the studies highlighted above, various bacteria are capable of reducing different
catalytically important transition metal ions and biosorbing the formed metal NPs
with high efficiency. Moreover, the formed NPs are often very small and
tightly bound to the microorganism’s membrane, which is highly advantageous
from a catalysis perspective. Also, it seems to be possible to recycle BWCSs
efficiently, as, for example, demonstrated by the study of the Skrydstrup
group where their BWCS could be separated by centrifugation as any other
conventional heterogeneous catalyst [134].
Another finding that is especially intriguing and that has been found to be
true for most of the studied BWCSs so far is that the interaction between the
metal NPs and the bacterial membrane proteins enable improved catalytic activity
compared to conventional heterogeneous metal catalysts in many cases. It will be
very exciting to follow the future developments in this area. Here, it would
be particularly interesting to see more demonstrations of new BWCSs as catalysts
for different organic transformations. There is certainly a huge potential for
more elaborate BWCS designs similar to the one reported by Foulkes et al. [139],
where biosorbed Pd NPs and an intracellularly expressed enzyme are used to achieve
an overall deracemization of an amine. By following this approach, it should be
possible to design more intricate cascade processes, which in turn could open up
for the synthesis of even more complex molecules. This synthetic approach
would certainly have the potential to bring organic chemists closer to the dream of
being able to design efficient cascade processes that can compete with the efficiency
and selectivity of Nature’s highly spectacular coupled enzymatic pathways.
5 General Conclusions
Many different strategies for interfacing nanometal species with biological systems
have been presented in this chapter. As has been demonstrated herein, bioinorganic
hybrid systems have found a wide range of applications in several different
research disciplines. In organic synthesis, metal NPs interfaced with either enzymes
or bacteria have been extensively studied as catalysts for different transformations.
Here, a particular focus has been dedicated to bioinorganic hybrids that display
multiple catalytic functions, as they have the potential to be applied in intricate
cascades that can be used to access highly complex organic compounds of value
for the fine chemical and pharmaceutical industry. In the field of bioelectrocatalysis,
the design of nanometal-enzyme hybrids is currently a major research frontier,
which is already yielding a variety of new efficient and robust EBCs that are
being evaluated as power sources for biosensors and actuators. This research is
expected to have a transformative impact on the field of medicine in a near future,
by enabling for the development of new implantable and wearable biomedical
devices that will be of useful for the treatment and monitoring of different diseases.
However, it is perhaps also safe to say that bioinorganic hybrid systems will
most likely see many more applications than those outlined in this chapter. As the
fields of nanotechnology and biology continue to move forward, new research
Nanocatalysis Meets Biology
269
catalytically important transition metal ions and biosorbing the formed metal NPs
with high efficiency. Moreover, the formed NPs are often very small and
tightly bound to the microorganism’s membrane, which is highly advantageous
from a catalysis perspective. Also, it seems to be possible to recycle BWCSs
efficiently, as, for example, demonstrated by the study of the Skrydstrup
group where their BWCS could be separated by centrifugation as any other
conventional heterogeneous catalyst [134].
Another finding that is especially intriguing and that has been found to be
true for most of the studied BWCSs so far is that the interaction between the
metal NPs and the bacterial membrane proteins enable improved catalytic activity
compared to conventional heterogeneous metal catalysts in many cases. It will be
very exciting to follow the future developments in this area. Here, it would
be particularly interesting to see more demonstrations of new BWCSs as catalysts
for different organic transformations. There is certainly a huge potential for
more elaborate BWCS designs similar to the one reported by Foulkes et al. [139],
where biosorbed Pd NPs and an intracellularly expressed enzyme are used to achieve
an overall deracemization of an amine. By following this approach, it should be
possible to design more intricate cascade processes, which in turn could open up
for the synthesis of even more complex molecules. This synthetic approach
would certainly have the potential to bring organic chemists closer to the dream of
being able to design efficient cascade processes that can compete with the efficiency
and selectivity of Nature’s highly spectacular coupled enzymatic pathways.
5 General Conclusions
Many different strategies for interfacing nanometal species with biological systems
have been presented in this chapter. As has been demonstrated herein, bioinorganic
hybrid systems have found a wide range of applications in several different
research disciplines. In organic synthesis, metal NPs interfaced with either enzymes
or bacteria have been extensively studied as catalysts for different transformations.
Here, a particular focus has been dedicated to bioinorganic hybrids that display
multiple catalytic functions, as they have the potential to be applied in intricate
cascades that can be used to access highly complex organic compounds of value
for the fine chemical and pharmaceutical industry. In the field of bioelectrocatalysis,
the design of nanometal-enzyme hybrids is currently a major research frontier,
which is already yielding a variety of new efficient and robust EBCs that are
being evaluated as power sources for biosensors and actuators. This research is
expected to have a transformative impact on the field of medicine in a near future,
by enabling for the development of new implantable and wearable biomedical
devices that will be of useful for the treatment and monitoring of different diseases.
However, it is perhaps also safe to say that bioinorganic hybrid systems will
most likely see many more applications than those outlined in this chapter. As the
fields of nanotechnology and biology continue to move forward, new research
Nanocatalysis Meets Biology
269