicol(CAP)competes with a complementary strand of a specific adapter that is specifically bound to a CAP that is immobilized on a test line(T-line)above the nitrocellulose(NC)membrane to compete for a limited fluorescent label Of the CAP aptamer,the fluorescence intensity of the detection line for the detection signal.In the control line(line C),a sequence that is independent of the CAP aptamer[18 adenines designed in this paper)is complementary to the fluorescently labeled linker-Cytosine in the system and only acts as a control,and its fluorescence signal Strength is stable.The LFSA has a linear relationship in the range of 1 to 1000 nM,with a detection limit of 1 nM.Thus,this study has shown that a simple and effective LFSA is successfully used for CAP detection without any special and laborious instruments.This system provides a new approach to the development of aptamers for the rapid field detection of antibiotic residues or other target screening tools.