Construction Of Aptamer-based Antibiotic Biosensors

Antibiotics are widely used to treat and prevent the infection of various pathogenic microorganisms to human beings and animals.However,the extensive use of antibiotics has seriously threatened the ecology and human health.Rapid and sensitive detection of antibiotics in the environment is extremely important,as it can monitor the harmfulness of antibiotics to ecosystems and human health and carry out safety assessment.At present,the problem of antibiotic residues in environmental is becoming more and more serious,so it is necessary to develop highly selective and sensitive detection methods to effectively monitor them.Nucleic acid aptamers are a kind of recognition molecular that can specifically recognize targets.They form a 3D structure through base stacking,hydrogen bonding and hydrophobic interaction between molecules.Nucleic acid aptamers have the advantages of small molecular weight,good stability and easy modification.Biosensors based on aptamer and nanotechnology were constructed in this paper.Three biosensors were constructed to realize rapid and sensitive detection of tetracycline(TET),kanamycin(KAN)and chloramphenicol(CHL).The main contents are as follows:1)TET aptamer biosensor was constructed based on TET aptamer and cyclodextrin host-guest competition modeFirstly,the sulfydryl-?-cyclodextrin(SH-?-CD)was used as the main body and the TET aptamer modified with ferrocene as the guest was immobilized on the gold electrode through the aptamer and SH-?-CD.When TET exists,the aptamer changed from the original upright state to the agglomerated state,away from the electrode surface,and the redox current intensity decreased.The influence of different conditions on TET detection was discussed.Under the best detection conditions.The sensor had a good linear response range(0.01-100 nM)to TET concentration in solution,and the detection limit could be as low as 0.80 pM.At the same time,the sensor had good specificity,stability and repeatability.2)KAN biosensor was construct based on the KAN aptamer and combine with molecular imprinting technology and nanotechnologyA molecular imprinting film was formed on the electrode modified with chitosan-graphene composite material,gold nanoparticles(AuNPs)were modified on the electrode to enhance electron transfer on the electrode surface,and KAN in the solution was captured by molecular imprinting.KAN aptamer and SH-?-CD were modified on Au@Fe3O4 composite and used as tag molecules.The combination of SH-?-CD and ferrocene provided electrochemical signals,while KAN aptamer bound to KAN captured on the molecularly imprinted membrane,which realized the specific detection.Under the best conditions.The sensor had a wide linear response range of(10-500 nM)and a detection limit of 1.87 nM for KAN.The biosensor constructed had high stability and selectivity and can accurately detect KAN in different solutions.This method provided a new method for the detection of environmental pollutants.3)A photoelectrochemical biosensor for CHL based on APT/AuNPs/g-C3N4/TiO2 was constructedAuNPs and g-C3N4/TiO2 nanocomposites modified on the electrode were combined by deposition method to form AuNPs/g-C3N4/TiO2 ternary composites,which were used as photoreaction substrates.Subsequently,the sulfhydrylated CHL aptamer was loaded on AuNPs/g-C3N4/TiO2 through Au-S bond to construct a biosensor for CHL.The effects of pH and aptamer concentration on the performance of the biosensor were discussed.The sensor showed a wide linear range(10-600 nM)for CHL,and the detection limit was 0.75 nM(S/N=3).The constructed biosensor was used for the detection of CHL in the environment and had the advantages of wide linear range,high sensitivity,strong specificity and the like,which provided an effective detection method for the detection of CHL residues in the environment.Three kinds of electrochemical aptamer biosensors were constructed in this paper by combining aptamer-centered recognition elements and multifunctional composite nanomaterials.Research showed that the sensor constructed by this technology has a relatively wide detection range and a relatively low detection limit for the target substances,as well as good sensitivity,specificity,stability and repeatability.This study provided new methods and ideas for the detection of pollutants,as well as certain reference value for the detection of pollutants in environment and food.