| In the recent years, the flourish of nanotechnology leads to a remarkable achievement in the preparation and characterization of metal nanoparticles, and some unique optical and electrical properties of nanoparticles have been gradually realized. Up to now, metal nanoparticles have been used in physics, chemistry, biomedicine and other subsequent researches. Using nanoparticles is not only a good way to study the interaction between light and substance,but also an important research method and a detection approach in biology. For example, studies on the unique properties of metal nanoparticles and its interaction with bio-molecules are significantly important for the development of near filed imaging and the detection of bio-molecules’spatial discrimination.Based on the significant importance of nanoparticles in biology researches, and current working projects of our group, we chose to simulate the optical properties of metal nanoparticles by using the Finite Difference Time-Domain (FDTD) method, explored their potential applications in biophotonics. Taking the advantages of localized surface Plasmon resonance, we designed a novel near filed LSPR amplifier, and analyzed its potential applications in biophotonics. With a full-scale understanding about the mechanism of interactions between nanoparticles and fluorescent molecules, further investigations of the roles of nanoparticles in spatial-resolved detection of fluorescent molecules have been done. Our research has addressed the LSPR features of nanoparticles, furthermore, its applications in biology have been discussed and optimized. The main results in this study are as follows:1. We have been systematically studied the LSPR features of nanospherical dimmers and explored the influence of localized surface Plasmon resonance on the enhancement of local field. Compared with the single nanoparticle, the dimmers have a stronger enhancement ability in local electric field. The space charge distribution and the interaction mechanism of electric charges were used to analyze the LSPR properties of nanospherical dimmers. This provides a theoretical foundation for further design and optimization of the nanoparticle dimmer amplifiers.2. We designed a LSPR amplifier that based on the nanospherical dimmers which helps a lot on the detection of weak fluorescence. By reducing the absorption loss of the metal particles via the coating of gain materials, the local electric field of nanospherical dimmers was dramatically enhanced. In part V, we investigated the influences of nanoparticle distance d on the local electric field distribution, examined the near field enhancement ability of LSPR amplifiers by setting an appropriate d, and discussed the applications of the amplifier. Relative results are calculated by finite difference time domain method (FDTD).The enhanced emission could be controlled by the parameters of the resonance wavelength.3. We also studied the bio-molecular interactions via the fluorescence emission of fluorophores nearby the metal nanoparticles. Besides the commonly used parameters such as fluorescence intensity, quantum efficiency, fluorescence lifetime and other related parameters were chosen for the characterization. This method can be applied to explore the intermolecular binding of protein, DNA, antibody and antigen in a more sensitive way.The finite difference time domain method (FDTD) was used to simulate and calculate in the launch of fluorescent molecules near the metal nanoparticles and mechanism of energy exchange was discussed afterwards. By comparison of the emission characters of fluorescent molecules near metal nanoparticles in different conditions, and detection of the spatial resolution of the fluorescent molecules via quantum yield and lifetimes, interactions between biological molecules can be finished. |
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