Preparation Of Gold Nanomaterials And Highly Sensitive Detection Of Small Biomolecules

Small biological molecules(water,glucose,dopamine,etc.)are the building blocks that make up biological macromolecules and the functional basis for maintaining normal life activities.They play an irreplaceable role in nutritional supplementation,metabolism regulation,tissue repair,and information transmission of living organisms.The content and activity of these small biological molecules(such as glucose and dopamine etc)are directly related to the health of the organism.Therefore,it is essential to detect small molecules such as glucose and dopamine with high sensitivity.The choice of catalyst material is the key to improve the sensitivity and stability of the biosensor.The commonly used precious metals of platinum and palladium are easily poisoned during the oxidation process,affecting the catalytic performance.Non-precious metal materials such as copper and nickel have high catalytic ability when used as catalytic materials,but the detection environment must be under alkaline conditions,which greatly reduces their application scope.Gold materials have good electrical conductivity,electrocatalysis,and biocompatibility,and thus have great potential application value in the non-enzymatic detection of glucose as well as dopamine and other small molecular.Therefore,in this paper,we choose gold-based nanomaterials as our target materials for the detection of glucose and dopamine.The commonly used detection methods for small organic molecules such as glucose and dopamine are as follows:enzymatic determination,electrochemical method,fluorescence analysis,gas chromatography,and high performance liquid chromatography.Chromatographic detection relies on large instruments and the complex sample preparation process is not conducive to instant detection.The enzyme activity in the enzymatic assay decreases with time and is susceptible to external conditions,which will reduce the sensitivity and accuracy of the test.By contrast,the electrochemical is more popular analytical method due to its simple operation and high accuracy.This paper combines the controllable preparation of gold-based nanomaterials and electrochemical analysis methods to conduct the following two aspects of research.1.Using gold electrode as the substrate and combining graphene,a gold/graphene nanocomposite was successfully prepared by one-step electrodeposition method.The experimental results show that the morphology of gold/graphene nanocomposites can be effectively controlled by adjusting the deposition voltage and time.When the deposition voltage is-30 V and the deposition time is 20 min,the gold/graphene nanocomposite has high electrocatalytic activity.Electrochemical non-enzymatic sensor based on this material showed a wide linear range of 0.05-14 m M and 14-42 m M,a high sensitivity of 604 and 267?A cm^-2m M^-1,and a low detection limit of 12?M and good stability(89%of initial sensitivity is retained after 30 days of testing).The actual sample test shows that this material can be applied to the detection of actual sweat.2.By adjusting the growth temperature,vertically grown 4?M ultra-long gold nanowire array(Au NWs/ITO)was prepared on indium tin oxide(ITO)substrate,and its electrocatalytic performance for dopamine was studied.The morphology and structure of the Au NWs/ITO were evaluated by scanning electron microscopy(SEM),X-ray diffraction(XRD),and transmission electron microscopy(TEM).Results show that the gold nanowires prepared at 50?can reach a length of 4 microns and grow vertically.Moreover,gold nanowire-based non-enzymatic electrochemical sensors have low detection limits(0.1?M),high sensitivity(1.479?A cm^-2?M^-1),and wide linear range(0.1?M-700?M)in the detection of dopamine.At the same time,the common coexistence interference AA and UA have no obvious interference.These results show that gold nanowire arrays grown vertically on the ITO surface provide a new idea for the development of high-sensitivity dopamine sensors in the future.