Biocidal Mechanisms of Metallic Copper Surfaces - Use of Biocidal Surfaces for Reduction of Healthcare Acquired Infections - page 115

Fig. 6.6 Effect of different media on the survival of E. Hirae wild-type and mutant strains on
metallic copper surfaces coupons. Cells were washed and applied to copper coupons in 0.1 M
Tris-Cl, pH 7 (a), water (b), or 100 mM NaPi, pH 7 (c), wild type ( filled circles );

Δ copB mutant

( open circles );

Δ copAB mutant ( open squares ), incubated at room temperature for the times
indicated, and washed off with phosphate-buffered-saline. Survivors were counted as CFU.
Shown are averages and standard deviation from triplicate experiments [ 61 ]

8

7.5

7

6.5

6

5.5

5

4.5

4

3.5

3

2.5

2

1.5

1

0.5

0

0 1 2 3 4 5

BTA concentration (mM)

Fig. 6.7 Effect of benzotriazole (BTA)-coating electroplated copper surfaces on the survival of
E. coli . Cells are applied, incubated for 30 min, washed and survivors were counted by CFU [ 23 ]

surface toxicity under this condition compared to when water or phosphate-based
buffer was used. Complementary results were obtained with inhibition of surface
corrosion, where Elguindi and colleagues [ 23 ] were the first to show that metallic
copper surfaces need to be naturally oxidized in order to display antimicrobial
properties. The presence of corrosion inhibitors, such as benzotriazole (BTA),
enhances bacterial survival on wet copper surfaces by lowering the copper ion release
from copper surfaces (Fig. 6.7 )[ 23 ]. Considering these results, new disinfection and
cleaning materials need to be developed to aid maintaining the antimicrobial activity
of copper surfaces.