Construction Of Biomimetic System Doped With Gold Nanoparticles And Its Application For Clinical Determination Of Neurotransmitters

Neurotransmitter,an important messenger molecule widely dispersed throughout the mammalian central nerve system,plays crucial roles in controlling the neural physiological function.The level of the neurotransmitter is involved in the human physical condition,such as Parkinson's disease,schizophrenia,sleep and appetite.In this work,two electrochemical sensors were established and employed for the detection of dopamine and serotonin in human serum samples.Molecularly imprinted technology,nanotechnology,doping method,self-assembly technique and electrochemical sensing technology were integrated to solve the crucial detecting problems such as the low levels of the two monoamine neurotransmitters and the interference of coexisting contents in the biological samples.Section 1.Research of molecularly imprinted polymers doped with gold nanoparticles modified electrode for the detection of dopamine.Dopamine,a naturally occurring catecholamine,is extensively distributed in the mammalian central nerve system,which has a significant role in human metabolism as well as in the central nervous and renal systems.It is involved in Parkinson's disease,Huntington disease and schizophrenia.Ascorbic acid and uric acid,which have similar oxidation potential to dopamine,usually coexist with dopamine in biological samples.It is important for clinical diagnosis to develop a convenient dopamine electro-analytical method with good selectivity,high sensitivity and low cost due to the low level of dopamine,interference of coexisting contents and it's electoactive nature.The details of this section are categorized as following:The sensing membrane of molecularly imprinted polymers doped with gold nanoparticles was prepared on the surface of gold electrode self-assembling with gold nanoparticles using dopamine as template molecules,functionalized gold nanoparticles as functional monomers and p-aminobenzenethiol as cross-linkers.The modified electrodes were characterized by scanning electron microscope and electrochemical methods.Moreover,the selectivity,stability and repeatability of electrochemical biomimetic sensor was evaluated by the methods of differential pulse voltammetry and amperometry.The results indicated that,the electrochemical property of molecularly imprinted polymers could be improved by appropriately doping gold nanoparticles into imprinted network,and the prepared sensor in this research showed favorable selectivity,stability and repeatability.The amperometric signal showed a good linear correlation to dopamine concentration in the range of 0.02 to 0.56 ?mol·L-1(r= 0.999)with the the detection limit of 7.8 nmol·L-1(S/N = 3).Meanwhile the as-prepared electrochemical sensor was used to detect dopamine in human serum samples,and the recoveries were in the range of 96.7-104.9%with the RSD?4.11%.Section 2.Research of rGO/PANI and AuNPs@MIPs double-layered sensing membranes modified electrode for the determination of serotonin.Serotonin(5-hydroxytryptamine),an important tryptamine neurotransmitter widely dispersed throughout the central nervous system,plays crucial roles in the regulation of mood,sleep and appetite.The abnormal level of serotonin is involved in anxiety,insomnia,anorexia and so on.Ascorbic acid,dopamine,uric acid and epinephrine,whose oxidation potentials overlap with serotonin from 0.1 to 0.3 V,usually coexist with serotonin in biological samples.The detection of serotonin in biological samples was interfered by these coexisting contents.Thus,it is important for clinical diagnosis to construct a convenient serotonin electro-analytical method with good selectivity,high sensitivity and low cost.The details of this section are categorized as following:The conductive sensing membrane of reduced graphene oxide/polyaniline was first modified on the surface of glassy carbon electrode.Then the membrane of molecularly imprinted polymers doped with gold nanoparticles was prepared using serotonin as template molecules,functionalized gold nanoparticles as functional monomers and p-aminobenzenethiol as cross-linkers.The structure of functionalized gold nanoparticles and reduced graphene oxide were characterized by ultraviolet-visible and Raman spectroscopy,respectively.The modified electrodes were characterized by scanning electron microscope and electrochemical methods.Moreover,the selectivity,adsorption capacity,adsorption time,stability and repeatability of electrochemical biomimetic sensor was evaluated by differential pulse voltammetry method.The results revealed that,the gold nanoparticles doped in the molecularly imprinted polymers could improve the conductivity and electrocatalytic activity of imprinted network,and the prepared sensor in this research showed favorable selectivity,adsorption capacity,adsorption time,stability and repeatability.The detection signal showed a good linear correlation to serotonin concentration in the range of 0.2 to 10.0 ?mol·L-1(r = 0.998)with the the detection limit of 11.7 nmol·L1(S/N = 3).Meanwhile the electrochemical sensor was used to detect serotonin in human serum samples,and the recoveries were in the range of 98.7-102.0%with the RSD ? 2.17%.