Author: Zhang, Yuanchi
Title: Nanoporous alumina membrane based FRET biosensor with graphene quantum dots and gold nanoparticles for DNA detection
Degree: M.Sc.
Year: 2014
Subject: Optical detectors
Nanostructured materials
Porous materials
DNA -- Analysis
Hong Kong Polytechnic University -- Dissertations
Department: Interdisciplinary Division of Biomedical Engineering
Pages: vii, 66 leaves : color illustrations ; 30 cm
Language: English
Abstract: DNA detection has become more and more important for the diagnosis and precaution of diseases due to the fact that the sequences of DNA have the genetic information and the main material basis of the biological inheritance, which are unique. In addition, there are many DNA sequences of different bacteria, virus and pathogen that can cause different disease having been confirmed. So with appropriate methods, these diseases can be diagnosed and prevented. Biosensor is one of good choices, which made of by two main parts, the biological sensitive element and the biotransducer. Recent years, biosensors have been developed fast with different technics such as electrochemistry, semiconductor and calorifics. Although there are many kinds of biosensors, optical biosensor has been becoming a focus because of the properties of fast process, high sensitivity, specificity, stability, portability and so on. Among various types of optical biosensor, the fluorescence resonance energy transfer (FRET) biosensor has caused lots of interests. FRET is a process describing the transfer of energy from one molecule to the other molecule when they are close enough. FRET biosensor can detect the targets and achieve the quantitative analysis of the results. In this study, nanoporous alumina membrane (AAO) was used as the substance to improve the interaction owing to the large surface area. In addition, graphene quantum dots (GQDs) and gold nanoparticles (AuNPs) have excellent optical properties. GQDs can emission blue light when excited by UV light. AuNPs have broad surface plasmon band (SPB) so that there is good overlap of between the emission spectrum of excited GQDs and the SPB of AuNPs. As results, GQDs as the donor and AuNPs as the quencher were used for FRET process. In this study, GQDs was firstly deposited on the surface of AAO through the combination between carboxyl and amino groups. Then the single stranded DNA (ssDNA) was conjugated with GQDs. Meanwhile, the complementary DNA (cDNA) was conjugated with AuNPs. After that, the AuNPs-cDNA was added on AAO and then DNA hybridization can make the GQDs and the AuNPs be close enough to cause FRET interaction.
We demonstrated the AAO based FRET biosensor with GQDs and AuNPs for DNA detection. We found that the saturation concentration of GQDs for the deposition on AAO, which was 30{471}g/mL. In addition, the AAO was proved to have much better carry capacity than alumina membrane through comparing the fluorescence intensity of the GQDs on the surface. Moreover, the ssDNA could enhance the fluorescence intensity of the GQDs. Furthermore, in the experiment, we summarized that the limit of detection (LOD) was around 1pM. Besides, we found that the quenching efficiency was almost not change eventually with the increasing of the concentrations of AuNPs.
Rights: All rights reserved
Access: restricted access

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