Preparation Of Metal Carbon Composite Nanomaterials And Its Applications For Chemical And Biological Sensing

Small biomecular are essential for living beings. Chemical and biologicalsensors that can record the level of small biomecular with real-time and dynamicmonitoring have been intensively explored recently. For example, glucose sensorsare crucial for the effective treatment of diabetics, who can test physiologicalblood glucose levels frequently with a glucose sensor to avoid diabeticemergencies. Hydrogen peroxide is a metabolic intermediate. The accumulationof hydrogen peroxide can produce reactive oxygen species that will result inoxidative stress such as DNA damage. Monitoring of hydrogen peroxide level isof great importance for biomedical science. Glucose sensors and hydrogenperoxide sensors based on enzymatic methods have been extensively investigated.However, the enzymatic sensors usually suffer from limited lifetime and aresensitive to light, heat, pH value and chemcals. Thus, it is imperative to developnonenzymatic sensors to figure out these problems. Nanostructured metal ormetal oxides have been employed to develop nonenzymatic sensors due to theiradvantages such as simplicity, sensitivity, selectivity, and cost-effective. Moreover,the high surface-to-volume ratio of these nanostructures shows enhancedelectrocatalytic response to the target molecular. Herein, we developednonenzymatic glucose and hydrogen peroxide sensors based on metal/carboncomposite nanomaterials, as described below.(1) A simple and controllable method has been proposed to prepare AgNPs/CNTs composite materials by ion implantation. Ag NPs with size of2-4nmare uniformly distributed in the CNTs after ion implantation. This processprovides a strong combination between Ag-NPs and CNTs and can effectivelyprevent the Ag-NPs from aggregation. A linear range of125μmol·L-1to10mmol·L-1and a sensitivity of0.269μA·cm2·mmol1·L towards glucosedetermination were obtained in0.1mol·L-1NaOH solution at an applied potentialof0.65V. The detection limit is25μmol·L-1. The Ag-NPs/CNTs electrode shows an antibacterial rate of94%towards E. coliand is favorable for continuousglucose minotoring.(2) Cu NPs/GO composite nanomaterials were prepared by reduction ofcopper ions on the polydopamine (PDA) film coated on GO. Cu NPs wereuniformly dispersed on the surface of GO. The nonenzymatic hydrogen peroxidesensor was prepared by dip-coating Cu NPs/GO on the surface of a glassy carbonelectrode (GCE). The sensor showed a sensitivity of141.54μA·cm2·mmol1·Ltowards hydrogen peroxide, with a detection limit of1.4μmol·L-1.(3) Decoration of CNTs with silver nanoparticles by reduction of silver ionson the PDA film coated on CNTs. The Ag NPs/CNTs exhibits good antibacterialactivity towards E. coli, with an antibacterial rate of100%at the concentration of25μg/mL and an antibacterial rate of94%at the concentration of6.25μg/mL.The Ag NPs/CNTs also displays good antibacterial activity towards S.aureus with an antibacterial rate of100%at the concentration of8μg/mL and anantibacterial rate of93%at the concentration of2μg/mL.(4) The photon-thermal properties of MWCNTs/gold nanostars under theexcitation of near-infrared light were investigated. Irradiation by808nm laserwith power density of1W/cm2for5min, the temperature of gold nanostars hasincreased to43.6℃. The MWCNTs/gold nanostars composite nanomaterialexhited enhanced photon-thermal activity as compared with that of goldnanostars.