Capillary and microchip electrophoresis for DNA separation as well as synthesis and optoelectronic applications of quantum dots
Date Issued
2006
Date
2006
Author(s)
Lin, Yang-Wei
DOI
en-US
Abstract
This thesis focuses on developing highly efficient and reproducible capillary electrophoresis (CE) and microchip CE (MCE) based techniques for DNA separation and preparing highly fluorescent quantum dots (QDs) for biosensing and optoelectronic devices. First, the sensitivity and resolution of DNA fragments have been optimized in CE, by applying on-line concentration and using a bubble cell (e.g. 300 um in diameter). When compared to that by conventional injection and use of a capillary without a bubble cell, up to 170-fold sensitivity improvements for the DNA fragments have been achieved. The impact of hexadecyltrimethylammonium bromide (CTAB) on the separation of ds-DNA by CE in conjunction with laser-induced fluorescence (CE-LIF) detection using 0.75% poly(ethylene oxide) (PEO) solution is described. With increasing CTAB concentration, the interactions of DNA with ethidium bromide (EtBr) and with the capillary wall decrease. Under optimum condition, a mixture of DNA markers V and VI within 8 min at -375 V/cm was separated, with the limit of detection of 2.0 ng/mL based on the peak height for the 18-bp DNA fragment. In microchip electrophoresis for DNA separation section, we have demonstrated a simple method for dynamically coating the wall of the separation channels that were fabricated on poly(methyl methacrylate) (PMMA) plates using poly(vinyl pyrrolidone) (PVP), poly(ethylene oxide) (PEO), and gold nanoparticles (GNPs) in sequence. The three-layer (PVP-PEO-GNPs) coated PMMA chips provide improvements in resolution and reproducibility for DNA separation when using 1.5% PEO(GNPs), allowing the separation of DNA fragments ranging in the size of 18-2176 bp. Besides, multilayer coating of PMMA chips with PEO, PVP, and PEO containing gold nanoparticles [PEO(GNP)] is important for achieve high efficiency. Using a 2-(PEO-PVP)-PEO(GNP) PMMA chip, the separation of DNA markers V and VI by MCE in 0.75% PEO(GNP) was accomplished in 3 min. In QDs section, a simple synthetic route to the preparation of high-quality CdSe QDs in aqueous solution was present. The thermal synthesis, assisted by laser irradiation at 532 nm, allows the preparation of CdSe QDs that possess higher quantum yield. After UV irradiation, the as-prepared core–shell CdSe/CdS QDs become stable and fluoresce strongly in the visible range. For biocomplement, we also prepare highly water-soluble core-shell-shell (CSS) silica–QDs–silica NPs that exhibit greater QYs, photostability, and chemical stability. This feature, together with their narrow emission spectral profile, suggests that the CSS silica–QDs–silica NPs may have a great number of biological applications. QD films are fabricated through layer-by-layer (LBL) assembly using citrate-stabilized CdSe@CdS QDs, 3-mercaptopropionic acid (MPA)-stabilized CdTe QDs, and poly(diallyldimethylammonium chloride) (PDDA). The colors and emission intensities exhibited by the highly fluorescent QD films are readily tunable by controlling the deposition order and the number of bilayers of (PDDA-CdSe@CdS)n and (PDDA-CdTe)n.
Subjects
DNA分離
毛細管電泳
晶片電泳
量子點
量子點薄膜
DNA separation
capillary electrophoresis
microchip electrophoresis
quantum dots
quantum dots films
Type
thesis
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