Surface And Interface Engineering Of Carbon-based Nanomaterials For Detection Of Biochemical Molecules

Biological and chemical(shorten as biochemical)molecules that are ubiquitous in our living bodies and the environment are closely related to our daily life.Some biochemical molecules such as the environmental pollutant of trinitrotoluene(TNT)and the biological signal molecule of nitric oxide(NO)have attracted extensive attention.The long-term use of TNT has caused serious environmental pollution and health problem.TNT contaminated water with pink color is difficult to clean,and can pass through the food chain to human body,which can cause diseases such as chronic poisoning,abnormal liver and hematopoietic system.Therefore,it is ctricial to detect TNT in a fast and senstivie manner.In addition,the globalization of terrorism puts forward security requirements for the rapid and ultratrace detection of TNT.On the other hand,NO as a messenger molecule is involved in a variety of physiological and pathological processes.At a normal level,NO can efficiently regulate biological functions such as vasodilation and wound healing.While abnormal concentration of NO is closely related to diseases such as inflammation of the respiratory tract and cardiovascular disease.Thus,to realize rapid and real-time detection of NO is essential in the early diagnosis of the above-mentioned diseases.Electrochemical sensing technique has been widely used in detecting target molecules such as TNT and NO because of its unique advantages including high sensitivity,real-time monitoring capability and easy operation.Electrode material that is the key component of the electrochemical sensors can determine the sensing performance such as sensitivity,response time,linear detection range and detection limit.To design and fabricate electrode materials with desired physicochemical characteristics is the current focus of electrochemical sensing applications.Carbon nanomaterials with rich types and unique physicochemical properties have been widely used as electrode materials in electrochemical sensors.As classified by the dimensions and morphology,carbon nanomaterials mainly include zero-dimensional carbon nanospheres/dots,one-dimensional carbon nanotubes/fibers,and two-dimensional graphene and graphdiyne.According to the requirements of the specific application,it is of great significance to tailor surface and interface properties of carbon nanomaterials to realize high sensing performance.Surface and interface engineering approaches mainly include functional group functionalization,heteroatom doping,defect engineering and pore structure modulation.This thesis chooses two types of carbon nanomaterials of porous carbon spheres(PCS)and graphdiyne(GDY),and conducts surface and interface engineering to fabricate carbon-based electrode materirals for high sensing performance.In the first part,based on PCS,surface engineering approach of synergetic nitrogen doping and amino function is used to fabricated nitrogen functionalized PCS(NPCS),which can achieve highly sensitive and rapid detection of TNT molecules.In the second part,hemin(HEM)is utilized to hybridize with GDY to fabricate GDY/HEM by self-assembly through?-?interaction and metal-sp carbon hybridization,realizing real-time and rapid detection of NO released from living cells.The contents of this thesis can be divided into two parts as followings.1.NPCS for fast and ultratrace detection of TNT.PCS materials were first prepared by a hydrothermal method,followed by carbonlization.NPCS was then obtained by nitrogen doping and amino functionalizing of PCS using histidine as nitrogen source.The successful preparation of NPCS was confirmed by various material characterization methods.The NPCS towards TNT exhibits a high sensitivity up to 60.2 m A cm^-2 ppb^-1 and a low detection limit of 0.15 ppb.Moreover,the response time of the NPCS is only half as that of the PCS.It is found that nitrogen doping accelerates the charge transfer of NPCS,and amino functionalization enhances the adsorption of TNT for NPCS,eventually realizing fast and ultratrace detection of TNT.2.Self-assembled GDY/HEM for in-situ sensing NO released from cells.GDY was hybridized with HEM through a self-assembly approach to fabricate a nanocomposite of GDY/HEM.Characterization methods such as spherical aberration electron microscopy,element mapping and XPS prove the successful fabrication of the GDY/HEM.The GDY/HEM delivers a high sensing performance towards NO with fast response time and low detection limit.It only takes 0.95 s to reach 95%of the maximum response current,and achieves a detection limit as low as 7 nmol L^-1.It is found that?-?interaction between the highly?-conjugated GDY and HEM,as well as the strong interaction between the alkynyl carbon atoms on GDY and the iron atoms of HEM make good dispertion of HEM on GDY in an atomic manner,thus greatly enabling high desnity of active sites while avoiding the aggregation of HEM.Such unqiue properties eventually make GDY/HEM a high sensing performance towards NO.Additionally,the GDY/HEM is used to modify nanoprobe electrodes,which realize the successful detection of NO released from single cells.It is discovered that cancer cells MCF-7 release a higher NO concentraton than the normal cells293A,providing a powerful tool for single cell analysis.