25-08-2017, 09:32 PM
Silver Colloids Impregnating or Coating Bacteria
[attachment=19642]
Introduction
In this communication we demonstrate that deposits of
metallic silver may be generated selectively inside or on bacteria
in a controlled manner and discuss several aspects of the
behavior of the combined metal-bacteria system. The methods
developed here are potentially of wide general use, for example,
in the study of the biochemistry and biophysics of bacteria or
in material science. Specifically, the methods can be applied
to the identification of bacteria, on one hand, as well as to the
control of the production of colloids in materials processing,
on the other hand, in line with the directions outlined recently
by Mann.
Results and Discussion
Electron Microscopy. Figure 1 shows an electron micrograph
of Escherichia coli with a silver colloid deposited mainly
on the bacterium wall (“wall colloid”). The TEM measurements
are done to determine the location of the silver deposits when
compared to various controls that show the bacterial image as
much less dense. Thus the micrographs shown here are made
without any of the usual preparations to enhance the image.
They utilize only the silver from the experiment to add density
to the bacterial image.
Surface-Enhanced Raman Scattering. Figure 6 shows the
Raman spectrum obtained from E. coli coated with a silver
colloid. The system consists of a Coherent Innova 90/5 laser,
a Jarrell Ash MonoSpec 27 single stage monochromator (Model
82499) with a ruled grating of 600 gr/mm, one or two Kaiser
Holographic SuperNotch filters, HSNF-514.5, and a PI 512
element intensified diode array.
Summary
In summary, we showed here that metal silver colloids can
form within and on bacteria. On one hand, the bacteria modify
the properties of the colloid, which is important for material
science. Specifically, stable nanocolloidal dispersions are
obtained under conditions that yield only powdery deposits in
the absence of the bacteria.
[attachment=19642]
Introduction
In this communication we demonstrate that deposits of
metallic silver may be generated selectively inside or on bacteria
in a controlled manner and discuss several aspects of the
behavior of the combined metal-bacteria system. The methods
developed here are potentially of wide general use, for example,
in the study of the biochemistry and biophysics of bacteria or
in material science. Specifically, the methods can be applied
to the identification of bacteria, on one hand, as well as to the
control of the production of colloids in materials processing,
on the other hand, in line with the directions outlined recently
by Mann.
Results and Discussion
Electron Microscopy. Figure 1 shows an electron micrograph
of Escherichia coli with a silver colloid deposited mainly
on the bacterium wall (“wall colloid”). The TEM measurements
are done to determine the location of the silver deposits when
compared to various controls that show the bacterial image as
much less dense. Thus the micrographs shown here are made
without any of the usual preparations to enhance the image.
They utilize only the silver from the experiment to add density
to the bacterial image.
Surface-Enhanced Raman Scattering. Figure 6 shows the
Raman spectrum obtained from E. coli coated with a silver
colloid. The system consists of a Coherent Innova 90/5 laser,
a Jarrell Ash MonoSpec 27 single stage monochromator (Model
82499) with a ruled grating of 600 gr/mm, one or two Kaiser
Holographic SuperNotch filters, HSNF-514.5, and a PI 512
element intensified diode array.
Summary
In summary, we showed here that metal silver colloids can
form within and on bacteria. On one hand, the bacteria modify
the properties of the colloid, which is important for material
science. Specifically, stable nanocolloidal dispersions are
obtained under conditions that yield only powdery deposits in
the absence of the bacteria.