Dissertation
Dissertation > Industrial Technology > Automation technology,computer technology > Automation technology and equipment > Automation components,parts > Transmitter ( converter),the sensor > Biological sensors,medical sensors

Preparation and Properties Study on Biological Membrane Mimetic Biosensors for Mercury Ioins Detection

Author ZhangZuoZuo
Tutor YueXiuLi
School Harbin Institute of Technology
Course Microbiology
Keywords mercury ions bionic nanoparticle sensor terbium fluorescence queching
CLC TP212.3
Type Master's thesis
Year 2012
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Mercury is a heavy-metal element with highly toxic and bioaccumulativeproperties that are recognizable even at very low concentrations. Once mercury releasedinto the environment, it can’t be eliminated. Mercury can accumulate in the brain,kidney and some vital organs which lead to a wide variety of disease. Therefore, it is animportant issue to develop a rapid and ultrasensitive method to detect mercury inenvironment.At present, a variety of analytical methods have been developed for the detectionof Hg2+, such as instrumental analysis method, fluorescence spectrometry andelectrochemical sensor. However, in terms of actual applicability, the samples ofinstrumental analysis method usually need complicated pre-treatment, the preparation offluorescent probes requires harsh reaction conditions and they are vulnerable to beinterferenced from other metal ions, electrochemical sensors are temperatureinfluenced. The most important point is that these methods are usually consume toomuch time to complete the detection, unable to carry out online for rapid detection.Silica is one of the objectives of many biomineralization simulation. Thetraditional methods to synthesize silica nanoparticles often needs acid, alkali and otherrigorous condition. Bionics open up a new world of principle for the preparation ofsilica nanoparticles. This subject explicitly introduced the concept of bionics, usingbiomineralization mechanism to guide the synthesis of fluorescent silica nanoparticlesthrough the process of simulation of mineral formation in vivo.Lanthanide-based sensor such as Tb and Eu have a vairety advantage. Herein aTb-based silica nanoparticle sensor for Hg2+analysis was successfully designed andsynthesised. The detection mechanism is Ethylenediamine tetraacetic acid dianhydride(EDTAD) was covalently grafted onto the surface of3-aminopropyltriethoxysilane(APTES) modified-silica nanoparticles by the reaction of amino group of APTESmolecules with anhydride group of EDTAD molecules. The resulting EDTA ligand isthen readily converted into a [Tb(EDTA)(H2O)3] complex on reaction with Tb3+. Oponexposure of the nanoparticles to calcium dipicolinate (CaDPA), the ligand of DPAcompete with water molecules to form [Tb(EDTA)(DPA)] complex, which significantlyminimizes the non-radiative quenching of the Tb3+emission, resulting in an increase inthe fuorescence intensity of terbium, While in the presence of Hg2+, Tb3+can bereplaced by Hg2+to form a [Hg(EDTA)(DPA)] complex, leading to the fuorescencequenching of the terbium-based nanoparticle sensor. The detection sensitivity wasevaluated by adding different concentrations of Hg2+into the aqueous solution ofTb-based nanoparticle sensor. Alinear relationship between the fuorescent intensity andHg2+concentration was obtained. Experiments show that the nanoparticles show the best fluorescence intensity whenthe concentration of CaDPA is100μM and the concentration of nanoparticles is3.0mg/mL, the detection takes only a few seconds to be completed, the fluorescenceintensity of nanoparticles showed a good linear relationship with the concentration ofHg2+, the detection limit was50μM, sensors exhibited a good detect property at pH7.0or7.5, other metal ions does not interfere with the detection, the sensor shows a goodselectivity for Hg2+.

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