Browsing by Subject "Magnetic bacteria"

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Open Access
Engineered bacteria with genetic circuits accumulating nanomagnets as MRI contrast agents
(Wiley, 2022-01-25) Yavuz, Merve; Ütkür, Mustafa; Kehribar, Ebru Şahin; Yağız, Ecrin; Sarıtaş, Emine Ülkü; Şeker, Urartu Özgür Şafak
The demand for highly efficient cancer diagnostic tools increases alongside the high cancer incidence nowadays. Moreover, there is an imperative need for novel cancer treatment therapies that lack the side effects of conventional treatment options. Developments in this aspect employ magnetic nanoparticles (MNPs) for biomedical applications due to their stability, biocompatibility, and magnetic properties. Certain organisms, including many bacteria, can synthesize magnetic nanocrystals, which help their spatial orientation and survival by sensing the earth's geomagnetic field. This work aims to convert Escherichia coli to accumulate magnetite, which can further be coupled with drug delivery modules. The authors design magnetite accumulating bacterial machines using genetic circuitries hiring Mms6 with iron-binding activity and essential in magnetite crystal formation. The work demonstrates that the combinatorial effect of Mms6 with ferroxidase, iron transporter protein, and material binding peptide enhances the paramagnetic behavior of the cells in magnetic resonance imaging (MRI) measurements. Cellular machines are also engineered to display Mms6 peptide on the cell surface via an autotransporter protein that shows augmented MRI performance. The findings are promising for endowing a probiotic bacterium, able to accumulate magnetite intracellularly or extracellularly, serving as a theranostics agent for cancer diagnostics via MRI scanning and hyperthermia treatment. © 2022 Wiley-VCH GmbH.
Open Access
Genetically designed microbes for bioimaging and biosensing
(2024-09) Yavuz, Merve
The advantageous approach to the utilization of the microbes for bioimaging and biosensing underlies under their active motility and self-propulsion characteristics besides their easy bioengineering feature to gain multi-functional activities. The emerging developments make use of microorganisms as therapeutic agents in disease diagnosis and treatment. The dynamic nature of the habitat forces the microorganisms to acclimate themselves to changing living conditions via evolving exclusive bio-functionalities for their survival. Therefore, the living microorganisms producing functional materials serve as a biohybrid system with unprecedented potential for enhancing the detection of a disease biomarker molecule or meeting the great need in cancer diagnosis. The synthetic biology approach, a multidisciplinary field of science, gives the ability to engineer and modulate the microorganisms to redesign existing natural pathways, resulting in the gain of the desired function. Inspiring form nature, the biomineralization of iron-oxide materials is demanding for their potential usage in antitumor effect due to their easy modulation, stability, and magnetic properties. Furthermore, the certain respiratory capacities of electrochemically active microbes enable the respiration of diverse inorganic and organic molecules for their survival in redox-stratified environments. The ability of exchanging electrons with electrodes possesses several diverse biotechnological applications like the construction of microbial fuel cells, electro-fermentation, and electro-genetics. In this thesis, the microbes were engineered for their utilization in bioimaging and biosensing applications. Firstly, intracellular and extracellular magnetite accumulating Escherichia coli bacterial cell machineries were constructed as contrast agents for the MRI scanning, promising for a cancer diagnostic. Secondly, the intracellular magnetite accumulating bacterial cells, possessing all the redox reactions that readily take place in their cytoplasm via synthetically produced proteins, were further engineered to improve their targeting capability for breast cancer tumor cells by displaying a certain nanobody on the cell surface. Thirdly, electronic sentinel bacterial cells were designed utilizing the electron transfer modules for extracellular electron consumption by targeted acceptors for their wireless biomonitoring applications upon detecting a disease molecule. The methodologies described in this thesis are envisioned as promising tools for diagnostic applications.