Theory Analysis And Experiment Research On The Anti-bacterial And Anti-adhesion Activities Of Polyaniline

Bio-adhesion is a common phenomenon in nature,form 20th century -80s to now,people studied the mechanism of biological adhesion and had a development of drug delivery systems. The study of adhesion theory for bio-blocking and related new blocking technology and methods could provide new ideas or methods to carry out researches in these areas such as bio-pharmaceutical, medical, and new materials researches. Researches in this field have an important value of academic research and potential applications. Because of high mobility of water, bio-adhesion is a common phenomenon of marine life. The purpose of this paper is to explore the interaction between the adhesion molecule(DOPA) and polyaniline. DOPA is common and crucial for marine life such as barnacles, diatoms, mussels and barnacles. Because conventional antifouling method had some disadvantages, it was necessary to develop and discover new method and materials. Therefore, we studied the antifouling paints to block biological adhesion by combining molecular dynamics, molecular biology, biochemistry and other interdisciplinary fields'knowledge, which can provide the powerful theory basis for studying the anti-bacterial and anti-adhesion activities of polyaniline ; meanwhile we also studied polyaniline to block the marine bacteria and diatom's adhesion, which provide the powerful experiment basis for to block the adhesion by using polyaniline. The research content and the result are as follows:â‘ By using quantum mechanics procedure, the structure and properties of Tyrosine and its oxides (DOPA, DOPA-Quinone and DOPA- DOPA) are theoretically studied. So are the three main models(emeraldine base, polaron and bipolaron) of polyaniline. In the reaction with charge control, positive and negative charges attract each other,the more charges of two atom, the stronger they attract .So is the adsorption energy. The calculations show that the functional groups(OH-)(about-0.2 ~ -0.25e) of Tyr, DOPA ,DOPA-DOPA and (O=) (about -0.36e)of DOPA-Quinone have highly negative charges, they will be attracted by positively charged position when they touch the surface. [1,2,3]Fukui is a effective method to study the electrophilic and nucleophilic reactions. In the figures, the more areas, the chance atoms are attacked. In addition, form the fig2.2, benzene ring in Tyr, DOPA and DOPA-DOPA tend to have electrophonic attacking than DOPA-Quinone. N atom of polyaniline is main active site. N atom of emeraldine base has positive charges and benzene ring has negative charges, but N atom of polaron and bipolaron has negative charges and benzene ring has positive charges.Fig2.3â‘¡Using molecular dynamics methods, we establish three different surfaces which consist of emeraldine base, polaron and bipolaron respectively to study for the interaction between the adhesion molecule (DOPA, DOPA-Quinone and DOPA- DOPA) and the three surfaces. The calculations showed: On the surface of emeraldine base, the interaction energies between DOPA-Quinone and surface is the biggest than the others, and Tyr is the smallest. The reason may be that they were attracted by N atom of emeraldine base, and O= has more negative charges than OH-. Tyr has only one OH-. On the surface of polaron and bipolaron, the interaction energies between DOPA-DOPA and surface is the biggest than the others, and DOPA-Quinone is the smallest. (Fig2.22)The reason may be that N is protonated and has negative charges, reducing the interaction with OH- and O=. From the Fig2.10, adsorption site of DOPA has became tilt apparently after molecular dynamics simulation. It may be because of the interaction between benzene rings. On the surfaces of polaron and bipolaron, the benzene ring in DOPA tend to have electrophonic attacking than DOPA-Quinone, so the energy of adsorption of DOPA=O is smallest. (Fig 2.2)â‘¢Using molecular dynamics methods, we establish the double-layer structure to study for the interaction between the adhesion protein (Mefp-1, Mefp-1'Mefp-3, Mefp-5) and the three surfaces. Mefp-1'is the Mefp-1 of which DOPA is replaced by DOPA-Quinone. The calculations show that the interaction energies between Mefp-1(Mefp-3 , Mefp-5) and the surface of emeraldine base is the smallest than other two surfaces, the reason may be that the adhesion molecule of Mefp-1, Mefp-3 and Mefp-5 is DOPA. The interaction energies between Mefp-1'and the surface of polaron is the smallest than other two surfaces(Fig3.2),which prove interaction energies of DOPA is smallest on the surface of emeraldine base and interaction energies of DOPA=O is smallest on the surface of surfaces of polaron again. We can study how to block the biological adhesion form this point.â‘£We also performed the experiments to study the anti-bacterial and anti-adhesion activities of polyaniline. The results show that, on the polyaniline's surface for 3days, the lowest blocking adhesion rate is 51% for the marine bacterial; 2 days, the diatoms blocking adhesion rate is 96.00%, 10days, the diatoms blocking adhesion rate is 71.63%; 25days, the diatoms blocking adhesion rate is 63.32% and 70days, blocking adhesion rate is 56.61%, which means polyaniline has the anti-bacterial and anti-adhesion activities. But after long term, the activities will decrease. The reason may be that the marine bacterial and the diatoms can oxidate or reduce the adhesion molecule to adapt different surfaces.Based on the experimental and theoretical research of computer simulation results, we can see that polyaniline has the anti-bacterial and anti-adhesion activities. Emeraldine base of polyaniline could effectively block the adhesive of DOPA of bacteria and diatoms , and polaron and bipolaron of polyaniline could effectively block the adhesive of DOPA-Quinone of bacteria and diatoms. Because the marine life can oxidate or reduce the adhesion molecule to adapt different surfaces, the anti-adhesion activities of polyaniline become lower.