Synthesis and Antibacterial Properties of Selenium Based Nanoparticles Made by Bacteria

Identifier:  TFM:407

Handle: https://hdl.handle.net/20.500.11797/TFM407

Authors:  Baranda Pellejero, Lorena

Abstract:
Bacterial infections are considered one of the most significant problems facing the healthcare system due to antimicrobial resistance (AMR) towards current treatments. According to the World Health Organization (WHO), AMR is causing over 150,000 deaths per year. Therefore, there is an urgent need for novel treatments against bacteria to avoid the use of antibiotics. Recent developments in nanotechnology proved the high potential of nanoparticles (NPs) as a long-term solution of AMR, due to the novel properties present at these low dimensions. However, physico-chemical methods to obtain these NPs often result in a potential environmental threat. Fortunately, green chemistry provides sustainable routes that take advantage of biological systems, such as bacteriogenic synthesis, which is based on the detoxification process that bacteria manifest in presence of metal ions. The produced NPs present a bio-coating surrounding their surface that might enhance their biocompatibility and antimicrobial properties. Hence, the aim of the present research is to explore bacteriogenic synthetic routes for the generation of selenium-based NPs to be applied in bacterial treatments. The present work is divided into two main objectives: in the first, selenium and cadmium selenide NPs made by Staphylococcus aureus and Escherichia coli were synthesized and their antibacterial activity against Gram-positive and Gram-negative bacteria studied. In the second objective, a novel route for the treatment of Helicobacter pylori infection by using Se-NPs was studied. Bacteria were treated with the NPs that they themselves created. The size, shape and charge of all the synthesized NPs were characterized by electron microscopy and dynamic light scattering and their composition by energy-dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy. After synthesis and characterization, the antibacterial properties were tested by bacterial growth curve analysis and colony-forming unit assays. Finally, the biocompatibility was explored by studying their cytotoxic effects on healthy human dermal fibroblasts.