Development Of Sensitive Optical Chemical Sensors With Dual Functional Catalytical Nanomaterials

Optical chemical sensors has a wide range of applications in areas such as publicsafety, human health and environmental monitoring due to their fast response,multiplexing capabilities and potential in naked eye detection. The catalytic activity ofnanomaterials can trigger a detectable signal amplification to increase the sensitivity ofoptical chemical sensors. In the present dissertation, dual functional nanomaterials withcatalytic activity have been employed for the design and development of opticalchemical sensors. This strategy paves the way to the devolopment of minaturizedoptical chemical sensors with high sensitivity. The main contents of the presentdissertation are as follows:1. A new fluorescent sensor has been developed by using a dual functionalnanomaterial with catalytic activity and fluorescence properties. Horseradish peroxidasefunctionalized fluorescent gold nanoclusters （HRP-AuNCs） was successfully preparedvia a biomineralization process. We found HRP remains active and possesses itsintrinsic catalytic activity, thus HRP-AuNCs have dual functions including thefluorescence and catalytic ability. The fluorescence of HRP-AuNCs can be quenchedquantitatively by adding H₂O₂. The sensitivity for H₂O₂detection of this method （LOD=30nM） has been improved by10times compared with that using BSA-AuNCswithout catalytic activity. Accordingly, using biologically functional proteins for thepreparation of fluorescent gold nanoclusters, without subsequent modification, canobtain nanomaterials with dual functions of the fluorescence properties and biologicalactivity, which can be directly used to build up optical biosensors.2. A new colorimetric sensor array for proteins detection has been designed byemploying dual functional iron oxide nanoparticles featuring intrinsic enzyme mimeticactivity and recognition capability. Two functionalized Fe₃O₄NPs were prepared andused as signal amplifiers in the array-based sensor for colorimetric protein sensing.Interactions between positively charged Fe₃O₄NPs and different analyte proteinsmodulate the peroxidase-like activity of Fe₃O₄NPs in different fashions, affordingcatalytically amplified colorimetric signal patterns, enabling the detection andidentification of11proteins at a50nM concentration, for some proteins as low as1nM. The sensitivity was increased by1000times when compared with the conventionalnanoparticles based protein array sensor, and equal to that of protein array sensor basedon enzyme amplification. Nanomaterials based enzyme mimic has better thermal andchemical stability than biological enzyme, and are cost-effective.3. An optical chemical sensor for ethanol has been proposed by using anaomaterial with dual functions of catalytic activity and adsorption capability as sensingmaterials. Analytes were trapped on sensing nanomaterials and detected in situ byrecording the cataluminescence （CTL） signals with fast elevated temperature. Comparedthe previous CTL sensor, its sensitivity is3,000times improved. The sensor wassuccessfully applied to monitor the ethanol concentration in human expired gas afterdrinking, and the results agreed well with the reference values. This miniature ethanolsensor offers higher sensitivity, faster response and lower power consumption, whichmake it very promising in developing hand-hold sensing device for feld detection.Furthermore, a variety of nanomaterials with dual functions of catalytic activity andadsorption capality have been used to develop a sensor array for pheromone sensing.