Preparation Of Nanoscale Optical Fiber DNA Biosensor And Application For Gene Diagnosis

Nanoscale optical fiber DNA biosensor will be widely applied in the detection of tissues and cells, genetic diagnosis and base mutation because of its unique optical properties and nanoscale sensitive element. Nanoscale optical fiber DNA biosensor is designed and prepared, and applied in genetic diagnosis in this article. First we successfully prepare a nanoscale optical fiber DNA biosensor, and then light transmission in the cone-shaped fiber is analyzed to design the nanoscale optical fiber meeting the optical requirements. Its characteristics are investigated. Multi-functional sample pool is designed and prepared for experimental testing, diagnosis. Finally it is employed for gene aberration, such as base mutation and defect. Our major contributions are summarized as follows:1. The structure and optical properties of tapered fiber probe was analyzed to design and optimize the structure of nanoscale optical fiber. We have made some continuous tapered fibers and optimized the design of optical fiber tips.2. The preparation of nanoscal optical fiber was studied using static HF tube etching, the geometry was influenced by etching solution concentrations and etching time. The size of conical tip was about 100nm by scanning electron microscopy, the surface is smooth, and shows a continuous cone-shaped structure.3. The methods were established to characterize the active groups on the taper tips of nanoscale optical fibers, SEM–EDS and fluorescence spectrometry. The comparison is done between nonactivated and activativated optical fiber. The results showed that carbon is not detected by SEM–EDS and intensity of fluorescence is not measured by fluorescence spectrometry in the nonactivated optical fiber, while they are detected in the activated optical fiber. They are new detective methods for the prapearetion of sensitive components of biosensors.4. Oligo DNA target molecules were immobilized on the tips by electrostatic adsorption and covalent bonding. The amount of DNA was determined by SmartSpecTM Plus to calculate the quantivity of on the tips of optical fiber. 5. Samples pool based on the principle of transmission-type optical fiber sensor was designed and made using a unique flat condenser cone-shaped cavity group to modulate the optical signals, increasing the optical signal coupling efficiency and sensitivity of the sensor. It can take advantage of the high photon counting detector of fluorescence spectrometery for signal processing to increase the sensitivity of the biosensor.6. Response time, detection limit and detection range, regeneration conditions, life and reproducibility were studied in this paper. The results showed that response time was about 15min; the minimum detection limit was about 8nmol/ml, its detection range was 8-57 nmol/ml; 90℃was regeneration conditions; life is 50 days and reproducibility was good.7. Man-made nanoscale optical fiber DNA biosensors had been applied to detect the gene mutation with different based mutation number (1, 2 and 4 base mutation and completely noncomplementary strand). The results showed that the more base mutations and their corresponding fluorescence intensity were lower.