Synthesis Of Gold Nanorods And Their Applications In Human Telomere DNA Conformation Detection

Gold nanoparticle and gold nanorods (AuNRs) have attracted much attention in recent years due to their unique structural and optical properties. AuNRs have tunable anisotropic structure and near infrared (NIR) absorbtion, which is appliable in several fields, such as metal ions detection, immunoassay, DNA sequencing, cancer cell imaging, light-heat treatment and nano-meterial assembling. Human telomere consists of tandem repetitive sequence of (TTAGGG)n and plays an important role in anti-cancer drug selection. The applications of AuNRs in monitoring G-quadruplex DNA conformation change was studied for potential anticarcinogen screening. This paper includes the flowing four parts:1. Gold nanoparticles with different sizes and AuNRs with different aspect ratios were synthesized and their optical properties were studied. AuNRs with optical absorption matches the emission spectra of fluorescent dye were prepreapred, which allows the FRET process to take place. Gold nanoparticle and AuNRs dispersed in organic solvet were also prepared.2. A facile and multi-response strategy for studying the transformations of human telomere DNA from single strand (ss) to double strand (ds) and G-quadruplex has been established by using positively charged gold nanorod (AuNR) as an optical label. The conformation change information of the telomere DNA was transferred into multiple optical signals, including changes in fluorescence emission, near infrared (NIR) absorption, plasma resonance light scattering (PRLS) and dynamic light scattering (DLS) response. The formations of dsDNA and G-quadruplex DNA induced fluorescence quenching of dye on DNA, and were accompanied by the intensity decrease and blue shift of the longitudinal absorption peak of AuNRs. Meanwhile, PRLS and DLS results revealed slightly increased AuNR aggregation due to increased charge density of dsDNA and G-quadruplex DNA as compared to ssDNA. Control experiment suggests that the AuNR-based assay is highly sequence specific; and the high sensitivity allows the study of human telomere DNA at a concentration as low as 58 nM. 3. We have studied the conformation change of human telomere DNA assembled on gold substrate by electrochemical impedance spectroscopy and sum-frequence generation (SFG). The telomere DNA with different conformation gives different electrochemical impedance and SFG response. The conformation change of telomere DNA on gold substrate can be studied by these two techniques.4. The AuNRs "ring array" structure was fabricated on silicon and gold substrates by micro contact printing combines with "Breath Figure" method, which was characterized by scanning electron microscope (SEM), optical microscope, and atomic force microscope (AFM). The AuNRs array on silicon and gold substrate may be used as a new substrate for Surface Enhancement Raman Spectroscopy (SERS) study.