Development of molecular- and nanomaterial-based probes for sensing biomolecules and metal ions

• Main Authors: Jia-hui Lin, 林佳慧
• Other Authors: Wei-Lung Tseng
• Format: Others
• Language: zh-TW
• Published: 2015
• Online Access: http://ndltd.ncl.edu.tw/handle/bjcq2q

博士 === 國立中山大學 === 化學系研究所 === 103 === The purpose of this thesis is to describe how to develop molecular- and nanomaterial-based biosensor for sensing biomolecules and metal ions. The thesis consists of four independent works. (1) A simple and label-free fluorescent method for sensitive and selective detection of adenosine in urine sample was developed based on adenosine-induced inhibition of adenosylhomocysteine hydrolase (SAHH) activity. Without the addition of nucleophile, 2,3-naphthalenedicarboxaldehyde (NDA) was found to selectively react with homocysteine to form fluorescent product. Adenosine is efficient to inhibit the production of homocysteine from the hydrolysis reaction between SAHH and adenosylhomocysteine. Taken together, the fluorescence of NDA-homocysteine derivatives decreased with an increase in the adenosine concentration. As a result, the SAHH-based probe provided high sensitivity (a limit of detection for adenosine of 0.3 μM) and high selectivity (more than 100-fold for andenosine over any adenosine analogs). (2) A set of two-input and three-input DNA logic gates was constructed using non-Waston-Crick base pairing-based molecular beacon (MB). The presence of Hg2+, Ag+, and coralyne promoted the conformational changes of MB via the formation of T-Hg2+-T, C-Ag+-C, and A2-coralyne-A2 coordination, resulting in its fluorescent quenching. It was found that thiols, complexing agents, and polyadenosine can remove Hg2+, Ag+, and coralyne from the hairpin-shaped MB, respectively. Based on these phenomenon, the designed MB generated a series of two-input, three-input, and set-reset logic operation at the molecular level. (3) Laser-induced light scattering technique with the adevantages of high sensitivity, low cost, portability, and miniaturization was applied for sensing three gold nanoparticle-based sensing systems, including salt-, thiol-, and metal ion-induced nanoparticle aggregation. The combination of a miniatuarized spectrometer with a 532-nm laser allows the sensitive detection of Rayleigh scattering from nanoparticles aggregation. As a result, the proposed system provided more than 10-fold sensitivity improvement as compared to colorimetric assay. (4) Fluorescent polydopamine particles was prepared through hydroxyl-radical degradation of polydopamine nanoparticles. The production of fluorescent polydopamine was demonstrated using transmission electron microscope, dark field microscope, and thermogravimetric analyzer. The possible chemical compositions of polydopamine dots were determined using Fourier transform infrared spectrosmeter and laser desorption/ionization-time-of-flight mass spectrometer. Additionally, fluorescent polydopamine dots were used for sensitive and selective detection of Fe(III) through coordination between the catechol group of fluorescent polydopamine dots and Fe(III). This sensing mechanism relied on electron-transfer-induced fluorescence quenching.