Silver nanoparticles are potent antimicrobials but they are expensive to manufacture and require toxic solvents to produce. A team of researchers from Khalifa University has found a new way to produce silver nanoparticles using biochemistry and magnetic fields.��

Metal and metal oxide nanoparticles are useful in a wide variety of commercial applications and consumer products, with manufacturers taking advantage of their unique electrical, optical and catalytic properties. Silver nanoparticles are one such example, as due to their potent antimicrobial activity, they are often incorporated into soaps, wound-dressings, creams and biomedical devices, such as catheters and valves, which are especially susceptible to bacterial growth.

They published their findings in Scientific Reports earlier this month.

The team included Prof. David Sheehan, Professor of Biochemistry and Dean of the College of Arts and Sciences, Dr. Siobhan O’Sullivan, Assistant Professor of Molecular Biology and Genetics, both from Khalifa University, and  Ameni Kthiri , Dr. Selma Hamimed, Abdelhak Othmani, and Ahmed Landoulsi, from Carthage University, Tunisia.

“The aim of our work is to reduce the use of potentially harmful reagents in the manufacturing of silver nanoparticles in order to mitigate any health or environmental risks,” Prof. Sheehan explained.

“Green chemistry uses environmentally sustainable routes to design, and manufacture chemical products, and one popular approach to green metal nanoparticle synthesis is to use biological systems. Various bacteria, fungi, plants and biological waste products can catalyze the reactions that reduce metals and lead to useful nanostructures.”

Reduction is a chemical reaction in which an atom gains electrons from a reducing agent. Reducing agents can be natural or synthetic, with green synthesis methods sometimes involving plant-based extracts or microorganisms to eliminate the need for hazardous chemicals. Green synthesis has the added benefit of being cost-effective and efficient, as well as helping to stabilize the resulting nanoparticles. The methods used also offer the ability to fine-tune nanoparticle size by controlling the amount and type of reducing agent used.

Some cells contain or secrete enzymes that are biochemical routes to metal reduction, but the exact way they work is poorly understood.

Additionally, the antimicrobial properties of the resulting silver nanoparticles depend on their average diameter – the smaller the nanoparticle, the more effective against bacteria. When silver nanoparticles were developed using baker’s yeast, Saccharomyces cerevisiae, they ranged between 11 and 25 nanometers.

Prof. Sheehan and his research team introduced a static magnetic field to the biosynthesis in their new approach. The nanoparticles from this method were significantly smaller than those typically produced biosynthetically, ranging from  2 to 12 nanometers in size. Plus, the nanoparticles obtained using the magnetic field were highly crystalline, stable and near-uniform in shape. Most importantly, the antibacterial activity was greater than that seen in the control cultures.

When a static magnetic field (SMF) is applied to this synthesis method, the nanoparticles produced are significantly smaller.

Magnetic fields are force fields created by a magnet, or as a consequence of the flow of electricity. A static magnetic field is one which does not vary with time, characterized by steady direction, flow rate and strength. They are constant and arise from a variety of sources including the Earth’s own magnetic field, direct current transmission lines, and domestic electrical devices, including microwaves and mobile phones.

The medical imaging technique, magnetic resonance imaging (MRI), uses strong magnetic fields to generate images of the organs in the body because they can “readily penetrate biological material and interact with charged species such as ions and proteins,” Prof. Sheehan said.

The researchers found that Saccharomyces cerevisiae, the baker’s yeast bacteria they used in their experiment to develop silver nanoparticles, experienced oxidative stress and a profound reduction in growth rate when exposed to a weak static magnetic field.

They found that the nanoparticles developed with a magnetic field were notably smaller and more bactericidal, or better at preventing the growth of bacteria.��

The research team hypothesized that the silver nanoparticles were formed by reduction of the silver nitrate due to the adsorption of silver ions on the surface of the S. cerevisiae metabolic products, such as enzymes and polysaccharides present. The nitrate collected into the pores of the metabolic products, leaving the silver nanoparticles free in solution.

The research team also suggested that the static magnetic field creates waves through the liquid where the reaction takes place, which enhances the decomposition of biomolecules through oxidative stress, releasing free radicals which then act as reducing agents.��

Additionally, the team believes this is the first method to use static magnetic fields to produce metal nanoparticles from biosynthesis. As nanoparticles could provide a viable alternative to conventional antibiotics, making silver nanoparticles in a cost-effective, efficient, and environmentally-friendly way could be vital to global public health and the fight against antibiotic resistance.

Jade Sterling
Science Writer
24 October 2021

The post Khalifa University Researchers Develop a New Environmentally-Friendly Way to Produce Nanoparticles that Fight Bacteria appeared first on Khalifa University.

Study Using Colloids and Mannequins to Assess Safety Levels in Hospitals and Effectiveness of Masks and Other PPEs

Read Arabic story here:

To hear an interview with Dr. Ammar Nayfeh on Abu Dhabi Radio, click and listen between 54:15 – 1:13:38.

Editor’s note: This story was updated on 24 November 2021.

Khalifa University of Science and Technology, in collaboration with Cleveland Clinic Abu Dhabi, announced that a team of researchers is developing a model to understand precisely how the COVID-19 virus travels through the air and how long it can stay airborne, in order to ensure safer hospital environment and lower transmission rates, while assessing the effectiveness of masks and other personal protective equipment (PPEs).

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Aerosol spread means that tiny droplets containing the SARS CoV-2 virus remain airborne for a long time and travel significantly farther than the six-foot separation recommended for social distancing. As some studies have suggested, the spread of COVID-19 by aerosols is both real and dangerous.

To create their model, the researchers spray a colloid made of silicon nanoparticles to simulate a patient’s cough and aerosol generation, making droplets of various sizes containing the nanoparticles. These nanoparticles glow red under UV light, allowing the researchers to see how the particles spread. The team will also be testing their model in a hospital environment with mannequins at Cleveland Clinic  Abu Dhabi.

Dr. Arif Sultan Al Hammadi, Executive Vice President, Khalifa University of Science and Technology, said: “Our researchers have been persistently engaged in scientific research that brings solutions through the use of advanced technology. The use of nanoparticles to ‘locate’ the SARS CoV-2 virus and find out how the airborne particles spread quickly is one model our research team is currently working on, as part of our efforts to contribute to mitigating the COVID-19 pandemic. We believe the outcome of this research will not only help identify how the airborne particles of the virus spread, but will also help ensure the care-providing environment such as hospitals and clinics are kept safer.”

Dr. Ahmad Rakad Nusair, MD, Cleveland Clinic Abu Dhabi, said: “Understanding the transmission of the virus is crucial in our fight against it. So far, the evidence for modes of transmission has been based on observations that have not been validated experimentally. As one would imagine, it would not be safe to experiment with the real virus, and hence, our decision to use nanoparticles to simulate the virus transmission in the healthcare environment. Globally, there are different recommendations to prevent the spread of the virus in the healthcare settings. While they all come from credible regulatory bodies, they are widely variant. The result of that is what we continue to see today, transmission of the virus in different healthcare settings and in different countries varies a great deal. There were hospitals in other countries that reported more than one third of their healthcare to have contracted the infection, while others reported minimal transmission. There are many factors that are responsible for the variation we see. The type of rooms that are used for patient care, the ventilation systems that are in place, the type of PPE that is being used. We are going to look into all those variables and understand each of those effects on the virus transmission. Our scientific experimental approach will enable us to give sound scientific recommendations for healthcare institutions to protect their staff against COVID-19.��

The research team, led by Dr. Ammar Nayfeh, Associate Professor, Electrical Engineering and Computer Science, comprises Dr. Ayman Rezk, Postdoctoral Fellow, Juveiriah Mohammed Ashraf, Research Engineer, and MSc students Wafa Sulaiman Alnaqbi and Aisha Al Hammadi. Their research has been published in the journal .��

The researchers will be using mannequins to simulate a breathing healthcare worker in a regular room and in a negative pressure isolation room. This is expected to improve the researchers’ understanding of the virus’ epidemiology, the effectiveness of masks and social distancing, and improve how we use our resources in hospitals.

Aerosols are tiny compared to droplets, which are larger in size and may be exhaled by people talking, coughing or sneezing. These droplets don’t travel far and quickly fall to the ground, but aerosols spread to far greater distances and can linger in the air for a longer time, making them more likely infecting others. What constitutes a safe distance from aerosols is much harder to define, especially in indoor spaces with poor ventilation.

At present, Cleveland Clinic Abu Dhabi is partnering with the research team to provide two patient care environments for testing. No patients are involved, and the team will use medical mannequins to simulate a breathing healthcare worker in a patient’s room.

In October 2021, a follow-up story to this research project was published in The National, which can be viewed .

Clarence Michael
English Editor Specialist

Jade Sterling
Science Writer

10 December 2020

The post Khalifa University and Cleveland Clinic Abu Dhabi Researchers Developing Model to Understand How Long and How Far COVID-19 Virus Remains Airborne appeared first on Khalifa University.

[vc_row][vc_column][vc_column_text]Mollusks Dosed with Amantadine Reveals Intracellular Trafficking Pathway

A paper published by Khalifa university faculty has enhanced understanding of nanoparticle toxicity, specifically which uptake pathway contributes most to the damaging effects of silver on a cellular level.
Nanoparticles are defined as materials that are between 1 and 100 nanometers. Metal and metal oxide nanoparticles (NPs) are used in many different kinds applications and products – like deodorants,
sunblock, electronics and even clothing, for their known and beneficial functions on macro scale. The Global Nanomaterials market was valued at USD7.3 billion in 2016 and is growing at a rate of 15%
annually, with a projected value of USD16.8 billion by 2022. However, how they behave on the nanoscale is not as well known, resulting in unplanned and unwanted impacts to plants and animals in
our environment.

“There is a growing body of literature to which I and my collaborators have contributed, that many nanoparticles cause oxidative stress because they stimulate production of reactive oxygen species. We
have found that this damages proteins in the cell by oxidizing them directly. It is unclear presently why some nanoparticles are very toxic while others are not,” said Dr. David Sheehan, Professor of Chemistry
and Dean of the College of Arts and Sciences.

Dr. Sheehan recently coauthored a paper titled “Redox proteomic insights into involvement of clathrin-mediated endocytosis in silver nanoparticle toxicity to Mytilus galloprovincialis” in the journal PLoS One
in collaboration with a research group at the University of Carthage in Tunisia.

Mollusks, as filter-feeders, are particularly sensitive to metallic micro-pollutants, as they extract and concentrate metals in their tissues. This makes them an ideal organism to study to research the impact
of nanoparticles.

“Bivalves like mollusks can be seen as a type of lab rat to assess aspects of nanoparticle toxicology, which is also relevant to human health. The idea was to selectively block uptake of the silver
nanoparticles by inhibiting each of the two main uptake mechanisms. In this way we could assess which was contributing most to protecting against toxicity,” explained Dr. David Sheehan, Professor of
Chemistry and Dean of the College of Arts and Sciences.

The silver nanoparticle is mainly absorbed by the mollusk through clathrin-mediated endocytosis – which is a cellular process where a eukaryotic cell absorbs proteins and fats through its membranes. In
their experiment, the team selectively blocked the clathrin-mediated uptake pathway with an inhibitor, the Parkinson’s Disease drug amantadine. Clathrin is a protein that plays a major role in the formation of
the large coated large structures within a cell that are made up of a liquid enclosed by a lipid bilayer, known as vesicles.

“This resulted in reduced toxicity of the silver nanoparticles, thus showing that this uptake pathway facilitates NP toxicity. Our study really just wanted to ask the question, which uptake pathway
contributes most to NP toxicity and was not primarily intended to point to prevention of NP toxicity,” Dr. Sheehan added.

He explained that this points future research to exploring the fate of clathrin-coated pits within the cell in assessing the role of intracellular trafficking in nanoparticle toxicity.

“We would like to generalize this study to see if other nanoparticles are taken up in the same way. In particular, I want to study iron NPs because iron is a toxic chemical that triggers production of “reactive
oxygen species” but also, iron is magnetic. In preliminary work with cultured human cells, I have found the cells become magnetized once iron NPs are taken up. This would, in principle, mean that we could
select subcellular organelles as the NPS are trafficked through the cell towards lysosomes and build up a picture of the trafficking process and how it contributes to toxicity,” Dr. Sheehan concluded.

Zarina Khan
Senior Editor
24 December 2018[/vc_column_text][/vc_column][/vc_row]

The post Cellular Uptake of Silver Nanoparticles Explored appeared first on Khalifa University.