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Based On Colloidal Gold Preparation Of The Dna Of The Gold Film Surface Plasmon Resonance Sensor

Posted on:2003-05-04Degree:MasterType:Thesis
Country:ChinaCandidate:Q WangFull Text:PDF
GTID:2208360092970162Subject:Analytical Chemistry
Abstract/Summary:PDF Full Text Request
The labelling of biomolecules, such as fluorescence labeling and enzyme labelling, is the most common in most of biosensing studies. However, the labelling procedures are generally labor extensive and operationally complicated, and labelling itself may even perturb the properties of the system under study and degrade the activity of the labelled biomolecules. Therefore, there has been increasing interest in the development of label-free techniques for biosensing studies in the past years. A typical example is the SPR-based biosensors. Due to its high sensitivity, rapid response and simplified measurement procedures, the SPR technique has become a powerful tool for the construction of novel biosensors that can be used for real-time detection and in-vivo probing of the interaction between biomolecules in biological systems.SPR sensors have found wide-spread applications in various fields including biomedical studies, process monitoring, drug screening and development and food analysis. With the advancement of life sciences, it's necessary to study further the interaction between biomolecules, so the application and research of SPR sensors will be expanded due to the availability of sensitive instruments and the expansion of strategies for studying biological or biochemical systems. Therefore, it's necessary to develop continually SPR sensors. Since low molecular weight compounds do not have sufficient mass to cause a measurable change in refractive index, small molecules are difficult to be directly detected using SPR instruments at present. Hence, sensitivity enhancement is one of the topics of keen concern in SPR sensing study. In addition, since the application and research of SPR sensors have been limited by high experimental expenses, lots of effort focus on the decrease of the experimental cost. Upon the mentioned above, the researches of enhancing the sensitivity and decreasing the gold film cost have constituted the main subject of the present thesis.The present thesis is composed of the following three parts:(1) The approach, which prepared stable thin films for SPR sensors based on colloidal Au, has been improved. In this procedure, gold nanoparticles were firstly assembled on modified glass slides as nucleuses, then stable gold films were formed inAu(III) solution upon the addition of appropriate reducing agent. From the experiments, it's found that the silanizing of glass surface and the size of colloidal Au were the key elements in the formation and the properties of Au film, accordingly, the resonance depth and peak half width were affected, and the sensitivity of sensors was affected. Through optimizing these conditions, the gold films with the deep resonance depth were obtained. Based on the thin gold films prepared in this way, SPR sensors were constructed for the determination of ethanol solutions and glucose solutions with bare gold films and for detection of DNA with probe DNA-modified gold film. The results obtained are consistent with those given by physically prepared gold films, indicating that such thin gold films can be utilized for SPR sensors. This method proposed here is simple, inexpensive, and highly reproducible. Most importantly, it suggests that it be used widely in SPR sensors. This research will be help to increase further the ration of performance to price.(2) An approach of enhancing the sensitivity of SPR sensors for DNA detection by applied electric field was demonstrated. In this approach, the orientation of DNA probes on gold surfaces could be modulated by the electric fields applied. With different electric fields, DNA probes were made to stand up or lie down. Because the hybridization efficiency is closely associated with the orientation of DNA probes, that is, when the gold film of SPR was electronegative, DNA probes stand straight up, therefore the hybridization efficiency could be increased owing to the decrease in steric hindrance; In contrast, when the gold film had positive charges, DNA probes lay on the gold surface and the hybridization process was...
Keywords/Search Tags:Surface plasmon resonance sensor, Sensitivity, Colloidal Au, Electrostatic field: DNA, small molecules containing anthracene
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