Electrochemical Biosensors And Drug Molecule Detection Studies Based On Bare Electrode Build Ratios

In recent years,the number of cancer patients has been increasing seriously due to the aging of population,damaged ecological environment,unhealthy lifestyles and other factors.Meanwhile,a considerable breakthrough has been made on tumor chemotherapy and the survival time of cancer patients was greatly extended.However,serious side effects of drug residues caused by incomplete metabolism will therefore cause secondary damage to the human body which limits the drug treatment to a certain extent.Thus,the determination of residual drug concentration in body fluids,especially in blood samples,is of great significance for the evaluation of drug safety.Electrochemical sensors have been a highly active research frontier in analytical science owing to its high sensitivity and good selectivity.Recently,with the continuous in-depth study on the construction of electrochemical sensors,the ratiometric dual-signal electrochemical sensors have widely attracted more attention of researchers.In this dissertation,ratiometric construction strategies of electrochemical sensors for anti-tumor drug(doxorubicin hydrochloride(DOX)and quercetin(Qu))detection based on the ratiometric strategy were proposed as follows:(1)Ratiometric electrochemical sensor based on the detection of anti-tumor drug DOX used bare glassy carbon electrode(GCE).Two substances-DOX and methylene blue(MB)-were directly put into the electrolyte without any modification for GCE in which the high electrochemical activity characteristics of DOX and MB were well utilized.There was a redox reaction for DOX on the surface of GCE bringing a significant electrical signal and MB with high stability was set as a parameter.When MB concentration was controlled as constant,the DOX-induced electrical signal is gradually enhanced with the increase amount of DOX,and the electric signal of DOX and MB is detected by the electrochemical workstation.There was a quick response and highly sensitivity of the as designed radiometric electrochemical sensor for DOX.Ratiometric dual-signal strategy can significantly reduce the inherent system error and accidental error of electrochemical sensors originating from environmental and personal operating factors,thereby significantly enhancing the reproducibility and stability of the experimental protocol.(2)A simple electrochemical sensor was developed to detect the Qu in the electrolyte based on the ratiometric strategy,and the signal was detected by using the bare GCE.In addition,thionine(TH)was set as an internal reference electrochemical probe.There was a good relationship between IQu/ITH and [Qu],and the detecion limit was as low as 3.1 nM.In the interference experiment of real food samples,the ratiometric detection method was highly selective and sensitive to Qu.Compared with previously reported works,the experimental results showed a wider detection range(0-15 ?M).Additionally,the advantage of this newly developed research is that the electrochemical determination of Qu can be carried out directly in electrolyte solution,similar to the widely recognized fluorescent sensing method in aqueous media.The method is simple designed and expected to be widely used,and can be extended to other similar electrochemical sensors in electrolyte,which would significantly contribute to the further development of electrochemical sensors.