Solution-Gated Graphene Transistor Biosensors For Antibiotic Detection

Antibiotics are organic compounds that can inhibit the growth of bacteria,fungi,protozoa,viruses,archaea and other harmful microorganisms or lead to their death.If antibiotics enter the human body,they can inhibit or kill harmful microorganisms.However,they will also directly threaten the safety of human body by disturbing the normal metabolism of human body and changing the microbial community in human body.Traditional analytical techniques,such as microbial assay,enzyme-linked immunosorbent assay(ELISA),high performance liquid chromatography(HPLC)and capillary electrophoresis(CE),are complex,time-consuming and expensive.With the development of nanotechnology and molecular biology,many new technologies for antibiotic detection have emerged.These new technologies provide higher sensitivity and lower detection limit for antibiotic detection,which is crucial to ensure the safety and effectivenessof antibiotics in various fields such as medical care,agriculture and environmental monitoring.In recent years,solution-gated graphene transistor(SGGT)sensors have been widely used in the field of biochemical sensors due to their advantages of high sensitivity,good biocompatibility and excellent chemical stability.In this thesis,the SGGT biosensor was designed and prepared for antibiotic detection.The design,preparation and modification of sensitive materials were also explored and the working mechanism of the sensor was studied.A new antibiotic detection method was developed.The main research contents are as follows.(1)The aptamers that can specifically bind to kanamycin were selected out and designed through the exponential enrichment ligand phylogenetic technique.The specific aptamers were modified on the gate electrode and a SGGT sensor was fabricated for the kanamycin detection.The limit of detection(LOD)was up to 1 a M and the sensor exhibited the good specificity.The specific 3D spatial configuration of nucleic acid aptamers provides the recognition and binding sites with kanamycin,which is the intrinsic reason for the specific recognition of aptamers to kanamycin.The sensing principle can be attributed to the specific bond of kanamycin and the aptamers on the gate electrode of SGGT,which changes the capacitance of the electric double layer(EDL)near the gate electrode,and thus lead to the current response.(2)A ssDNA-modified SGGT sensor was designed and prepared for the bleomycin detection.Because the signal transduction mechanism of bleomycin detection depends on the interaction between metal-bleomycin complex and DNA,the DNA with specific recognition sites were used as a probe to identify bleomycin.The LOD of the sensor was up to 1 a M,which was much lower than the traditional detection method.There was a good linear relationship between the channel current and the logarithm of metal-bleomycin concentration in the range of 1 a M-10 n M.In summary,we designed and fabricated biosensors based on DNA-modified SGGT for SGGT for the antibiotic.The sensor not only has the advantages of good biocompatibility,low detection limit and easy integration,but also can be applied to the detection other analytes by changing the sensitive materials modified on the gate electrode,which shows great potential as the sensor platform.