Palladium-based nanoparticles produced by Escherichia coli: Insights into synthesis and physicochemical characterization of microbial nanoparticles

Abstract

Microorganisms such as bacteria can produce a wide range of metallic nanoparticles, including the highly versatile palladium nanoparticles (Pd NPs). Current industrial methods for NP production often require large amounts of energy, use toxic chemicals, and generate waste. Microbial processes offer a green alternative for NP production, and the possibility to engineer these processes using genetic tools. Pd NPs are invaluable tools across numerous exciting applications in medicine, engineering, electronics, and chemistry. Understanding and controlling the synthesis of Pd NPs is crucial as their magnetic and catalytic properties are strongly dependent on their size, shape, and on the presence of other metals such as iron (Fe) that could enhance their performance even further. Surprisingly, little is known about the production of Pd-Fe nanoparticles by bacteria, despite their promising uses. In this thesis, we employed various advanced techniques to characterize Pd and Pd-Fe NPs produced by Escherichia coli bacteria, uncovering valuable insights into their composition, size, localization, and catalytic activity. These results will enable the use of bacterial Pd-Fe NPs as efficient and sustainable catalysts for applications like wastewater treatment and fine chemical synthesis in the future. Additionally, our novel methodology for studying the magnetism of Pd-based NPs directly within bacterial cells opens doors for exciting future research.