Mechanism Of Using Silver Ion To Improve The Antibacterial Properties On Green Building Materials

As the abundant utilization of chemical drugs such as Antibiotics Disinfectant And Sterilant, also the increase of resistance to microorganism, in order to prevent the occurrence of Microbial disaster events, it has been a trend to research and make use of new kind of antibacterial material. For the characteristics of high antibacterial activity, broad antibacterial spectrum, and low toxicity, The silver-supported inorganic antibacterial material becoming the most commonly used inorganic antibacterial materials. The silver-supported inorganic antibacterial material plays its antibacterial activity mainly by releasing silver ions, thus, making deeply research on antibacterial mechanism of silver ions will supply theory basis for developing more broad-spectrum and high efficient antibacterial material.This article researched antibacterial mechanism of Silver nitrate on bacteria from the aspect of biochemistry and molecular biology. Escherichia coli (CICC 20235) and Staphvlococcus aureus(CICC 20235) is selected as model bacterial for the experiment, the antibacterial capacity of Silver nitrate. was assayed by the minimal antibacterial concentration of Silver nitrate on Bacteria and the percentage of antibacterial, the effect on the growth situation of Silver nitrate on Bacteria was tested from their growth curve, the destroy of bacterial membrane was determined by those effect showed on the destroy of cell surface properties by Silver nitrate, and the experiment of Silver nitrate. affecting bacterial DNA and protein was made to observe how Silver nitrate. affects on bacterial hereditary material.The growth of Escherichia coli and staphylococcus aureus can be completely inhibited as silver nitrate reached 2.891mg/L and 5.781mg/L. silver nitrate at low concentration can prolong the lag phase of Escherichia coli and staphylococcus aureus, and the higher silver nitrate concentration is, the longer lag phase takes.After dealing Escherichia coli and staphylococcus aureus with 5.208mg/L silver nitrate solution, their hydrophobicity of cell surface respectively was 32.2 and 34.83, respectively 22.78% and 14% less than the untreated, hydrophobicity of the untreated showed minimal change,14% droped.Activity of the bacterium dehydrogenase can be inhibited by silver nitrate solution at low concentration, and activity of the bacterium dehydrogenasecontinued to drop as the silver nitrate concentration increased, the activity was inhibited completely while silver nitrate reached to a certain concentration.Silver nitrate solution of different concentration can enlarge membrane permeabilityof both the two bacterial membrane, there is a certain amount of protein in bacterial cell wall and membrane, also a large amounts of protein in nucleus. The disposal of silver nitrate led to the damage of cell membrane so that these protein leaked out, the result of scanning electronic microscopealso reflected the damage of cell membrane.Ag+combined with DNA after it entered the cell and destroyed the structure of DNA, made the DNA of Escherichia coli damaged, then genome DNA split and was degraded to DNA fragments of different molecular weight. silver nitrate has effect on the metabolism of protein, it can be known that disposal of silver nitrate has accelerated the degradation of some protein in the process of the bacteria metabolism, and that disposal could be likely to accelerate synthesis of some stress protein within a short time.