Patent Application
20080063728
In the following the invention will be described with the help of exemplary embodiments.
In Table 1 an example of a glass composition is specified which is finished with an antimicrobial surface via ion exchange in the solution.
In the case of the glass specified in the table it is a soda-lime glass which exhibits the composition specified in Table 1 in percentage by weight.
The glass specified in Table 1 was ground up once in an inert solution, i.e., in water. This glass powder served as a reference sample with regard to the antimicrobial activity.
In order to demonstrate the increased antimicrobial effect through the antimicrobial finishing according to the invention, the glass from Table 1 was ground in a zinc nitrate solution and in a further embodiment was ground up in a silver nitrate solution.
First the production of an antimicrobial finish with zinc ions will be described.
For this purpose 200 g of a glass in accordance with Table 1 are poured into 110 g of a 5% Zn(NO3)2 solution and ground or mixed for two hours in a small grinding container.
Then the obtained solution with the glass particles was dried for 19 hours in the annealing furnace at 100° C.
The pre-dried sample was then sintered for 100 minutes at 240 C so that the Zn ions could exchange with the alkali ions or diffuse in the surface of the glass particles.
The inventive method is summarized in tabular form in the following Table 2.
The finished glass particles with an antimicrobial surface comprising Zn ions are marked as Sample C.
Along with the finishing with Zn glass particles were also antimicrobially finished with Ag. The inventive method for this is given in Table 3.
For this purpose a largely inert glass with a composition in accordance with Exemplary Embodiment 1 in Table 1 was ground after melting in an AgNO3 solution. In this connection a mass of 200 g of the glass powder was added to 100 g 5% AgNO3 solution and ground for two hours. This relates to Sample D. In Sample E 200 g of a glass mass in accordance with Table 1, initial example 1, was ground with 10 g 5% AgNO3 solution for two hours. In the case of Sample F 200 g of glass mass in accordance with Exemplary Embodiment 1 in Table 1 was added to 100 g 0.5% AgNO3 solution and ground for two hours.
In the case of Sample G 200 g of a glass mass of the composition in accordance with Table 1, Embodiment 1 were added to 10 g of a 0.5% AgNO3 solution and ground for two hours.
In the case of all Samples D, E, F as well as G after the grinding the solution comprising the ground glass particles was pre-dried for 19 hours at 100° C. so that essentially the aqueous solvent could evaporate and after that dried or sintered for 100 minutes at 240° C.
Table 4 shows the antimicrobial effect of the various samples.
In this connection the germ-killing effect of the glass powder was investigated in various compositions with the bacteria escherichia coli, pseudomonas aeruginosa, staphylococcus aureus, candida albicans, aspergillus niger.
The initial value at 0 hours designates for all samples the number of bacteria that were initially added to the culture medium. The values at 48 hours, 7 days, 14, days, 21 days, 28 days describe the number of germs that were found after addition of the silicate glass powder in a concentration of 1 percent by weight for nutrient solution for Sample A and 0.1 percent by weight glass powder for nutrient solution of Sample B. Samples A and B describe silicate glass powder which was not subsequently antimicrobially finished. These samples constitute the reference samples. As Table 4 shows, the reference samples show only a slight antimicrobial effect.
Through the subsequent finishing with Zn or Ag ions the antimicrobial effectiveness is increased as subsequently described.
The mean particle diameter of all glass powders listed in Table 4 amounted to 4 μm.
Samples C.1 and C.2 designate glass powders which were treated with a Zn(NO3)2 solution in accordance with Table 2 Sample C and were added in a concentration of 1 percent by weight for Sample C.1 to a nutrient solution. As can be clearly seen, an antimicrobial effect is detected for the bacteria escherichia coli, pseudomonas aeruginosa, staphylococcus aureus, since these bacteria had been completely destroyed after 14 days, resulting in a value of 0 in the corresponding table.
If one adds only 0.1 percent by weight of a glass powder which in accordance with Sample 4 in Table 2 has been finished with the antimicrobial ion zinc to the nutrient solution, the antimicrobial effect is somewhat weaker, however a complete disinfection is also achieved for the bacteria escherichia coli and pseudomonas aeruginosa, resulting in a value of 0 in the table.
As shown from Table 4 for Samples D.1 and D.2, a very strong disinfectant effect can be achieved by finishing largely inert glass powders with Ag ions.
Sample D.1 describes a glass powder finished in a 5 percent AgNO2 solution in accordance with Table 3, Sample D. This glass powder in accordance with Sample D was added in a concentration of 0.1 percent by weight to a nutrient solution comprising the bacteria escherichia coli, pseudomonas aeruginosa, staphylococcus aureus, candida albicans, aspergillus niger.
As can be inferred from Table 4, already with a slight concentration of only 0.1 percent by weight of the antimicrobial glass powder in accordance with Sample D a disinfection is achieved for the bacteria escherichia coli, pseudomonas aeruginosa, staphylococcus aureus after 7 days. If one adds Sample D in a concentration of 1.0 percent by weight to the nutrient solution, the disinfectant effect can be demonstrated already after 48 hours for all of the examined bacteria.
Through the invention it is possible for the first time to finish soda-lime glasses, which belong to the class of water-insoluble silicate glasses, that are to be produced in large quantity quite cost-effectively and with an increased antimicrobial effect. Through the subsequent antimicrobial finishing it is possible, through corresponding selection of the concentrations, the pre-drying and tempering conditions, to selectively set the antimicrobial effect of a glass powder.
Escherichia
Pseudomonas
Staphylococcus
coli
aeruginosa
aureus
Candida albicans
Aspergillus niger
| Number | Date | Country | Kind |
|---|---|---|---|
| 103 45 815.8 | Sep 2003 | DE | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/EP04/10923 | 9/30/2004 | WO | 00 | 12/1/2006 |
