Condensation Of DNA Caused By PAMAM And Photodetachment Of H~- Near The Metal Surfaces

The effect of DNA on the function of tissue and organs is direct in the vitalmovement, so it's nessary to research new drugs which can control the structure and the behavior of DNA. In this paper, the new dendrimer which is called PAMAM and particularly payed attention to is researched. Owing to the highly symmetrical amino-group outside and the cavity inside, it's great to be a carrier for drug and gene, now the interaction of PAMAM and DNA is studied.Magnetic tweezers and AFM technology is used to study the coagulation of DNA caused by PAMAM as the time increasing. The condensed characteristics of one DNA caused by 2.0G PAMAM is studied by magnetic tweezers technology at the molecular level. By simulating and software analysising, the result that the DNA shortens inconsecutively and jumps as the time increasing, this can be explained perfectly by the primary condensing theory of DNA. Using AFM technology, the relation of the distribution and concentration of PAMAM on the mica is studied firstly, at a relatively low concentration, it tend to be film, at a certain concentration, it may form a graininess structure. Then the condensed characteristics of DNA caused by PAMAM is studied, comparing with the image of PAMAM and DNA, one or several DNA changing from shrink to concentration with time. After 26 hours later, round shape distribution comes out, the central part is the most closely packed.The photodetachment of H- near the band gap metal surface based on the semiclassical closed orbit theory is investigated, it's in a real system. Comparing with the theory system, when the detached electron energy is between the threshold and the image potential, the staircase structure of the photodetachment cross section presents some more sophisticated structure in each step as the photon energy increasing. The corresponding Fourier transform spectrum shows that the longer the image state lifetime is, the larger the high frequency amplitude of the Fourier transform spectrum corresponding to the photodetachment cross section is.