Efficient disinfection of water with silver sulfide quantum dots in a peptide coat
Water contaminated with bacteria is a large threat to global health. A
Chinese research team has described a simple new method of disinfection
in the journal Angewandte Chemie. It is based on tiny
biocompatible assemblies of atoms, known as quantum dots, made of silver
sulfide with caps made of a silver-binding peptide. When irradiated
with near-infrared light, they kill bacteria in water with high
efficiency through synergistic effects.
© Wiley-VCH, re-use with credit to 'Angewandte Chemie' and a link to the original article.
Particularly in developing nations and remote regions of the world,
it can be very difficult to access clean drinking water. Pathogenic
bacteria, such as E. coli, enterococci, salmonella, or cholera
pathogens, can cause serious infections. A single swallow can sometimes
have fatal consequences. Traditional disinfection methods widely
implemented in recent decades, such as UV light, chlorination, and
ozone, have disadvantages, including high costs, poor efficiency, poor
biocompatibility, and carcinogenic by-products. An alternative is
needed.
A team led by Xushen Qiu, Wei Wei, and Jing Zhao has now introduced a
new method that is based on quantum dots made of silver sulfide (Ag2S).
Quantum dots are nanoscopic structures made of about one-to-ten
thousand atoms that are “confined” in space. Their quantum-mechanical
properties correspond more to those of molecules than macroscopic
solids, which can lead to interesting opto-electronic effects.
Silver sulfide quantum dots are already used in photodynamic and
photothermic therapy, including for the treatment of certain tumors and
skin diseases. They can be used as contrast agents and as fluorescence
thermometers. So far, they have not been used much for disinfecting
water, partly because previous methods for preparing them have been
complicated and expensive. The team from Nanjing University and the
Nanchuang (Jiangsu) Institute of Chemistry and Health has now developed a
simple, inexpensive production method, in which the quantum dots are
enclosed by caps made from a specially developed biomimetic
silver-binding peptide (AgBP2).
When irradiated with near-infrared (NIR) light, the new AgBP2-Ag2S
quantum dots effectively kill bacteria in water. They are chemically
stable, photostable, and biocompatible. Their strong activity is due to a
synergistic combination of two effects. First, irradiation causes them
to produce highly reactive oxygen species, and second, they cause strong
local heating. Neither of the two effects alone leads to success, but
their synergistic combination effectively destroys bacterial cell
membranes. They are able to kill over 99 % of E. coli bacteria within 25 minutes of NIR irradiation—a highly promising strategy for antibacterial disinfection of water.
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About the Author
Dr. Jing Zhao is a
Professor at Nanjing University in Chemical Biology. His main specialty
is bioinorganic chemistry, especially metallodrug development and the
synthetic biology of long-chain biopolymers.
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