Fabrication Of Two-dimensional Nano-gold Particles Monolayer And Its Application

Application of nanogold particles is wildspread in many of fields owing to good stability,excellent surface effect and special biological affinity.It is important to generate and assemble highly ordered film structure of nanoparticles based on its application.Here, we focused on the preparation of highly ordered two-dimensional LB monolayer of nanogold particles and discussed experimental condition of preparation of the film.Then we studied the application of the prepared film in electrochemistry.The work is as follows:1.Preparation of two-dimensional LB monolayer of nanogolds particles:(1) Hydrophilic nano-gold particles treated with methyl docosanoate were extracted in chloroform.The chloroform solution containing nanogold particles was spread in Langmuir tough to form a stable Langmuir membrane.Finally,a uniform and steady nanoparticles monolayer was obtained on air-water interface.(2) N-hexadecyl mercaptan was spread evenly onto the surface of subphase containing nanogold particles which assembled n-hexadecyl mercaptan layer to self-assemble a stable mixed Langmuir membrane.The two-dimensional nanogold monolayer was more closely.2.The application of nanogold particles monolayer is following:(1) Hemoglobin was directly immobilized onto nanogold LB monolayer modified with methyl docosanoate using adsorption method.Direct electrochemistry of Hb was studied. The modified electrodes possessed of excellent electrocatalysis activity and rapid response to H₂O₂with a linear relationship between current response and the concentration of H₂O₂ ranging from 2.5×10^-6 to4.1×10^-4mol/L and a detection limit of 6.2×10^-7 mol/L.The reaction rate constant was calculated to be 0.66s^-1 and the apparent Michaelis-Menten constant was 0.20mmol/L.(2) Horseradish peroxidase was immobilized onto two-dimensional nanogold membrane which adsorbed n-hexadecyl mercaptan using dipping method to fabricate H₂O₂ biosensor.The result indicated that the biosensor provided an excellent response for H₂O₂with a linear relationship between current response and the concentration of H₂O₂ ranging from 2.5×10^-6 to 2.1×10^-3mol/L and a detection limit of 8.6×10^-7 mol/L (R=0.9958).The reaction rate constant was calculated to be 1.32s^-1and the apparent Michaelis-Menten constant was 1.72mmol/L.Therefore,the biosensor is looking farward to detecting H₂O₂ in foodstuff.(3) Myoglobin was immobilized onto two-dimensional nanogold membrane modified with methyl docosanoate by the Langmuir-Blodgett technique.Direct electrochemistry of myoglobin was studied.The result showed that the nanogold particles could accelerate the electronic transfer of myoglobin molecules efficiently and the reaction rate constant which is larger than that of myoglobin molecules immobilized using other methods was calculated to be 1.415s^-1.