Tese_Tânia Vieira.pdf - Ubi Thesis

Abstract
Bacterial infections have been a constant threat to human health throughout the history.
Bacterial colonization of biomedical devices and implants causes enormous problems for
healthcare systems worldwide, costs and increases patient’s suffering. Silver has been known,
since the antiquity, by their antimicrobial properties and was used to produce reservoirs of food
and with medical purposes. With the development of nanotechnology, silver nanoparticles have
attracted the attention of different researchers due to their properties, as antimicrobial
properties and high surface to volume ratio. However, these nanoparticles can form aggregates,
which have toxic effects to the human cells. Recently, silver nanoparticles have been stabilized
with several polymers and surfactants in order to avoid these problems.
In this work, silver nanoparticles were produced and stabilized with chitosan/dextran. The
produced nanoparticles were characterized by Scanning Electron Microscopy, Ultraviolet-Visible
and Fourier Transform Infrared spectroscopy. Furthermore, the antibacterial activity of the
produced nanoparticles was evaluated and it was found that they are effective in the prevention
of the growth of Escherichia coli through a minimum inhibitory concentration. These particles
were also studied in contact with human osteoblast cells in order to ascertain if the particles
that had an antibacterial effect to the bacteria do not have a toxic effect for human cells. The
results herein obtained revealed that the nanoparticles can be used in a near future as a coating
material of medical devices in order to avoid their bacterial colonization.
Keywords
Antibacterial mechanism; Chitosan/dextran nanoparticles; Escherichia coli;
Nanotechology; Silver nanoparticles.
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