Synthesis Of ZIFs Derived Nanocomposites And Application In Electrochemical Sensor For Drugs

Electrochemical sensing methods could used to achieve efficient,sensitive and specific determination of targets with the advantages such as facile operation,low cost,fast response and easy miniaturization,which have drawn great attentions in recent years.Drug molecules(eg.flavonoids,neurotransmitters,purines)are of great significance for the study of life phenomena and the development of drugs.Many researchers have used their properties of electrochemical activity to study human physiological activities.For example,ascorbic acid(AA)plays an important role in cancer prevention and immunity development.As an important neurotransmitter acting as a messenger between brain cells,dopamine(DA)is involved in the functions of central nervous,endocrine,cognition and emotion systems.Uric acid(UA)is the end product of metabolic breakdown of purine nucleotides,which can lead to gout,renal failure,leukemia and lymphoma at higher blood concentration.These biomolecules not only play important roles in the physiological and metabolism functions of human,but also for diagnosing diseases.Flavonoids(such as rutin,quercetin and luteolin)are belonged to plant polyphenolic compounds abundant in fruits and vegetables,which exhibit a wide variety of biochemical and pharmacological effects including antioxidant free-radical scavenging,anti-inflammatory,anti-carcinogenic and other beneficial properties.AA,DA,UA,rutin,quercetin and luteolin plays an important role in physiological functions and diagnosing diseases.Therefore determination durgs plays an necessary role in bio-sample and medicine.In general,the low electron transfer rate of drugs on bare electrodes led to the lower,the sensitivity and selectivety that cannot satisfied the needs of society.Therefore modified electrodes are used to improve peak shape which incresed sensitivity and lower detection limits.Nanomaterials can tremendously improve performance of electrochemical sensors in sensitivity,stability and selectivity.Among them,nanomaterials drived from zeolitic imidazolate frameworks(ZIFs)own the advantages of easy preparation,porous structure,large specific surface area and multiple active sites.In this thesis ZIFs are used as raw materials and combine with nitrogen-doped graphene,three-dimensional reduced graphene oxide aerogels,gold nanoparticles and single wall carbon nanohorns to preparenanocomposites,which act as electrode modification materials to improve the conductivity,specific surface area,and pore volume of modified electrodes interface.The following is the main research content and conclusions:1.A voltammetric sensor was developed using nitrogen-doped porous carbon derived from ZIF-8 and nitrogen-doped graphene nanocomposite modified glassy carbon electrode(GCE)for simultaneous determination of ascorbic acid(AA),dopamine(DA)and uric acid(UA).Detailed characteristics of nanocomposites were investigated by SEM,TEM,XPS,XRD and FT-IR.Experimental conditions such as accumulation time,accumulation potential and buffer solution pH were optimized.The sensor demonstrated a linear plot of 0.01~15.0mmol/L for AA,0.08~350.0 ?mol/L for DA,and 0.5~100.0 ?mol/L for UA,with detection limit of 1.99 ?mol/L(3 ?),0.011 ?mol/L(3 ?)and 0.088 ?mol/L(3 ?),respectively.The established method exhibited excellent reproducibility,anti-interference and stability,which have applied for AA,DA and UA determination in real urine samples with recoveries between100.2 % and 102.0%.2.Three-dimensional reduced graphene oxide hydrogel(3D rGH)was synthesized by hydrothermal method and cobalt imidazolate framework-67(ZIF-67)was further in situ grown on 3D rGH matrix directly.Then ZIF-67 load three-dimensional reduced graphene oxide aerogel(ZIF-67@3D rGA)were obtained via freeze drying.The resulted ZIF-67@3D rGA nanocomposite was checked by different techniques including SEM,TEM,FT-IR,XPS,XRD and TGA.The presence of 3D rGA acted as the backbone for the loading of ZIF-67 and the resulted ZIF-67@3D rGA nanocomposite exhibited an interconnected porous structure with large surface area and high conductibility due to synergistic effects,which was applied to the electrode modification and used for rutin detection.The developed method showed excellent performances of a wider linear range(0.05~200 ?mol/L)and lower detection limit(0.028 ?mol/L,3?)in rutin tablet samples analyzed satisfactorily.3.A core-shell ZIF-8@ZIF-67 was synthesized by direct precipitation,which was further pyrolyzed to get a Co nanoparticle-embedded N-doped carbon nanotube hollow polyhedron(Co@NCNHP).Then Au nanoparticles were formed on the surface and core of Co@NCNHP to obtain an Au-Co bimetal decorated NCNHP(Au-Co@NCNHP).The resulted nanocomposite was characterized by various methods including TEM,SEM,XRD,XPS,Raman and FT-IR.The Au-Co@NCNHP-based electrochemical sensor displayed an obviously higher electrocatalytic response to the oxidation of quercetin,which could be attributing to the synergic effects of the Au and Co bimetal nanoparticles and nitrogen-doped carbon with hollow polyhedron.Under the optimal conditions,the oxidation peak currents exhibited in two linear dynamic ranges(0.05~35.0 and 35.0-80.0 ?mol/L),and the detection limit was as low as 0.023 ?mol/L(3 ?).The analytical application of the proposed electrochemical sensor was gained by analyzing the content of quercetin in medical and onion samples with satisfactory results.4.A simple and sensitive electrochemical method was fabricated for the determination of luteolin based on the single walled carbon nanohorns(SWCNHs)-Co@NCNHP nanocomposite modified GCE.The electrochemical behaviors of luteolin indicated that SWCNHs-Co@NCNHP/GCE could enhance the electrocatalytic activity in the redox process of luteolin,which led to a considerable improvement of the redox peak current for luteolin development of a sensitive voltammetric sensor for the determination of luteolin.The experimental parameters including the pH of supporting electrolyte,accumulation times and accumulation potential of luteolin were optimized.The results showed that the oxidation peak currents increased linearly with the concentration of luteolin in the range of 0.1 to 4.0 ?mol/L with a detection limit of 0.01 ?mol/L(3?).The analytical performance of this sensor had been evaluated for detection of luteolin in Duyiwei capsule sample with satisfactory results.