Non-enzymatic Electrochemical Sensor For Saliva Glucose Detection

Diabetes,as a chronic disease with metabolic disorders,has been one of the most dangerous diseases in addition to cardiovascular disease and cancer,and continuous monitoring of blood glucose concentration is essential for the diagnosis and treatment of diabetes.At present,the monitoring of glucose concentration in human bodies generally relies on invasive commercial blood glucose meters.However,blood collection not only causes pain to patients,but also has potential health risks such as cross-infection so that it is urgent to develop a reliable non-invasive glucose monitoring technology.As an important component of body fluid,saliva contains rich biochemical information with the advantages of non-invasive collection,stable components,and low interference.Meanwhile,the high correlation between saliva glucose and blood glucose has been proved while glucose concentration in saliva is lower,so it is necessary to establish a highly sensitive technology to detect saliva glucose.This paper has developed a highly sensitive non-enzymatic electrochemical sensor for monitoring saliva glucose based on the advantages of point-of-care testing and electrochemical analysis.The detail works are as following:（1）A non-enzymatic electrochemical sensor with working electrode of platinum electrode was developed based on the electrochemical response of glucose in acidic media which was generated by applying positive potential to electrocatalyze glucose.This innovation avoided the addition of strongly acidic reagents,so it can be applied to in-situ glucose detection.The experimental results illustrated that the sensor was suitable for continuous monitoring of high glucose concentrations with the sensitivity of 60.5μA m M^-1cm^-2,detection limit of 0.45 m M,linear range of 1.0 m M-16 m M,higher stability and reproducibility.However,the sensitivity,detection range and detection limit of the sensor has limited its application in monitoring saliva glucose.（2）A non-enzymatic electrochemical sensor with working electrode of copper-tin alloy was developed based on the electrochemical response of glucose in alkaline media which was generated by applying negative potential to electrocatalyze glucose.This innovation avoids the addition of strongly alkaline reagents,so it can be applied to in-situ glucose detection.The experimental results showed that the sensor possessed higher selectivity and better anti-interference ability to glucose with the advantages of high sensitivity(480μA m M^-1cm^-2),low detection limit（6.6μM）,and wide linear range（20μM-320μM）.Furthermore,copper-tin alloy owned higher stability and reproducibility which can be reused by simple mechanical polishing treatment.（3）In summary,the electrochemical sensor with working electrode of copper-tin alloy was integrated into a smart toothbrush based on the assets of alkaline media to generate an innovation for the portable and non-invasive saliva glucose monitoring.The experimental results exhibited that the sensitivity of the sensor is 771μA m M^-1cm^-2,the detection limit is4.7μM,and the linear range is 20μM-320μM,and results can be detected,collected and transmitted wirelessly to smart phone by the electronic module on the toothbrush.