arXiv subjects

Mohamed Y. El-Naggar

Publications and source records attributed to Mohamed Y. El-Naggar.

4 recordsLinked to original sources

arXiv2026

Spin-Dependent Electron Transport through Bacterial Cell Surface Multiheme Electron Conduits

Multiheme cytochromes, located on the bacterial cell surface, function as long-distance (> 10 nm) electron conduits linking intracellular reactions to external surfaces. This extracellular electron transfer process, which allows microorganisms to gain energy by respiring solid redox-active minerals, also facilitates the wiring of cells to electrodes. While recent studies suggested that a chiral induced spin selectivity effect is linked to efficient electron transmission through biomolecules, this phenomenon has not been investigated in the extracellular electron conduits. Using magnetic conductive probe atomic force microscopy, Hall voltage measurements, and spin-dependent electrochemistry of the decaheme cytochromes MtrF and OmcA from the metal-reducing bacterium Shewanella oneidensis MR-1, we show that electron transport through these extracellular conduits is spin-selective. Our study has implications for understanding how spin-dependent interactions and magnetic fields may control electron transport across biotic-abiotic interfaces in both natural and biotechnological systems. Electron

physics.chem-ph↗

arXiv2025

Imaging and controlling electron motion and chemical structural dynamics of biological system in real time and space

Ultrafast electron microscopy (UEM) has found widespread applications in physics, chemistry, and materials science, enabling real-space imaging of dynamics on ultrafast timescales. Recent advances have pushed the temporal resolution of UEM into the attosecond regime, enabling the attomicroscopy technique to directly visualize electron motion. In this work, we extend the capabilities of this powerful imaging tool to investigate ultrafast electron dynamics in a biological system by imaging and controlling light induced electronic and chemical changes in the conductive network of multicellular cable bacteria. Using electron energy loss spectroscopy (EELS), we first observed a laser induced increase in π-electron density, accompanied by spectral peak broadening and a blueshift features indicative of enhanced conductivity and structural modification. We also traced the effect of ultrafast laser pumping on bulk plasmon electron oscillations by monitoring changes in the plasmon like resonance peak. Additionally, we visualized laser induced chemical structural changes in cable bacteria in real space. The imaging results revealed carbon enrichment alongside a depletion of nitrogen and oxygen, highlighting the controllability of chemical dynamics. Moreover, time resolved EELS measurements further revealed a picosecond scale decay and recovery of both π-electron and plasmonic features, attributed to electron phonon coupling. In addition to shedding light on the mechanism of electron motion in cable bacteria, these findings demonstrate ultrafast modulation and switching of conductivity, underscoring their potential as bio-optoelectronic components operating on ultrafast timescales.

physics.chem-ph↗

arXiv2016

Queuing models for abstracting interactions in Bacterial communities

Microbial communities play a significant role in bioremediation,plant growth,human and animal digestion,global elemental cycles including the carbon-cycle,and water treatment.They are also posed to be the engines of renewable energy via microbial fuel cells which can reverse the process of electrosynthesis.Microbial communication regulates many virulence mechanisms used by bacteria.Thus,it is of fundamental importance to understand interactions in microbial communities and to develop predictive tools that help control them,in order to aid the design of systems exploiting bacterial capabilities.This position paper explores how abstractions from communications,networking and information theory can play a role in understanding and modeling bacterial interactions.In particular,two forms of interactions in bacterial systems will be examined:electron transfer and quorum sensing.While the diffusion of chemical signals has been heavily studied,electron transfer occurring in living cells and its role in cell-cell interaction is less understood.Recent experimental observations open up new frontiers in the design of microbial systems based on electron transfer,which may coexist with the more well-known interaction strategies based on molecular diffusion.In quorum sensing,the concentration of certain signature chemical compounds emitted by the bacteria is used to estimate the bacterial population size,so as to activate collective behaviors.In this position paper,queuing models for electron transfer are summarized and adapted to provide new models for quorum sensing.These models are stochastic,and thus capture the inherent randomness exhibited by cell colonies in nature.It is shown that queuing models allow the characterization of the state of a single cell as a function of interactions with other cells and the environment,while being amenable to complexity reduction.

cs.ET↗

arXiv2015

A Stochastic Model for Electron Transfer in Bacterial Cables

Biological systems are known to communicate by diffusing chemical signals in the surrounding medium. However, most of the recent literature has neglected the electron transfer mechanism occurring amongst living cells, and its role in cell-cell communication. Each cell relies on a continuous flow of electrons from its electron donor to its electron acceptor through the electron transport chain to produce energy in the form of the molecule adenosine triphosphate, and to sustain the cell's vital operations and functions. While the importance of biological electron transfer is well-known for individual cells, the past decade has also brought about remarkable discoveries of multi-cellular microbial communities that transfer electrons between cells and across centimeter length scales, e.g., biofilms and multi-cellular bacterial cables. These experimental observations open up new frontiers in the design of electron-based communications networks in microbial communities, which may coexist with the more well-known communication strategies based on molecular diffusion, while benefiting from a much shorter communication delay. This paper develops a stochastic model that links the electron transfer mechanism to the energetic state of the cell. The model is also extensible to larger communities, by allowing for electron exchange between neighboring cells. Moreover, the parameters of the stochastic model are fit to experimental data available in the literature, and are shown to provide a good fit.

cs.ET↗