| Point-of-care testing(POCT)was defined that medical diagnostic testing using portable detection system with test paper and reagent for rapid analyse and diagnose at or near the time and place of patient care.However,for now the most point-of-care devices were not only higher costs,but also required professional knowledge for the interpretation and operation.Furthermore,sensitivity is another major factor limiting the development of point-of-care device.Hence,the development of a portable,low cost,and easy to used detection system with high sensitivity sensor play an important role in the filed of point-of-care testing.In this study,we developed smartphone-based amperometric electrochemical sesing system,including smartphone-based cyclic voltammetry(CV)system,smartphone-based differential pluse voltammetry(DPV)system,smartphone-based differential pluse amperometry(DPA)system,and smartphone-based square wave voltammetrys(SWV)system.The smartphone was used for parameter setting,command control,data analysis,data processing,and result display,which could be used to reduce the cost of whole system,improve the efficiency of data analysis and processing,and enhance the convenience of operation.The detector was used to generate electrochemical excitation signals,monitor the resultant currents on the sensors,convert the current into digital code,and send them to smartphone.Then,the reliability of the system was demonstrated by testing redox couple and the results were compared with those of commercial electrochemical workstation.Futhermore,the nanomaterials was not only attempted to modify on the surface of screen-printed electrodes to construct sensors,but also directly constructs screen-printed graphene electrodes with self-made graphene inks.The nanomaterials modified electrodes showed excellent stability and electrochemical properties,which could be used to improve the sensivity.Finally,the nanomaterials modifeid electrodes were combined with smartphone-based amperometric electrochemcial system for the quantitative analysis and detection of nutriment,biochemical small molecules,drugs and neurotransmitters.The main contents and contributions of this thesis are given as following:1.Development of smartphone-based cyclic voltammetry system and reduced graphene oxide/3-amino phenylboronic acid modified electrodes for nutriment detection.As a popular electrochemical method,cyclic voltammetry has shown its great practicability for quantitative detection and electrodes modification.In this study,a smartphone-based cyclic voltammetry system with a simple method of electrode modification was constructed to perform electrochemical detections.The system was composed of these main portions:modified electrodes,portable electrochemical detector and smartphone.The reduced graphene oxide and 3-amino phenylboronic acid could be modified by the system on the screen printed electrodes for glucose detections.Finally,the experimental data of the system were shown the linear,sensitive,and specific responses to glucose at different doses,even in blood serum as low as about 26?mol/L with 3?/slope calculation.Thus,the system could show great potentials of detection and modification of electrodes in the field of point-of-care testing.2.Development of smartphone-based differential pulse voltammetry system and reduced graphene oxide/gold nanoparticles modified electrodes for biochemical small molecules detection.Ascorbic acid,dopamine,and ric acid are important electroactive biomolecules for health monitoring and they coexist in serum or urine.Their quantitative determination by electrochemistry could provide the accurate reference for diseases diagnosis and treatment.In this study,a smartphone-based differential pluse voltammetry system was developed for simultaneous detection of biochemical small molecules.The system contained a disposable sensor,a coin-size detector,and a smartphone equipped with application program.Screen-printed electrodes were used as sensors for the detection,on which reduced graphene oxide and gold nanoparticles were electrochemically deposited.Then,the system was applied to detect standard solutions of the biomolecules and their mixtures.The results showed that the peak currents of each substance increased with higher concentrations and the method allowed the discrimination of the different potentials of the studied species.The limit of detection for ascorbic acid,dopamine,and uric acid were 1.04 ?mol/L?0.29 ?mol/L and 5.4?mol/L,respectively.The results exhibited that the system with reduced graphene oxide/gold nanoparticles modified electrodes showed great potential to carry out trace detection of the biomolecules in the field of point-of-care testing.3.Development of smartphone-based differential pulse amperometry system and single-wall carbon nanotubes/gold nanoparticles modified electrodes for drug detection.Parkinson's disease caused by lack of dopamine in brain is a common neurodegenerative disorder.The traditional treatment is to replenish levodopa since it could pass through blood brain barrier and form dopamine.However,its accumulation can cause patients' movement disorders and uncontrollable emotion.Therefore,it is critical to control the levodopa dosage accuracy to improve the curative effect in clinical.In this study,a smartphone-based differential pulse amperometry system was developed for rapid monitoring of levodopa.The system involved a disposable sensor,a hand-held electrochemical detector,and a smartphone with designed application.Single-wall carbon nanotubes and gold nanoparticles modified screen-printed electrodes were used to convert and amplify the electrochemical current signals upon presence of levodopa molecules.The smartphone-based differential pulse amperometry system was demonstrated to monitor levodopa at concentrations as low as 0.5 ?M in human serum.Furthermore,it has also been verified to be able to distinguish levodopa from other representative substances in the body.With these advantages,the system can be used in the field of point-of-care testing to detect levodopa and provide the possibility to solve clinical demand for levodopa detection.4.Development of smartphone-based square wave voltammetry system and screen-printed graphene electrodes for neurotransmitter detectionNorepinephrine is an important catecholamine neurotransmitter in the mammalian central nervous system.It is well known that norepinephrine plays an important role in the control of arousal,attention,mood,learning,memory,and stress response In this paper,a smartphone-based square wave voltammetry system with screen-printed graphene electrodes was developed for in-situ detection of norepinephrine.The system composed of sensors,coin-sized detector,and smartphone.Graphene ink was printed on soft substrate to construct flexible screen-printed graphene electrode.The electrodes were used as disposable sensors,exhibited high electron transfer rate,low contact resistance,and long-term stability.Then,the system with the screen-printed graphene electrodes was used for norepinephrine detection.The limit of detection for norepinephrine was as low as 0.265 ?M with 3?/slope calculation and the dose-dependent fitting curve.It has also been verified to be able to distinguish norepinephrine from other representative interfering substances in the body.Hence,the system with flexible screen-printed graphene electrodes showed great potential in the field of point-of-care testing. |
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