Medical And Environmental Sensing Detection Technology Based On Silver Nano-functional Materials

Silver?Ag?nano-functional materials have become a hot research topic in the catalysis,medical antibacterials and photoelectric sensing fields,due to they can possess some excellent properties like high catalytic activity,electroconductivity,biocompatibility and excellent photoelectricity.In this thesis,silver functional nanomaterials were prepared and combined separptately with titanium dioxide?TiO₂?,melamine?MA?,and Hemin to establish three sensing and detection platforms for the efficient analysis of anthrax DNA,mercury ions(Hg²⁺),and blood glucose,respectively.The contents of the thesis mainly include:?1?A visuable colorimetric sensing technique has been developed with wettable microwells array through photocatalytic silver deposition route for the colorimetric analysis of Anthrax DNAs in blood?Chapter 2?.Firstly,polyacrylic acid,cetyl trimethoxysilane,sodium hydroxide and other reagents were used to construct the hydrophobic substrate and hydrophilic microwells on the glass plate.Furthermore,dopamine-coated TiO₂ nanoparticles were immobilized in the microwells for anchoring capture probes of Anthrax DNAs.After the hybridization of targeting Anthrax DNAs,exonuclease I?Exo I?was introduced into the microwells to selectively digest the single-strand DNA probes unhybridized.The silver deposition was further conducted by the synergic photocatalysis of TiO₂@DA and photoreduction of guanine bases,thus achieving the amplified silver signals for the visualized colorimetric analysis of Anthrax DNAs.The results indicate that the so-farbricated microwells array with the wettable interfaces could not only accumulate DNA analytes to realize the ultrasensitive detections,but also circumvent any crossover contaminants between the sample droplets.The as-developed colorimetric method with microwells array was subsequently applied for the ultra-sensitive analysis of Anthrax DNAs in blood with the levels down to 1.0 fM.Single-base and double-base mutations DNAs could also be identified accurately.?2?A Hg²⁺sensing and removal technique has been developed uisng mesoporous silver melamine?Ag-MA?nanocomposites?chapter 3?.Mesoporous silver-melamine?Ag-MA?nanocomposites were synthesized by the controlled supramolecular self-assembly route,with various structural morphologies and low peroxidase activity.It was discovered that rod-shaped Ag-MA nanocomposites could present the Hg²⁺-enhanced catalysis by forming Ag-Hg alloys.Meanwhile,the Ag-MA nanocomposites can present high specific surface area and environmental stability,so that the adsorption and enrichment of Hg²⁺ions could be achieved through the highly selective coordination of MA with Hg²⁺ions.The so developed Hg²⁺ions sensing technology based on the catalytic performance of Ag-MA nanocomposites can achieve the sensitive colorimetric analysis of Hg²⁺ions in blood samples with the detection limit of 0.025nM.In the meantime,the Ag-MA nanocomposites could be used as the adsorbents to remove Hg²⁺ions from wastewater,with the removal rate of 99.76%and the adsorption capacity of598.99 mg/g.?3?A blood glucose colorimetric method has been developed using gold-silver Hemin mimetic enzyme and glucose oxidase?chapter 4?.MA-Hemin complex was synthesized by covalently binding Hemin to MA by the activation chemistry,which was used as a template for the synthesis of MA-Hemin-Au-Ag nano-mimetic enzyme under alkaline conditions using a certain proportion of gold and silver ions.Systemaitical studies were conducted on the catalysis dynamics of the mimetic nanoenzyme,showing a high peroxidase-like catalysis activity.Moreorever,the so prepared nanoenzymes were combined with glucose oxidase to form a complex enzyme to be applied for the rapid and highly sensitive colorimetric analysis of H₂O₂and blood glucose,with the detection limit down to about 2.50?M and 1.80?M.