Fluorescence resonance energy transfer-based biosensor between graphene quantum dots and gold nanopaticles for optical diagnostic of staphylococcus aureus oligonucleotide

Pao Yue-kong Library Electronic Theses Database

Fluorescence resonance energy transfer-based biosensor between graphene quantum dots and gold nanopaticles for optical diagnostic of staphylococcus aureus oligonucleotide

 

Author: Li, Hui Jun
Title: Fluorescence resonance energy transfer-based biosensor between graphene quantum dots and gold nanopaticles for optical diagnostic of staphylococcus aureus oligonucleotide
Degree: M.Sc.
Year: 2014
Subject: Staphylococcus aureus.
Staphylococcus aureus infections -- Diagnosis.
Hong Kong Polytechnic University -- Dissertations
Department: Interdisciplinary Division of Biomedical Engineering
Pages: iv, 61 leaves : color illustrations ; 30 cm
Language: English
InnoPac Record: http://library.polyu.edu.hk/record=b2757736
URI: http://theses.lib.polyu.edu.hk/handle/200/7551
Abstract: Staphylococcus aureus (S. aureus) as the most common bacteria both in the skin infection and food-poisoning, requires a sensitive and specific diagnosis strategy for the daily direct detection. An efficient optical detection strategy for S. aureus, involving binary probes in a sandwich FRET between GQDs and AuNPs, was designed in this study. Fluorescence resonance energy transfer (FRET), referring to the effect of transferring energy from fluorescent donor to quenching acceptor, is distant-depended and required spectrum overlapping between donor and acceptor. GQDs are excellent emitter with strong fluorescence, in addition to AuNPs are well-known peachy fluorescence quencher due to the wide range absorption spectrum, making them as partners in the fulfillment of spectral requirement of FRET, and thus have been chosen to be as donor and acceptor respectively in this sandwich structure FRET system. Without labeling target directly on the GQDs or AuNPs as probe, amine-modified and thiol-modified complementary single-strain oligonucleotide were synthesized for the conjugation of DNA immobilized GQDs and DNA immobilized AuNPs to form capture probe and reporter probe. In the process, capture probe hybridized with target cDNA with complementary sequence, then the reporter probe subsequently hybridized with the remaining unbinding sequence of target, bringing GQDs and AuNPs into proximity, leading the energy transfer from GQDs to AuNPs under excitation. The quenching efficiency of oligonucleotide immobilized AuNPs was found to increase with the increasing target concentration, and it reached a plateau with the beginning concentration with 100nM and tend to be stable at 200nM with approximately 80% efficiency. The linear working range of detection was from 100pM to 100nM with a detection limit of 10nM. The strategy also possesses a high selectivity when comparing to the single-base and double-base mismatch oligonucleotides, with a trend that increasing number of mismatch base increasingly decreases the quenching efficiency.

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